lars

As all you Q-Jet tuning guys know, I've been keeping and updating a Q-Jet carb listing/application chart over the years. This chart shows carb numbers, applications, and correct jetting for the various carbs. The chart is not all-inclusive, but I keep adding carb numbers to it on an irregular basis.

Lately, I've been receiving a lot of tech e-mails requesting information on sources for Q-Jet jetting components. Sad story is, the jetting parts for these carbs are being discontinued faster than I can drink beer. But some parts are still available from GM. It's odd, though, how parts for the 1975+ carbs are being discontinued faster than the parts for the 1967-1974 carbs. Those of you with 1978 carbs are really screwed, as all primary jet/rod parts for 1978 carbs are gone... So if you're into tuning Q-Jets, start scrounging and saving parts...

The latest version of the Q-Jet listing Chart shows all the parts that are still available with green highlights. Looking at the chart, I think you'll be shocked at how many parts are now gone.

If you'd like an MSExcel version of the latest chart, drop me an e-mail request to:
V8FastCars@msn.com

..and I'll keep adding more numbers and facts to it as I go along...

turtlevette

can't you get parts through Edlebrock?

I got primary jets a few years back through them.

turtlevette

can you get parts from Edlebrock?

i got some primary jets from them once.

lars

Yes, Edelbrock has some tuning parts - all EDL parts available are outlined by part number in my Q-Jet Tuning Paper.

But you have to be careful on the EDL primary rods for the 1975+ Q-Jets: The EDL rods are TRUCK rods - not passenger car rods. The truck rods have .036" diameter power tips instead of the .026" passenger car (Corvette) tips. If you use these EDL rods in your carb, your WOT mixture will go extremely lean, and you'll have significant problems with your tuning for best power. The only way you can use and tune with the EDL rods is to use metering area information to keep WOT area constant when switching from .026" rods to the .036" rods. Since #77 jets are the biggest jets you can get, you can't use the EDL rods at all in a carb that needs jets any bigger than #73 with the standard .026" rods. (#73 jet with correct passenger car .026" rod produces the same WOT metering area as a #77 jet with the EDL .036" truck rod. Since you can't get a jet bigger than a 77, you're very limited what you can use the EDL rods for).

Here are all the EDL part numbers that are available:

Primary Metering Rods (pairs) for 1974 & earlier:
.035” #1936
.037” #1937
.039” #1939
.041” #1942
.043” #1944
.045” #1946

Primary Metering Rods (pairs) for 1975 & later:
.048” #1941
.050” #1943
.052” #1945
.054” #1947

Secondary Metering Rods (pairs) for all years:
CC #1950
CK #1952
CL #1954
CE #1951
AY #1953

Primary Metering Jets (pairs) for all years:
.068” #1968
.069” #1969
.070” #1970
.071” #1971
.072” #1972
.073” #1973
.074” #1974
.075” #1975
.076” #1976
.077” #1977

Boofers

I purchased some EDL rods and I found that these rods were tapered at the tips whereas my stock ones had steps. I didn't use them because I didn't think the taper was right. Now that you mention the 0.036" tips its a good thing I didn't use them!

Just emailed you Thanks Lars!

PRNDL

lars, a few years ago I got an Echlin choke thermostat spring for my 68 bigblock at the Napa store. I checked a few weeks ago and they stopped making them!

lars

PRND -
The Camaro restoration places still carry them if you need one: the coil for the Camaro big block is the same as the Vette BB.

djcwardog

I am still not sure how the recent Edelbrock (basically an updated Rochester) 1901 to 1905 carbs fit the picture. My car came to me with a #1902 carb. They are said to have different float heights, triple venturis, different rods and jets, etc... Can I use old (pre '74) parts or am I locked into what Edelbrock currently offers? I may need to richen her up a bit after I go from stock manifolds to 1 7/8 Hooker headers. Can I get straight scoop on the difference between the carb that came stock on my '73 and the #1902? Any reason I should try to get a correct 1973-spec carb and sell off the #1902?

lars

The Edelbrock carbs are re-pops of the early (1968-1974) and late (1975-1980) Q-Jets. You have to identify which version you have. The EDL carbs that duplicate the early Q-Jets can use all GM jetting components (jets & rods). The EDL carbs that use the later components use the .036" power tip rods, and you have to consider this when doing jetting & rod changes.

As for your jetting requirements, all you have to do is bump primary jet size up 2 sizes. You can use either EDL or GM jets - they are identical.

lars

All requested papers have been e-mailed out as of 2-24-05. If you requested a copy and did not receive it, please let me know...

turtlevette

didn't get mine. jimmack0000@aol.com

djcwardog

Hey Lars,

You have been great to answer my questions on your recent thread. I would like to read your papers.

You mentioned that I would have to determine whether my Edel #1902 is an early or late carb design. Not being sure, I went to Edelbrock's web site. Check this out:

Reconditioned Q-Jet Carburetors

Professionally rebuilt at Edelbrock headquarters in Torrance, California, these reconditioned Q-Jets are completely disassembled, inspected and thoroughly cleaned before reassembly. Any parts that are reused are inspected and tested using strict QS9000 quality control standards. Components that don’t measure up are replaced with brand new parts. All reconditioned carburetors are 100% guaranteed, assembled with new gaskets and pressure tested to 6 PSI to insure leak-free operation. 30-day factory warranty.
New Carb Part No. Reconditioned Part No.
#1901 (750 cfm, divorced choke, early) #9971
#1902 (750 cfm, divorced choke, late) #9972
#1903 (795 cfm, hot air choke) #9973
#1904 (795 cfm, electric choke, S/B) #9974
#1910 (850 cfm, electric choke) #9975
#1905 (795 cfm, electric choke, TQ) #9976
#1906 (795 cfm, electric choke, B/B) #9985

Seems like the #1901 uses early parts and the #1902 uses late parts. The stock carb for my car was part #7043201 Rochester 4MV - which Edelbrock cross references to require use of their #1901 carb. From the specs below both the #1901 and #1902 carbs use the same rods and jets... So I am still confused about what parts are in there! Should I pull that carb off and buy something else - what? They make a model 1910 performance Q-Jet at 850 CFM:

Performer RPM Q-Jet, 850 cfm, electric choke ....#1910

Only 850 cfm Performance Q-Jet That’s Ready To Go!

This carb is a high-performance version of the Q-Jet calibrated for use with Performer RPM Q-Jet manifolds and other high performance, non-emissions applications. It has an 850 cfm air flow capacity, and the .145" diameter needle and seat assembly provides fuel flow to support 500+ horsepower. The unique secondary air valve has special mixture distribution tabs for improved air/fuel distribution and large idle discharge ports to provide sufficient idle control for use with long duration camshafts. A totally unique feature is the adjustable cruise air/fuel ratio for part throttle calibration. Other features include: early Chevy (1966-73) throttle arm and integral electric choke. Main Jet: .074; Metering Rods: Primary-50M, Secondary-CE.

Compare with their basic Q-Jets:

Edelbrock Q-Jet Carburetors
Edelbrock Performer Series Carbs for Q-Jet Applications
All-New Carburetors - Not Rebuilt!
Engineered and Calibrated to Stock Specs
Triple Booster Primary Venturis for Best Fuel Economy
Carburetors Include all Required Vacuum Ports

Manufactured by Magneti Marelli Powertrain USA, Inc. with all new components, Edelbrock Q-Jets are not reconditioned. They are 50-state street legal for the Chevrolet/GMC vehicles listed below and they also replace stock Rochester Quadrajets listed on cross reference guide. They are compatible with all stock linkage and components for the years listed, and will fit stock intake manifolds. For optimum street performance these carbs may be used with a street legal/stock replacement Performer manifolds. Not compatible with Buick, Olds, Pontiac and Cadillac throttle linkage.

750 cfm with divorced choke ....#1901
Q-Jet Series Carburetor - 4MV - 1966-73
For 1966-73 327-454 Chevy/GMC trucks and cars with a divorced style choke. Compatible with EGR. Main Jet: .069; Metering Rods: Primary-36B, Secondary-DR.



750 cfm with divorced choke ....#1902
Q-Jet Series Carburetor - 4MV - 1974-78
For 1974-78 350-454 Chevy/GMC trucks and cars with a divorced style choke. Compatible with EGR. Main Jet: .069; Metering Rods: Primary-36B, Secondary-DR.


I will be running oval port aluminum heads, 9:5:1 CR, and a high lift, low duration cam for power down low - perhaps the Lunati Voodoo 256 or similar. I may use stock-type flat top pistons and select a smaller chamber volume (110 cc or even 100 cc)on the heads to get my CR.

Here is Edelbrock's web site: http://www.edelbrock.com/automotive/index.html

Thanks!

djcwardog

ttt for thoughts?

lars

What's your question..?

djcwardog

Lars,

My question is basically this (paraphrased down from above):

Seems like the #1901 uses early parts and the #1902 uses late parts. The stock carb for my car was part #7043201 Rochester 4MV - which Edelbrock cross references to require use of their #1901 carb. However, the previous owner installed the #1902 which is on there now. From the specs (above...) both the #1901 and #1902 carbs use the same rods and jets... So I am still confused about what parts are in there! As far as rods and jets go between the 1901 and 1902, seems they use the same even though they say 1901 is early and 1902 late... Should I pull that carb off and buy something else - what? They make a model 1910 performance Q-Jet at 850 CFM:

Thanks for helping me understand the details on these carbs!

lars

The 1901 and 1902 are both first generation Q-Jets with a divorced choke. Thus they are both "early" carbs and use the pre-'75 primary metering rods. The split on primary rod usage occurs starting with the 1975 model year: This is the Q-Jet that uses the integral choke system (big black round choke cover on the side). Any Q-Jet with the integral choke uses the late style primary rods.

There is no reason for you to swap out the carb - the carb you have can be set up just fine as long as you use the correct series rods in it. Typically, the EDL carbs are jetted quite lean in order for EDL to get CARB approval on the products. If you have the stock rods in the carb, just bump your primary jet size up 2 sizes - I'll bet the carb will respond quite well.
Lars

kodaclr

I hope you don't mind me jumping in on your thread,

I'm having the same problem with mine, although I have a rebuilt roch. Here is the set up used on mine, any suggestions. I have a 1969 350, 300hp. I know engine was rebuilt but don't have any information from previous owner.

Carb #4850: 1969 Remanufactured for Chevrolet 327 or 396

Has .067 Jets
Has #44 Primary Metering Rods
Has Hanger letter "O"
Has "AN" Secondary Metering Rods