Thinking about scrapping my stock q-jet in favor of holley pro-jection 2-bbl system (#502-20S). Basically, I want fool-proof, long lasting driveability and better fuel economy. Something I'm not getting with my old q-jet. Was just wondering if anyone is using that system and if it has necessary vacuum ports for stock hei distributor, ecs (vapor can) and egr? Also, any hood clearance problems? Just curious at this point. Any opinions?


[Modified by trs77, 9:00 AM 11/10/2001]

 

trs77,

I'm running a stock system myself, so I can't answer your question. I'm just interested in the answer because it's one of the alternatives I've "toyed" with too; along with dropping in a RamJet or a used LS1/LT1 or some other "modern" FI engine / OD trans combo.

When I looked at the 2bbl & 4bbl Holly systems, I wondered if the 2bbl would be more fuel efficient or not. It you only used the additional 2bbls on the 4bbl when you really "needed" it, would it be just as economical as the 2bbl?

BTW, have you seen the HorsePower TV (I think it was them) & Corvette Fever (I believe they used a '77) articles about installing one of these systems?

 

The mechanic I talked to, who is into racing, said the 4 bbl was overkill for a stock engine.

 

yeah i just put it on today i have to work a couple of bugs out on it but other then thats WOW and ton more low end power and very responsive..great adjustability,its the 950cfm setup so i have it turned down low for this motor.

 

I ran a Holley Pro Jection 2bbl for about three years with a 355 with a Crane 272 cam and the performance diff over a q jet was amazing. Much quicker off idle and much more responsive. It is plenty for a small block. It is now in a box since I switched to TPI on my 383. It's for sale at a reasonable price.
email me at will_shepherd@hotmail.com for details.

 

Sounds good. Thanks, gents. I'm might have to make this my spring project. thx again. tom

 

Here's my experience. I have used the 2 barrel projection on three different engines. The first was a Buick V6 that I mounted in a Triumph TR7. The second was on my boat with the 4.3L V6. The third was on my Corvette. The one on my boat runs great. The one on my V6 worked well but always got poor gas mileage (probably not the fault of the pro-jection -- more likely related to the weight of my foot :) ). I could never get the 2 barrel one tuned in right on my big block. It gave me lots of power and great throttle response, but it seemed I always had to tweak it to keep the mixture right. I then put the carb back on my vette and was very dissapointed in the loss of power. So, I put a 900 CFM Pro-jection system on. This is the analog system (about 10 years old). I am having the same problem keeping the mixture right. I will tune it one day and the next it will be running rich or lean. So I tune it again, only to have it change again. I don't know if it is related to temperature or what. I am giving up on the analog system -- the digital systems might work lots better. At least they use a MAP sensor.

So, to fix the problem, I am putting in a chevy ECM. I mounted a MAP sensor, and built a IAC (Idle Air Control) for idle control. I also got the wiring harness from a 1990 chevy van to make hook-up easy. I am waiting for the custom PROM, which should arrive this week. I am going to use the 900 CFM Holley Pro-jection throttle body with this system. When I get it running, I will post with the details.