3rdgen Fbody with 3500 heads

[ForcedFirebird]

they are different height, you'll need custom pushrods.

If you feel like risking it, the measurements for the FWD "Hybrids" have been posted before but i guess it's best to measure with the propper tool.

are the 3400 pushrods the same length as 3500's? Russel used 3400 rods in his 3.4/3400 swap...

(post #150) http://forum.camarov6.com/showthread.php?t=64963&page=4

[Superdave]

are the 3400 pushrods the same length as 3500's? Russel used 3400 rods in his 3.4/3400 swap...

(post #150) http://forum.camarov6.com/showthread.php?t=64963&page=4

Yep, same length...


hmm, i know the 3400 top end on a 3.1 block with the flat tappet cam required custom pushrods to get the propper preload. There was one guy that swore the 3400 ones were "close enough" but iirc he blew the engine after a month of driving and went to a full gen3 after that.

I'd measure it either way, geometry is important..

[ForcedFirebird]

Yep, same length...


hmm, i know the 3400 top end on a 3.1 block with the flat tappet cam required custom pushrods to get the propper preload. There was one guy that swore the 3400 ones were "close enough" but iirc he blew the engine after a month of driving and went to a full gen3 after that.

I'd measure it either way, geometry is important..

Blew it because the valves were stying slightly open, or because another issue?

Everything is getting measured at final (*fingers crossed*), but if I know what to look for now, it will make it easier in the end. The 3.1 and 3.4 use the same lenght pushrod, and to my knowledge the cam to deck height hasn't changed from the 3.1 to the 3500, but I'll get back once I'm that far.

Just picked up the 3400 exhaust gaskets today, and while I was there, ordered a set of Cavi seals, and loner666 sold me a set of '02 3400 heads with LS6 springs on them with a bent valve and stripped rocker stud on each. Didn't think it was a good idea to try and use the seals after bent valves were pushed through them, lol. Also picked up a set of the 3400 metal LIM gaskets so I can re-build the heads and port them for someone

[Superdave]

He never clarified what happened.. and then he dissappeared.

[loner666]

Blew it because the valves were stying slightly open, or because another issue?

Everything is getting measured at final (*fingers crossed*), but if I know what to look for now, it will make it easier in the end. The 3.1 and 3.4 use the same lenght pushrod, and to my knowledge the cam to deck height hasn't changed from the 3.1 to the 3500, but I'll get back once I'm that far.

Just picked up the 3400 exhaust gaskets today, and while I was there, ordered a set of Cavi seals, and loner666 sold me a set of '02 3400 heads with LS6 springs on them with a bent valve and stripped rocker stud on each. Didn't think it was a good idea to try and use the seals after bent valves were pushed through them, lol. Also picked up a set of the 3400 metal LIM gaskets so I can re-build the heads and port them for someone

'03 not '02..lol..doesnt make much difference i know..glad you picked up seals..i hated those 318 seals at are on there..they leaked since they day i started the car

[ForcedFirebird]

What exactly is the advantage to using 2.2/318 seals? I measured the 2.2 Cavi seals against 3500 seals and they appear to protrude above the guide the same amount (~.15"). Am I missing something? Are the press-on seals just better then the insert type?

I also noticed the install height, do we need the shims? Is that just to give more seat pressure?

Sorry about the noobish questions, but I have searched for a solid answer and there is conflicting information.

[SappySE107]

The fit around the guide is the problem. The 318 need to be shaved on the ID to fit the guide easier. The 2.2 seals are direct fit. I have no idea why you would want to run all exhaust seals though. I used intake and exhaust from the 2.2.

[ForcedFirebird]

The fit around the guide is the problem. The 318 need to be shaved on the ID to fit the guide easier. The 2.2 seals are direct fit. I have no idea why you would want to run all exhaust seals though. I used intake and exhaust from the 2.2.

Maybe you misunderstood the question. I bought two complete sets of Cavi seals (4int, 4exh). Is there a reason we NEED to use these, it seems as though the 3500 seals would work fine. This is my first time dealing with the spring swap, and just didn't understand the reasoning behind the seals and shims (unless the yellow springs require a 1.6" install ht).

I'm sure I'll upgrade to some better springs, but this was a cheap way to get running with all the collecting of parts that's been going on over here .

[SappySE107]

The yellow LS6 springs do not fit the stock seal/seat combination. You need to use the isky seats, or bore the ID of the LS1 seats to fit the guide. Then you use those seals.

[ForcedFirebird]

The yellow LS6 springs do not fit the stock seal/seat combination. You need to use the isky seats, or bore the ID of the LS1 seats to fit the guide. Then you use those seals.

Oh, I see now. you guys are going to have to bear with me here. I bought the used heads from loner666 with the yellow spring conversion already on them. I just went to the garage and lifted a couple of the shims and see what you mean now.

Actually, there doesn't appear to be any seats on these 3400 heads, I'll get some pics in a few...

[SappySE107]

Oh man I hope that isn't the case!

[ForcedFirebird]

Oh man I hope that isn't the case!

Well, I don't see any seats here...



Not too concerned bacause basically I paid for shipping to get the heads with the springs, but I was hoping to rebuild these heads to sell


Could be the reason for a bent valve in each head?

[SappySE107]

Those shims are what some people use for seats. I use the ls1 spring seats.

[ForcedFirebird]

Those shims are what some people use for seats. I use the ls1 spring seats.

AHHH, I posted that the shims were on there, maybe you missed it. Do the LS1 seats keep the springs centered? Eh, I'll just pick up a set of the springs from the store later and use the shims for now.

Just want to get this thing back together! I'm going to run into more problems after the install, I'm sure.

Anybody have a Vortech truck TB cable laying around, lol. That's the only one I know that is long enough to reach around the TB on a 3.4 hybrid .

[Superdave]

i've used just SBC copper shims like that on 2 different 3x00 engines, no problems yet!

the LS1 seats do keep the spring centered, i'm planning on swapping to those this winter...