distributer advance settings

satelite

satelite

Senior Member
I'm working on a friends 31 model A with a new Miller overhead valve head. Someone told me there is a distributer expert on this site that has the answers. The engine has been totally rebuilt including inserted bearings. The problem is that the car sputters and back fires during acceleration under load. Ok when standing still except under sudden acceleration from an idle. I have replaced the coil and condenser, points are OK. The distributer is a single point Mallory. The system is 12 Volt and I have a New Rex timing kit so I can use a timing light. Initially I set the timing at 3 degrees at 600 RPM which yielded 25 degrees at 2400 RPM. I tried with 10 degrees at 600 RPM which yielded 25 degrees at 2000 RPM.
Still no power and it backfires during acceleration under load. Compression test shows 115 PSI on all cylinders.
Any suggestions on what to do ?
Don in SC
 
Ron you were right. After changing the distributor advance curve to get the best response, I still had the problem of little power on acceleration. When I pulled the choke out it improved greatly. I have ordered larger primary and secondary main jets and will try that.
Thanks Don in SC
 
The engine needs 30 degrees at 2500 rpm to work with that cylinder head.
We rework our Mallorys to get that much advance and use the lightest springs available.
Be glad to curve your distributor to make it work....
317-487-9460 Bubbas Hot Rod Shop...

And remember that 99% of time the problem is fuel! Unless you are talking to the carb guy then 99% of the time the problem is ignition...
We have done a few of these and they like some extra fuel ( like a stromberg 48-81 etc)...
 
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Hi Bubba,I have a 1947 stock engine that ldles normal but under load spudders.I pull the choke half way and it runs normal.I have replaced all the fuel fifter and fuel lines with fuel emisson lines,rebuilded the carb using all new gaskets,new power valve and jets from Ken Ct,I bypassed the mechical pump and ran it directly with a electric pump,replaced the vacuum line going to the distributor,I retorqued the intake manifold.I replaced the distributor with one I got from you and still does the same,I didn't try to the tweet the timing.Did I missing something ? Help, Moe
 
Cool coupe - usually when you choke the engine, that is a fuel related issue. How is that condenser?
 
coolcoupe said:
Hi Bubba,I have a 1947 stock engine that ldles normal but under load spudders.I pull the choke half way and it runs normal.I have replaced all the fuel fifter and fuel lines with fuel emisson lines,rebuilded the carb using all new gaskets,new power valve and jets from Ken Ct,I bypassed the mechical pump and ran it directly with a electric pump,replaced the vacuum line going to the distributor,I retorqued the intake manifold.I replaced the distributor with one I got from you and still does the same,I didn't try to the tweet the timing.Did I missing something ? Help, Moe
Click to expand...

Like wga mentioned I would always suspect a condenser ,but the choke fix makes me think maybe a fuel problem , maybe a air leak etc. Spray around with carb cleaner etc.......
I guess a weak coil could cause it but adding fuel seems to run out ok?
 
Would advancing or retarding the distributor make any different,I don't want to touch it ,if you think it won't help !!
 
Satelite, If you have a weak spark the engine might run fine at idle, however when you apply some throttle, if this weakens (leans) the air fuel ratio, the plugs may fail to fire.
A lean mix requires a better (higher voltage) spark, to fire it (than a richer mixture)
I have read some fairly negative comments about the mallory chinese made condensors.
I have no personel experience with them. Bubba might make a suggestion on what he prefers.
 
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