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TR4/4A 67 tr4a runs rough and losses power when hot but not over normal temp

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HelpingTRresto

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resto project for friend. pro mechanic and myself working on. replaced points, condenser, coil, plugs, wires to plugs, rebuilt carbs. do not know what prev owner did. did find a wiring error to ign switch that did not send volts to coil when starter engaged, fixed that. volts jumps from to 0 - 20 and back. thank you all for help! oh by the way starts fine and idles well for a while. fuel pump and lines bypassed with elecric pump. did find that vacuum guage attached to intake manifold at egr port with adapter read only 5 in vac. should we read at ign vac adv port on carb?
 
Welcome to BCF.

I'm thinking fuel starvation, likely due to vapor lock. Not enough to kill the engine, but vapor lock would result in insufficient fuel flow.

Just my two cents.
Tom M.
 
NutmegCT said:
Welcome to BCF.

I'm thinking fuel starvation, likely due to vapor lock. Not enough to kill the engine, but vapor lock would result in insufficient fuel flow.

Just my two cents.
Tom M.
Click to expand...
HelpingTRresto said:
resto project for friend. pro mechanic and myself working on. replaced points, condenser, coil, plugs, wires to plugs, rebuilt carbs. do not know what prev owner did. did find a wiring error toWhen i switch that did not send volts to coil when starter engaged, fixed that. volts jumps from to 0 - 20 and back. thank you all for help! oh by the way starts fine and idles well for a while. fuel pump and lines bypassed with elecric pump. did find that vacuum guage attached to intake manifold at egr port with adapter read only 5 in vac. should we read at ign vac adv port on carb?
Click to expand...
When it acts up, kill the engine and pull and examine the spark plugs.
As far as the vacuum gauge, it needs to read manifold vacuum.
You won't find that at a location that supplies vacuum to a vacuum ADVANCE module .
If there is a fitting directly on the intake manifold or one for a vacuum RETARD that's the one .
 
Just check the flex hoses in the fuel line toward the rear.
part 85 or 100
They can swell and reduce flow esp if bio fuel is high content.
I had thus on my 3a would be ok at idle revving but would die on a run.
it’s a dollar fix even if it’s something else.
 

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Not only can they swell but leak if you have the fabric cover old lines. the fuel pump can suck air into fuel line that can starve fuel. Two Vacuum is the same as hydraulic any place should get the same reading. At sea level Vacuum could get up to 20 # Look for Vacuum leak at block. What does the RPM due with oil filler cap off
 
When the engine is idling the vacuum will be different at a manifold source than it is at a ported vacuum source.
It's important to know the difference when connecting a vacuum gauge
 
Thank you for the info. 1 less thing to do. Buy the way, progress update. We have gone through the carbs again. Went well. fuel lines done. Ordered new choke cable, it was sticking. All ignition system done. The main issue seems to be distributor not advancing at all. Ordered a new electronic distributor from watford-classics in UK. Thanks to all for your help.
 
HelpingTRresto said:
...The main issue seems to be distributor not advancing at all...
Click to expand...

If all the innards are present and unbroken then that usually means it just needs disassembly and a good cleaning.

Probably something you will want to do if only to have a spare distributor when the electronic one fails.

The stock ignition system is so basic you can hold it all in one hand - takes so little space I always carry a spare of everything and sort out any problem when I get home:

One-Hand.jpg
 
HelpingTRresto said:
resto project for friend. pro mechanic and myself working on. replaced points, condenser, coil, plugs, wires to plugs, rebuilt carbs. do not know what prev owner did. did find a wiring error to ign switch that did not send volts to coil when starter engaged, fixed that. volts jumps from to 0 - 20 and back. thank you all for help! oh by the way starts fine and idles well for a while. fuel pump and lines bypassed with elecric pump. did find that vacuum guage attached to intake manifold at egr port with adapter read only 5 in vac. should we read at ign vac adv port on carb?
Click to expand...
 
Mine did similar. Check low tension lead to coil. Over time vibration caused the wire to fail at the spade connector. Only acted up when motor at full operating temp. Stripped wire and reconnected spade. All good

Bob
 
I really appreciate everyones input. got accuspark electronic distributor from watford-classics. probably could repair old one, however owner wanted to go electronic to omit points. new one cost about what we might spend working on old one. found the new one on ebay. It works great. problem solved. the major running issue was no timing advance in old dist. car runs and drives as good as new. owner thrilled. best regards to all.
 
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