Rod bushing spec

[BenM]

When using boreable pin bushings for a 12v rod what is the acceptable limit to bore off center to raise the piston up for a little more compression.

Dead center bushing, the piston is .013 out of the hole. Would it be safe to bore .010- .015 off center to get the piston .023-.028 out??

If anyone has any experience with this what would be the safe limit of boring the rod bushings for more piston to deck height?

I hope that this was worded correctly enough to get my point across to everyone.

 

[9724VF350]

That can depend on the bushing manufacturer and how thick the bronze layer is. About all you can do sometimes is offset bore and find out how thick it is.

I've seen them where .005 is too much, and some bushings can go .020 without going through.

 

[BenM]

Rod bushings

Thanks I will check the one that was already bored and see how deep the material is.
I forgot to add the reason I'm leaning towards this way is the orings would have to be remachined if I decked the block.

Thanks

 

[lenahan05]

seems like a lot of work for a little compression. why not run a thin gasket and deck your head? just curious...

 

[BenM]

Specs

seems like a lot of work for a little compression. why not run a thin gasket and deck your head? just curious...

Deck the head?? Sorry I'm not following you and how that would help the C/R? Please explain.

The head has been machined to get the valves to not sit so deep to improve airflow into the cylinders. I wouldn't want to take much more off the head then the valves would have to be reset deeper?

Do you mean the block?


What headgasket is thinner than the stock 24v gasket I'm using now?

How much would .010-.015 of a difference make in C/R using .040" over RV 275 pistons?

 

[Tate]

Typically, you'd lose 0.5:1 with a .010" thicker gasket, 1 point for a 0.020" gasket.

 

[lenahan05]

thanks tate...beat me to it. how far do your valves set down in the head now? .050 or more i bet especially if you did a valvejob. you would have to sink it unless you went with a bigger valve or different angles. you sink valves and i've seen a substanial drop in CR.

 

[SPEEDSHIFT]

Why would you weaken the parts that need to be strongest for high compression?

I would deck the block to go the route your after. What is this engines purpose? DD or Race, if its going to be a performance build I would look at billet rods. What is your goal CR?