I have a stock, other than Fireball ignition, 76 2.0 for 20 years. Runs flawlessly. Recently when first started, as I back out of the garage, I get a few random mild backfire-like pops from the engine. As soon as I put the car in 1st and drive away, it never does it again. I have not had the valves adjusted for the last 10,000 miles and they make no noise, so I haven’t bothered. Could this initial backfiring be a sign that the valves finally need adjusting?

Djet ..... Gremlins. But it still runs 50 years later
So dont mess with it.

But they dont make noise so haven't bothered?
Thats asking for it !

Go adjust your valves then if it still backfires it's likely too rich or too lean.

Hey logo, you sound like my wife! She says that I’m always asking for it!

10k is too long besides.

Go adjust your valves then if it still backfires it's likely too rich or too lean.
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How can you tell if the mixture is too rich or too lean?

I was told, rich backfires from exhaust, lean up through the intake.

[quote name='oakdalecurtis' date='Sep 10 2020, 12:18 AM' post='2849916']
Go adjust your valves then if it still backfires it's likely too rich or too lean.
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How can you tell if the mixture is too rich or too lean?
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To get it exactly right, you need a wideband O2 sensor to read what your AFR is at part load and WOT.
Lots of options out there, but this is what I used PLX AFR

That sounds correct to me as well.

Others have said, adjust your valve lash, it's past due.

Probably something like a CHT or MPS that is finally starting to fail.

Good for you for keeping a 76 stock.

Don't know if some of the other posts are "braintrust worthy"

As you probably already know the 76 is a little bit different animal than the others. A good 76 completely stock is worth more than most other 914-4's due to the low production numbers if that is your thing.

Like a couple of others have posted,check you valve lash first....10k is a bit over time for not adjusting and is probably the likely cause.

The next thing I'd check is a vaccum or slight exhaust leak.

Don't know what distributor you are running but if a dual diaphram stock type on the dizzy I'd check those for leaks first.

Post some pics if you can....very rarely do I see a good running stock 76,

Valves are noisy if too loose. They can also become too tight, which is very problematic.

Just got my teener back from a valve job. Mechanic said a few of the valves were “tight”, which he defined as opening a little too much. No more backfire on startup!

Great. Thanks for the follow-up to let us know what you did and that the issue was resolved.