3900 discussion

[95SleeperAcheiva]

did you guys know this thing has powdered metal rods? and main caps? the cam is "assembled" lobe by lobe?

Anyone got one laying around? I'm curious on the lower intake to head bolt pattern, lifter bore size, cam bearing ID's, cam center line to crank center line measurement... I'll think of more wait...

I wonder if a 3500 intake will bolt up? stock TB is 72MM, Ben can you make a 75?

Do you see what happens when you can't sleep and you have a forum available at 4:37 AM?

Oh Oh Oh, there's a 3-valve per cylinder coming out too!!!

[bszopi]

The cams have been assembled lobe by lobe since mid-93, when the 3100 first came out.

[bszopi]

And in case you didn't run across it, here is a pretty good thread (with pics) about it:

http://60degreev6.com/showthread.php?t=32343&highlight=3900

Then there is always all of the pictures in the gallery for it. I'm not sure if its back up or not yet, but there is also a multi-page GM press release highlighting the engine as well.

The 3500 also uses powdered metal rods. I have 1 bent and 1 broken one in my basement.

And there is a discussion on here about the 3-valve heads as well.

[IsaacHayes]

Adapt a 4.3l 70mm TB to work, that'd be the easiest/quickest route. Midnight made adapters before for it (for the 3500).. 3500/3400 etc stuf wont bolt up, at least not the upper intakes. It does appear that the upper needs to be port matched, as it looks like tiny openings compared to the lower which looks already opened up all the way to the gasket!

Is the 3500 lower like that too? Gasket matched factory? I know the plenum needs to be opened up quite a bit!