Differences between 3.1 and 3100 heads

[Intlcutlass]

I have seen a lot of you post that you are using heads from a 3100 because they are better. Hell.....even Jeff M I think is using them.

 

What are the differences?

 

Do you have to modify anythink if i wanted to use heads from a 3100?

 

If I use 3100 heads, would i still benifit from using proformance roller rocker arms, springs, and pushrods?

 

Are the heads from a 3100 the same as a 3400??

[weisinator]

You have to use the whole 3100 top end: plenum, intake manifold, and exhaust manifolds if you want the heads. Ports don't line up with MPFI parts.

 

The heads flow 17% better on the intake and 30% better on the exhaust, when compared to aluminum MPFI heads. The intake valve is 1.76" vs 1.72". Not sure about differences in plenum and manifolds, though.

[GnatGoSplat]

Personally, I feel like if you're changing the whole top half of the engine anyway, why not go ahead and change the bottom half too?

The 3100 has a roller camshaft and the block is stiffer and better reinforced.

[Intlcutlass]

That sounds like too much to change......

I will just get the ones i have Ported & polished.

And Shawn brings up a good point too.....but I already have torn apart the bottom half of the motor and it looked really good. I just have to order the main bearings & some other stuff,....It's comin along. I just was not sure what would need to be changed....

[Brian P]

Good news is that if you keep the 3.1 bottom end, you can get a performance camshaft from GM for under $100...with the 3100 you have to get a stock one custom ground, which would be minimum $250+

[Intlcutlass]

Actually Brian, My brother-n-law and I got a quote from comp cams for $180.00 .......

[MaD]

...That's still an $80 difference

 

-MaD-

[Brian P]

damn , $180 is good still