Choppy during cruising, but accelerations without any issue?

[kawahonda]

Damn. I thought I killed it at 16-16.5. Sounds like I really should replace the intake gasket.

If I had plans let's say, in a year, to replace the intake with an air gap, is it worth the hassle? At 16-16.5", it starts good, runs good, zero issues, and even heat-soak issues are minimized...

Just wondering effect of maximizing vacuum further for the "near term". And is it reasonable to expect several inches of vacuum gain just from the intake gasket? That seems wishful thinking for 2-days of effort. I don't know, just thinking out-loud.

Are 5mm vacuum hoses OK to use for the 340? The hoses say "5mm (1/4")"

[Cuda Cody]

What cam grind will have an affect on the vacuum.  The vacuum of 16.5 is fine.  If you go under 12 I would be worried.

[Bullitt-]

A new gasket will only help if you have a leak at the gasket now....
Running with a leak creates a lean condition which can cause other issues but I'm not seeing that your having problems of that ilk ..
I'd say Diagnose by spraying carb cleaner around the gasket area & if you don't see a change leave it be..

The one thing I think all vacuum leaks have in common are the inability to get the engine to idle slowly enough... I can back mine down to like 500RPM before it starts to die...Also the idle mixture screws don't have much of an effect.  What RPM are you idling at?

[kawahonda]

16-16.5" @ 800 RPM, 8 BTDC.

The 1/4" carb gasket was a must because there was a leak and it solved my heat soaking issues.

My intake still has a leak but I am wondering if it's worth doing anything about. Car runs great. I'll be upgrading the intake, cam, carb in a year, so may not be worth fussing with anymore.

[Cuda Cody]

What makes you think you have an intake leak?

[kawahonda]

Spraying starter fluid causes a drop in RPMs in some sections of the intake/Head connection.  Maybe other parts of the engine is picking up the spray. Not sure. I want to say that even blasting my new carb gasket with it causes a drop in RPM. I didn't use a sealant with carb gasket.

I've had to go out and retorque the carb bolts a few times now after some warm/cool cycles. Hopefully it will be tight at 10lbs next time I check.