3500 lower is not the same as the 3400

[SappySE107]

I had read that the 3500 lower was the same, because the plenum bolts up to both. Not the case. The 3500 ports to the head are much higher than the older engines, and willnot line up properly without welding in metal to the head and porting both manifolds (and thats just a maybe).

Found out the hard way as I got an upper and lower off ebay even though it was listed at a 3400 lower....

Plenum looks sweet though.

[pmwltd]

RE: 3500 lower is not the same as the 3400

Would you be interested in selling the manifold?

[Manitcor]

RE: 3500 lower is not the same as the 3400

however if you use 3500 heads your fine, correct?

[El_Diablo]

i thought the head were different too....










(how they line up to the block)

[SappySE107]

After I take some measurements on the manifold, I would be interested in selling it. I don't really know what its worth right now though. It better bolt up to 3500 heads:P

[Manitcor]

well I know that, but I mean the 3500 heads bolting to the 3400 block

[El_Diablo]

well I know that, but I mean the 3500 heads bolting to the 3400 block

me too... i mean will there be an alignment problem with the intake if the head bolt to the block? never know

im kinda doubting the 3500 heads are a direct bolt on (duno why but i have this feeling lol)

[SappySE107]

It matchs up with the coolant passages for the most part on the 3400 head, and the dimensions externally look the same when bolted up the to the 3400 head as the 3400 lower does. I dont have a block here to test fit it though.

[pmwltd]

The 3500 heads do bolt up to the 3.4 block. I have one bolted up in the shop right now. Other than the height of the intake ports, all the bolt patterns look the same.

[matt_p]

if you need to, get a pair of head gaskets to check.

when more parts are easier to get, 3400/3500 hybrids could be made to fit in our vehicles. no worries of the 24x trigger

[SappySE107]

Id be more worried about shrouding and the combustion chamber overlaping the gasket. If that all checks out, then hell yeah! I gotta do a new bench so I can change my cylinder for the larger bores.

[El_Diablo]

Id be more worried about shrouding

nothin that a good port and polish man cant take care of

[SappySE107]

Um, if you are porting and polishing the cylinder walls, thats great. I am talking about the combustion chamber being close in size for the 3500 bore since that is the smallest bore those heads will see stock.

[El_Diablo]

Um, if you are porting and polishing the cylinder walls, thats great. I am talking about the combustion chamber being close in size for the 3500 bore since that is the smallest bore those heads will see stock.

you weld the cumbustion chamber and port it to the shape you want/need

[SappySE107]

Then you are back into the valve area. The 3500 has larger valves from what I can see in the pictures.