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71 engine won't idle

I recently put my 71 engine back into my 69 bug. The engine is completely new with the exception of the case, crankshaft and camshaft. I replaced every other part on the engine with a new, identical part that came off the original engine. I took it to the local bug expert here in North Chicago to put the finishing touches on because I'm in the military and just didn't have time. The car ran fine at first and then at idle speed, began to die at idle speed whether the engine was cold or warm. So I broke out the Hayne's and followed it step by step to re-adjust my 34 pict

3 carb. Voila, it ran just fine for a few days and then started quitting at idle speed again. I re-adjusted again and got her purring yet again. You guessed it, a few days later and same problem, except this time, I can't get it to idle at all no matter how I adjust the carb. Changed out the entire fuel line thinking maybe I had a small leak that had gotten bigger somewhere in the metal line between the fuel tank and the engine. No change. Seems to run just fine at driving speeds, but I'm pretty sure the momentum of the car is what is keeping it going. Hope I didn't confuse anyone with all these and please post any suggestions!!!!!
Reply to
69bugger
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Assuming you have solid lifters as most air cooled bugs had, you may need to adjust the valves. Especially on a new (rebuilt) engine the valves should be adjusted 500 miles after rebuild, then again at 1500 miles. The book recommends 3,000 mile intervals after that, but my local VW experts recommended oil change and valve adjustment every 1500 miles. There is more variance in the valve lash than usual during the break in period.

Reply to
Ed B

A problem like this can be tough to pinpoint. You need to do a methodical check.

If the valve adjustment is OK, do a compression test; that will allay any fears of an internal engine problem.

Check timing. Timing must be set for the distributor that is actually on there, not by year or engine. If you have the bone-stock distrib with 2 vac hoses, verify that both vac chambers work. Suck on each hose and see if the advance plate moves to the stop and stays there when you block off the hose (I stick my tongue in the hose). If it fails the suck test, you can not time it.

Since it runs at highway speed, fuel delivery is not an issue.

Vacuum leaks in the manifold could be a problem, especially in an engine which has been apart. The 2 rubber booties are suspect as are the manifold to head gaskets. Spraying a solvent around these places while running can show up a leak - the RPM will go up.

Double check that the idle cutoff solenoid (left side of carb) is screwed in tightly; if loose, idle will be intermittent.

Last but not least, there may be dirt in the carb idle passages. This is tough to correct and all the rebuild kits in the world won't fix it. It takes disassembly, solvents and compressed air to cure.

Speedy Jim

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Reply to
Speedy Jim

Thanks for the fast replies, heading out to the garag now to start making her purr again. Will let you know how it goes.

Reply to
69bugger

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