VVT/non VVT parts interchange?

[NateD4]

You might be right. However I won't know until I bolt one up to see.

The gasket does match and the dowel pin holes line up. Unless there is a small mismatch that I can't see.

The 3900 I have uses a spacer gasket.

And my best efforts to measure the rocker put the ratio at 1.52:2 to 1.53:1.

Of course the actual ratio is not constant.

Maybe the LZG uses different rockers then a LZ9??

I don't think the heads are a perfect swap, especially when it comes to valve to bore clearance, but I think you could bolt them together... Perhaps even use the intake and coolant crossover.

Maybe if I have time tonight I'll try to set a 3900 head on a 3400 block. See what happens...

[SappySE107]

Why do I bother...

[pocket-rocket]

Someone has to pilot the Failboat

[NateD4]

Hey I have the parts here for now. Once the engine is together no more data can be gathered.

[SappySE107]

you put your 3900 heads on your 3400 block, and ill put my 3900 heads on my 3400 block, and we can see if GM made the same 3900 heads and 3400 blocks.

[NateD4]

Funny.... But why not.

I can put the 3400, & 3100 heads on my 3900 block as well.

What specifically makes the 3900 heads not fit on your 3400 block? Dowels? Bolt holes? Intake manifold?

[carbon]

Look through the bottom of the block at how the combustion chambers line up with the cylinders...

Actually, we mounted a 3500 head to the 3900 engine and it appeared that the holes were in the correct locations. The problem is that the combustion chamber is not centered with the bore. GM moved the cylinders out 1.5mm on each side, making the block and heads wider. Whether it would be capable of running that way, I do not know. You would want to keep the 3900 top end anyways.... much bigger ports and valves.

[NateD4]

I fit a 3900 LZ head to the 3400 LA1 block.

Dowels lined up. I even could move the valves without collisions.

Combustion chamber over hangs a bit. I'll have to see if the gasket for the 3400 will seal.

[gectek]

Honestly, with the valves that close to the chamber wall, why would you even try it? You lose ALL the flow characteristics by putting them on a smaller bore.

[NateD4]

It'll physically work if the head gasket seals. Flow probably isn't optimum.

A picture is worth a thousand words in this case.

[ericjon262]

on the subject of the UIM, do any of the 4th gen UIM flow better than the LX9 or 3400 intakes? Sappy said they can work with adapters, but if there is no gain to be had I wouldn't worry with it.

[SappySE107]

I did not say they can work with adapters. I said I have an adapter in reference to a cable driven TB to be used on the VVT uppers.

[3400-95-Modified]

Funny.... But why not.

I can put the 3400, & 3100 heads on my 3900 block as well.

What specifically makes the 3900 heads not fit on your 3400 block? Dowels? Bolt holes? Intake manifold?

Coolant passages between the block and the head, check all of those you'll find some that are not properly open or going to seal when installed. Maybe it was more due to the MLS design but I know if I had use those gaskets that were fitted to the VVT motor they would have leaked coolant into the cylinders IIRC. A 3400 gasket will BARELY seal a 3500 head so if its known that a 3900 combustion chamber is larger then your just wasting your time.

Oh an yeah just because it fits doesn't mean it will work. Accepting that you'll take the flow characteristics away from optimal is simply the dumbest comment I've heard before. Why not just pull a spark plug wire off while your at it, you'll get non optimal combustion.

There is also plenty more info in this thread.
http://60degreev6.com/forum/showthread.php/34884-3900-heads-on-the-3500-!

If nothing came from that then what makes you think you having the idea will make it work?

[ericjon262]

I did not say they can work with adapters. I said I have an adapter in reference to a cable driven TB to be used on the VVT uppers.

sorry, I thought you were refering to the intakes when you posted about adapters in the other thread.

do they flow any better though? and do the ports line up at all?