I have my q-jet mounted on a open adapter but after reading what Randy and a few others has said about it I'm going to switch it out to the 4 holes style...
Q-jet on a square bore Edelbrock manifold?
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pontiacgp said:
I would like to confirm though someone has actually had success with this. When will you be doin the change? I went to E-brock's site and the only "Q-jet on a Square Manifold" option they have is the open style. The 4 hole versions are for the OTHER direction (Square bore on a qjet manifold).
I've never tried going spread to square, but the idle and light throttle response is similar on both carbs and it damn sure works the other way. Only problem might be if the flow is disturbed going the other way. Edlebrock use to say not use a spreadbore other than Holley on an adapter, but that was before they started selling them.
I'll be doing the change in a few weeks before I put my car back on the road. I doubt the differences would be something noticeable and if they are it's probably in my head. To properly analyze the differences I would need to dyno it before and after. If it give me as few more feet out of a gallon of gas I'll be happy.....
I would just like to add something here. The engine I just had put in my Malibu is running a high rise single plane manifold (spread bore)with an Edelbrock carb. And my mechanic also out on a 4 hole adapter/spacer, he said these carbs run better with them. And he's been building and tuning race cars for over 30 years.
guys i dont see the problem with power. i have a q-jet with an open adapter on a square bore intake it seems to work great and idle great. ive tried both adpaters and i didnt feel a diffrense. if it is robbing power i sure cant notice it from the other one.
not trying to be a dick or tell u guys ur wrong cuz ur probly right i just wanted to give my opinion lol sryjacobdavis1979 said:
Update: I finally got the Q-jet installed. After some tinkering I got it running great! I went from 12 miles per gallon freeway to 16.44mpg freeway on a 99 mile trip (with some stop and go the last 10 miles and some traffic idle) with most of it being at 73 MPH and not being very light on the peddle away from the toll booths. I would say that is a VAST improvement.
At idle I have it set to 650 RPM and 750 in Park. I noticed that since I no longer have a dual plane essentially that adjusting on either side of the carb does not have as great of an effect as it did when I just had the Square bore carb and no spacer. I could use a little more fine tuning but I THINK that the last bit of roughness is because I do not have a cross over tube on my exhaust and I have a little bit of back pressure on my exhaust. The RPM is not constant but kind of varies about 10RPMS either way at idle. Maybe it needs a little more RPM, but I think 650 is where it is supposed to be BONE STOCK, but as I have a vortec heads, a mild Edelbrock cam, 1.52 ratio rockers and slightly .03 over the 350 there might be need to up the idle
My vacuum at 650 in Drive is 15. In park I am around 19. Does that seem right?
At idle I have it set to 650 RPM and 750 in Park. I noticed that since I no longer have a dual plane essentially that adjusting on either side of the carb does not have as great of an effect as it did when I just had the Square bore carb and no spacer. I could use a little more fine tuning but I THINK that the last bit of roughness is because I do not have a cross over tube on my exhaust and I have a little bit of back pressure on my exhaust. The RPM is not constant but kind of varies about 10RPMS either way at idle. Maybe it needs a little more RPM, but I think 650 is where it is supposed to be BONE STOCK, but as I have a vortec heads, a mild Edelbrock cam, 1.52 ratio rockers and slightly .03 over the 350 there might be need to up the idle
My vacuum at 650 in Drive is 15. In park I am around 19. Does that seem right?
I think I just found my answer...
Since I am running Flows and a true dual is this the "Sound" I am hearing at Idle and the reason for the RPM surges that seem to coincide with the pulse of the exhaust tone?
Since I am running Flows and a true dual is this the "Sound" I am hearing at Idle and the reason for the RPM surges that seem to coincide with the pulse of the exhaust tone?
im getting a bit dizzy....sorta like when a customer calls the store needing parts for an 98 Oldmobile 88 or is it a 88 Oldsmobile 98.... 
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