please help, engine problem.

[chappy89]

Okay, so let me give you the rundown on a series of events and outcome.

last year i took the rail to a race (was not racing) and the car had been running a little strangely. low power etc. so in the field we found #1 was cold, pulled the plug and sure enough was fouled. did a field cleaning and checked gap, voila! engine runs right as rain if not a little rich. did the race crew thing for the day then afterwords was going to take a friends niece for a ride, started it up and let it warm and off we went . . . . about 100 yards and then POP fump fump fump fump . . . plug is gone and wire hanging. i figured stripped head and limped back to camp and went home. now to save some time im going to say i ended up pulling the heads in a cluster of mistakes (on my part) with exhaust studs . . . got all that fixed and put the engine back together. (NOTE: at no time did i mess with timing or carb and upon reassembly, reset valve lash to .006") i started the engine and now does not want to run right, i was expecting this and was planning on tuning the carb to fix rich issue. i used the carb tuning procedure here: http://www.vw-resource.com/34pict3.html

also since i foolishly let it sit with fuel in the carb i ran a take of fresh gas with seafoam through it

this brings me to my issue.

i have the idle relatively set (no tach) but after warmed up by idle from a cold start there is slight popping in the exhaust then i take it around the block and it seems to run fine for a bit but then as temps increase i get bad hesitation and popping out the exhaust at low rpm i.e. from a stop or low rpm in 2nd going around a corner.

i cannot for the life of me figure this out and dont have much in the way of money to take it to a shop and im trying to get this thing running right for King of the Hammers next month.

please help

thanks

edit:
some equipment particulars
1641 DP stock internals
34PICT-3 carb
009 dizzy with pertronix
NGK plugs
flamethrower coil

[Mal evolent]

sounds like a textbook example of a vacuum leak from here.

forget that silly nonsense about spraying propane at the carb. soap down the intake tract, put the outlet of a freshly washed shop vac down the throat, and look for bubbles
_________________
73 Beetle Baja, Ghia front brakes, Type 3 rear brakes, 2220 ( 94 X 80 ), Weber Progressive, Bosch SVDA, '97 Mustang seats

Baja Bugs for Volkswagen Virgins: Index

[chappy89]

Propane? Never heard of that, but I did spray carb cleaner at all connections and no reaction. New gaskets at head, never removed carb from manifold, and new hoses and clamps at end castings.

[Wulfthang]

There's a few things that can cause an engine to run worse when it heats up but the most common is a mixture that's to rich for the conditions. When the engine is cold, it needs extra fuel to run correctly. That's why it gets choked, to richen up the mixture. As it gets warm, it needs a leaner mixture to run right. What you're describing sounds like it's to rich for the conditions.

The problem is to find out why it's to rich. To rich is not always a carb problem. It can be caused by low compression or bad timing and even a plugged exhaust. Pull the plugs and check your compression. Check your timing. Then rebuild your carb.

[Pam's buggy]

Never heard of pressure testing like that .
Cool idea though.
Wonder if it would work to check head gasket .
Hmmmmm.

I agree it's probably rich.
Does it start easy?
Will it start without the choke?.
Carbed to lean and too rich will both spit and pop.
Clean the end of the exhaust the run it to see if it soots up again .
Or pull the plug.
Recheck timing.
Physically check spark .
Weak intermittent fire will cause same issue.
And make you think it's running rich.

A old triumph mec taught me ...
( Most carb issues are timing issues)
If it's points.. do you have copper core wires?
Graphite wires don't work well on points.

If all checks out drop a size on pilot jet.

[chappy89]

Thank you for the information, I have checked compression all cyl around 120 psi and holds, rebuilt the carb. And I just need to check timing then re tune the carb