My Rochester Quadrajet 4MV...does the right parts??


New Member
Nov 18, 2015
Abitibi, Québec
GMC 1976 G35 V8-400cid 6,6L.
I am a francophone from Quebec, so I hope my translator does not pose a problem for our understanding !?
Sometimes, if the word is not well written, the translator translates nothing or not much.

I need help with my carburetor, which I believe, and this in spite of my lack knowledge on the subject,

it was put together with parts that are not necessarily intended for it.

For an overview, here's my vehicle and its components;
- Recreational Vehicle (RV) 17 feet, with a net weight of 2949 Lbs.

Rear drive axles with 1 double 1 ton (10,000 GVWR), rear wheels 8.75 - LT 16.5.

The front (truck, engine, transmission)

- GMC Vandura 1976 G35, 400-V8 6.6 Liter.

- Regular unleaded gasoline.

SBC Block;
<<What are the specifications of the book of my truck>>
- Small-block 400cid-V8 , HD LF4, 6.6 Litres.(Federal, not California).
- Casting #330817.
- Horse Power @ rpm 175 @ 3600.
- Torque @ rpm(ft. lbs.) 290 @ 2800.
- Bore and Stroke(in.) 4.125 x 3.750.
- Compression Ratio 8.5:1 .
- Oil Pressure @ 2000 rpm 40.

Idle Specifications (RPM)-Heavy Duty Emission Requirements;<<What are the specifications of the book of my truck.>>
- Curb idle 700N.
- Fast idle 1600.
- Idle mixture 770/700.
- Emission family GM113.

- Intake / manifold, cross-type H (not sure) ..?!
- No air conditioning.
- Transmission Automatic Turbo Hydra-Matic 400.

- Rochester Carburetor * 4MV, Quadrajet GM, 4 barrels # 7045225 (Z9, 3434)
Divorced automatic choke is manifold.

* Carburetor Components 4MV;
- Metering rod-primary '36B' dual tap.
- Jet-primary '71', Group C -> (full 60 degree).
- Metering rod-secondary 'DL'.
- Secondary metering rod Hangers 'K'.
Sorry, I'm a perfectionist, especially when I lack of knowledge
on a subject.

??Questions ??

- Do you think my carburetor does not have the right parts?
(metering rod prim. and sec., and jets)

- Do you think that I must change everything to what is supposed to be there?
(if not the right parts)

- I think the elements which I have described, are not good, is it could?

!!!!! Difficulties

- I'm not able to do all of my components coincide with the carburetor model of my truck,

and the model of my carburetor ... really too weird!

- I think I lack of power on the road, because I have any difficulty to have 100 km / hrs. when the engine is not heated.

NB :
- What are the specifications of the book of my truck.

I do uses that were me, and I dwell in northwestern Quebec 48th parallel,
in which case it would be useful in connection with the atmospheric pressure.

I have not taken the Compressing nor the timing on the engine again.
(I wanted to go up the carburetor before, but on the job,
I ran to numbers that do not match either, is that I can find on the market).

Thank you for any help you can give me.



Staff member
Nov 18, 2019
1978 Monte Carlo 383 slammed
Q-jets are to complicated for most people, and there is not aftermarket support. bolt on a Edelbrock performer that's what most people do ...

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