Re: My HMT 78 Chevy Monte Carlo
 

That's how they function. Plus with them you can run alot less jet and maintain a good a/f during cruise. On my last turbo car they were the cure. I dropped 2 points in the a/f ratio with the vent tubes. Then I jetted the carb back down till I got a satisfactory a/f ratio. Ran great and didn't make the people behind gag during cruise.

Re: My HMT 78 Chevy Monte Carlo
 

you need to point your vent tubes, when extended, AT the incoming charge. it'll help loads, and people have dropped 15-20 in jets, and get better off-boost afr's

Re: My HMT 78 Chevy Monte Carlo
 

I am going to try the bigger needle and seatsand see what kind of effect it has on the carb. If that doesn't do it, I will give the vent tube extensions another shot, but this time with less jet than 72 and 82.
I was thinking today that my tank still has the stock pick up with 5/16 line and a factory style sock. I think I am going to drop the tank, remove the pick up and modify it the HMT way to run a 1/2 feed line to the pump and all the way to the regulator. I figure 50 dollars or so on material and it would definitley give me peace of mind. I don't know why I didn't think of running it that way in the first place. That 5/16 line could definitely be the draw back of my fuel system. I am going to try swapping the needle and seats first and try the vent tubes again, but I don't think that either will be enough until I get rid of the restrictive 5/16 feed line.

Re: My HMT 78 Chevy Monte Carlo
 

any updates????? ;D

Re: My HMT 78 Chevy Monte Carlo
 

I finally got the demon carb running right. Basically, I fixed the lean condition at wot using vent tube extensions. When I first tried them, the car used to buck and stumble and not run right. Then, I figured out that I can tune it by adjusting the length of the vent tube extensions. I shortened both vent tube extensions and all the stumbleling is now gone and the air fuel ratio remains rich. It is now running 17 lbs of boost, #69 jets in front, #90 jets in rears and 21 degrees of timing at full boost. Hopefully I can make it to the dyno soon to see what it does.

Re: My HMT 78 Chevy Monte Carlo
 

17psi on 93oct.? you mentioned before you were ~9.5:1 CR right?
thats gotta make some ------ NICE power.

Re: My HMT 78 Chevy Monte Carlo
 

Yeah, the car pulls like a freight train. It does have 9.5:1 compression so I am probably pushing the motor a little too much with 17lbs, but I just can't convince myself to change the wastegate spring to lower the boost. What really should be done to this motor is lower the compression and crank up the boost, but for now, I am just running it the way it is.

Re: My HMT 78 Chevy Monte Carlo
 

take it to dyno/track yet?

Re: My HMT 78 Chevy Monte Carlo
 

No. Ever since gas went up past 4 dollars and me flat rating less hours at work, I barely look at it. I took it out the other night to the gas station and to 7 eleven, leaned into it a little and then parked it. I hope to do something with it sometime this year.

Re: My HMT 78 Chevy Monte Carlo
 

can u give me some info on ur turbo setup

i am looking to build a turbo'd 383 for cheap next summer

and was curious about ur turbo and intercooler, prices, how they work, and if u like them etc

thanks
-thedocta