carb problem or compression problem?

[agent fabricateur]

So the little 12a in my 84 GSL starts and will run but only appears to be pulling fuel through one primary venturi well, the other just dribbles occasionally. I bought the car not running, knowing it had starting issues.

Would this be possible blown seals on one rotor? I assume the scientific chuff chuff test would be accurate enough to answer this? Just wondering before I pull the carb if it's worth it

Assuming on a 12a you can physically see the seals through the spark plug holes like you can in a 13b?

Thanks in advance, I searched a bit but couldn't find relevant info.

Connor

[codge]

They've talked about using a boroscope on here before now. Great idea to see inside.

[agent fabricateur]

Hmmm don't think I have access to one of those. Just looking for ways to minimise the time I put into this engine that I'll eventually pull out and sell.

The seals must pass right over the spark plug like in a 13b though so I'll see tonight.

[TOOL]

You can see about 60% of the apex seals as they pass by the exhaust port. You'll be able to spot major apex seal failure, but that's about it.

You won't know what's going on with the corner or side seals or check the condition of the housings.

Turn it over with the plugs in. Listen for the chuffs. 5 strong chuffs indicates an issue most likely with a side seal, possibly stuck.
4 strong chuffs is more likely an apex seal issue, affecting the rotor chambers on either side.

A compression test is the only way to accurately determine what's going on.

Having said all that, your carb sounds like it needs a rebuild from your description.
At this point, I think you've just got carb issues.

[agent fabricateur]

Thanks TOOL, fingers crossed for the miracle of carb cleaner.

[TOOL]

*online diagnosis

[agent fabricateur]

Diagnosis spot on! Strong, even chuffs. I fixed the dodgy fuel pump wiring and ran a couple cans of carb cleaner through the carb which seems to have made things worse. The rear float does move up and down as evidenced by using my phone's camera as an inspection mirror, but it seems the needle isn't actually seating and the carb quickly begins flooding into the #2 rotor secondary. I also don't seem to get anything through the main jets when cranking and the accelerator pump doesn't prime enough to get it to catch. Rapping the carb with a drift and hammer hasn't seemed to unstick anything.

I found a local guy who rebuilds Nikkis on craigslist who quoted me $200, what's a good running, complete 12a with a rebuilt carb and all of the emissions stuff intact worth these days over a core with good compreConnoru


I'm thinking tomorrow evening will involve a hail Mary attempt at getting it going on carb cleaner and then parking it on the street so I can do some repairs on a 928 GT that my brother has recently bought.

Thanks for listening to my drivel and hopefully answering my question.

Connor

[TOOL]

It's worth almost nothing not running.

A good running 12A has got to be worth $500.

You decide.

[agent fabricateur]

Thanks, I think I'll go for it. Maybe somebody with a SA or an RX3 will take everything!

[agent fabricateur]

So I pulled the carb off and I have two questions... What's the deal with the little vacuum pot operated butterfly in the #2 rotor primary runner?

More importantly should I replace the coolant seals in the intake manifold while I have the carb off? It's an '84 GSL.

Thanks!