Hello guys im rebuilding my first engine and need help on pistons and piston rings for 74” 351W? First should I replace my pistons? Is this nessacery? They look to be in good shape; second piston rings, I was watching a do it yourself video and the guy was using Keith Black rings which needed to be filed to fit. Is there any rings that I could buy that do not require me to file them? Or do I even need to replace my rings?
help on pistons and piston rings for 351W?
- Thread starter nitequill
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If the pistons look ok than you don't need to replace them. Depends on what you are doing with the car. As far as the rings go...I never used the rings you are talking about, and I had never heard of filing down the rings to fit.
If you have bored the cylinders out at all than you would need new pistons and appropriate rings.
If you have bored the cylinders out at all than you would need new pistons and appropriate rings.
classic boost
Founding Member
it is mire than just the pistons that need inspection, the cylinder bores also need checking for taper and out of round. more than about .005" of either and you really should bore the cylinders to make them straight and round again.
for piston rings, if you choose to use the same pistons, you can get a set of rings that dont need gapping per say. but as indicated you do need to check the ring gaps to see if they are in spec.
gt500lw there are two types of rings sold, those that are gapped close to spec from the factory, and those that need gapping as they are designed to be custom gapped by the engine builder.
for piston rings, if you choose to use the same pistons, you can get a set of rings that dont need gapping per say. but as indicated you do need to check the ring gaps to see if they are in spec.
gt500lw there are two types of rings sold, those that are gapped close to spec from the factory, and those that need gapping as they are designed to be custom gapped by the engine builder.
yes there is a spec for ring gap. any repair manual worth anything will give you the spec you need.
classic boost
Founding Member
ratio411
Founding Member
If you don't put in new rings and refresh the crank and bores to some extent, you are not rebuilding the engine.
You are just disassembling it and putting it back together.
Now, I am going to offer some advice since you are working on a 351w...
Instead of turning the crank, pay just a little more and get a cast 3.85" stroke crank.
Then, instead of buying new 351 pistons in .030" over, buy cheaper 302 pistons in .030" over. (get the block cleaned up .030" over, of course)
These two mods will go back together just as stock, however you will have about 42 more cubic inches. 393w instead of 351w for only slightly more dough than turning a crank and using 351 pistons.
Dave
You are just disassembling it and putting it back together.
Now, I am going to offer some advice since you are working on a 351w...
Instead of turning the crank, pay just a little more and get a cast 3.85" stroke crank.
Then, instead of buying new 351 pistons in .030" over, buy cheaper 302 pistons in .030" over. (get the block cleaned up .030" over, of course)
These two mods will go back together just as stock, however you will have about 42 more cubic inches. 393w instead of 351w for only slightly more dough than turning a crank and using 351 pistons.
Dave
jb1dsl
Member
milner351
Founding Member
Nope!
I have a scat 3.85 crank, I went with DSS pro lite pistons and H beam rods for this combination, but, even with a stock 351w rod and stock replacement 302 piston, you don't have to worry about grinding the block.... at least I didn't.
I have a scat 3.85 crank, I went with DSS pro lite pistons and H beam rods for this combination, but, even with a stock 351w rod and stock replacement 302 piston, you don't have to worry about grinding the block.... at least I didn't.
Italian-LX
Member
I agree.
I just finished my 351w with a 4.100" stroke and my block didn't need clearing. My block is a D2 (1972).
ratio411
Founding Member
The beauty of this particular stroker is that it only adds a little to the cost of a stock rebuild...
I see you took it to the max though!
classic boost
Founding Member
if he's not upgrading heads, intake, and cam, then the 393 route isn't that good of an idea. the engine will hit a wall before 4,000 rpms.
302 coupe
Founding Member
classic boost
Founding Member
ratio411
Founding Member
I don't agree.
40+ more cubes for maybe 200 extra bux on the rebuild...
Can't beat it.
If you keep a 2v and stock cam on a 351 it hits that same wall.
So what's the difference?
By your reasoning, they never should have used the 289/302 design and made the 351w to begin with.
Most of them had heads, cam, exhaust, and intake same-same as any smogged 302.
Agree?
Hey, go back to this gapping thing. I have built about four engines (new rings and all that good stuff). I have also helped my dad rebuild engines. He has been a mechanic for over thirty years. This is the first time I ever heard about gapping your rings, other than checking the gap of the old rings that you are pulling out.
Italian-LX
Member
Who picked your rings out? Certainly anybody who has done any kind of ring "shopping" has heard of file-fit rings.
Ask your machinist -- I bet he has heard of them.
. . . if not, then you may want to find yourself a different person to do your machine work.
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