Allis stroke

[Pig_Iron]

Hey guys, I have a few sets of pistons laying around for my WD with 226 motor in it. If I offset grind my crank to 5", which pistons would be better to use? Tractor has 170 8:1 flat tops in it now, and I have a set of M&W SP48 pistons. Both are 4 inch bore. Which of those two would be a better choice for the 5" stroke? And does anyone know what the compression would be on the 5 inch stroke? Im running 14.9x38 FR on 14x38 pressed steel and need a bit more power for 5,000 lb 3mph. Thanks for the help.

 

[Anonymous-0]

the 8.1 comp ratio pistons should be .590 below deck. So the half inch of stroke halfed would be .250 from .590 =.340 below deck that with the full 5 inches of stroke is a static comp ratio of 13.9 . thats with a 4 inch bore 4.250 gasket bore with a thickness comprssed to .042. hope this helps. the maw I am not for sure what the comp ratio was to begin with but i do think it would be slightly less compression .

 

[Pig_Iron]

At that compression ratio, would those 170 pistons stay together? And would I need to use a copper head gasket?

 

[Anonymous-0]

I ran 14.1 on the felpro blue gasket without any promblems for several years . As for the pistons I cant answere that as to the ones i used in the 14.1 engine were forged and not cast. The compression ratio is a ball park it could be lower than 13.9 If the first compression ring land is down more than .250 thousandths from the piston top . ring land placement makes some what small but a difference in comp. ratio

 

[jd plowboy]

this is what i done to my wd45. i offset ground the crank from 2 3/8 rod journal to 2 inches and used the wd45 buda diesel rods in it. this made 4 7/8 stroke. i put the wc 4 1/8 bore sleeves and flat top pistons in it which that made it a 1/8 overbore. this puts the pistons 400 thousandths from the top of the block and has a cam from tommy richardson in it but now it would have to come from barney taylor. dont know what the comprssion ratio is but it is way higher than it was stock. i burn 110 racing fuel in it and it pulls like a champ up to 6500lbs. a wd45 with the overbore 45 dish top pistons cant hold a light to it. it has pulled against m farmalls, oliver 77 and 88 and has been in the top if not first. took it to a pull saturday and in the 5000 and 5500 lb classes got 1st place out of 3 tractors. i am well satified with this setup and the way it pulls. it is also setup at 10 percent over on the rpms. it hasnt run out of power yet at a pull.have pulled it to 6500lbs.also this is a used set of sleeves and pistons that i put in it 5 years ago and paid 100 for them.

 

[Anonymous-0]

plowboy your comp ratio by the numbers given in your reply is 11.9.1