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Thread: Exhaust manifold crack again

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    VCVC Member lvjjj's Avatar
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    Exhaust manifold crack again

    Help, don't know what to do. Every time we tow our trailer with the '94 Suburban something breaks, this time, for the second time, new exhaust manifold cracked. I had had them replaced a few months ago cause the originals were leaking where the bolt heads broke off. When one of the new ones cracked shortly thereafter,I had it replaced under warranty, but just broke again. So I wonder if the mechanic used cheap Chinese parts? But, I can't even find a new Genuine GM part passenger side manifold (350 with A/C).

    We're almost home from a 4,000 mile trip from NW Washington to Prescott AZ on old blue highways including Route 66. The engine still sucks but its doing a lot better than the last time we took a long trip, with the dual exhaust, dual air intake, adjustable timing control, fastchip and AC Delco tuneup parts. Lots of mountain passes, so got around 7 mpg average, pulling lots of hills and passes in 2nd gear at 55 mph. Got that 350 screaming all day long. Luckily when the manifold heats up it quiets down.

    So, I'm thinking shorty headers instead. Any problems I'm going to run into there?

    (God I miss that 292, it never gave me a single problem). Just wish it would tow a 6,000 lb trailer and power a 6,000 lb suburban.
    LARRY OF THE PACIFIC NW
    1965, 292, TH350
    purchased Nov. 22, 1970

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    VCVC Charter Member Vanner68's Avatar
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    I have an 89 K2500 with the 350, just did head gaskets over the winter and replaced the exhaust crossover pipe. This is a 100% original truck, and I was amazed how thin the castings are on the manifolds. They are prone to cracking, especially under stress. Short of trying to find earlier manifolds that are thicker, and having a new y pipe made to match, headers may be the next best option. DO NOT wrap them, they will rust out in a few years. Also, watch out for the oil filter adapter on the driver side, it's pretty tight in that area.
    Gregg Groff


    There's no place like 127.0.0.1

    1968 Chevy G20 108 panel Now with 454 power!

    1965 Chevy G10 panel- OHC Pontiac inline 6

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    VCVC Member kookykrispy's Avatar
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    just replaced a cracked exhaust manifold on my '99 silverado after heavy towing during our move down the west coast. Cracked manifolds suck, but it happens. You might consider headers, which would give you a little torque increase, and if you eventually swap to vortec heads, the headers will fit



    64' wikivan 230/4 onda tree/2.56 posi
    '64 Red Baron no engine/trans
    '66 "Lucky" 230/3 onda tree/project

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    Remember, they're still printing money, but they aren't making any more earlies!

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    VCVC Member lvjjj's Avatar
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    I was thinking headers but the ones for $250 at Rock Auto, etc., are probably real cheap and won't seal well. How expensive would I need to go to get good ones? I'd want shorty headers that connect to the stock exhaust pipes with donuts.

    Also, even though the engine did a lot better this time because of the exterior improvements I made, it was frustrating to have to pull it down to 2nd a lot to go up hills, I'd run around 4,000 rpm between 55 & 60 mph. It was screaming but didn't seem to care too much.
    Part of the problem is that its a 1300 lbs over the GVRW rating of the Burb. Its a K1500 and I think the GVRW is 10,000 lbs. We weighed the combo on the way home to day and the rig weighs 11,300 lbs. It's very stable, stops great and runs smooth, its just the lack of power that bothers me.

    Got a friend mechanic/car restorer who suggested I get a 383 stroker that would be built in Spokane to my specs and he thought he could get it installed for less than $5000, total. Real tempted to sell the van in order to get some money to do that. I've heard the 383 is quite powerful and would do a lot better towing than my current 350 cause of its longer stroke.

    As for selling the van, I'm thinking about it cause my HOA rules won't let me keep the van on my lot, I keep having to move it around to different storage units, and its just sitting there deteriorating and I hate to see that. And at 73, I may not have a lot of RV'ing years left so I need to do something.
    Last edited by lvjjj; 05-24-2019 at 04:22 PM.
    LARRY OF THE PACIFIC NW
    1965, 292, TH350
    purchased Nov. 22, 1970

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    VCVC Member kookykrispy's Avatar
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    you don't need a 383. You have a perfectly good running 350, which is a quite capable power plant, just needs some improving. Its just that your 94's stock swirl port heads and stock "peanut" cam basically suck big time. Swap to vortecs and then have delta camshaft in Tacoma custom re-grind your existing camshaft to give your cam a new custom profile to take advantage of the heads. Combine the cam and heads upgrade with headers, and a re-flashed computer and you will see great gains... and it won't cost anywhere near $5k

    The 3/4 length "shorty" headers should be fine. Here's some chrome ones for $97 shipped. https://www.ebay.com/itm/Exhaust-Hea...EAAOSwuG1c0XIX

    They will seal fine if you use my trick for headers. Put ultra copper hi-temp RTV on both sides of the gasket. Let it set up several minutes before assembling, so the RTV gets tacky and develops a "skin" on it. Then assemble. Letting it set up before assembling, the RTV does not squeeze out when you bolt it down, and makes a nice seal that doesn't leak.
    Last edited by kookykrispy; 05-24-2019 at 07:22 PM.



    64' wikivan 230/4 onda tree/2.56 posi
    '64 Red Baron no engine/trans
    '66 "Lucky" 230/3 onda tree/project

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    Remember, they're still printing money, but they aren't making any more earlies!

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    VCVC Member joyrde's Avatar
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    First if you are towing in second gear at 55 mph that 350 is screaming, and way pass the max torque - - - - slow down. That mph is cooking exhaust valves, heads and exhaust manifolds

    If I were in your situation I would replace the manifold with another like unit.

    With stock cam, intake, etc the mid '90's engine had low HP & torque - - - IMHO - - the best fix is to change the Final drive gears going down at least one gear ratio - - - if you have 3.36 - - - then 3.55 if you have 3.55 then 3.73, and so on

    If you are getting 7 MPG - - - lower gears will not hurt, may actually improve mileage

    Second gear has a gear ratio of 1.62:1 use the following calculator to figure out what engine rpm is best for your rig
    https://spicerparts.com/calculators/...rpm-calculator


    If you are going to replace the manifolds, I would not go with headers - - - although not cheap - - - Sanderson headers would be the way to go. - - - if the will clear - - - if not - -- slow down - - - keep the engine near the peak torque curve . . . . Most likely the headpipes will need to be made ???
    https://www.summitracing.com/search/...Ascending&ar=1


    My best advice - - install lower Final Drive gears and slow down - - - operate the engine around 80% of peak torque RPM
    Last edited by joyrde; 05-29-2019 at 05:35 PM.

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    VCVC Member kookykrispy's Avatar
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    joyrde makes a really good point about gearing. For a tow rig, you want 3.73 or lower gears. 4.10's are even better. check your gearing



    64' wikivan 230/4 onda tree/2.56 posi
    '64 Red Baron no engine/trans
    '66 "Lucky" 230/3 onda tree/project

    Quote Originally Posted by Vanner68 View Post
    Remember, they're still printing money, but they aren't making any more earlies!

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    VCVC Member lvjjj's Avatar
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    I've got 3.73's. Truck has towing package which includes this lower gearing. Most of the time it does fine in 3rd. When the road has a slight rise it will seem to shift down a couple hundred rpm's, I guess that is the torque converter unlocking? One thing I noticed, that if I kept it at around 3,000 rpm in 3rd it had a lot easier time going up those 2% hills. I think I was going around 64 mph (my speedometer is off 3-4 mph, shows faster than I'm actually going). If I kept it at 60 mph at 2700 rpm or so, it would struggle some when the TC unlocked.

    When heading up the mountain passes at 6% grades, it will shift down to second at about 55 mph and I have to stay on the gas to get up the hill, it seems to like high rpm's. We go up the grade at 3900 to 4200 rpm.
    Last edited by lvjjj; 05-25-2019 at 12:02 PM.
    LARRY OF THE PACIFIC NW
    1965, 292, TH350
    purchased Nov. 22, 1970

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    VCVC Member kookykrispy's Avatar
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    3.73's are ok. If your primary use of this suburban is towing, you might consider 4.10's.



    64' wikivan 230/4 onda tree/2.56 posi
    '64 Red Baron no engine/trans
    '66 "Lucky" 230/3 onda tree/project

    Quote Originally Posted by Vanner68 View Post
    Remember, they're still printing money, but they aren't making any more earlies!

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    VCVC Member lvjjj's Avatar
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    So this morning, I'm ready to take the Burb 40 miles up in the hills to Loren the mechanic to replace the cracked exhaust manifold. Check under the hood first and see that the other one cracked too. Cancel the appointment cause I can't afford the $100 an hour he's going to charge me to replace both. Plus he'll have to order another one. The manifolds themselves are still under warranty (lifetime), but labor only warranted for 6 months, its been a year.

    Loren agreed with you guys that said I shouldn't be running 4,000 rpm in second towing up hills and that's what causes them to crack. So, I'm going to do the work myself cause we spent all our money on gas on the trip. So, that means we'll be crawling up passes at 3,000 rpm which sucks here in the mountain west. Now thinking headers again cause don't think they will crack????, plus give me a little more power maybe.

    Obviously need a better motor, or smaller trailer.
    LARRY OF THE PACIFIC NW
    1965, 292, TH350
    purchased Nov. 22, 1970

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    VCVC Member jrinaman's Avatar
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    x2 on what k.k. said!!! swap the heads, upgrade cam and reprogram the computer. ignore the peak h.p. ratings and select a cam for towing, low end torque and power off idle. headers will help but not much, since yours are cracked already, just buy the headers.
    '64 chevy, 292 40 over, 206/526 cam, 2004r trans. 9.75:1, dual webbers, Langdon cast headers, 1.94 valves

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    VCVC Charter Member Vanner68's Avatar
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    Quote Originally Posted by lvjjj View Post
    So this morning, I'm ready to take the Burb 40 miles up in the hills to Loren the mechanic to replace the cracked exhaust manifold. Check under the hood first and see that the other one cracked too. Cancel the appointment cause I can't afford the $100 an hour he's going to charge me to replace both. Plus he'll have to order another one. The manifolds themselves are still under warranty (lifetime), but labor only warranted for 6 months, its been a year.

    Loren agreed with you guys that said I shouldn't be running 4,000 rpm in second towing up hills and that's what causes them to crack. So, I'm going to do the work myself cause we spent all our money on gas on the trip. So, that means we'll be crawling up passes at 3,000 rpm which sucks here in the mountain west. Now thinking headers again cause don't think they will crack????, plus give me a little more power maybe.

    Obviously need a better motor, or smaller trailer.
    The 350 should be able to tow, but you have been used to a six cylinder that has a bore and stroke closer to a 400 cubic inch engine, and a manual trans (IIRC)

    I had a couple F150's with the 300 inch six and 5 speed manual. Both would tow like crazy, but overdrive was useless. My 89 K2500 has a 350, TH400 and 3.73 gears. While it can do 80mph, it's screaming to do so. It likes 60mph best. Even so, the big sixes just seemed to have more guts "seat of the pants".

    If you are cracking exhaust manifolds, you are working that engine hard. I bet they are cherry red when you are pulling uphill.

    Here's the bottom line- comparing your van and the Suburban is apples and oranges. The Suburban easily weighs 1 1/2 times what the van weighs, and you stated you are over the limit of the recommended towing capacity.

    Most manufacturers were going to diesel for the heavy duty towing rigs, so gas engine vehicles weren't really built for it. You have pretty much identified your problem though, you need more motor or less trailer.
    Gregg Groff


    There's no place like 127.0.0.1

    1968 Chevy G20 108 panel Now with 454 power!

    1965 Chevy G10 panel- OHC Pontiac inline 6

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    VCVC Member Wookee's Avatar
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    Cool

    Click image for larger version. 

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    Sorry Larry it is ether creature comforts or built to tow horse power.
    You said in the past you built your 292 to tow your travel trailer.
    how ever the wife wanted A/C and a few other things.
    Changing the upper end of the Suburban's SBC with a Vortec top end might answer your issues.
    Be warned after paying a shop to do this you still might still not be happy with the Suburbans performance....
    I know we have foot hills they call mountains out here on the east coast.
    Slow and steady wins the race.

    Around here down and out the back exhaust manifolds are pretty common in the salvage yards.
    The General ran these exhaust manifolds on all of his trucks and vans from the mid 70's till the Vortec engines came out.
    Find a pair and have the guys cut the exhaust down pipes to get them off.
    take them home and work the long studs over with a good penetrating oil & replace them with the same length stainless steel studs and lock nuts..
    Or trade your small block Suburban in for a big block Suburban.

    .......Wookee
    Last edited by Wookee; 06-14-2019 at 08:23 AM.
    Its a "van thing". A life style you have to live to understand!!!!

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    VCVC Member joyrde's Avatar
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    agree with all that Wookee shared

    My '67 108' , back in the day it had a "stock" 350 out of "something" running the stock center dump 283 exhaust manifolds, The trans was a 350THM Trans and 3.36 gears, running 30" tall rear tires (L60X15").

    It towed our 25 foot tandem axle just fine - - -ran about 190 highway (60-65)- - - 210 around town

    The Van had a & still has a stock bellypan (dropped 3" in the front) a re-cored stock radiator (4 core), factory fan shroud, 5-blade clutch fan.

    We travelled all over the East Coast - - up mountains & down

    The Van now has a '97 350 Vortec, changed to a carb with a towing camshaft - - 700R trans and a 3.73 12 bolt rear, still running 30" tall tires (275-60X15). Dual A/C, front & rear disc brakes, and power steering. With the power steering an A/C, I guarantee you it would tow that camper trailer, even better now than then

    As Wookie said, get either rear dump, or center dump exhaust manifolds - - 2 1/2" outlets would be best, but stock will do and slow down - - 60-65 tops IF YOU HAVE at minimum a front sway bar and good steering/spring components.

    I would also, as I mentioned before dropping one rear gear ratio - - - my 3.73's combined with the 30" tires and the OD trans works great.

    Slow down, When pulling hills gear down, keep engine rpms below 3000 rpms - - - if the Van slows down pulling hills, just gear down and put the 4-ways on

    Good Luck
    Last edited by joyrde; 05-30-2019 at 03:43 PM.

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    VCVC Member lvjjj's Avatar
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    joyrde you reminded me of something maybe weird about the Burb when you mentioned that your 350 ran at 190. That's what mine does, runs real cool all the time even in 2nd gear at 4,000 rpm, never got over 200 and was usually cooler than that. The radiator on the 94 is HUGE, and has oil and trans cooler running thru it (also has stock external trans cooler).

    So I spent most of the day Saturday putting on the two new manifolds (one made in China the other in Vietnam). The mechanic (Loren) who first replaced the manifolds a year ago was an instructer for GM trucks a few years ago and really knows GM trucks. He said that these 350's had no gaskets between the exhaust manifolds and head to aid in cooling. Don't get it but when he fixed them they didn't leak at all. But when I fired it up Saturday, had many small leaks, so guess I didn't get the mating surfaces cleaned up enough. Used a Dremel too with small wire wheel. Wasn't much on them anyway as no gaskets or gasket sealer was used. He advised against using headers but didn't say why. Plus I screwed up the power steering pump bracket by cutting off the left hand prongs so I could get the bolt out. So its all screwed up so myswell try headers.

    I think I'm going to ignore all the well intentioned advice (even though I appreciate getting it) and order some Pace Setter Headers from Summit for $213 and give them a try, reviews were pretty good. I don't want to spend a lot of money for this experiment, don't care if they corrode and rust (no ceramic coating, the Clifford headers on the van and Thorley headers on my '88 454 had no coating and they are still going great) I figure that even if I get Loren to remount the manifolds to get rid of the leaks, I still can't use the Suburban like I want to so its worth it to me to try the headers and hope they will give me a little more power and can pull hills farther in 3rd and maybe run a little more than 3,000 rpm in 2nd. Probably going to sell the Burb anyway unless it does pretty good with headers. It will cost me a lot less to buy and install headers than have Loren re-mount the manifolds to stop them from leaking. I remember that when I installed the headers on the van and '88, the improvement was immense, particularly the early. The condition of the exterior and interior is so good and pristine they will probably overshadow the weak engine and maybe headers will impress somebody to buy it that don't know much like me.
    LARRY OF THE PACIFIC NW
    1965, 292, TH350
    purchased Nov. 22, 1970

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    VCVC Member joyrde's Avatar
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    Quote Originally Posted by lvjjj View Post
    The mechanic (Loren) who first replaced the manifolds a year ago was an instructer for GM trucks a few years ago and really knows GM trucks. He said that these 350's had no gaskets between the exhaust manifolds and head to aid in cooling.
    FYI - - I am an ASE Master Certified Tech and taught Auto tech for 30 years - - - small block Chevys have exhaust gaskets - - from the factory - - depends on the year . . used ALL of them the surfaces warp and pit.

    In the kindest possible terms, do what you wish - - - just think of the tens of thousands of small blocks that do not crack their manifolds - - again, IMHO, you need to slow down, run at a lower RPM, and possible lower the rear gear ratio.

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    VCVC Member lvjjj's Avatar
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    Yeah, I was really surprised to hear that about the gaskets, or not. Btw- have always appreciated your expert help. My engine definitely did not have exhaust manifold gaskets from the factory. If fact, it still doesn't. Loren replaced them 1 and one half times and I just replaced the cracked manifolds myself (scary) without gaskets and there are no leaks. Well there was cause the donuts that came with the manifolds weren't correct, so they leaked at first, but got the right ones and now working like new.
    LARRY OF THE PACIFIC NW
    1965, 292, TH350
    purchased Nov. 22, 1970

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    VCVC Member lvjjj's Avatar
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    So, the Pace Setter headers came and took one look and sent them back. The middle flange area was an eight of an inch higher than the two end ones when I put a straight edge across it. So there was no way they would seal. Get what you pay for, luckily Summit is taking them back.

    Now we're looking for a better tow vehicle or a smaller trailer. Found a Tahoe with a 6.2 liter engine, never heard of that, what is it? Sounds like it might be powerful. I had a 6.0 for a while and it was great. Also located a Yukon Denali XL with an 8.1, but its pretty beat up, temping though.

    My engine education stopped in 1988.
    LARRY OF THE PACIFIC NW
    1965, 292, TH350
    purchased Nov. 22, 1970

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    VCVC Charter Member Vanner68's Avatar
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    Have you considered going diesel?
    Gregg Groff


    There's no place like 127.0.0.1

    1968 Chevy G20 108 panel Now with 454 power!

    1965 Chevy G10 panel- OHC Pontiac inline 6

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    VCVC Member kookykrispy's Avatar
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    Quote Originally Posted by Vanner68 View Post
    Have you considered going diesel?
    If the primary purpose of this vehicle is towing, I sure would look at diesels. In my opinion, the ultimate tow rig SUV is the 99-02 Ford Excursion with the 7.3L Powerstroke Diesel. Even the '03 and later 6.0L was a good engine too, but the 7.3L is the legend
    Last edited by kookykrispy; 06-14-2019 at 08:14 AM.



    64' wikivan 230/4 onda tree/2.56 posi
    '64 Red Baron no engine/trans
    '66 "Lucky" 230/3 onda tree/project

    Quote Originally Posted by Vanner68 View Post
    Remember, they're still printing money, but they aren't making any more earlies!

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    VCVC Member lvjjj's Avatar
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    update

    After looking a many '04-'08 Yukon Denali's, XL (and Tahoe style), and finding that they are usually quite worn and not nearly as nice as our '94 Suburban, I've decided to have the engine replaced with a 383 Stroker. I've spoken to S&J engines in Spokane and they can build me one with roller cam for $2300. A local car restorer/mechanic will install it for me for $1250. Just can't pass this up. They claim 350 horsepower and have a 7 year, 100,000 mile warranty. We've replaced many parts on the '94 and know that it's clean, straight and in great shape, I figured I have to replace the same parts on anything else I bought, so keeping the Burb is the best thing right now. I really like the way it rides and runs, so comfortable, just need some power.. Also, with only 158,000 on the odometer, its less than most of the Yukon's we looked at. The swap is scheduled for September after our planned summer trips, just have to go slower for a while.
    LARRY OF THE PACIFIC NW
    1965, 292, TH350
    purchased Nov. 22, 1970

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    VCVC Member kookykrispy's Avatar
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    Pay attention to the heads. Cylinder heads and camshaft is what is responsible for making power (or not) in any engine. Request vortecs or some other upgrade, such as aftermarket heads. Your stock '94 swirl ports are some of the worst heads for performance, coupled with the stock peanut cam, that's basically why your 350 sucks and other people have a 350 capable of 10 second quarter miles. '96-99 Vortecs were pretty much the best gen 1 factory heads available.

    You are spending a whole lot of money to get 33 additional cubic inches, but without carefully paying attention to heads and cam, you may be in for a disappointment. You've got a strong 350 that could be modified to really perform.

    Another comment is if you're spending the money for a 383, why not buy a 400 SBC?? for the same price (or possibly even less money), you get extra cubic inches. Both engines are small block chevies and use all the same external parts. The 400 will just make more power and torque all the time. I never understand this. I think its from good marketing so people can brag they have a "stroker", even though my 400 small block is bigger and makes more power, and cost less because it uses stock parts and doesn't need trick "stroker" stuff. Just checked S&J website, a 400 small block is $1430 + 300 core

    Spend the extra $$ on good heads and get a cam ground from Delta Cam in Tacoma. The 400 SBC was made to tow
    Last edited by kookykrispy; 07-29-2019 at 09:48 PM.



    64' wikivan 230/4 onda tree/2.56 posi
    '64 Red Baron no engine/trans
    '66 "Lucky" 230/3 onda tree/project

    Quote Originally Posted by Vanner68 View Post
    Remember, they're still printing money, but they aren't making any more earlies!

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    VCVC Member panelmanrd's Avatar
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    the thing about the 400 sb is that it likes to run hotter, i used to have 3 different ones in 3 different cars. all
    ran hotter than the 350. to me not worth the extra hassle.
    54 chevy panel truck 355 tpi 700r4 325/9in
    64 chevy 90 5.7 tpi 700r4 336 8.2
    69 chevy panel van 5.7 tbi 700r4 336 8.2

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    VCVC Member kookykrispy's Avatar
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    Quote Originally Posted by panelmanrd View Post
    the thing about the 400 sb is that it likes to run hotter, i used to have 3 different ones in 3 different cars. all
    ran hotter than the 350. to me not worth the extra hassle.
    The 400 SBC does not inherently run hot. There are a couple tricks that need to be done, like drilling steam holes in the heads, but any engine will run hot if you have any number of problems with your cooling system. We see plenty of posts here from guys with engines running hot and they usually do not have a 400.

    Obviously, you need to have a capable cooling system for the 400, because its basically a big block in a small block package, and it makes alot of power and torque, so you need to make sure the cooling system is big enough, but Larry's suburban should be quite sufficient, especially if it has the towing package. Those full size trucks and suburbans usually had huge radiators

    I had a 400 SBC in my '65 van Hella Sunshine, and it did not run any hotter than the 305 it replaced. I had a good cooling system in that van: big aluminum radiator, big electric fan and high-flow water pump. It did not overheat and for awhile I had a supercharger on there too. I sold the van with the 400 to a vanner down in FL and never heard any report of running hot. Also, my father had a built 400 from racing head service in his 2wd '76 blazer, and never ran hot. That rig was fast too

    I currently have two 400's. One I just completed with Edelbrock heads that will go into the Lucky '66. The other is stock, and waiting for build. That one will probably end up in the Red Baron
    Last edited by kookykrispy; 07-30-2019 at 09:18 AM.



    64' wikivan 230/4 onda tree/2.56 posi
    '64 Red Baron no engine/trans
    '66 "Lucky" 230/3 onda tree/project

    Quote Originally Posted by Vanner68 View Post
    Remember, they're still printing money, but they aren't making any more earlies!

  25. #25
    VCVC Member jrinaman's Avatar
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    with a $900 dollar savings to get a bigger motor, i would get the 400 and upgrade the rad (if even needed). more cubes for towing. ignore peak hp and focus on usable rpm's. rv type cam with shorter duration. you will never miss 50 hp at 6500 but gaining 50 at cruising rpm's is huge.
    '64 chevy, 292 40 over, 206/526 cam, 2004r trans. 9.75:1, dual webbers, Langdon cast headers, 1.94 valves

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    VCVC Member joyrde's Avatar
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    the key - - - slow down - - - torque is what pulls the load, if you are running close to 4000 rpm's the engine is way past the tirque curve - - - as KK mentioned install 4.10 gears - - - keep the rpms between 3,000 - 3,500

    I believe someone mentioned a head and cam upgrade - - - I would get a hold of cam company, give them all your 'burb info, ask them what came to use with stock heads - - -

    are you running dual exhausts? If not, do so - - - even if you need to install a catalytic converter in each pipe

    slow down, keep rpms down

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    VCVC Member kookykrispy's Avatar
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    64' wikivan 230/4 onda tree/2.56 posi
    '64 Red Baron no engine/trans
    '66 "Lucky" 230/3 onda tree/project

    Quote Originally Posted by Vanner68 View Post
    Remember, they're still printing money, but they aren't making any more earlies!

  28. #28
    VCVC Member jrinaman's Avatar
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    Click image for larger version. 

Name:	compare1.jpg 
Views:	29 
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ID:	40049 here is a comparison of 2 different engines (not chevy) that shows how peak hp is misleading. the infinity has more hp but the bmw has much more all the way to 6k+. at 2k, where we drive, it is nearly double! the 'weaker' motor clearly wins in torque. peak horsepower gives you bragging rights while sitting on the bar stool, torque gets you off the line or up the mountain. I can not stress enough to ignore peak figures and focus on power where you need it. bone stock '70's 400 cid only made 265 hp but that was at 2400 rpm's! that 375 horse 383 may not reach 265 until well above 2400. regardless which engine you pick, get a cam with a range from idle to 4500 and a flat torque curve.
    '64 chevy, 292 40 over, 206/526 cam, 2004r trans. 9.75:1, dual webbers, Langdon cast headers, 1.94 valves

  29. #29
    Certifiable Vanatic Leroy Jackson's Avatar
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    A Chevy 1500 max gvw is around 7000 lbs. Towing capacity is just shy of 10,000.

    11,000lbs is a bit much. It also puts you into CDL territory if you drive across multiple states. Interstate travel of a vehicle with a combined gross vehicle weight of 10,001 lbs requires a class c CDL.

    A 1500 series in stock trim isn't designed to haul that much weight. 1500 series is in reality a 1/2 ton truck. 2500 series is a 3/4 ton truck and better suited. But 11,000 lbs is 1 ton territory.

    Things will break if you grossly overload a vehicle. Not to mention it is also a road hazard and other people's lives are put at risk when the brakes get over loaded or the chassis fails.
    The Raped Ape
    1970 G-20 Krylon black
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    VCVC Member joyrde's Avatar
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    My '67 long wheel base Van has a stock '97 Vortec Engine, except for the cam and springs, replaced the FI with a 600 Edelbrock Carb - - - 3.73 gears, 700R

    This set-up will easily tow the trailer you described - - - Given the weight of the trailer and the weight of my Van, I would not tow anything over 4500 lbs total



    Cam specs - http://www.compperformancegroupstore...Code=RLERCAMXE

    http://www.compcams.com/Company/CC/c...?csid=185&sb=2

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    VCVC Member kookykrispy's Avatar
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    Thumbs up

    hard to beat a 350 with vortec heads and a properly matched cam



    64' wikivan 230/4 onda tree/2.56 posi
    '64 Red Baron no engine/trans
    '66 "Lucky" 230/3 onda tree/project

    Quote Originally Posted by Vanner68 View Post
    Remember, they're still printing money, but they aren't making any more earlies!

  32. #32
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    Chassis Dyno

    Quote Originally Posted by jrinaman View Post
    Click image for larger version. 

Name:	compare1.jpg 
Views:	29 
Size:	59.6 KB 
ID:	40049 here is a comparison of 2 different engines (not chevy) that shows how peak hp is misleading. the infinity has more hp but the bmw has much more all the way to 6k+. at 2k, where we drive, it is nearly double! the 'weaker' motor clearly wins in torque. peak horsepower gives you bragging rights while sitting on the bar stool, torque gets you off the line or up the mountain. I can not stress enough to ignore peak figures and focus on power where you need it. bone stock '70's 400 cid only made 265 hp but that was at 2400 rpm's! that 375 horse 383 may not reach 265 until well above 2400. regardless which engine you pick, get a cam with a range from idle to 4500 and a flat torque curve.
    These torque curves look unusual to me. They should be much smoother if they are engine dyno runs. If they are chassis dyno runs then perhaps they are composite runs based on the engine speed. When making a power map dyno run, we would typically run the engine to near top RPM with no load and then slowly apply the load, stopping when we got close to idle. Gas engines would be loaded more quickly as they are more likely to overheat. A minimum of three runs are done for repeatability, but then most of my dyno experience is on large Diesel trucks not gasoline vehicles.
    JRinaman makes a good point with the torque curve comparison and usable power band. IMHO, a good cruising speed is just above peak torque RPM. That way, your engine lugs down to peak torque requiring fewer gear changes. That is if your goal is a highway cruiser. JM2C
    108VanGuy...
    1969 Chevy Panel, 250 CID, 3 Spd.with OD, 3.36 "WedgieVan" Daily Driver
    1967 Chevy Panel, 230 CID, 3 Spd. 3.36 "UtiliVan" 292 TFI coming. Owned since 76
    1964 GMC Panel, 194 CID, 3 Spd. "CrunchoVan"
    1965 GMC HandiBus Custom, 194 CID, 3 Spd. "MilkVan" Seized Engine
    1965 Chevy Panel 350 CID, 3 Spd. "RustoRoof" Runs but wiring bad
    1969 Chevy 108 Display 307 CID THM 350 Power Brakes 3.73 Posi
    1965 Chevy Panel, V8, 3 Spd. "Gold Hills Van" Best body of my 65s
    1965 CamperVan, V8, 3 Spd.

  33. #33
    VCVC Member jrinaman's Avatar
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    Quote Originally Posted by 108VanGuy View Post
    These torque curves look unusual to me. They should be much smoother if they are engine dyno runs.
    108VanGuy...
    didn't even look at that, it was the only one I found with 2 engines on one graph for simplified comparison. comp cams has several for their different small block chevy cams, much better info but not nearly as easy to make my point. joyrides cam is right about where he should be for more overall power without sacrificing low rpm power. even the 268 gives up a little where he needs it the most, I have always considered it a 'safe' cam for all around use but still too much for heavy loads up a mountain. back to kk's point, why not just swap the heads and cam? looking at these dyno charts, several good options for plenty of pulling power. http://www.compcams.com/Pages/401/dyno-sheets.aspx
    '64 chevy, 292 40 over, 206/526 cam, 2004r trans. 9.75:1, dual webbers, Langdon cast headers, 1.94 valves

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