Technical Stumble off idle 4x2 97's

Getting a few road miles on the 31 and am having off idle stumbling when starting out in gear. The 97s are older pieces but I did go thru them for full tear down and rebuild. Running 41 jets non progressive. Engines starts easy and idles. Has good response once you open up the carbs but doggy at very low speed when trying to accelerate.

Timing is set at 10, doesn't like it any lower. Mallory flat top rebuilt by Bubba with vac adv. Engine at idle only making 11 inches of vac. With vac hooked up timing jumps to 25 at idle and at around 2500 it is out at 50. Ran with vac unhooked, performance seemed better but still stumbling off idle.
Acc pumps are set on summer.
Engine is rebuilt Olds 324 with a Ross cam and adjustable rockers. Pretty plain build nothing to exotic.
Oh, air cleaners are frogsmouth with only metal screens. Plugs are running a chocolate color if that is of any value given the gas we have in the area.
Any pointers would be appreciated as this is a learning experience for me for certain.​

 

sounds like accelerator pumps Are you using the leather or synthetic types?

 

Flatjack, first thing I checked. Using leather pumps and all are squirting. I am leaning toward timing but I don't know if 25 degrees at idle is suspect or not. I disconnected the vac and saw no difference. I may add two degrees to initial and see what that does tomorrow.

 

Give the engine all it wants of initial advance. Maybe limit the total to 36-40 degrees.
Try locking out the distrib (IF the starter will crank it) as a test to see IF initial advance is the problem.
(locking out distrib.....zip tie the advance weights to full advance)
6sally6

 

^^^This. And disconnect the vacuum advance .

 

.041 is too lean. Try .045. You may even have to go to .048.
We run .051 on 320 inch flatheads with 4 97's.

 

Thanks for the tips fellas. If I get out there today I will add some timing and leave the vac disconnected. And Pete I had 45's in all 4 but the plugs were really black so I put in 41's. Probably chasing my tail what with the new gas formulas. Need a 02 set up to do it right but that is not in the cards at the moment.
I just found out that one station over in town is now offering regular gas so I may put a few gallons in this thing to see the effect. Back at you soon.

 

Keep in mind that if you're driving the car around, come back to your garage and then check your plugs . . . you're not reading anything of value. They will almost ALWAYS look black with some soot. When idling, the main jets are not even being used - so if you're checking them after idle time you will soot up your plugs (especially with 4 carbs).

Also, hopefully you have a "UniSyn" to synchronize your carbs - you need to get the same amount of air flowing through them.

You have to load-test the engine/carbs and shut it down and put the clutch in (while rolling) and kill the engine - to see how rich/lean the plugs are. Today's fuels make it difficult to check for plug coloring (everything tends to burn "white" - not choculate like in the past). Once you get your total timing figured out (you can't be running 50 degrees under load!), then work on the carbs. I'd use the outer location for the accel-pump push rods - they always seem to work better that way for me. As Pete noted, you're probably too lean on your main jets - so increase jet sizes and see if that influences your performance. As you noted, having an O2 meter really helps tuning a multi-carb setup. Best of luck.

 

When I was a kid...(A LOOONG time ago) a full-on redneck usta run a light-weight galaxy 427 at the local strip.
The way he checked plugs were, to get up nice and early on Sat. morning....gap and install plugs ...push the car out into the road in front of his house....fire it up...run it full throttle...rowing gears all the way.
After it RPM'ed out he cut it clean.....and read the plug on the side of the road !!!
That's how ya get a proper read on the plugs he told me...
Original good-old-boy from Georgia !!!
6sally6

 

All 4 97's were totally pulled apart and cleaned. Tubes were checked for any evidence of over tightening., all passages were cleared and had carb cleaner forced thru them as were the idle tubes. New power valves and check balls installed.
All the accelerator pumps are working with both squirters providing fuel on acceleration.
Weather permitting, I may be able to get outside today to work on this.

 

I find you get a better and quicker "squirt" with the synthetic pumps.