Miss/Vac leak

[72Hardtop]

I noticed the bus missing at idle/low speed drive (1st gear) a few days ago and decided to do a full tune-up (valve adj., new adj. screws/nuts, Plugs (NGK B5ES), wires, rotor, and cap all Bosch) using Pertronix. While removing the spark plug connectors I found that #2 had a nice triangular piece missing from the end of the connector near the plug. Figured that was causing the miss. Nooooo!....Still had the idle/low speed miss that I could hear thru the exhaust. No miss at cruise speed. Could only hear the miss at idle occasionally or if I was driving slowly in first or going down an incline in 1st or 2nd gear. Bus would slightly pop thru exhaust. Checked all exhaust>head nuts and all were good no signs of leakage.

Started looking for a vacuum leak and I found two. First one was a small hose that I used to plug the balance tube on the 1 & 2 side (running IDF's) The second one appears to be at the intake>head manifold gasket at cylinder #1 area. The hose had a plug in it. I removed the old hose and replaced it with a new piece using the plug from the old hose. First vac leak fixed.

As for the second vac leak I've purchased some manifold gaskets from (Aircooled.net) as well as some carb to intake manifold gaskets. I purchased the HP manifold gaskets and was wondering if anyone has had any experience with them? The following is what I purchased. Never mind the photo it shows. It doesn't match the item I purchased (Type-4).

http://www.aircooled.net/new-bin/viewpr ... 17&cartid=

also purchased

http://www.aircooled.net/new-bin/viewpr ... 1140579988

Soft mount...These are paper???

Damn...and I just got done rebuilding/syncing the carbs about 6 mos ago. No vac leaks then. Oh well. Any other suggestions while I've got the carbs & manifolds off? Any recommendations as to the intake manifold gasket application? Go on dry or add any sealant of any kind to improve seal?

[bajaman72]

Dry, and mabey a little blue threadlocker on the intake studs.

[Amskeptic]

Any recommendations as to the intake manifold gasket application? Go on dry or add any sealant of any kind to improve seal?

Paper gaskets, use a thin layer of grease.
Colin

[72Hardtop]

First issue I've had involving intake>head leak on the bus. The manifolds are Webers I purchased back in 88' so I don't anticipate any issues with them. I had them squared up originally when I originally installed them back then. They have been off a few times but not since my last build 7 years ago. I was thinking of applying an old trick to the gaskets that involves using a small roller and some Permatex sealant (fuel resistant) to both sides of the gasket (paper) and then allowing it to dry fully before installing the gaskets. Going to use the following sealant:

http://www.permatex.com/products/Automo ... ealant.htm

Thanks for the replies gents

[72Hardtop]

I removed the intake manifolds this morning and I'm now in the process of cleaning the manifolds. They look very good and appear to be very flay at both sides. I'm going to tackle cleaning the cylinder head surfaces tomorrow. Any suggestions on easy removal of any stuck on gasket material? Most of it came off with the exception of some on the lower side near the studs and in between. I was thinking Acetone. Anything else? What do you guys do to keep any crap from going down the intake while cleaning?

I know I could stuff a rag in there but it seems it would be in the way while trying to clean.

I also have some blue Hylomar and was thinking of using that on the gaskets at the heads. Figure it would be better suited than the Permatex 1. It also has a higher operating temp and is non hardening. Used this stuff in the Navy on turbine engines and worked fantastic even without gaskets.


Thanks guys.

[Amskeptic]

What do you guys do to keep any crap from going down the intake while cleaning?

blue Hylomar is non hardening.

Paper towels stuffed in the ports do not get in the way of cleaning the flanges. They will bring up any crud as you remove them.

Blue hylomar sounds good enough if it is gasoline resistant..
Colin

[72Hardtop]

I finished the job. I ended up using the Permatex 1 on the surfaces (gaskets/flanges). It appeared that the hylomar might have ended up being to thin. Just finished syncing up the duals and took her out for a run. Bus is running great so far.