3.1L+3500 top swap=not possible?

[englundjd]

I've seen people say that the 3500 heads dont fit on the old school 3.1L iron head boat anchors... can someone elaborate as to why? I know the 3100 and 3400 tops can swap to a 3.1L but why not the 3500 top end?

[bszopi]

http://60degreev6.com/forum/showthre...-onto-a-93-3-1

Post #3.

[englundjd]

so the combustion chambers are larger then the bore if i am reading that correctly?

[bszopi]

Yes.

[englundjd]

so then would I be able to put a 3500 upper and lower intake on the 3400 heads and gain anything over the 3400 intake setup?

[caffeine]

3.1L+3500 top swap=not possible?

Only the upper with a 3400 lower.

[Superdave]

so then would I be able to put a 3500 upper and lower intake on the 3400 heads and gain anything over the 3400 intake setup?

3500 upper + 3400 lower is fine on 3400/3100 heads.. 3500 lower has a different port shape and location and won't match up to 3400 heads

[englundjd]

ahh I see, so the best thing to do in this case is to stick with the 3400 intake on the 3400 heads?

[caffeine]

You can use a 3400 lower and 3500 upper

[JoeNoble]

May be a noob question but what would be the advantages of using the 3.4 lower and 3.5 upper on a 3.1? Better flow? Would it hurt fuel mileage? What else would have to swapped to make it work? Throttle body?