3rdgen Fbody with 3500 heads

[loner666]

the shims were used as the seats as the stock seats dont work..the LS6 springs dont fit over them (i have them still BTW somewhere if you want them and the springs) the bent valve are because the alignment pin on my cam broke allowing it to turn which caused the valve to be open at the wrong time and BAM!! lol..i wasnt to happy to find out the the pin broke

[Joseph Upson]

I was concerned for a moment about the springs having installed LS6 spr on my heads. Are the springs that different that the stock 3500 springs can be run without a seat and the LS springs can not?

The 3900 valve stem seals have seats has anyone considered them for a better fit or are they likely the same as the LS seals since the heads were designed after the LS1 LS6 heads.

[ForcedFirebird]

I was concerned for a moment about the springs having installed LS6 spr on my heads. Are the springs that different that the stock 3500 springs can be run without a seat and the LS springs can not?

The 3900 valve stem seals have seats has anyone considered them for a better fit or are they likely the same as the LS seals since the heads were designed after the LS1 LS6 heads.

The shims don't work, as SuperDave has discovered. We need to use LS1 seats modified to fit. This will keep the springs centered.



Worked on my engine finally for a little bit today instead of everyone else's, lol. Got another 3500 comming in tomorrow, and will be dissasembling/cleaning all day.

Got the cam bearings out...



And honed the cylinders...











Now I got to order the rings (hopefully tonight after the kids are in bed), and maybe this week the crank, cam bearings and oil pump will go in.

[Joseph Upson]

The shims don't work, as SuperDave has discovered. We need to use LS1 seats modified to fit. This will keep the springs centered.

I'm trying to recall correctly since I don't have the extra heads with me at the moment but my LS6 springs are installed on 3900 heads which I recall having seals with a built on seat. It would make sense given that LS6 springs were installed on the HO engine at the SEMA show and the stock heads are designed after the LSx heads.

When I compared the stock 3900 springs to the LS6 springs I only noted a slight height difference. On the other hand since they are stronger I didn't install the LS6 springs with the metal dampening cup that was installed with the stock springs that added about .040" more preload by shortening the install height. I'm not using any type of shim.

[El_Diablo]

IIRC, the pistons are actually the same units from the ls1... anyone can correct me if they wish, just something i remember hearing

seems the 3.9 takes a lot from the lsx series

[ForcedFirebird]

Got the cam bearings in after a slight snag yesterday, also the crank, rods and pistons are done...

[19Cutlass94]

wow! looks good! nice and clean parts! haha

[ForcedFirebird]

Got the timing cover clearanced today.

Here's the interference...



Here's some shots after modification...









How does it look mocked up? I think the silver block is growing on me. Probably going to use a set of our polished valve covers to match the plenum (plenum is getting re-polished before install)...








Just wish I had a cam to put behind that timing cover, lol. Didn't have time today to call Delta, but by next week the cam and lifters will be here.

I think I may have decided to raise the compression a bit. The 3.4 gakets will give 12.33:1, but I am afraid the .030" clearance isn't enough after seeing Dave's valve/piston slap (.040" is ideal). The 3x00 gaskets and 3.4 piston-to-deck clearance will give ample room, but I don't know about keeping a .050" quench. 3400 gaskets will make 11.56:1, and 3500 gaskets will be 11.5:1.

[Joseph Upson]

Beautiful work, since I have a plasma cutter I doubt fabbing up mounting adaptors and accessory brackets will be a problem for the 3500 swap into my cousins blazer, I should be able to slice a notch out of the crossmember and box it in to clear the aluminum oil pan. I've all but lost my interest in the V8 given the work GM has done with the 60 degree engine. I'm addicted to the sound of high reving V6 engines and turbos with matched exhaust systems.

[ForcedFirebird]

If it's only the oil pan, why not adapt a Gen1 pan to fit the gen 3 block?

[IsaacHayes]

All silver would look good. It looks good sitting there. Even the blue valve covers would look good too. Paint the LIM silver while you're at it.

[ForcedFirebird]

All silver would look good. It looks good sitting there. Even the blue valve covers would look good too. Paint the LIM silver while you're at it.

Naw, going to use a set of my polished covers, put them on today to see...




Have to hit the planum with the buffing wheel again, and clear laquer everything. The LIM migh get blasted to match the timing cover, but no paint. Everytime I paint aluminum, it chips too easily and looks like crap after taking the bolts in/out a couple of times. Myabe even laquer the timing cover and LIM, but no paint.

The GM covers I made will now probably get stripped unless someone wants to trade them for an unpainted set.


Blasted the dampener and pulley today, then painted them gloss black...



Pics of them after paint, when I'm at the shop and think about it, lol.

[IsaacHayes]

Looks good. I've had good success with painting aluminum the trick I've noticed on mine is to get it thick with many layers so it's tougher. I've noticed on the parts I did thin it likes to chip off easy. But I'm careful with the painted stuff now too.

[Canyonero]

Nice work! I haven't rebuilt an engine yet, but I want to. I'm wondering if building a hybrid like this would be too much for me to take on. I just upgraded my Isuzu from a 2.8L TBI to 3.4L SFI, maybe I should force myself be content for a while.

[ForcedFirebird]

Nice work! I haven't rebuilt an engine yet, but I want to. I'm wondering if building a hybrid like this would be too much for me to take on. I just upgraded my Isuzu from a 2.8L TBI to 3.4L SFI, maybe I should force myself be content for a while.

It's actually the same as rebuilding any other engine, but you have to research/find the compatable parts that will work best for you.

The shortblock is a standard rebuild, actually.