Starting a pretty odd project that I need some advice on. (TBI to MPFI conversion)

Hey, guys! Figure this would be the best place to ask a few questions about this project.

Here's what I'm working with so far:
-1995 Hummer H1 (yes, you read that right)
-TBI 350
-4L80E trans
-2.73 gears
-40" tires

This is gonna be along read, but I'd appreciate any input! :)

Alrighty, so me and a friend are starting a project for the H1. So far, we have intalled a Whipple on top of a Performer for a little more power, and installed a Walbro adjustable fuel pump with a 454 2" throttle body, with stock injectors, but now we wanna go bigger and badder, and have a basic plan.

My buddy, who owns the H1, picked up an Edelbrock 3502 intake (info HERE) and wants me to build the motor up a bit. So far it looks like we're gonna do:
-Aluminum heads
-Cam swap, I wanna go roller if it isn't already.

And obviously gonna need a tune for all this. (Already emailed Mark, waiting for a response.) We have the Edelbrock MPFI chip, but we need it tuned for the Whipple, and it is a different chip than the current computer uses.

Right now, I need to know what type of heads y'all recommend. Are there any nice aluminum heads around that offer good performance and fit the TBI intake bolt pattern?

What type of cam would y'all recommend?

Also, according to this chart:
http://i41.tinypic.com/2ahsfab.jpg

I should be running at least 4.88's, so what gears do y'all recommend personally?

I appreciate any info y'all may have! We'd like to start as soon as possible! :)

Dont forget the H1's have portal axle hubs that have a gear reduction of something like 1.96. So combine that with the stock 2.73 gears gives you a final axle ratio of close to 4.69.

You'll want to keep the heads and cam on the small side to help the 350 build some bottom end torque for that heavy rig. I'd run the ZZ4 cam and a set of AFR 180 heads. The ZZ4 cam has a large duration split favoring the exhaust, which is needed with forced induction. It also has mild lobes which should work well with the springs that come with the AFR heads. You can also run stock hydraulic roller lifters with the spider retainer in your block. Use 1.6 rockers on the intake side.

Quote:

---

Originally Posted by JeepsAndGuns

Dont forget the H1's have portal axle hubs that have a gear reduction of something like 1.96. So combine that with the stock 2.73 gears gives you a final axle ratio of close to 4.69.

---

Thanks for the info! So will I benefit at all by going a little taller, maybe 3.42s or 3.73s in the differentials?

Quote:

---

Originally Posted by Roadknee

You'll want to keep the heads and cam on the small side to help the 350 build some bottom end torque for that heavy rig. I'd run the ZZ4 cam and a set of AFR 180 heads. The ZZ4 cam has a large duration split favoring the exhaust, which is needed with forced induction. It also has mild lobes which should work well with the springs that come with the AFR heads. You can also run stock hydraulic roller lifters with the spider retainer in your block. Use 1.6 rockers on the intake side.

---

Thanks for the recommendations! Will those heads fit the MPFI intake bolt pattern? I'll look them up now.

Quote:

---

Originally Posted by jdyates

Thanks for the info! So will I benefit at all by going a little taller, maybe 3.42s or 3.73s in the differentials?

---

Use this calculator to find your new info. Just when you enter in the axle ratio, do not forget to add in the portal axle reduction.

http://www.grimmjeeper.com/gears.html

From what I entered in, if you went to 3.73 gears, your RPM at 70MPH would go from aprox 1930 up to 2342.
Its very handy for figuring out what to expect with tire and or gear changes.