66ninetyeightls

Intermitently but more often then not the engine will completely bog down after the 1 - 2 shift. This only happens when I am at WOT from a dead stop. If I back off the throttle for a split second then get back onto it again it will power through it.

Any ideas what could be causing this? Timing or carb adjustment.

MDchanic

Details?

Type of carb., compression, type of ignition, type of cam, type of transmission, converter stall speed?

First guess: You've got a QuadraJet and the secondary air valve spring is adjusted too loose, allowing the air valve to flop open under acceleration, and flooding the engine.

- Eric

66ninetyeightls

Other than a newer quadrajet, Edelbrock performer intake and the recently installed dual exhaust its 100% stock. Still running points ignition, factory cam, TH400 tranny, Stall Speed (NO IDEA).

Do you have a pic of the spring in question?

MDchanic

1966 car: switch-pitch tranny? Or has it been replaced / converted? Stock converter, presumably.

- Eric

66ninetyeightls

yeah it is a switch pitch. I performed the adjustment as per the manual at its still the same.

This article is interesting.
http://www.montess.org/airvalve.html

MDchanic

I'm still thinking secondary air valve spring setting.
Either that of gunk in your carb.

- Eric

66ninetyeightls

Im thinking you are correct about the spring. Doubtful the carb is gunked up as it was professionally rebuilt less than 500km ago.

MDchanic

I don't trust "professionals."

The car owner who spends a week slowly disassembling and cleaning his carb and putting it back together, stopping to re-read the parts of the manual he doesn't understand until he figures it out, will probably do a better job than the guy who can assemble a carb with his eyes closed, doing a dozen or more in a day.

Call me overcautious.

- Eric

mfgusa

If it screams up until a moment before the up shift then I think your carb is running out of gas. Check your float setting for starters.

Of course IMO.

MDchanic

If it's running out, I'd check the fuel pump.
Since it's not heavily modified, I wouldn't worry about the size of the fuel lines or the spec. capacity of the pump.

He said after the 1-2 shift, though, so I was thinking more carburation, but you may be right...

- Eric

oldcutlass

If you feel the carb is ok, I would look at my total timing!

66ninetyeightls

The issue only happens after the 1-2 shift. NEVER have a problem at high RPM this thing just wants to keep pulling.

Pretty sure its a carb problem since if I back off on the accell slightly and then back on again the bogging will go away.

navvet

My 64 88 has the same issue. I do need my carb rebuilt, but I have had an old time olds mechanics (@ 30 +years exp.) tell me all adjustments are maxed out on my carb including my secondary valve spring. He says it was a common adjustment when he would do a tune-up back in the day.
My car does want to just rip and keep pulling after the second shift!! Can't wait until next year...a rebuilt carb next spring

BlackGold

When you have a fuel delivery problem, it's not just the high RPMs that causes it. It's also the G-force working against your pump. If you're pulling 1g as you accelerate, you're actually asking your pump to "lift" the fuel about 10 feet.

Since the acceleration is quickest in first gear, you are move likely to run out of fuel at the top of first gear, or just after the 1-2 shift, than at the top of 2nd gear.

One more oddball possibility:
Check your coil wire (between coil and center of distributor) and also the plus and minus wires for the coil. If you have a bad connection, and if your 1-2 shift is firm, the jolt might temporarily dislodge the wire and break the connection. I've had this exact situation before. My coil wire was actually sitting almost an inch above the distributor, with the spark normally jumping the distance. But the sudden jolt would separate the wire just enough to cut out the engine, then the wire would return and the spark would continue again. Bizarre.

Bill in NC

Do you get a puff of smoke at all when it happens?

66ninetyeightls

No nothing.

navvet

So what is the verdict?? Did you find the problem?