3400 heads are they worth it

[rx191]

so i'm trying to make a decision and need a little help, i'm in the middle of doing a 3400-3500 top end swap on my 95 3100, i'm debating on swapping a set of 3400 heads off of 03 or just grinding on the intake and putting it all back together, i don't want to swap the motor as it's lot more work right now, i know the heads flow better than the ones i have now but how will the fuel mileage be, if it goes down a lot i don't know if i want to do the swap the car is driven daily let me know your opinion!

[SappySE107]

Id be surprised if mpg went down from bolting 3400 heads on your 3100.

[rx191]

i guess i was thinking that the increase in flow would hurt low speed air flow and thus hurt economy, how much more power are we talking though over just the intake swap approximately 10 or 15 maybe?

[asylummotorsports]

I can't see the heads hurting fuel mileage, unless of course you have your foot buried in it all the time enjoying the new found power, however I have to ask/mention.

IMHO it would be easier to swap engines than re and re heads with the engine in the car.

No?

[SappySE107]

If you don't have a hoist, it would be much more difficult:P

[IsaacHayes]

3500 heads wont work on a 3100, the combustion chamber would be larger than the bore.

3400 heads and intake will help with MPG actually. I'm still using my original heads, but the intakes helped with my mileage. The car doesn't have to downshift on the highway to pull a steep hill at 70mph with a locked torque converter at 2,000 RPM anymore.

[rx191]

decisions suck sometimes! well i think i mite just go with the 3400 heads, there isn't that much work to get them off with the intake off right now any way, and there is more positives than negatives, thanks for the input.

[torq455]

there aren't any negatives to upgrading to the 3400 heads. they are simply better, or GM wouldn't have put them on. they would have kept the 3100's heads. they won't hurt mileage at all.