302 to 306

thePH03NIX · 02-11-2009, 06:09 PM

first off, i'll say this to the mods, i'm not sure if this is the right section for this, but if it's not then please move to tech section.

alright, now that that's done, my question: my motor is in need of a rebuild soon, and i would like to increase the cid from 302 to 306. about how much would that cost to do? and would i need anything special to do it after the machine shop is done?

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mjr46 · 02-11-2009, 06:17 PM

rebuild often will consist of boring from 4.000 to 4.030, and new pistons would be needed and all parts need to be checked against spec

thePH03NIX · 02-11-2009, 06:22 PM

so about how much money should i plan to save up for all of this? and would i need to get new heads too? i just have the stock gt heads. i guess those are e7 heads?

mjr46 · 02-11-2009, 06:27 PM

use the e7's as door stops, as far as rebuild, depends on what needs to be done as far as cost goes and quality of parts used, a ready to go good quality short block can be had easy for under/ around 1000.00

thePH03NIX · 02-11-2009, 07:07 PM

okay, now i also found a freshly rebuilt cobra shortblock, it's described as "The motor is a fresh rebuild. It's a new stock shortblock. It has been hot tanked and magnafluxed, honed with new rings and bearings. Crank has been polished. Has stock pistons casting #f3ze-aa. This is a fresh shortblock and has never been ran."

selling for $500, now what is the difference in power if i go with a 306 instead?

AdderMk2 · 02-11-2009, 07:10 PM

maybe 4-5 hp

you wont notice much from a 302-306 unless you bump the compression

FORD TOUGH · 02-11-2009, 07:12 PM

Quote:

Originally Posted by thePH03NIX

okay, now i also found a freshly rebuilt cobra shortblock, it's described as "The motor is a fresh rebuild. It's a new stock shortblock. It has been hot tanked and magnafluxed, honed with new rings and bearings. Crank has been polished. Has stock pistons casting #f3ze-aa. This is a fresh shortblock and has never been ran."

selling for $500, now what is the difference in power if i go with a 306 instead?

There would be no difference other than 4 cubic inches. I would be afraid of that motor it sounds like it just got new bearings and rings. The reason people have a 306 is because their cylinders need cleaned up so they were bored .030''. You will not notice any more power with 4 cubic inches.

TrimDrip · 02-11-2009, 10:32 PM

there is no difference unless you stroke it or add compression.

S-Trimmed302 · 02-11-2009, 10:41 PM

If your engine needs a Rebuild and you can get by with Just honing the Cylinders and Not Boring it Id leave is Standard bore your not going to feel any power difference from boring it .030 and adding 4ci.If you do have to bore it you can expect 250-550 on a set of Pistons,$30-100 on Rings, and up to $250-300 for the machine work to Clean the Block,Bore and Hone.Dont bore it unless the cylinders need to be.

TrimDrip · 02-11-2009, 10:58 PM

I have a set of forged pistons that you can have for a hundred bucks.