machine shop questions?

[wicked_TurboLV]

Im getting ready to take my 109 block to a machine shop but have a few questions and maybe you guys could give me a few questions to bring up to the machine shop. first of all to bore the block is .30 over done for maximum performance or due to damage on the block, my block has no damage so if going .30 over is the way to go for maximum performance than thats what ill do. next i would like to use only the two center billet main caps along with the girdle, now i know the main caps need machining but will there be a problem using the stock and center billet caps after machining. I know you guys are probably saying why not go with all the caps or just the girdle, sorry just the way i am and the way i want to go. your input would be appreciated, thanks

 

[sumnerw]

I wouldn't bore it any more than the minimum necessary to clean up the cylinders and ensure that they are true (using a torque plate). The conventional view is that the block cannot be reliably bored beyond 0.030 over (walls become too thin) so that once you do that, you have consumed all of the useful life of the block. If something happens where you scuff a wall or encounter any kind of damage that requires more boring, the block will probably be toast.

If you are looking for more performance, I'd look at increasing air and fuel throughput, optimizing tuing, improving traction, reinforcing the block (girdle), reducing losses and weight, etc.

I don't see any problem with using just the center caps with the girdle. It's just added insurance and if you can afford it, go for it. It's my impression that lot's of people have used just billet center caps with stock front and rear caps and I don't recall hearing any problems with that.

Good luck,
Buzz White in Houston, TX

 

[wicked_TurboLV]

thanks for the info, so really since the block has not had any major damage to it i should just bore it out only the minimum to clean up the walls and save the life span on the block by doing so, right. what about the main caps what kinda machining do they do to them just curious. thanks

 

[MSDGN]

I'm in the same boat...getting ready to take a 109 block to the machine shop...I'm going .020 over on the bore...that way I have another bore in the block if need be...you could probably go .010 over but not sure pistons are readily available for that...can get many brands easily for .020 and .030...as for the steel caps you will have to get an align bore/hone...I'm using the stock caps with a girdle and I should only need an align hone...it's all in how much you want to spend...IMO with a girdle steel caps are overkill but to each their own...

 

[49-blues]

I think the diamond pistons come in .010, .020, .030 so bore it as little as it needs and save the block for a few more rebuilds. I ve even heard cal or someone else gets pistons starting at .005.