Checked timing on 440 - now what?
06-12-2018, 02:18 PM
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Checked timing on 440 - now what?
I recently purchased a restored 1969 GTX and when I floor the accelerator at low rpms there is a bog/hesitation. The car has a MSD Pro Billet distributor so I looked at the mechanical advance springs and they are the light silver ones (quick advance). I then checked timing which read 17 degrees at idle and 37 degrees total. So I think I've ruled out timing. What next? The Carter AFB carburetor is rebuilt and looks like new - maybe it needs adjustment? Appreciate your thoughts!
06-12-2018, 07:22 PM
#2
Mopar Lover
Coach -
17 initial/37 total may be a little high, unless you have a fairly big cam.
Unlikely, but the mech advance might be coming on too quickly
I would look at the carburetor settings.
Sorry, more familiar with Holleys than Carters.
Std things would be:
1. Vacuum leak
2. Accelerator pump (not working correctly, not right size)
3. Too big a carb
4. Too big an intake plenum
Could use more engine / car specs
Archer
17 initial/37 total may be a little high, unless you have a fairly big cam.
Unlikely, but the mech advance might be coming on too quickly
I would look at the carburetor settings.
Sorry, more familiar with Holleys than Carters.
Std things would be:
1. Vacuum leak
2. Accelerator pump (not working correctly, not right size)
3. Too big a carb
4. Too big an intake plenum
Could use more engine / car specs
Archer
Last edited by Archer; 06-13-2018 at 08:27 AM.
06-13-2018, 05:06 AM
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Thanks Archer. Carb is likely Carter AVS not AFB. This is the standard carb that came from the factory. Engine is stock except for MSD Pro Billet distributer, Blaster Coil and 6AL ignition box, headers and Flowmaster exhaust. I haven’t yet looked into whether any adjustments can be made to 6AL box.
06-13-2018, 07:48 AM
#6
Super Moderator
Today's fuel is hard on carb parts as in accelerator pumps and even fuel lines, just because it looks fresh doesn't mean that it's still good to go. The carb might be full of corrosion or debris clogging offices. It's probably time for a kit.
06-13-2018, 08:32 AM
#7
Mopar Lover
Coach -
I know hindsight is 20/20, but on a stock engine, the Mopar replacement ignition box and distributor would have served you better than the MSD stuff.
AND, it would have been more "original".
Still since you're talking about a bog off the line, that really point to carb / intake than ignition.
Since you didn't replace the intake, that leaves the carb.
And for the record, Holley 4Vs, in 600 - 625 cfm were stock on some of those motors.
So, do a though inspection of the carb, confirm that gas squirts out when you move the throttle.
Determine if the problem is on the primary or secondary side.
Check the vacuum with a gauge, and squirt water around the carb and vac lines and listen for any changes in rpm.
Archer
I know hindsight is 20/20, but on a stock engine, the Mopar replacement ignition box and distributor would have served you better than the MSD stuff.
AND, it would have been more "original".
Still since you're talking about a bog off the line, that really point to carb / intake than ignition.
Since you didn't replace the intake, that leaves the carb.
And for the record, Holley 4Vs, in 600 - 625 cfm were stock on some of those motors.
So, do a though inspection of the carb, confirm that gas squirts out when you move the throttle.
Determine if the problem is on the primary or secondary side.
Check the vacuum with a gauge, and squirt water around the carb and vac lines and listen for any changes in rpm.
Archer
06-14-2018, 11:10 AM
#9
Mopar Lover
All Good Points..... I am Sure it is in need of rejetting at this point... But sure sounds like some adjustments need to be make to get rid of that bog... Also, You sure your trans linkage is in proper adjustment? (If its an Automatic Transmission)
10-08-2018, 09:22 PM
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timing
I recently purchased a restored 1969 GTX and when I floor the accelerator at low rpms there is a bog/hesitation. The car has a MSD Pro Billet distributor so I looked at the mechanical advance springs and they are the light silver ones (quick advance). I then checked timing which read 17 degrees at idle and 37 degrees total. So I think I've ruled out timing. What next? The Carter AFB carburetor is rebuilt and looks like new - maybe it needs adjustment? Appreciate your thoughts!
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