boring g block

[jdo]

can anyone tell me if it is possible to bore a g block to 6 1/2" , can i get pistons this big, what would compression ratio be with 6 1/2" bore stock stroke [7"] i think, and flat head would it be better to bore block .125 over and leave it at that

 

[jd b puller]

(quoted from post at 01:19:05 02/13/09) can anyone tell me if it is possible to bore a g block to 6 1/2" , can i get pistons this big, what would compression ratio be with 6 1/2" bore stock stroke [7"] i think, and flat head would it be better to bore block .125 over and leave it at that

6-3/8" is common in the G's. I don't know of any "off the shelf" piston, but you can make darn near anything if you have to.

 

[JDGnut]

Will it bore that big, probably.. will it live.. maybe.. depends on the condition of the block (rustying and pitting in the water jacket, how centered the cylinders are on the castings, and how much compression you are going to run. Guessing you are going to try the early D pistons.
If you try it, bore the block from the bottom, and don't bore it all the way to the top of the block, then cut the diameter of the pistons down (above the top ring) to fit into the smaller bore, this will give you a little more strength.
You will be much happier at a smaller bore.
I have not tried the styled G block.
JDGnut

Attached a pic on Maybe it will and maybe it won't. top the bore is a little over 6.5.

 

[jdo]

what would be the ratio 63/8" bore with flat head 7" stroke ,what about HP

 

[jdo]

just wondering if anyone has a set of 16.9-38 fireston tires for sale they have to be uncut

 

[Anonymous-0]

maybe 65, 70 hp on the high side. you'll have to shave your head or go flat, maybe swap blocks if you've got an unstyle. roughly 130 psi compression.

 

[JDGnut]

If you use stock rods, everything is going to depend on what you use for pistons.. and what block.. and which head.. if you use the M&W styled pistons with a styled head its about 7.5 to one.. with a flat head, about 10 to 1.. But you can always use the styled head, and lengthen the rods..
Most of the 6 3/8 pistons are short pistons, so you will have to have the rods welded to make up for the short pistons.. compression ratio will depend on how long of a rod you choose...
JDGnut

 

[Anonymous-0]

I bored and ran "G" Power Block pistons in a early "G" block for years. Ran water in it. " 70" power block pistons in a mid year block. Hard block was used.
Would I do it again? No. I'd go 6.375 and be safe and happy.

 

[430WLPG]

Did you blow out that block on a dyno?

 

[JDGnut]

Yes.. warmed the tractor up running under a load... first time to put a load on it, it broke... It won't break like that twice.. haha.. it might crack.. but it won't knock the chuck out..
JDGnut