Where to start?

[JimC]

I am intrigued with the idea of Q-jets working like FI.  I have 3 Q-jets, I am wondering which would be the best platform to start with?

     17081226
     17082226
     Edlebrock 1904

I have Cliff's book and 3 other Q-jet books.  Right now, I have a Holley on my truck, but I believe I can do better.  My vehicle is an 81 Jimmy.  I have a new 249hp 350 crate motor with an EPS intake and a 570 Street Avenger. (I have 2 more Holleys).  I still use the cast iron exhaust manifolds, but have gone to 2" dual exhaust.  Since the warranty is still good on my engine, I have not made any real changes to it.  I have, however, changed the drive train.  It came stock with 2.54 rearend.  Shocked(GAG) Now I have 3.73 front and rear with LSD's.  I am only interested in fuel economy and torque.   

So where from here?

Jim

[comp]

i'd do headers and 2 1/4 or 2 1/2" pipes with a H or X , before diving into this ,,,but thats me 

[JimC]

Thanks for the come back.  Headers are in the future, but also, I want to start from the top down.  Carb and intake, then I have to change the radiator and waterpump.  Finally a 700r4 tranny.  I have a th-350 now and I would like OD.  The headers are next.  Most of the parts I have all ready.  I am hoping to figure out which carb should be my base to start.

Thanks again,

Jim

[jamesF]

Jim-
I think in the book, Cliffs states that he likes the later Carbs (76-79) For their flexibility.

Based on the Numbers Article on Cliffs site here:

http://www.cliffshighperformance.dreamhosters.com/tech_carb_ID_2.html

From what I can discern your Q-jet carbs both appear to be Chevy Carbs. One is an 81 one is an 82.
Probobly identical except the year.
Based on http://www.cliffshighperformance.dreamhosters.com/tech_qjet_history_5.html
It sounds like you can make good use of those carbs once you remove the EEC "stuff"

I cant speak to the merits of the Edelbrock. Im sure Cliff will respond.

[makomark]

Jim:

If memory serves me right, 81 was the year of the electronically controlled solenoids and reinforces JamesF's "EEC stuff" observation. Based on your choices, assuming you don't have an ECU with your crate motor, go with the edelbrock - those electronic controlled beasts aren't worth modifying to a pre-1981 state.

I'd do the transmission first as the OD will help with the economy. You also won't have to remove those "recently installed" headers, with their rusty bolts, if you adjust your plan - just a thought.

[JimC]

The 81 had EEC type chip and distributor.  The thing merely detects engine knock and the retards the timing.  The good thing is that the carb has no solenoids or switches.  I have a Mallory(Summit brand)  distributor an MSD box and MSD Blaster 2 coil now.  I experimented with various configurations of the HEI, but the MSD setup gave me the best fuel economy. 

Everything I have ever read, says the Q-jet works best off-road and on.


Thanks,

Jim

[Cliff Ruggles]

Jim, the 1980's Chevrolet carburetors are excellent, and exactly what Edelbrock used as a base-line for their 1910 "850" cfm high performance quadrajet.  The last chapter in our book should be used to custom tune the later non ECM controlled units with the single main airbleed design.

Any of those carburetors will make as much or more power than the Holley carburetors, and be a LOT more reliable in long term service.  They are also a much more efficient design, so expect superior off idle throttle response,  improved fuel economy and overall driveability......Cliff

[JimC]

Thanks for all the info.  One thing I have not found yet is what size were the main well plugs tapped?  I found what the smaller plugs were, but not the larger ones.

My Edelbrock 2101 will have to come out of mothballs and be cleaned and setup for the Q-jet.

Thanks again Cliff and others.

Jim

[Cliff Ruggles]

Jim, all of the factory bottom plugs were pressed in aluminum or lead.  They did not use threaded plugs.

We recomend the pressure test as outlined in our book, and then tapping the castings and installing screw in plugs if needed.  We have the correct screw in plugs available separetely from our rebuild kits.  The casting will need to be tapped to accept them.....Cliff

[JimC]

Thanks Cliff.  I do appreciate it.


Jim