Which Q-jet??? (M4ME, M4MC, 4MV)
07-07-2002, 11:41 PM
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Which Q-jet??? (M4ME, M4MC, 4MV)
Well the time has come, I guess Im growing up and starting to think economically. Im really not making much power with my current setup, and Im gettin crap mileage with the edelbrock carb. I've decided to go q-jet cause i can get a rebuilt fairly cheap (i work at a parts store) and i think i might be able to get some better mileage from one (170 per tank sucks). And when the time comes, I believe I can get failry decent power from one. So in my spare time at work today, I was lookin through the carb book and came upon the 3 different q-jets mentioned in the subject, and I was wondering what the difference was between them. Im pretty sure they are all non-cc carbs, and there were variations between each over the years. Like the M4MC had three diff part numbers, one for 75, then 76-77 and 78-79. It seems the M4ME stayed the same through the 70's/80's and the 4MV was constantly changing. Im just curious as to what the difference between the 3 are, and maybe some of the differences in each through the years, if anyone knows and would like to share I'd appreciate it greatly!!!
Thanks
Thanks
Last edited by CamaroZ_85; 07-07-2002 at 11:43 PM.
07-08-2002, 07:32 AM
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Car: 4
Engine: 6
Transmission: 5
DON'T get a M4M anything. That's the 70s emissions version.
4M is the universal Q-Jet model number. The first character before the 4, if there is one, tells whether it's the original Q-Jet before emissions (no letter); M for the "modified" one that was partly responsible for such wonders as 350s that produced 170 HP and got 13 MPG; or E, for the "electronically" controlled one.
The last letter refers to the choke style: V for divorced (the kind where the choke thermostat sits in a little well on the intake), C for the integral style (choke stat mounted on the side of the carb and plumbed to some tubing that goes through the intake's exhaust passage), and E for electric. The model that was OE for our cars is a E4ME, which is an electronically controlled Q-Jet with electric choke.
But that's only the broadest possible division into approximate groups. Each motor that came in each chassis in each brand of car over the years has had a different carb; there are a dizzying array of internal calibration differences, passages that act as restrictions or metering parts, variations in how fuel lines hook up, and on and on. There's a whole lot more to look at than just that model designation when picking one for your car. Each one of those has a number, 7 digits up to the early 70s, 8 digits after that. The first 3 digits tells you what sort of carb it is: 702 for non-emissions, 704 for early emissions (about 71-73), 1704 and 1705 for the "M" series carbs, and 1708 for the "E" series. The next digit is the year; and the last 3 tell what chassis it's for. Most Chevy car carbs have a 2 and 2 more more digits there. So for example my 83 L69 carb is a 17083204.
The type of carb to get, if you want something that will perform well and install gracefully on your car and be easy to mod, happens to be a 4MV, since that's the style of choke used on most older Chevy motors. The one to get is part # 7029202, which is for a 69 350. It will bolt right up to any aftermarket Q-Jet intake, and it's easy to get a choke stat that will work with it. Incidentally, if you use a Edelbrock intake, don't use their choke stat with a OE Q-Jet, because it works backwards from a GM one: i.e. it pulls down to open the choke where a GM one pulls down to close it.
I take it you have already swapped out your distributor for a non-CC one, with vacuum advance... if not, don't bother with your carb until you do, the engine will never run right with a CC dist and non-CC carb, or worst of all, a CC dist and no computer hookup at all.
4M is the universal Q-Jet model number. The first character before the 4, if there is one, tells whether it's the original Q-Jet before emissions (no letter); M for the "modified" one that was partly responsible for such wonders as 350s that produced 170 HP and got 13 MPG; or E, for the "electronically" controlled one.
The last letter refers to the choke style: V for divorced (the kind where the choke thermostat sits in a little well on the intake), C for the integral style (choke stat mounted on the side of the carb and plumbed to some tubing that goes through the intake's exhaust passage), and E for electric. The model that was OE for our cars is a E4ME, which is an electronically controlled Q-Jet with electric choke.
But that's only the broadest possible division into approximate groups. Each motor that came in each chassis in each brand of car over the years has had a different carb; there are a dizzying array of internal calibration differences, passages that act as restrictions or metering parts, variations in how fuel lines hook up, and on and on. There's a whole lot more to look at than just that model designation when picking one for your car. Each one of those has a number, 7 digits up to the early 70s, 8 digits after that. The first 3 digits tells you what sort of carb it is: 702 for non-emissions, 704 for early emissions (about 71-73), 1704 and 1705 for the "M" series carbs, and 1708 for the "E" series. The next digit is the year; and the last 3 tell what chassis it's for. Most Chevy car carbs have a 2 and 2 more more digits there. So for example my 83 L69 carb is a 17083204.
The type of carb to get, if you want something that will perform well and install gracefully on your car and be easy to mod, happens to be a 4MV, since that's the style of choke used on most older Chevy motors. The one to get is part # 7029202, which is for a 69 350. It will bolt right up to any aftermarket Q-Jet intake, and it's easy to get a choke stat that will work with it. Incidentally, if you use a Edelbrock intake, don't use their choke stat with a OE Q-Jet, because it works backwards from a GM one: i.e. it pulls down to open the choke where a GM one pulls down to close it.
I take it you have already swapped out your distributor for a non-CC one, with vacuum advance... if not, don't bother with your carb until you do, the engine will never run right with a CC dist and non-CC carb, or worst of all, a CC dist and no computer hookup at all.
Last edited by RB83L69; 07-08-2002 at 07:35 AM.
07-08-2002, 09:51 AM
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thanks for all the info, you answered all my questions and really cleared things up for me. As for the distributor, I ditched the cc deal along w/ the carb so I've had thins setup correctly from day one, I'm just sick of the edelbrock. So if I get the carb you recommend, the 7029202, will it have an electric choke on it? Or one of those hot air kinds or whatever? And If it doesnt have an electric choke, are you saying that I can put one on from a newer q-jet?
Thanks
Thanks
10-27-2002, 09:17 PM
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Car: 97 200sx se-r, 82 Trans/Am
Engine: 350 bored to 355
Transmission: 700r4
Axle/Gears: 9 bolt 3.45
Originally posted by RB83L69
It's a 4MV. It will have a divorced choke. AFAIK it would be impossible to make it electric.
It's a 4MV. It will have a divorced choke. AFAIK it would be impossible to make it electric.
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