Engine rebuild

[torq455]

what head gaskets are you using? i know the Camaro 3.4s were .040 and the bore is 3.75". that will change CR a tad.

[project89]

what head gaskets are you using? i know the Camaro 3.4s were .040 and the bore is 3.75". that will change CR a tad.

all above are with a 3.1 since thats the only thing a 2.8 piston would fit.
so 3.1 with the rwd gasket and 3.1 with fwd gasket

[torq455]

yeah, but i didn't think either iron nor aluminum 3.1 had a head gasket available in a 0.040. only the iron head camaro with the 3.4.

[project89]

im pretty sure the iron head 2.8/3.1 has an .040 compressed gasket

[geoffinbc]

Damn I would love to do it but I think the machining cost would be prohibitive. I will talk to the shop and see how much of a hassle machining the deck will be. I will also have the stock deck UT'd at work to see how thick it is. Does anyone know how much material can be removed from the deck or heads before the intake needs to be machined? If I do get this done then I will gasket match the intake to fix any port alignment problems that may arise.

[project89]

Damn I would love to do it but I think the machining cost would be prohibitive. I will talk to the shop and see how much of a hassle machining the deck will be. I will also have the stock deck UT'd at work to see how thick it is. Does anyone know how much material can be removed from the deck or heads before the intake needs to be machined? If I do get this done then I will gasket match the intake to fix any port alignment problems that may arise.

ur not machining the deck, u machine the tops of the 2.8 pistons, any machine shop should do this cheap.

my recommendation if u do this is to use stock/factory pistons, there is no guarantee that an aftermarket pistion will have the same thickness crown

but if u do have diff pistons it is easy to measure and see , ill see if i cant borrow a camaera and take some pics on how to do it

[torq455]

Franz ( XLR8ING) had the deck machined so the pistons would be at zero deck. i don't believe he had to machine/port match his intake.

[gectek]

ive seen .020 shaved off heads that was very close. i think that is right on the gray area.

ive done .010 on 2 sets of heads and have had no problems at all

[geoffinbc]

ur not machining the deck, u machine the tops of the 2.8 pistons, any machine shop should do this cheap.

my recommendation if u do this is to use stock/factory pistons, there is no guarantee that an aftermarket pistion will have the same thickness crown

but if u do have diff pistons it is easy to measure and see , ill see if i cant borrow a camaera and take some pics on how to do it

Thats what I mean machining the pistons will be expensive. Not machining the deck. There is no way machining 6 pistons and putting a custom dish in the top will be less money that machining the deck or heads down. Also consider no one has done it to a set of stock pistons and I don't want to be the one to try it on a vehicle I need to be reliable and cheap. If it were My S-10 engine I would try it because I would have a backup engine if anything were to go wrong.

[gectek]

people do it all the time. you are worrying too much again. machining isnt $$$ at all. you dont machine a dish, you just cut the top off. even machining a dish, you put it in a lathe and cut. not hard at all. any machine shop worth its salt could do it.

of course cutting the heads/deck isnt much either

[geoffinbc]

I'll ask but I am sure it would be a lot more. Plus they are going to have to calculate the amount of dish I will need in order to get the compression I want. I cannot go with a flat top piston on a 3.1L or the compression will be too high for me. So I will need a dish. It would be nice to get a spherical dish in the piston like the LS series pistons. It is reported they make good power and burn well.

Plus if .193 is left after machining 4mm off a 2.8L pistons whats going to be left if you add an additional dish into the piston. Its starting to sound a little thin to me.

[gectek]

umm sorry, most LS pistons are flat top. almost all dish pistons are spherical....just like the 3400 pistons stock. if the LS piston has any CC under 10...its just 2 valve reliefs, otherwise they are flat

stock LS pistons are flycut .080. then hit with a huge cam....meaning 240dur +++ and nitrous 100+++.

[geoffinbc]

No most dish pistons are a cut dish with flat bottoms. The spherical ones look like a ball was pressed into the top of the piston to make the dish.



Although what you get depends on the compression you want.

[gectek]

oh hah....no ls piston is like that.

trust me i know, i work with LS pistons ALL DAY. the forged are either flat top, dished like a 3400, big valve reliefs, or a huge dome. those are hard to find...but you can still cut something like that on a lathe.

they flycut them big for high comp, big cam and spray. the most i have seen them flycut is .090, most do .080 just for clearance on a big cam. they use 58cc heads to bring comp up to 12:1 or higher and still run a big hit of nitrous

[geoffinbc]

Well you haven't seen them all then because that is a stock GM LS9 piston A couple guys on this years engine masters challenge have taken this design and report it makes great power and burns very evenly