351 crank in a 302 block?

[DADDYJUSTANG]

Is this possible? I have a friend who keeps telling me it is and that he has done it before. But I want to give the Guru's of stangnet a challenge. If it is possible what cubic inch would it yeild? Do I need 351 rods and pistons or the 302, or custom? Thank you for taking the time to ponder.

 

[stang2841]

yeah, i believe its a 327, and if u bore it .30 over it is a famous 331 stroker, you can use the same rods, and pistons but might as well upgrade that all if ur stroking it out,

DSS sells some good forged kits......

 

[87'GTstang]

Aren't the journals for a 351 block larger than that of a 302 - dictating a larger crank journal diamter?

 

[93-331-29psi]

You are correct the main journals are not the same between the 302 and 351.

 

[Rick 91GT]

the 351 has a 3" main journal, 302 is 2.25" it will not work.....

 

[stang2841]

oops wrong.....

atleast i learned somethin

 

[FoxChasis]

Some old school 302 strokers used 351C cranks, but that was before there were aftermarket stroker cranks available. The main journals can be cut down but that weakens the crank and limits maximum RPMs and or HP limit and or power adders.

302 = 2.49" mains
351C = 2.75" mains
351W = 3.00" mains

 

[tjm73]

..... The main journals can be cut down but that weakens the crank ....

I've always question the logic behind this "theory". All cranks are machined some degree. If the crank starts with a 3.00" main journal and is machined down to 2.50", how does this weakin it? The crank doesn't know it's got a smaller journal. 302 and 351 cranks are made from the same material. Maybe I'm missing something.

Maybe it's weaker compared to annother 351 crank, but it should have just as much strength as the 302 crank.

 

[hllon4whls]

I agree that if it can be done, it is not worth it. There is very little in this world that cant be done. Cant be done practically and cheaply are other things.

2nd if you were to put a 351 crank in a 302 it would make it 351 cubic inches unless you offset grind the rod journals to reduce the stroke.

To explain:The 302 and 351 share the same bore size, so if the stroke is equal (by use of a 351 crank) then it would equal the same cubic inches.

Welcome back Justin!

 

[hllon4whls]

I've always question the logic behind this "theory". All cranks are machined some degree. If the crank starts with a 3.00" main journal and is machined down to 2.50", how does this weakin it? The crank doesn't know it's got a smaller journal. 302 and 351 cranks are made from the same material. Maybe I'm missing something.

Maybe it's weaker compared to annother 351 crank, but it should have just as much strength as the 302 crank.

I believe that it would have something to do with the crank being cast. Not sure how much material is good all the way to the center of the crank. There are imperfections in every casting. IF the crank was forged, then I believe it would be damn nearly as strong (within reason) with either set of journal diameters.

 

[IndyBlk5.0]

I bet that would be an interesting rod angle.

 

[tjm73]

I believe that it would have something to do with the crank being cast. Not sure how much material is good all the way to the center of the crank. There are imperfections in every casting. IF the crank was forged, then I believe it would be damn nearly as strong (within reason) with either set of journal diameters.

Hmmm...good point. I never thought about the casting quality through out the crank.

 

[Kid wita 5oh]

2nd if you were to put a 351 crank in a 302 it would make it 351 cubic inches unless you offset grind the rod journals to reduce the stroke.

To explain:The 302 and 351 share the same bore size, so if the stroke is equal (by use of a 351 crank) then it would equal the same cubic inches.

Welcome back Justin!

not true, the 351 uses a longer rod and has a taller deck than the 302

simply puting a 351 crank in a 302(not that it would fit anyway) would lengthen the stroke but it would still not be equal to a 351

 

[hllon4whls]

not true, the 351 uses a longer rod and has a taller deck than the 302

simply puting a 351 crank in a 302(not that it would fit anyway) would lengthen the stroke but it would still not be equal to a 351

The rod has very little to do with the swept area of the piston in the cylinder. You would need a shorter deck piston height to work in the 302. The crank is going to still pull the piston up and down the same amount in the cylidner weather it has a 4.7 inch rod or a 6.7 inch rod.

The whole point is that it will not work. You dont see any 351 stroker kits (based on a 302 block) out there for a reason. Even a 347 is based on an overbore. Lunati sold one that was 350 cubes, but that was with a 60 overbore. A stock 351 has no overbore compared to the 302.

 

[DADDYJUSTANG]

Thanks Guys, I guess it would be cool for bragging rights. But definatly doesn't sound like it's worth it. I think I'll just stick with the 331 stroker plans.
Hey hllon4whls I'm not exactly back I still have to use the PC at my parents house to get online. By the way I'm working at Tire World now behind the taco bell in mandeville. We got a guy up there with a 70'ish camaro that runs low 12's and I witnessed a 11.97 on only one run. You need to come by and shut him up. See ya later. By the way i'm off on thursdays.

 

[87'GTstang]

The rod has very little to do with the swept area of the piston in the cylinder. You would need a shorter deck piston height to work in the 302. The crank is going to still pull the piston up and down the same amount in the cylidner weather it has a 4.7 inch rod or a 6.7 inch rod.

The whole point is that it will not work. You dont see any 351 stroker kits (based on a 302 block) out there for a reason. Even a 347 is based on an overbore. Lunati sold one that was 350 cubes, but that was with a 60 overbore. A stock 351 has no overbore compared to the 302.

Agreed. All the rod length has to do with it is to help acheive a larger stroke if it applies in the sense that the piston doesn't travel too far down into the block or vice versa: too far above the block and into the cylinder head. This is the only reasoning for connecting rod length. If from centerline to journal distance is 1.5" on the crank, then your total stroke will be 3" overall - regardless of connecting rod length.

 

[StormWatch]

OK guys, just for the record the stock 302 main journals are 2.25, not 2.49. The 351C is 2.75 and the 351W is 3.5.

It is possible, but would be far cheaper to just by a stroker crank from Eagle or Scat or even better, the whole kit. Either 351 crank is basically a raw casting when used in a 302. Just about every surface of the crank needs to be worked. The counterweights need to be reduced, rod and main journals turned to 2.1/2.25", crank snout modified, rear main seal mods, etc.
--
I own a 357 inch 302 stroker. It has a worked 351C crank, FPS did the crank work. They modded the crank to fit the 302 main saddle, ground the rod journals to 2.1,the rods are Eagle 5.4 H-beam rods and a custom piston for TFS High Ports. The engine is on a stand and is waiting for a car and was bought used from a local racer. He did supply the build sheet, quote for the job and all reciepts for work that was done. Ford Performance Solutions verified the engine and FPS build number on the block.

FWIW...The 2.1 rod journals are a Chevy spec, but most performance combos based on the 302 block use these.