northiam

I recently bought a ZH fairlane donor car with all the good running gear, 351, FMX, 9" disc diff, electronic dizzy, remote starter relay etc. I discovered the engine was not what I thought! Although the car was definately a 351 originally the motor was replaced many years early with a 302, that explained the closed chamber heads, the 3" stroke and subsequatly the 302 on the crank!
Now since I must have a 351, can I use the 302 conrods 6.02" on a 351 crank with lower height pistons or 351 crank 302 rods standard height pistons stroked to 3.7 inch or so? or just replace all the rods and crank for 351 components?? Can anyone tell me whats the cheapest and what would be the most reliable setup?

qwikcorty

acl make a 302 rod 351 race series kit, ive used one in my 351.

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1976 351c td cortina

351freak

Hi all...

I am interested in knowing more about the 302 rod/351 crank set up as I am in the process of deciding how to build up a clevo for my XD.

Is it a stroker? What advantages does it give?

thanks heaps

the freak

davis

I don't think of a 302 rod with a 351 crank as being a stroker, but it is in every essential way. I think of it as a "different sized rod" 351. There is no reason why it isn't a stroker 302, but I'd generally term the concept of a stroker as being a block with a larger than "factory produced" stroke.

We never had a 302C. All of our 302s were 8.2" deck Windsor-style small blocks. These are well-stroked at 347" and they are small packages that pack a serious punch. My 347" stroker made 520 HP.

With the same block used for the 302 and 351, I think of the 302C as a "destroked" 351 and a 3.500" stroke simply as a 351. The addition of the longer rods is a relatively minor difference. If you could, you might want to consider sourcing a set of 5.778" 351C rods as they can't be terribly expensive. Here, we throw them away or at most charge $20-30 for a set of used factory rods that need reconditioning. Of course, this is a lot of extra work if you don't have factory sized 351C pistons, to go with it, too. I like the shorter rod 351C design, but I regularly recommend the shortest rod that gets the job done, but nothing wrong with the 302-rodded 351C, especially if it works for the budget. I'm just not sure that I'd call it a stroker.

The advantages of using a 351C crank over a 302C crank should be obvious. An additional 49 CID or a 16% increase in capacity. I'd venture to say that there is no engine-specific advantage in using the 302C rods, but if you've already got them then you're money ahead in the game. I'd recondition them and use them.

:davis:

STROKEXD

If it was me I would buy another 351 outright even if it is a bit worn. You should be able to pick one up for a few hundred bucks. Out of the 2 motors you should be able to put a good 351 together and still use the 302 heads on the 351 internals. Easier on a budget if you stick to standard 351 stroke configuration.

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northiam

Today I found a 4MA crank which should be ok with a grind 010" undersized. I will check out ACL for the lower comp height piston to use the 6.02 rods. Or can I stroke the 351 crank to use the 302 rods and alternative pistons?

xbgs351

There are three long rod piston manufacturers being:
Hypatec
ACL
KB

TruBlu351

The pistons you are after are called Short Deck pistons. ie: the piston is shorter as viewed from the side, to make up for the longer conrod - otherwise your pistons would obviously smash thru your heads.

To answer your question FREAK - why do some people use the longer 302 6" rod in a 351?

Imagine the whole crank/rod/piston set up when viewed from the side. The top of a 6" rod is always higher up the cylinder compared to a 5.7" rod. As the piston starts moving up the cylinder from the bottom of it's stroke, the angle between the rod and the cylinder wall is at its greatest until it moves up to TDC where this angle reduces to zero (parallel). This angle can be broken down to horizontal and vertical components - vertical is good, horizontal is trying to shove the piston thru the cylinder wall. Supposedly, this reduction in side forces applied to the cyclinder walls allows the motor to rev slightly better with less stress applied to the engine.

I put a 4MA in my 351 with 6" rods and new hypereutectic pistons - really not that expensive. You'll have to get the whole thing machined anyway for the rebuild. I say, get the new crank, buy new pistons and use everything else from your 302. Make sure you look into how much you'll deck the block and what your final Comp Ratio will be with the CC heads. Get your machine shop to record everything they do for your future reference. Get your 302 rods shotpeened and polished - this will reduce the potential of them letting go!

What you paying for the 4MA?

Cheers

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XE Falcon
393 Tremec TKO 9"

russxr67

stroking a 351 crank involves offset grinding of the big ends to a new(usually small block chev) dimension and in doing so it it made smaller,sizing down from 2.311 to 2.1.This precludes the use of standard conrods.350 chev conrods are used for the 3.7 stroke version with standard deck height pistons along with counterweight and piston pin mods.

northiam

I paid $180 for the 4MA crank! to much but it was the only one in brisbane at the time. How much would I expect to pay for stroking the crank and chev rods?