Just passing this along as an option to seal the manifold to heads. Skip on the o-rings and use flat 1/16 thick exhaust gasket material and make your own. Outline the gasket material with the manifold, I then used 2 vice-grips (2 small c-clamps would work too) to hold in place while I cut out the middle section and made the screw holes. I also used Yamabond 4 to hold it in place, used a thin coat and let it dry overnight.


Tighten screws in a criss-cross pattern to ensure a even seating to the heads.

Just to let everyone know, I had the wrong thickness on the gasket material, it is not 1/8. it is corrected in the text now.

Yea this is a great tip. Anyone recall my dealing with this problem lead to a Ben Herr manifold and that led to intake leaks on the other end I hope to find a cure for soon, (The machinist just left) Intake leaks are sometime hard as heck to determine by normal means but in each case, even the smallest leak caused the carb to cough and spit back when no other reason was present..

I may end up following this tip because the Ben Herr did come with some extra gaskets that would do this. Great idea Erbman02, but then your one that's always on top of the game!

MS1700 wrote:
Intake leaks are sometime hard as heck to determine by normal means but in each case, even the smallest leak caused the carb to cough and spit back when no other reason was present..


My last issue with intake leaks was a pain to find. Never could I find a leak with wd40, so started to look for leaks with carb cleaner, well, on my last leak, carb cleaner did not find any, but had a feeling there was one, someone recommended to use starting fluid since, as they told me it was more volatile, sure enough, starter fluid found 2 leaks, both at manifold to head on both jugs, one on top in front, bottom on rear. After new gasket installed, using starter fluid, did not find a leak.

Yes i tried carb cleaner, incense, a Cig, I landed on started fluid also. It worked. When the dealer was doing this under warranty, I could tell it was leaking by the way it was coughing back through the carb. It would pass all normal tests at the dealer only the test where they put the probes in the exhaust to measure the exhaust gases would indicate the leak. It had leaked so long and so bad one time (at 13K miles) they had to rebuild the engine.

I think a lot of people who complain of a Carb cough or backfire through the carb have an small intake leak and don't know it. When mine is sealed up tight you can't make it cough.

Hope people come in tune to this reading this thread.

My most recent leak is at the Carb manifold junction. I used a larger o ring in the groove on the carb, and one behind that too, and some rescue tape behind that and pressed it in. So far so great! Even did a cold fire today and not one cough! .

Great tip , I'm pretty sure mines leaking.Let off the gas and the rpms stay up for a few seconds.

sal wrote:
Great tip , I'm pretty sure mines leaking.Let off the gas and the rpms stay up for a few seconds.


usually a slow return to idle rpm's does indicate a lean condition imo, but does not necessarily indicate an air leak, could be from jetting being lean too. been there a few yrs back, 1/8 turn pilot screw adjustment was all that I had to do. but, easy enough to check for leaks to rule it out. If the gasket or o-ring have been on for a couple yrs, does pay to check for leaks, they do get dried out. And also check for vacuum leak on manifold vacuum port if the AIS has been removed, those rubber caps dry out with all the heat in that area.

I tried the gasket you describe when I had leaks on the rear. Just didn't help.

Went with a Nemesis carb joint and DK sent me extra O rings with a gooey silicone sealer with it. I think it is like a sticky grease in a small bulb tube.

I used the Tech article on installing the Nemesis with a hammer handle and have had no trouble. I even re-installed it with new O rings after engine work and have no trouble.

My original manifold just gave up the ghost!

Rayjay wrote:
I tried the gasket you describe when I had leaks on the rear. Just didn't help.

Went with a Nemesis carb joint and DK sent me extra O rings with a gooey silicone sealer with it. I think it is like a sticky grease in a small bulb tube.

I used the Tech article on installing the Nemesis with a hammer handle and have had no trouble. I even re-installed it with new O rings after engine work and have no trouble.

My original manifold just gave up the ghost!

I have the Nemesis too, could never get it to seal with o-rings, tried 5 installs. I finally slotted the holes so didn't need the hammer trick. and went with gasket. First time used o-ring and gasket, after 2yrs developed a leak , last install just the gasket. There were 2 designs on the Nemesis flanges, the thicker flange required the hammer trick, but slotting it allowed it to seat without binding on the screws.

Can you just use an RTV silicone to make the gasket?

That's what I did. Put a bead around the outside of the O'Rings, let it dry a little then installed and when tightened a small bead of silicone formed all around the outside of the flanges.

Scott B.