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Author Topic:   Strange combination..
Pit Bull
Dirt Full Roller

Total posts: 65
posted December 14, 2001 11:18 AM
A buddy of mine just picked up a few chevy small blocks for almost no money, and in the bunch was a 307. I haven't heard much about these motors, but I noticed on further research that they have the same stroke as a 327. Now, here is my thought: What if I put a 307 crank in a 400 block? And then, use a set of 6 in. rods and stock 400 pistons? My thought is that the stroke is 1/2 inch shorter with the new crank, and the 6 inch rods are (almost) 1/2 an inch longer than the stock 5.557 inch rods. The combo would be off approx. .057 of an inch, but some "machine work" to the piston face could cure this. I know I will have to use spacers on the Mains like I would if I built a 377. Has this ever been done? Is this even worth the effort, or will this be a sweet combo? I think the cold weather is getting to me....racing season needs to get here quick before I go crazy....

[This message has been edited by Pit Bull (edited December 14, 2001).]

Racer14K
Dirt Freak

Total posts: 247
posted December 14, 2001 04:51 PM
Stock 400 piston is going to be to tall, its going to stick out of the top of the block about .180" thats almost 3/16" of an inch.
ROSS makes a piston for this stroke and rod combo, #95261 in a .030" only.

hughes
Dirt Maniac

Total posts: 141
posted December 14, 2001 06:07 PM
It will be a 358 cu.in. A 307 has the same stroke as a 327 but with a smaller bore. A 327 has a 4" bore and I believe the 307 has 3.85 don't quote that bore size. but it's a general ballpark

[This message has been edited by hughes (edited December 15, 2001).]

6pack
Dirt Maniac

Total posts: 128
posted December 14, 2001 08:04 PM
With a 4.125 bore and a 3.25 stroke, you would have about 347.5 CI.
You would have a 1/2 inch difference on the stroke, but it would be 1/4 on the "top" and 1/4 on the "bottom".

Homer62
Dirt Roller

Total posts: 10
posted December 14, 2001 08:40 PM
Pitbull, one combination that will fit using the 307 crank is a 6.00 rod on a piston for a 5.7-rodded 400. The compression height is 1.433", added to the six inch rod and 1/2 the stroke-1.625"= 9.058". That puts the piston above the deck, so a thick copper gasket is in order. Another way is to use a 5.940" rod instead, that came in some Chevy Caprice V-8's. Good luck racin'. Homer.

hughes
Dirt Maniac

Total posts: 141
posted December 15, 2001 07:12 AM
that was my mix up on the 377 vs 358 in my earlier post. Isn't a similiar set up to what nascar runs. So they can get under the cubic inch limit, but still rap it out

chevyscrounger
Dirt Full Roller

Total posts: 43
posted December 15, 2001 02:43 PM
Hot Rod magizine did a article on "The engine Chevrolet should have built" back around 1997.They used a 307 crank and
300-6 cylinder Ford rods and custom pistons.They used aluminum heads and roller cam.
They built it with high compression and used 87 octane fuel cause the long rods are supposed to help prevent detonation.I think it make about 500 horsepower on the 87. A little later they tried the same idea on a Ford but I don't remember how that went.

6pack
Dirt Maniac

Total posts: 128
posted December 15, 2001 05:10 PM
3.34 stroke will get you under 358CI.
You can get those 5.94 rods at www.sdpc2000.com , a Dirt Forum sponsor.

Pit Bull
Dirt Full Roller

Total posts: 65
posted December 16, 2001 07:12 PM
Homer,

So let me see if I understand this - If i use the 5.94 rods and the 400 pistons for a 5.7 inch rod, I will have it so the piston doesnt come above the deck, correct?

Homer62
Dirt Roller

Total posts: 10
posted December 16, 2001 10:24 PM
Pit Bull, add 1.433 to 5.940, then add 1.625. If that number is smaller than 9.025, it will fit.
Good luck racin', Homer.

cowboy85
Dirt Roller

Total posts: 5
posted December 30, 2001 03:09 PM
use a 6.125" rod and 377 pistons that are for a 6" rod.

DodgeBoy76
Dirt Full Roller

Total posts: 73
posted January 29, 2002 10:07 PM
quote:
Originally posted by Pit Bull:
A buddy of mine just picked up a few chevy small blocks for almost no money, and in the bunch was a 307. I haven't heard much about these motors, but I noticed on further research that they have the same stroke as a 327. Now, here is my thought: What if I put a 307 crank in a 400 block? And then, use a set of 6 in. rods and stock 400 pistons? My thought is that the stroke is 1/2 inch shorter with the new crank, and the 6 inch rods are (almost) 1/2 an inch longer than the stock 5.557 inch rods. The combo would be off approx. .057 of an inch, but some "machine work" to the piston face could cure this. I know I will have to use spacers on the Mains like I would if I built a 377. Has this ever been done? Is this even worth the effort, or will this be a sweet combo? I think the cold weather is getting to me....racing season needs to get here quick before I go crazy....

[This message has been edited by Pit Bull (edited December 14, 2001).]


I do know that a few guys here in OKC run that same combo on a 1/2 mile track in a pro stock, and the will twist the crap out of them...like 8500-9000, and they really FLY!!!

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