Bottom end rebuild.. - The 1947 - Present Chevrolet & GMC Truck Message Board Network

mongoose · 12-17-2010, 10:49 PM

Rebuilding a bottom end for my 350 and need some input on something.. Not so much building it for power.. maybe 425, but more so rpm... maybe 7 grand.. or so..

I've acquired a bunch of parts that will work except for some pistons..

eagle crank, with that esp coating.. strong as nod crank supposedly...
stock x/o rods with some good bolts..
4 bolt that will get some studs..

now the pistons, I do have a set of TRW L2304F's here.. that I want to mill down flat so they will work with 64cc heads nicely, but do you think they are too heavy to be spinning that fast with those rods? was thinking if i couldn't use these to pick up some hypers, (this is a low buck motor.. everything has been free except labour) would they be any better than the heavy forged units?

Marv D · 12-18-2010, 01:13 AM

Not sure you can mill the 2304's to a flat top. Check the underside. If there's anything left, they'll be paper thin. The L2304's are the old LT1 clones and yield a 11:1 ratio with a 0.025 deck, 0.020" steel shim gasket, 64cc chamber. Do the math .. with a 76cc chamber and the same setup you have 9.6:1. VERY workable combinations with those pistons. Yes the TRW's are about as heavy of a forged piston as it comes, but they take tons of abuse. Do a good balancing job and they'll take 7200 jaunts over and over.

I used to run a set in a reasonably mild little 350 that made roughly 380HP. then added 400horse of nitrous in 2 plate systems, and spun her to 7500 for every shift. In fact that motor is still together in the SAME form, with the same components in a street car here in AZ. The realitively short stroke of a 350 is pretty tolerant of rpm's

mongoose · 12-18-2010, 01:31 AM

yeah.. that's the thing i already have my heads done, and i don't think i can sell them for a decent amount to go towards another set of heads.. and they're small chambers, so that's why i wanted to mill them off...

how thin can i go for a piston top? I was going to take em in and get them pressed of so i can measure it better.. even if i can get some/most of it off... it will be better in the compression end of things.

12-17-2010, 10:49 PM	#1
mongoose Registered User Join Date: Feb 2009 Location: slurrey, bc. Posts: 1,134	Bottom end rebuild.. Rebuilding a bottom end for my 350 and need some input on something.. Not so much building it for power.. maybe 425, but more so rpm... maybe 7 grand.. or so.. I've acquired a bunch of parts that will work except for some pistons.. eagle crank, with that esp coating.. strong as nod crank supposedly... stock x/o rods with some good bolts.. 4 bolt that will get some studs.. now the pistons, I do have a set of TRW L2304F's here.. that I want to mill down flat so they will work with 64cc heads nicely, but do you think they are too heavy to be spinning that fast with those rods? was thinking if i couldn't use these to pick up some hypers, (this is a low buck motor.. everything has been free except labour) would they be any better than the heavy forged units? __________________ -'73 c/10 - Low with Go - will be complete... probably never. -'90 2wd Blazer - well... soon enough anyways. -'84 SWB - the daily gas guzzler.

12-18-2010, 01:13 AM	#2
Marv D Registered Truck Offender Join Date: May 2008 Location: hells training ground (aka Ariz) Posts: 3,118	Re: Bottom end rebuild.. Not sure you can mill the 2304's to a flat top. Check the underside. If there's anything left, they'll be paper thin. The L2304's are the old LT1 clones and yield a 11:1 ratio with a 0.025 deck, 0.020" steel shim gasket, 64cc chamber. Do the math .. with a 76cc chamber and the same setup you have 9.6:1. VERY workable combinations with those pistons. Yes the TRW's are about as heavy of a forged piston as it comes, but they take tons of abuse. Do a good balancing job and they'll take 7200 jaunts over and over. I used to run a set in a reasonably mild little 350 that made roughly 380HP. then added 400horse of nitrous in 2 plate systems, and spun her to 7500 for every shift. In fact that motor is still together in the SAME form, with the same components in a street car here in AZ. The realitively short stroke of a 350 is pretty tolerant of rpm's __________________ Still playin with trucks, even at my age! When you're dead, it's only a problem for the people around you, because you don't know you're dead. .....It's kinda the same when your STUPID. I just did my taxes and reviewed my SS statement. Thanks to the current administration it looks like I will only have to work till noon on the day of my funeral.

12-18-2010, 01:31 AM	#3
mongoose Registered User Join Date: Feb 2009 Location: slurrey, bc. Posts: 1,134	Re: Bottom end rebuild.. yeah.. that's the thing i already have my heads done, and i don't think i can sell them for a decent amount to go towards another set of heads.. and they're small chambers, so that's why i wanted to mill them off... how thin can i go for a piston top? I was going to take em in and get them pressed of so i can measure it better.. even if i can get some/most of it off... it will be better in the compression end of things. __________________ -'73 c/10 - Low with Go - will be complete... probably never. -'90 2wd Blazer - well... soon enough anyways. -'84 SWB - the daily gas guzzler.



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