Rod Lengths???

[rking]

I have a 3.625 stroke crank and I need help figuring out what rod lengths would be good. I found some 6.625 in rods, but I am thinking that those are too long. I just need some help on what lengths you guys are running with this crank. TIA

BTW I dont have a short deck block.

Thanks

 

[KendallF]

6.50s will work; that's what I have. The 6.65s will be too long to get a workable piston. You'll probably end up with a bridged oil ring even with the 6.50s.

 

[Scott231]

You will need custom pistons for that long of a rod (6.50 or 6.625). I thought I had heard that the 6.625 would work with a plugged piston. Check with some of the TR engine builders.

 

[re-evaluating]

wouldn't do it

The rings in the pin aren't the worst of it.. I don't think there is anyway of getting enough dome thickness (negative dome if you will) with that long of a rod under 12 to 1 compression.. 6.5 is it with a 3.625 stroke.. You will be much happier with a 6.2 to 6.3 and a max of 6.5.. You can use the longer rods with a shorter stroke. Hope this helps. Dave

 

[rking]

Thanks alot guys! What do you think about running those rods with a 3.50 stroke crank??

 

[slimtastic]

with the 3.625 crank you could have a GOOD rod ratio of 1.82 (professional racers use a r.r. of about 1.7-1.8 for reduced friction). the 3.5 crank would give you 1.89....thats too high i think

 

[slimtastic]

the best ratio i can see would be the 3.625 crank with the 6.5 rods. that'll give you a 1.79, hell it even looks plausable.