Why not a 351 Windsor in at GT40

[Jim Craik]

Guys,

I'm wondering, how does a 331, differ from a 347, and how do they differ from my 302 based Roush 342R?

 

[Fran Hall RCR]

Bore and stroke....the 342/347 has a higher piston/rod angle due to longer stroke...

I prefer the 331 myself..

I recall issues with piston rock , and high oil consumption ...pistons also see high wear due to excessive side load/thrust ...also the ring issue Cliff mentions..

 

[Jim]

Jim, you might want to consider a 331 instead of a 347. Apparently the lower piston ring on a 347 is just about coming out of the bottom of the piston bore....and the rod angles are starting to get pretty extreme in the 347 too. Just a thought. A well designed and built 331 will crank out 400+ hp/tq, which is loads of power in a car weighing sub-3,000lbs.....

Thanks Cliff. I have heard of that before. The last stroker engine I built was a 408. I used an eagle kit. Do you have any experience with C.A.T? I have a line on a 331 kit with a sportsman block. I've heard C.A.T isn't that great with the quality so I'm reluctant to jump on it.

 

[Scott]

Jim and Jim C,
From the reading I have done considering the ford small-block strokers, 302 has 3inch stroke 4 inch bore, 331 has 3.25 stroke and 4.030 inch bore, 347 has 3.4 inch stroke and 4.030 inch bore, and the 342 uses a boss block with a 4.125 inch bore with a 3.25 stroke.

Stock 302 roller blocks are good up to about 500hp, as long as you are not beating on them all day. At that power level or less any of the Scat cast stroker cranks are fine. Upgraded rods and pistons are preferred. If you are going to go racing/tracking, all forged assemblies are reccomended. (no comment on C.A.T. no experience, eagle stuff is good, so is Scat)

As far as blocks, the Dart blocks are considered to be at the top. The sportsman blocks have some issues, as well as the Boss blocks. (mustang forums provide plenty of insight) The cylinders on the Boss block are a little shorter than the stock or dart blocks, so on a 3.4 inch stroke/347 the pistons come a little too far out of the bore causing problems. I would only consider a 3.4 inch stroke if using a dart block for longevity.

For reliability/longevity 3.25stroke/331 or 342 with 4.125 bore/dart block would be my choice. Caveat emptor, Scott

 

[Jim]

Jim and Jim C,
From the reading I have done considering the ford small-block strokers, 302 has 3inch stroke 4 inch bore, 331 has 3.25 stroke and 4.030 inch bore, 347 has 3.4 inch stroke and 4.030 inch bore, and the 342 uses a boss block with a 4.125 inch bore with a 3.25 stroke.

Stock 302 roller blocks are good up to about 500hp, as long as you are not beating on them all day. At that power level or less any of the Scat cast stroker cranks are fine. Upgraded rods and pistons are preferred. If you are going to go racing/tracking, all forged assemblies are reccomended. (no comment on C.A.T. no experience, eagle stuff is good, so is Scat)

As far as blocks, the Dart blocks are considered to be at the top. The sportsman blocks have some issues, as well as the Boss blocks. (mustang forums provide plenty of insight) The cylinders on the Boss block are a little shorter than the stock or dart blocks, so on a 3.4 inch stroke/347 the pistons come a little too far out of the bore causing problems. I would only consider a 3.4 inch stroke if using a dart block for longevity.

For reliability/longevity 3.25stroke/331 or 342 with 4.125 bore/dart block would be my choice. Caveat emptor, Scott

Thanks Scott. Do you know if a 289 block has shorter skirts than a 302? I have heard that for years and I never confirmed it. I have a 66 289 block and I was curious if it can be used for a stroker engine.

 

[Scott]

Jim,
The experts say that is mis-information. (according to what I have found on the net) The cylinders are all roughly 5.125 in length between a 289 and 302 give or take a 16th due to casting differences. The early block is beefier, but has no roller provisions. It is also heavier, and is obviously not set-up for roller cam. Stroking it should not be a problem.

Best, Scott

 

[colin artus]

289 block cylinder length: 5", 302 length :5 3/16".

 

[colin artus]

Perhaps I should add those measurements were taken from a '66 289 and a '70 Mexico 302.

 

[Jim]

Perhaps I should add those measurements were taken from a '66 289 and a '70 Mexico 302.

Thank you! I put a roller in my last engine which was a 69 block (351). I used a kit to convert the block to accept a roller. I had to drill and tab a few threads in the valley of the block. It worked well.

 

[Jim Craik]

Scott, Jim,

Thanks very much for the info, of all the GT40 info out there, engine data is my weakest area.

I looked on the Roush site, assuming they can be believed, they state that the 342R uses the Dart, Sportsman block. I'm not sure if that is good or bad. Now I really do not push my motor super hard, but I've gotten over 30,000 miles out of mine and it runs just like it did when new.

 

[Jack Houpe]

If I had to do it over again I would go with a small block windsor, 302-331. I guess I will just change the cam in my engine (427cu in dart 351 block) to make an easy 400hp.

 

[Ray]

Okay, how about the Ford 363 crate motor in the motorsport catalog? will it be even sketcher than the 347, because thats the motor I would like to use in the 40.
Cheers Ray