Low carb screw having no effect.

[Adamam]

Apart from air leak, anything else that could bring this about?

 

It's a 372. It idles correctly regardless of screwing OUT the low screw. You can get it to race by screwing it in, but from 1 turn out, it gives the same results regardless.

 

Pressure test pump is borked, so can't test it easily.

 

Crank seals have been changed during the problem with no change in behaviour.

 

Intake boot is new. Cylinder gasket good.

 

Funny.

[Stubby]

Its not a problem then really . if it idles ok , is it ?

[Adamam]

Its not a problem then really . if it idles ok , is it ?

 

I dunno why I asked really; it's obviously an air leak. The idling is probably just a coincidence.

 

Idling correctly at 1 turn, 2 turns, 3 turns isn't right.

 

 

Anybody recommend a vacuum/pressure kit that's cheaper than a mityvac and actually works? I spent more time fixing my Chinese one than I did using it!

 

[Sawchip]

I dunno why I asked really; it's obviously an air leak. The idling is probably just a coincidence.

 

Idling correctly at 1 turn, 2 turns, 3 turns isn't right.

 

 

Anybody recommend a vacuum/pressure kit that's cheaper than a mityvac and actually works? I spent more time fixing my Chinese one than I did using it!

 

Try this one Adam...I have one and its been fine.

Its in amongst the listings on Ebay that you can find if you look for ....Vac/Pressure brake bleed tester

[Stubby]

Does it over rev on full chat though ?

[Adamam]

Try this one Adam...I have one and its been fine.[ATTACH]207785[/ATTACH]

Its in amongst the listings on Ebay that you can find if you look for ....Vac/Pressure brake bleed tester

 

That's what I bought last time. First one didn't work at all, replacement lasted only slightly longer.

 

If they're cheap enough, maybe I'll chance a third...

 

 

Stubby, no it doesn't over rev, but there must be an air leak so I would think it's going to soon...

[spudulike]

A leaking welch plug can cause these symptoms as can an air leak. As far as the test equipment, I have two systems that I use and always have a backup.

 

The 372s will fail a leakdown test on the clutch side seal and the impulse line as a common fault. the decomp tends to leak also.

 

Sounds like you need some better test gear long term!

[Adamam]

Stupidest issue ever!

 

The (new, aftermarket) sleeve for the throttle cable was slightly too long, so the throttle was being held open slightly, even with idle screw all the way out.

 

What a waste of time!

 

Doh!

 

 

 

There's probably a lesson there somewhere, but I don't know where...

[spudulike]

Stupidest issue ever!

 

The (new, aftermarket) sleeve for the throttle cable was slightly too long, so the throttle was being held open slightly, even with idle screw all the way out.

 

What a waste of time!

 

Doh!

 

 

 

There's probably a lesson there somewhere, but I don't know where...

 

Always the stupidest of faults that catch even the best of us engine builders out. You live and learn.