Electrical: Severe lugging when engine is hot in 63 Avanti

[Steelerfan]

Gents,

I am experiencing severe lugging of engine when starting from a stop only when the engine is up to full operating temperature. I have a 1963 R1 with carter 4 bbl that I recently rebuilt. I have also done a tune up but discovered that I do not have the original Avanti dual point distributor but instead a single point distributor from a 1960 Lark. However in the past, the car ran fine and did not lug with this distributor. One question I have is should I set the point gap and dwell to those spec'd for the 1960 Lark distributor or should I set the timing etc. as per the Avanti specs? Timing degrees are both 4 Percent; the major difference is the Dwell angle range for the Lark is 28-34 and for the Original Avanti 27-31. I set it at 27. I set rpm around 700 and have tried higher rpms but still lugging. Not sure if the timing set up is the cause of my engine lugging. The only other variable is that I installed a new electric fuel pump rated for 4-7 psi but it seems to be getting plenty of fuel and I replaced the rubber hoses and gas filter. When car was running well it also had an electric pump. Any suggestions as to what I should concentrate on would be appreciated!

[gordr]

Your car isn't lugging. "Lugging" is running with too much throttle opening in too high a gear, instead of shifting down. Very hard on rod bearings, and can cause detonation, which destroys pistons. But it doesn't just happen. You have to drive it wrong for that to happen.

Maybe your car is bucking or surging? Output of engine varies cyclically, and car lurches ahead, then slows down, over and over? Carb too lean, most commonly/

[Mike Van Veghten]

Agree with gordr.
Lugging is when you are driving up a steep hill, with four, 250lb. people in the car and a trailer full of Studebaker engines...in high gear..!

Now try to explain in other terms.

Mike

[PackardV8]

Gents,One question I have is should I set the point gap and dwell to those spec'd for the 1960 Lark distributor or should I set the timing etc. as per the Avanti specs? Timing degrees are both 4 Percent; the major difference is the Dwell angle range for the Lark is 28-34 and for the Original Avanti 27-31. I set it at 27. Any suggestions as to what I should concentrate on would be appreciated!

Definitely set them for the distributor you have; 30 - 32 degrees dwell.

Did you replace the rotor, cap, spark plug wires and spark plugs when you did your tuneup?

Have you confirmed the centrifugal and vacuum advance are operating?

Are you using a major brand premium gasoline?

Does your GT still have the exhaust heat riser valve? Does it open fully when hot?

jack vines

[Steelerfan]

Thanks for the replies. The condition I inappropriately described as lugging is: when I accelerate from a stop or crawl (when the engine is hot) the engine has no power. I pump the gas but to no avail. I have an automatic trans (recently rebuilt) and down shift to try to get it revving in a lower gear. It eventually revs up and I am able to accelerate to speed. I do not have many miles on the rotor cap, points or plugs since my last tune-up (done by a mechanic) so I don't think that is the issue. I will reset the dwell to 30-32 and investigate how to check the centrifugal and vacuum advance. I have been using no-ethanol Shell gas but can only get it in 89 octane. Is the heat riser valve you refer to the thermostatic valve in the carb? if so, it seems to be working. This may be a stupid question, but the car was not in running shape when the transmission was rebuilt. Could there be an adjustment they need to make? thanks again.

[gordr]

Yes, quite possible that the transmission throttle valve linkage is set wrong. It is not just a kickdown like it is on Brand X cars. That linkage is the only way for the transmission to "know" how much power you are demanding from the engine. There is no vacuum modulator valve, which helps provide that necessary signal to other brands of automatic transmission. If you don't have a shop manual, please get one. The proper adjustment procedure is described in it.

[Stody]

I had this same problem. Eventually found that I not only had a bad vacuum advance but that someone had spliced the metal vacuum line with a piece of rubber vacuum hose. The rubber disintegrated and not only did I have zero advance, I also had a big ole vacuum leak. New vacuum line and a new advance and everything runs great!

[Steelerfan]

I will check those suggestions. thanks!

[Bud]

If you have the stock advance curve in the Delco window distributor that is now installed in your engine, it has the wrong spark advance curve in it for your engine. The distributors used in the non R engines have too much centrifugal and vacuum advance in them for the higher compression R or JT engines which can cause detonation problems leading to eventual engine failure. Bud

[Steelerfan]

Ok. So what would your advice be. The car is restored to be a driver, not pure restoration. Would you advise I replace with a modern electronic ignition system or try to find an original R1 distributor? Or, are there other options? Thanks again.