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What's a poppin'?

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Jim_Newman

Jim_Newman

Jedi Hopeful
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Beautiful sunny day 60deg F. 80mph on freeway, cruising great, engine temp at 140F, oil pressure 55psi.
I hear the occasional pop/cough from somewhere. Seems like it's under the car or from the engine bay. Doesn't sound like a "normal" backfire and there is no apparent change in performance. It happens maybe 4 times in 10 miles. Then I'm off the freeway back to 55-60mph and I don't hear it again.
Car is domesticated former vintage racer with high compression pistons and triple Webers.
Any ideas out there??
Cheers
 
With today's gas,we get a alot of cars in that have Webers & have dirt or debris in idle jets. Normally popping at speed is indicative of plugged main jet,lean misfire, easy to pop cover off& remove emulsion tube & clean jet. cheers Genos2
 
May not be related, but one thing I have learned from the Porsche community to note is that higher compression (racing) engines usually mean really high octane (>>93). The absence of it requires dual ignitions (twin spark plugs). Not sure how the Healey racers get around it, but Porsche race engines have a second plug opening tapped into the head for each cylinder.
 
Genos2 wrote
"With today's gas,we get a alot of cars in that have Webers & have dirt or debris in idle jets. Normally popping at speed is indicative of plugged main jet,lean misfire, easy to pop cover off& remove emulsion tube & clean jet."
Sounds like good advice but does anyone have advice on the best way to go about cleaning these jets?
As always, thanks for the input.
Cheers
 
If your car is really running at 140' F then that seems to be a little too cool .
Don't you have a thermostat installed ?
Mine will backfire if I step hard on the gas before it is warmed up all the way ( at least 160' F). After it is warmed up, it never backfires.

Ed
 
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