712 "bogs" right after idle on takeoff

[kc4mne]

Hello

My 712 "bogs" right after idle on takeoff. There is like a small "dead spot" on the throttle. I know this is fuel starvation. Is there any adjustment on the carbs to make them inject a little more fuel a little sooner when the throttle is opened? After you rev past the "dead spot" engine runs great. This only occurs when starting from a standstill or you are on 1st or 2nd in idle and stomp on the gas pedal.

Manny

710K/ 712M/ Volvo Tgb1111

[grayroad]

Do you have pertronix? I had the same symtom till I got rid of the points. Best $85 I ever spent.

[EvanH]

Sounds a bit like my truck. I already have the Pertronix and a new coil. My truck is suffering from worn carburator shafts. The extra air leakage is enough to upset idle and off-idle performance, but not a problem at high RPM.

[Kiwibru]

Gee, I am not the only one either! I have Pertronix too... I thought this was just a normal "quirk". It is worse when the engine is not up to full operating temperature but still around to a small degree when it is. I am hopeful that going to the EFI system will eliminate this "bog". And yes, my carbs have recently been balanced, adjustments made. Idle is smooth, then bog, then up through the rpm's with not a whimper. I really wonder how a set of carbs with 23k miles can have any worn and leaky parts? One theory is the distributor...but timing was also recently checked.

[EvanH]

Actually, it is worst when you are eight miles down a gravel road that is 30 miles away from the nearest town. How about having to walk eight miles, then hitchhike in the rain, only to have to call your ex-girlfrieind to rent an trailer and come and rescue you? Just after she has had a pedicure? I swear the lesbians who picked me up were looking for an excuse to slash me from top to bottom. The only thing more humiliating was that the motel I got in town offered free horse stalls. Yippee. I was actually hitching on I-70 in southern Utah. I was wanting to go westbound to Salina, and all I could see was a steady stream of Jeeps on trailers eastbound headed to Moab. I did manage to look down my nose at them as they drove by, but somehow the victory felt hollow.

Your mileage may vary...

-Evan

[75pinz]

I have had three Pinzs and they all have done this when cold. Now cold here means COLD. I notice my 712 runs much better with the grille partially covered when the temps are 0F or lower. Last winter it was -32 one morning and we had blowing snow over the road. The Pinz didn't seem to mind but I was cold in the cab. We may be dealing with different environments.

[kc4mne]

My 710 does not do this.

Any I am talking about a bog on a warm engine.

This is not an ignition problem in my opinion.

I guess nobody has tried fixing this with carb adjustments

Manny

[milesdzyn]

Last time I had that problem I stepped back the advance at the distributor by a degree or two, then readjusted the idle rpm at the carbs.

Miles

[David Dunn]

Manny
Have you checked the operation of the accelerator pump in the carbs for proper operation? A flat spot is a classic symptom.... or better yet, why it's there.

Dave Dunn

[kc4mne]

both accelerator pumps are working

The intent of my question was to ask if anybody knew what the adjustments on the accelerator pump did.

The rod to the pump has a threaded adjustment and the lever itself has 3 positions for mounting the rod.

Manny

[M Wehrman]

On the 2 trucks I've had I found a slightly higher idle speed (appx 1100 rpm) cured the issue. This made for a better charge rate and I liked the manners in rough stuff. this may be a Band-aid but it works for me.
Mark

[MASSIVE PINZ]

Try bumping up the timing a couple of degrees... I added 5 degrees of initial advance to my dizzy and solved the issues I was having that were very similar to yours..

[Hawkeye Pinz]

I'm having similar problems with my 710. It idles pretty good then "bogs down" right after taking off in first or second gear. I've also noticed a sort of backfire coming from the exhaust. Not a loud bang or pop but kind of like a snort or cough. I'm not much of a mechanic but I'd guess this is a timing issue. I have a Pertronix ignition so points aren't the problem. Any advice on how to solve this? Thanks, Dave.

[Jimm391730]

I had the same symptoms on my 712 when I first got it; despite seeming 100% fuel related, the civi ignition kit cured half of it (already had the bogging with a Pertronix and stock coil/wires) and getting the proper float level solved the balance.

IIRC the Pinz carbs are supposed to have the most aggressive mechanical connection to the accellerator pump, using the hole furthest from the end of the linkage.

Best of luck,

Jim M.
712W and 710M