369 Engine Any opinions?
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Team Owner
Joined: Feb 2005
Posts: 32,519
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From: central America
St. Jude Donor '08-'09
369 Engine Any opinions?
Hello.
this is my first time posting on this board, though I've been reading it for quite a while. I have to do a rebuild on my 72 L48 and after talking to my vette mechanic, he suggested building a 369, which uses 2.2L chrysler turbo rods for a mild stroke. He built one for autocrossing a decade ago, and had excellent luck in his class. Is this an engine that is worth building or am I wasting my time? thanks for any responses
trw
this is my first time posting on this board, though I've been reading it for quite a while. I have to do a rebuild on my 72 L48 and after talking to my vette mechanic, he suggested building a 369, which uses 2.2L chrysler turbo rods for a mild stroke. He built one for autocrossing a decade ago, and had excellent luck in his class. Is this an engine that is worth building or am I wasting my time? thanks for any responses
trw
Le Mans Master
Joined: Jul 2001
Posts: 9,622
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From: absecon nj
They use toyota rods in small blocks in a oval track class up north here.They use all kind of combo's these days.
"
The wheel has already been invented and this does not sound like any improvement"
Then i guess nothing should be changed then.We would still be driving model t's.
"
The wheel has already been invented and this does not sound like any improvement"
Then i guess nothing should be changed then.We would still be driving model t's.
Race Director
Joined: Mar 2001
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From: Living in the Hartland
Originally Posted by 72 stingray owner
Hello.
this is my first time posting on this board, though I've been reading it for quite a while. I have to do a rebuild on my 72 L48 and after talking to my vette mechanic, he suggested building a 369, which uses 2.2L chrysler turbo rods for a mild stroke. He built one for autocrossing a decade ago, and had excellent luck in his class. Is this an engine that is worth building or am I wasting my time? thanks for any responses
trw
this is my first time posting on this board, though I've been reading it for quite a while. I have to do a rebuild on my 72 L48 and after talking to my vette mechanic, he suggested building a 369, which uses 2.2L chrysler turbo rods for a mild stroke. He built one for autocrossing a decade ago, and had excellent luck in his class. Is this an engine that is worth building or am I wasting my time? thanks for any responses
trw
Tech Contributor
Joined: Aug 1999
Posts: 14,377
Likes: 6,376
From: At my Bar drinking and wrenching in Lafayette Colorado
Changing the length of the rods will not change the stroke or the cubic inch displacement of the engine. Stroke is determined by the crank. You can change the length of the rods and make up for the length change by having custom pistons made, thus changing the rod/stroke ratio, but this will not give you a 369 engine. A stock 350 Chevy engine has a 4" bore and a 3.48" stroke. You have to change the stroke - not the length of the rod - to get a 369. For example, you can take a 350 block, bore it .030" oversized, and then install a 400 crank in it to get a 3.75" stroke. This will produce a 383 engine.
You can get a 369 engine by using the Chrysler rods as follows: You can bore the 350 .030 oversized to get a 4.030" bore. Then, since the 2.2 rods have a smaller large end journal, you can offset-grind a 350 crank to produce a 3.61" stroke. A 4.03 bore with a 3.61 stroke will get you a 369. You then top it of with a set of custom pistons. Easy!
Seriously... why would you ever want to go through such an excersise when you can simply buy complete rotating kits in any stroker size you want..?
You can get a 369 engine by using the Chrysler rods as follows: You can bore the 350 .030 oversized to get a 4.030" bore. Then, since the 2.2 rods have a smaller large end journal, you can offset-grind a 350 crank to produce a 3.61" stroke. A 4.03 bore with a 3.61 stroke will get you a 369. You then top it of with a set of custom pistons. Easy!
Seriously... why would you ever want to go through such an excersise when you can simply buy complete rotating kits in any stroker size you want..?
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From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Originally Posted by 72 stingray owner
Hello.
this is my first time posting on this board, though I've been reading it for quite a while. I have to do a rebuild on my 72 L48 and after talking to my vette mechanic, he suggested building a 369, which uses 2.2L chrysler turbo rods for a mild stroke. He built one for autocrossing a decade ago, and had excellent luck in his class. Is this an engine that is worth building or am I wasting my time? thanks for any responses
trw
this is my first time posting on this board, though I've been reading it for quite a while. I have to do a rebuild on my 72 L48 and after talking to my vette mechanic, he suggested building a 369, which uses 2.2L chrysler turbo rods for a mild stroke. He built one for autocrossing a decade ago, and had excellent luck in his class. Is this an engine that is worth building or am I wasting my time? thanks for any responses
trw
Radical rods require non standard pistons and crankshaft journal sizes. Money can get out of hand way to fast. You would be better off having your mechanic build you a 396 ci 3.875 stroker with a 4.030 bore.
Ask him about that combo and post back on the forum and tell us what he says
Last edited by gkull; Feb 16, 2005 at 12:06 PM.
Tech Contributor
Joined: Aug 1999
Posts: 14,377
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From: At my Bar drinking and wrenching in Lafayette Colorado
72 sting -
Seriously, don't over-complicate your rebuild. There are ways of wrapping up a ton of money in something, and there are ways of going fast at a reasonable cost. A well-built 350 will tear your head off without going to exotic and odd-ball strokes and rod ratios. You don't need to do this. Really.
Simply do a good bottom-end rebuild on the 350. Have the rods prepped right and install some good rod bolts. Install a good set of pistons - the lighter the better. Balance the rotating assembly. Spend your money on a good set of aftermarket heads that will get your compresion ratio up into the 9.5 range, slap a nice cam in it (in the 270 advertised range), get some headers, a good intake and a carb. This combination will produce an easy 350-370 horse at a very fair price, and will fry the rubber off your rear tires while putting you in a neckbrace.
Seriously, don't over-complicate your rebuild. There are ways of wrapping up a ton of money in something, and there are ways of going fast at a reasonable cost. A well-built 350 will tear your head off without going to exotic and odd-ball strokes and rod ratios. You don't need to do this. Really.
Simply do a good bottom-end rebuild on the 350. Have the rods prepped right and install some good rod bolts. Install a good set of pistons - the lighter the better. Balance the rotating assembly. Spend your money on a good set of aftermarket heads that will get your compresion ratio up into the 9.5 range, slap a nice cam in it (in the 270 advertised range), get some headers, a good intake and a carb. This combination will produce an easy 350-370 horse at a very fair price, and will fry the rubber off your rear tires while putting you in a neckbrace.
Thread Starter
Team Owner
Joined: Feb 2005
Posts: 32,519
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From: central America
St. Jude Donor '08-'09
Thanks for the advice lars.
Just out of curiosity, I've been trying to figure out my combustion chamber size on my heads. I'll admit I haven't run the numbers yet, but I suspect their fairly large. Do you recommend 64cc with 202 intake/1.6 exhaust valves? also i'd like to keep the 336 rear end with the 4 speed wide ratio tranny just for highway crusing (my local corvette club likes to take trips). What intake/exhaust runner will give me the best balance? Thanks for the help.
Just out of curiosity, I've been trying to figure out my combustion chamber size on my heads. I'll admit I haven't run the numbers yet, but I suspect their fairly large. Do you recommend 64cc with 202 intake/1.6 exhaust valves? also i'd like to keep the 336 rear end with the 4 speed wide ratio tranny just for highway crusing (my local corvette club likes to take trips). What intake/exhaust runner will give me the best balance? Thanks for the help.
Tech Contributor
Joined: Aug 1999
Posts: 14,377
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From: At my Bar drinking and wrenching in Lafayette Colorado
For a performance engine, you want to go with a combustion chamber no bigger than 64 cc. With flat top pistons (with about 10cc's of valve reliefs in them), a .040" deck height (pretty normal on a block that is not decked), a .038" head gasket thickness (normal thickness), a 64cc head will give you 8.96:1 compression ratio. You can bump that all the way up to 9.76 simply by decking the block down to a "0" deck, and the comp ratio will be higher if your valve reliefs are smaller than 10cc.
For a solid street performance engine, I run heads with about a 200cc maximum intake runner (small block). This is a good balance between too big and not enough flow: With a solid bottom end and a good cam, you want to be able to flow well up through 6500 rpm, and 200cc's do that without any loss of low end torque.
For a solid street performance engine, I run heads with about a 200cc maximum intake runner (small block). This is a good balance between too big and not enough flow: With a solid bottom end and a good cam, you want to be able to flow well up through 6500 rpm, and 200cc's do that without any loss of low end torque.
