Car Bogs
Thread Starter
Burning Brakes
Joined: May 2006
Posts: 774
Likes: 1
From: Round Rock Texas
The bog may be timing .
Not sure how you decided what jet size to run but it sounds like your making changes with no rhyme or reason to see if they stick.
Go back to basics , button up the ignition side.. Set float level , set transition slots , , start car set idle and a/f mixture..
Not sure how you decided what jet size to run but it sounds like your making changes with no rhyme or reason to see if they stick.
Go back to basics , button up the ignition side.. Set float level , set transition slots , , start car set idle and a/f mixture..
Keep you posted when he does.
Thanks.
Burning Brakes
Joined: Apr 2013
Posts: 926
Likes: 2
From: Castle Rock CO
If the car is running too rich it can be a multiple issues. First being Timing if the timing is too retarded it will bog down and maybe it is not your carb but distributer shaft gone bad. This will wobble and create infrequent spark than cause the plugs to go black. the HEI Distributers in most mid 1970s to 1980 cars would start to wobble between 75,000 to 100,000 miles because they would wear out. I had 3 Chevy cars a 1972 El Camino, 2 1976 Malibu Classics and 2 out of 3 of them I had to replace the distributor between 75,000 to 100,000 miles the other was replaced shortly after 100,000 miles. Put a Timing light on it and see if the timing drifts a lot than you will know the distributor bearings have gone bad. It should be steady and not drift at all even with HEI. If the plugs were White I would say your burning too lean. Black either means not enough spark or too rich or in accurate timing settings.
I will not go into Dwell and the shaft wear on a distributor since you have a HEI ignition system. Well I will on my early Points Ignition engines the shaft the points ran on would wear uneven if not properly greased and points used to only last between 7000 to 15,000 miles. 7000 would be that dude that did not put di-electric grease on the plastic contact on the shaft. With HEI you still have contact points on the shaft and that shaft becomes worn out down in the engine it self there are no bearings just oil to keep it lubed. It will wobble after many miles over 75,000.
http://www.crankshaftcoalition.com/w...EI_distributor
http://www.73-87.com/7387garage/drivetrain/hei.htm
I will not go into Dwell and the shaft wear on a distributor since you have a HEI ignition system. Well I will on my early Points Ignition engines the shaft the points ran on would wear uneven if not properly greased and points used to only last between 7000 to 15,000 miles. 7000 would be that dude that did not put di-electric grease on the plastic contact on the shaft. With HEI you still have contact points on the shaft and that shaft becomes worn out down in the engine it self there are no bearings just oil to keep it lubed. It will wobble after many miles over 75,000.
http://www.crankshaftcoalition.com/w...EI_distributor
http://www.73-87.com/7387garage/drivetrain/hei.htm
Last edited by MakoJoe; Apr 10, 2014 at 11:36 PM.
Thread Starter
Burning Brakes
Joined: May 2006
Posts: 774
Likes: 1
From: Round Rock Texas
If the car is running too rich it can be a multiple issues. First being Timing if the timing is too retarded it will bog down and maybe it is not your carb but distributer shaft gone bad. This will wobble and create infrequent spark than cause the plugs to go black. the HEI Distributers in most mid 1970s to 1980 cars would start to wobble between 75,000 to 100,000 miles because they would wear out. I had 3 Chevy cars a 1972 El Camino, 2 1976 Malibu Classics and 2 out of 3 of them I had to replace the distributor between 75,000 to 100,000 miles the other was replaced shortly after 100,000 miles. Put a Timing light on it and see if the timing drifts a lot than you will know the distributor bearings have gone bad. It should be steady and not drift at all even with HEI. If the plugs were White I would say your burning too lean. Black either means not enough spark or too rich or in accurate timing settings.
I will not go into Dwell and the shaft wear on a distributor since you have a HEI ignition system. Well I will on my early Points Ignition engines the shaft the points ran on would wear uneven if not properly greased and points used to only last between 7000 to 15,000 miles. 7000 would be that dude that did not put di-electric grease on the plastic contact on the shaft. With HEI you still have contact points on the shaft and that shaft becomes worn out down in the engine it self there are no bearings just oil to keep it lubed. It will wobble after many miles over 75,000.
http://www.crankshaftcoalition.com/w...EI_distributor
http://www.73-87.com/7387garage/drivetrain/hei.htm
I will not go into Dwell and the shaft wear on a distributor since you have a HEI ignition system. Well I will on my early Points Ignition engines the shaft the points ran on would wear uneven if not properly greased and points used to only last between 7000 to 15,000 miles. 7000 would be that dude that did not put di-electric grease on the plastic contact on the shaft. With HEI you still have contact points on the shaft and that shaft becomes worn out down in the engine it self there are no bearings just oil to keep it lubed. It will wobble after many miles over 75,000.
http://www.crankshaftcoalition.com/w...EI_distributor
http://www.73-87.com/7387garage/drivetrain/hei.htm
Thanks.
Intermediate
Joined: Feb 2005
Posts: 43
Likes: 0
From: GA
several good points made here. I have had similar problems in the past.
Once I trouble-shot a problem to a manufacturer defect inside the carb (it was a brand-new square bore) so that a slow leak continued internal to the carb. It was only evident on continued slow RPM like used during in-town driving. As soon as you got on the throttle it would bog then you'd clean it out and she was good to go for awhile.
Once I found a problem on another square bore carb with the choke plate (e-choke). It took forever to find this because I checked it out more than once when it was ice-cold and watched the thing idle until it warmed up. The e-choke slowly opened like it should. BUT, as soon as we shut it off it would start to close way way way too soon. I could come back on a warm day and the choke would be closed again. So I adjusted the choke opening and closing and then found that the choke plate was getting caught on the inside of the air cleaner jamming either open or closed. I swapped the e-choke and the problem disappeared.
Also, on another car I used an aftermarket mechanical pump on a small block and under high rpm the fuel would overflow the carb (square bore). Essentially the fuel pressure was high enough at RPM that the fuel would push up the float needle and overfill the fuel bowls. Then the car would bog. I put in a cheap inline regulator and replaced the fuel line at the carb with a chrome line that had a tap for a fuel pressure gauge. I adjusted the pressure from 6 psi down to about 4.5 psi and all the problems disappeared. No issues on full throttle accel either.
Incidentally, my best trouble-free square bore experience bar-none has been with a holley street-avenger 670 on a SB...worked out of the box. Yes, I did fine tune all of it, but I drove the carb as-is first just to see if the carb swap solved my problem. For a daily driver that needs a square bore...holley street-avenger for me--thanks.
Once I trouble-shot a problem to a manufacturer defect inside the carb (it was a brand-new square bore) so that a slow leak continued internal to the carb. It was only evident on continued slow RPM like used during in-town driving. As soon as you got on the throttle it would bog then you'd clean it out and she was good to go for awhile.
Once I found a problem on another square bore carb with the choke plate (e-choke). It took forever to find this because I checked it out more than once when it was ice-cold and watched the thing idle until it warmed up. The e-choke slowly opened like it should. BUT, as soon as we shut it off it would start to close way way way too soon. I could come back on a warm day and the choke would be closed again. So I adjusted the choke opening and closing and then found that the choke plate was getting caught on the inside of the air cleaner jamming either open or closed. I swapped the e-choke and the problem disappeared.
Also, on another car I used an aftermarket mechanical pump on a small block and under high rpm the fuel would overflow the carb (square bore). Essentially the fuel pressure was high enough at RPM that the fuel would push up the float needle and overfill the fuel bowls. Then the car would bog. I put in a cheap inline regulator and replaced the fuel line at the carb with a chrome line that had a tap for a fuel pressure gauge. I adjusted the pressure from 6 psi down to about 4.5 psi and all the problems disappeared. No issues on full throttle accel either.
Incidentally, my best trouble-free square bore experience bar-none has been with a holley street-avenger 670 on a SB...worked out of the box. Yes, I did fine tune all of it, but I drove the carb as-is first just to see if the carb swap solved my problem. For a daily driver that needs a square bore...holley street-avenger for me--thanks.
