New user, new project, and a blower question.

[hemmigremmie]

Hello.
Im new to the forum and thought Id introduce myself and my project.
My name is Rod and Im 38 years old. My car is a 5 year project and is a 73 prostreet Gremlin. Its fully tubbed with 18.5 inch rear tires, 4 point cage, 2 speed glide, racing seats, guages n tach, fuel cell and all the goodies.
The engine is a freshly bored 030 over 350 Chevy with a factory steel crank n rods, Speed pro blower pistons, 465-485 X 279-280 cam @ 114 degrees of lobe seperation. Edelbrock Alluminum rpm heads. Steel balancer, Weiand 6-71 blower with 2 Edelbrock 500cfm carbs, milidon water pump, MSD distributor with MSD box, rev limiter and boost retard.
The kit came with pullies that produce 10-12lbs of boost and I have right at 8-1 comp ratio.
Im told that with alluminum heads its like having 7-1 comp ratio. Ive also been told that with my setup and with the boost retard that I can run pump gas, but the chart has me at about 12.7-1 at 12lbs of boost???
I was told that with my cam n heads that it should bleed off and make less boost and since its a street drivin ride and will only see 5800-6000 rpms that I'll be OK. Any thoughts on this? Thanks, HG

[34ford]

Well welcome aboard anyway. All the other stuff is greek to me except I did have a Gremlin I bought new in 70's so I know what you are talking about. Ordered it with the biggest 6 they had and boy was that a mistake, drank gas like it was going out of style.

bob

[kb426]

The statement about alum heads isn't quite correct. You will loose some combustion heat at full load but nothing like a full point. The following are things you need to have to run more than 7 lbs. of boost: the block and heads should be oringed, 4 bolt main block, forged steel crank, really good rods, balancer needs to be double keyed, head studs, no more than 28 degrees ignition timing. My exp. with these has been to run the blower at 10 % under drive in ratio. As a rule, anything more than 7 or 8 lbs. on a street motor and you'll have detonation and loose the motor. Even with the ignition retard, there's a real risk of detonation. The 6 is alot of blower for a small block street car. We ran those on a blown alky dragster at 6% over and had a flyer. The alky makes that possible. Blown gas is the equivalent of driving around with a bomb that you don't know how much fuse you have. I don't know what your exp. is but if you haven't been around a roots blower before, see if you can find a real exp. racer to spend some time with you and explain the basics of blower maintenance and show you how to make sure everything is ok before you fire it so you don't ruin your parts. One backfire will ruin your blower. Be really careful.