[C2] 327/300 question
Team Owner
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From: Greenville, Indiana
If you need further clarification, go to GM Heritage center and look up the AMA specs
Do you have another question?
Last edited by MikeM; Jun 18, 2019 at 05:06 PM.
Thread Starter
Race Director
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C1 of Year Finalist (performance mods) 2019
On another note which is kind of the opposite of my original question, Chevrolet rated the h.p. differently on the exact same LT1 engine in 1970 for the Corvette and the Z28. Hence my original question as nothing would surprise me regarding what Chevrolet MIGHT do.
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Team Owner
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From: Greenville, Indiana
The AMA specs don't back that up. Well, not exactly. About the chrome rings vs. standard cast iron. It's a little vague there as well.
But neither would change the power output to any substantial degree..
But neither would change the power output to any substantial degree..
Drifting
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From: Hightstown NJ
Check your P&A book and look up all the parts. They share both applications. I know some of you want to believe that Corvettes are always somehow "special" in some way, but Flint assembled all the 300hp engine internals the same way.
Verne
Verne
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Army
I have no illusions about my 63 original 250hp "truck" motor - it is what it is and is a creampuff of a driver...
Like the 300hp if some hot-rodder put the mill in a non-Corvette "build" he would be bragging all over about the "Corvette engine"....
How many times have we heard that over the years ? And how much horsepower does that add ?
Like the 300hp if some hot-rodder put the mill in a non-Corvette "build" he would be bragging all over about the "Corvette engine"....
How many times have we heard that over the years ? And how much horsepower does that add ?
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From: Greenville, Indiana
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P.S. HI, Don - good to see you here again!
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https://www.caranddriver.com/reviews...d-test-review/
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Nope. The Saginaw Foundry didn't change the "recipe" for pouring iron for any specific application; every Corvette block casting number was also used in passenger cars and trucks. Nothing special or unique about any block used in a Corvette.
P.S. HI, Don - good to see you here again!
P.S. HI, Don - good to see you here again!
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From: Washington Michigan
Instructor
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From: SoCal
327/300s with manual transmissions in both pass. cars and Corvettes had 2.5" manifolds from '62 to '65, but the pass. cars had 2" pipes so the pipes had to be expanded to fit the manifolds. After '65 all had 2" manifolds, so the Corvette 2.5" pipes (manuals) had to be adapted to the 2" outlet, except PG that had 2" pipes.
For '66 the conn. rods were redesigned adding a little "hump" of material adjacent to the bolt seats that makes these rods more durable than the early rods that were prone to fatigue failure, especially on high revving mechanical lifter engines.
A new camshaft was released for '67. The base cam for all '57-66 engines (220, 230, 245, 250FI, 275FI HP/ 283s , 250 and 300 HP/327s) was replaced with this new cam that recognized that big port heads as machined by Flint are restrictive on the exhaust side, so a few more degrees exhaust duration via a slightly earlier opening exhaust valve is advantageous. This cam/pin assembly, 3896929 (Federal Mogul CS-74) has 194/202 degrees .050" lifter rise duration, 112 LSA and the IPOML is 108 deg. ATDC. The prior cam was a single lobe design 196 degrees .050" lifter rise with about the same LSA and indexing. Chevrolet did not increase rated power, and I don't know if a difference could be measured on a dyno. One advantage of the later cam is that it has milder lobe dynamics, so it's easier on the valve train. A new slightly higher rate valve spring was released for this cam (and ALL other small blocks) and I think it also used a new retainer that yielded slightly higher spring height. If you set up the valve springs for .090-.100" coil bind clearance the valve float speed is in the 67-6800 range, but a 327/300 engine will be wheezing at 5000 without head massaging.
Another change was the appearance of the abominable nylon cam sprocket in 1965. Prior to that the "wide" silent chain was used on pass. cars and Corvettes. I don't know if the 327/300 was available in any truck models, but if it was, the engine would have had the double row roller chain.
Duke
For '66 the conn. rods were redesigned adding a little "hump" of material adjacent to the bolt seats that makes these rods more durable than the early rods that were prone to fatigue failure, especially on high revving mechanical lifter engines.
A new camshaft was released for '67. The base cam for all '57-66 engines (220, 230, 245, 250FI, 275FI HP/ 283s , 250 and 300 HP/327s) was replaced with this new cam that recognized that big port heads as machined by Flint are restrictive on the exhaust side, so a few more degrees exhaust duration via a slightly earlier opening exhaust valve is advantageous. This cam/pin assembly, 3896929 (Federal Mogul CS-74) has 194/202 degrees .050" lifter rise duration, 112 LSA and the IPOML is 108 deg. ATDC. The prior cam was a single lobe design 196 degrees .050" lifter rise with about the same LSA and indexing. Chevrolet did not increase rated power, and I don't know if a difference could be measured on a dyno. One advantage of the later cam is that it has milder lobe dynamics, so it's easier on the valve train. A new slightly higher rate valve spring was released for this cam (and ALL other small blocks) and I think it also used a new retainer that yielded slightly higher spring height. If you set up the valve springs for .090-.100" coil bind clearance the valve float speed is in the 67-6800 range, but a 327/300 engine will be wheezing at 5000 without head massaging.
Another change was the appearance of the abominable nylon cam sprocket in 1965. Prior to that the "wide" silent chain was used on pass. cars and Corvettes. I don't know if the 327/300 was available in any truck models, but if it was, the engine would have had the double row roller chain.
Duke
1964 Corvettes with the 327/ 300 HP and Powerglide had 2.0" pipes and exhaust manifolds while 4-speeds had 2.5".
Last edited by Ornery; Jun 19, 2019 at 09:29 PM.
Drifting
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From: Hightstown NJ
Verne
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