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51
Dialing in your rebuilt Quadrajet carburetor / Re: is it ok to mix and match metering rods
« Last post by MRSOFTE on April 17, 2026, 03:26:25 PM »
Was just out driving with no surging at cruise as far as I can tell. Nothing jumps out at me no pinging leaning into it, feels good, and I bumped up the timing 5 more degrees to 32 total all in by 2500.  That made the throttle a little crispier.

I will put in one 46 rod today just to richen the cruise a tad.
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Dialing in your rebuilt Quadrajet carburetor / Re: is it ok to mix and match metering rods
« Last post by lightning boy on April 17, 2026, 12:58:39 PM »
You can try a richer rod no problem. Bit be careful chasing afr numbers. If you see and improvement good deal. If not go back to the old ones. If it is lean at part throttle it will buck and surge. Give the motor what it wants, don't trust the afr.
53
Dialing in your rebuilt Quadrajet carburetor / Re: is it ok to mix and match metering rods
« Last post by MRSOFTE on April 16, 2026, 06:45:34 PM »
14.7 into low 15 zzzzz at idle no real stink. Now with 44 rods, oh my gosh burning the eyes at idle. But at that same time I had cliffs blue power spring in. So this engine as I said only pulls 12.5 Hg. So maybe the blue spring wasn't my best idea.
WOT is ok at 12's.
Black spring and 46's and I believe I saw cruise at 12's maybe low 13.  So jumped right to 48's.

Starts and runs real nice but just maybe I feel a surge on occasion? I do see my AFR gauge slip into high 16 and maybe low 17 once in a while. I also know that not all cylinders will see the same thing.

This is why I ask is it permissible to keep one 48 in and go 46 with the other. Is that a silly idea? Ha!






54
Dialing in your rebuilt Quadrajet carburetor / Re: is it ok to mix and match metering rods
« Last post by 77cruiser on April 16, 2026, 05:52:52 PM »
Is the idle stinky with it that lean? Mine gets stinky at idle when it lean.
55
Dialing in your rebuilt Quadrajet carburetor / Re: is it ok to mix and match metering rods
« Last post by 70GS455 on April 16, 2026, 02:52:16 PM »
Quote from: MRSOFTE on April 16, 2026, 07:43:37 AM
Running a 7043213 on a bone stock original 1973 Z-28. 74/48 and Cliffs black spring combination. Engine at idle only shows 12.5 inches with an A/F of 14.7 or so. I threw all that in, in case its relevant. Oh, I'm at 4600 ft elevation.

At cruise 35 MPH the A/F is approx 14.7-15.6 at 60MPH 15.5-16.3. Finally, my question, are these A/F's ok? If not can rods be mixed to achieve a different overall A/F?

Yes, those are fine. What are AFRs at WOT?
56
Dialing in your rebuilt Quadrajet carburetor / Re: is it ok to mix and match metering rods
« Last post by 77cruiser on April 16, 2026, 10:15:11 AM »
How does it run?
57
Dialing in your rebuilt Quadrajet carburetor / is it ok to mix and match metering rods
« Last post by MRSOFTE on April 16, 2026, 07:43:37 AM »
Running a 7043213 on a bone stock original 1973 Z-28. 74/48 and Cliffs black spring combination. Engine at idle only shows 12.5 inches with an A/F of 14.7 or so. I threw all that in, in case its relevant. Oh, I'm at 4600 ft elevation.

At cruise 35 MPH the A/F is approx 14.7-15.6 at 60MPH 15.5-16.3. Finally, my question, are these A/F's ok? If not can rods be mixed to achieve a different overall A/F?
58
Quadrajet Carb Talk and Tips / Re: HEI Distributor mechanical advance curve options
« Last post by Cadman-iac on April 14, 2026, 03:16:40 PM »
 Ok!!!! Well my preliminary tests show that I've got everything wired correctly, and the timing light goes off like it's supposed to, so it looks like the only thing left is to figure out exactly how to mount the distributor to this drill press tool.

 I did notice that an aftermarket ignition module, although it is good and the vehicle ran on it, in this test situation it does not put out as big of a spark as a factory ignition module does.

 That was also something that I had read earlier, so thought I'd swap to a factory module and see if there was any truth to that. Yes, it's true.

 
 Now, something I'd like some help with, as it's set up, the spark plug fires 8 times per revolution of the distributor shaft. Which is ok, except it makes trying to pinpoint the degree of rotation on the distributor for a particular plug rather difficult. 

 Can anyone tell me how to break this down a bit? Right now it's like trying to check your timing with your timing light connected to the coil instead of the number one plug.
 Is there any way to isolate a particular spark?

 I thought about taking an old pick up coil and an old timer core and cutting/grinding off all but one point, but I'm not sure if that'll work, or if I'd just be ruining a coil and core.
 Any thoughts anyone?

 Rick
59
Quadrajet Carb Talk and Tips / Re: HEI Distributor mechanical advance curve options
« Last post by Cadman-iac on April 14, 2026, 03:00:07 PM »
Quote from: DJD OLDS 4MC on April 13, 2026, 08:52:13 AM
Hi

Weaker springs will allow the advance to begin at a lower rpm, but will not increase the total advance available for centerplates and flyweights I tested. The combinations were taken to 2000 distributor rpms (4000 crank rpms) to make sure all the advance available was extracted.

 That's what I thought, but I had also read that a weaker spring could let your weights continue to advance, at least if your center plate is upside down from the factory setting.
 In the correct position, I wasn't sure if this was also the case.
 Thanks for posting.

 Rick
60
Quadrajet Carb Talk and Tips / Re: HEI Distributor mechanical advance curve options
« Last post by DJD OLDS 4MC on April 13, 2026, 08:52:13 AM »
Hi

Weaker springs will allow the advance to begin at a lower rpm, but will not increase the total advance available for centerplates and flyweights I tested. The combinations were taken to 2000 distributor rpms (4000 crank rpms) to make sure all the advance available was extracted.
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