Vaccum Secondaries or Mechanical Secondarys whats everybodys preferance

[A/Fuel]

Re: Vaccum Secondaries or Mechanical Secondarys whats everybodys preferance

I have a 750 vac. secondary on my camaro, when I used to bracket race it I did just what the other guy said, I put a stiffer spring in it and it was real constitant. At the time my brother-in-law worked for Bo Laws, and we built it there.
It worked good enough that they started selling them for a while, they still might. We later put thinner throttle blades, a 50 cc pump and a .045 shooter in and with a lighter spring ran as good as a double pumper. We also put a metering plate in the back, milled the choke horn, things like that....I still have it on my car after trying a few other carbs.

[groucho]

Re: Vaccum Secondaries or Mechanical Secondarys whats everybodys preferance

I was at the track yesterday for a test and tune and had been having carb running concerns with the 650 dp mech secondaries. So my friend gave me a 750 vac that was set up to run on his Cleavland. I put it on and the difference was so much better. I think I definitely am liking the vac secondary carb.

Vac/no vac may NOT be the reason for the improvement

[nosnerd]

Re: Vaccum Secondaries or Mechanical Secondarys whats everybodys preferance

double pumpers and solid rollers

yeah baby!!! ;D

[SpiderGearsMan]

Re: Vaccum Secondaries or Mechanical Secondarys whats everybodys preferance

heavy cars are said to prefer vac sec

[Schtauffer]

Re: Vaccum Secondaries or Mechanical Secondarys whats everybodys preferance

Having messed around with both, I like mechanicals.

[Bamfster]

Re: Vaccum Secondaries or Mechanical Secondarys whats everybodys preferance

Mechanical and solid lifters (too poor for a roller)

[Screaming Detroit]

Re: Vaccum Secondaries or Mechanical Secondarys whats everybodys preferance

I agree that the dp/mech carb is the way to go, but for my hodge podge motor that isn't the most powerfull thing it does like the vac carb. I tried a 600 Holley, EHHH motor didn't like it not enough fuel with bog out of the hole, then came the 650 dp/mech good power going down the track bog out of the hole. 750 vac no bog best time yet. Maybe its time to get my hands on a 750 dp/mech and see what happens.

[yellomalibu]

Re: Vaccum Secondaries or Mechanical Secondarys whats everybodys preferance

heavy cars are said to prefer vac sec

If you have enough converter, the DP is fine... I would never use a vac sec on my Chevelle.

[squirrel]

Re: Vaccum Secondaries or Mechanical Secondarys whats everybodys preferance

It's all about getting enough airflow when you open up the throttle. Lots of ways to do that...mostly they involve having the right size carb, and letting the engine rev up (don't force it to run at full throttle at low rpm).