CarburetorsCarb discussion and questions. Upgrading your Third Gen's carburetor, swapping TBI to carburetor, or TPI to carburetor? Need LG4 or H.O. info? Post it here.
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I just bought another car its an 85, it has the L69 motor in it. It needs some carb tuning it has the cc qjet on it. I've been doing some reading on the q-jets and I want to give a go at it if It doesn't work I'm going to put a 1406 on it.
The L69 has 9.5:1 CR and bigger exhaust manifolds so a decent platform to start improving.
First I'm swapping the manifold to an edelbrock performer (not rpm) which I've read is worth ~20hp. Should I keep the EGR? (Will it hinder performance, is it necessary for proper carb/computer operation?) I took the smog pump and A/C off. Stock timing is 6* base I'm thinking of trying 10*. (have to get timing tab first, will power tuning work on these cars or not?) Plugs look old too, going to put in AC R44TS plugs gapped .040".
Now onto the carb, im going to clean it up while its off and from what I've read in the tech article I need to set my choke up right and I need to set the Air Valve tension at 0 so it flops open real fast and then I need to buy CK rods and G hangers for the secondaries. Should I do this is this correct information?
And what about getting rid of the AV stop so that the AV opens all the way? The article then says I need CC rods if I do this, sound right? Looking on what to do with this q-jet, I dont have much experience with them, I can tune holley's and carters but this is new to me.
Replace the carb and you'll also have to replace the dist, they're both computer controlled. An Edelbrock would not be an upgrade from a properly functioning qjet.
The performer manifold probably won't net you much increase at all. It's not much more than a stock replacement.
I'd keep the EGR. It won't have any affect on WOT performance but losing it may cause pinging (and subsequent timing retard) at cruise with light throttle.
The L69 should have the better rods/hangers.
A good cleaning and verifying everything is functioning correctly should be all you need. If it's really gunked up a re-build may be due.
__________________ "A man who voluntarily drives a car like that and still manages to maintain such impervious confidence that it will faithfully start the next time he turns that key is an encouragement for us all to take greater risks in life."
the eldebrock would be a last resort im trying to keep the motor as original as possible I just want to improve the performance. I think i'll tune it up first and see where im at.. just want some more info on what mods to do to the q-jet and what rods and stuff I need. Someone was telling me I need to take the choke rod off because it makes the secondaries open too late?
Someone was telling me I need to take the choke rod off because it makes the secondaries open too late?
No. Secondary air valve opening is regulated by the air valve tension AND the choke pull off. Removing the choke pull off linkage will make it virtually impossible to get the air valves dialed in. The problem is not always having them open too late, but opening too early will cause a bog as well (otherwise why would you need them at all?).
Check your existing rods and hangers for the secondaries. They should be fine.
finally got a chance to look at the car today, fixed the idle, but the choke doesn't open fully all the way 90*. If you free rev it the comes down but goes back up like its just loose. Looks like someone took the AV rod off already also, front vacuum break doesnt hook up to anything.
Also unrelated question, the tach is intermittent, im suspecting the tach filter since all connections look good, can I just delete the filter will it fry anything to test?
Yep the first thing I checked was the voltage from that wire and the contacts, the choke is semi working though, just doesn't open 90*. I did not see any kind of ground wire though..
The tach didn't work when I bought the car then it started working while i was driving it home, now it stopped again, funny thing is it will come up when the key goes on but not while its running, same thing happens in my buddy's 79, im thinking filter maybe?
No wonder this thing didn't have any power the secondaries were never opening, luckily mine opens 90* and I don't have to mod it, so I just wired the secondary lockout open and set the AV tension, have to put it on the road first to see if it bogs without the AV rod.. They flip open real nice when I free rev it, waaaaamp, I can see why the q-jets rule they got some massive secondaries for power and tiny primaries for gas mileage/response.
I'm going to grab a couple of q-jets the next time i go to the junkyard along with a lot of other stuff, the junkyards around here suck though its hard to find old cars, I had to go to 3 different ones to find a vac advance distributor once.
I gave it new plugs and set the timing to 8* with the electronic advance disconnected. The smog and AC belts are missing and im thinking of taking all the air stuff off to try and clean the engine bay up a little, its a mess so many vacuum lines and wires and hoses everywhere..
Sounds like your choke mechanism isn't free to move through its entire travel. First thing to try would be to push down on that green weight/lever on the passenger side. But, about the only way to know why would be to take it apart.
You're going to need the linkage that goes from the vacuum break to the secondary air valve door arm. Without it you'll get a quick bog when you nail it no matter how much tension you put in the spring. You should NOT be able to see the secondary air doors open just giving quick revs in the driveway.
Fortunately, the linkage rod is the same on CC-Qjets and earlier non-CC-QJets. Grab one off most any junkyard Qjet. Install and adjust it so that there is just a TINY bit of slack left in the linkage with the vacuum break fully retracted (vacuum applied).
If your choke isn't opening fully, check to make sure you're getting 12V at the wire that hooks up on the side of the choke (engine running). If not, find out why and fix it. If so, the choke element itself is probably shot (check it's resistance to ground- should be about 10 Ohms, 20 on the high side, any more and it's toast). Obviously, spray the choke linkages down thoroughly with carb cleaner to make sure they aren't gummed up and sticking.
I got it to not bog without the rod, but it was restricting the opening, i went and got the rod and set the tension and holy cow it really woke up the motor, no bog/delay either..
Where should I be checking the resistance to ground on the choke? I checked it from the connector and it was 5.5 ohms.. I'm getting 14v at the wire.. I think the element might be toast.. choke light doesnt come on.. I just have it wired open for now.. summers coming I dont really a choke
