Holley n h leak

Topics Last Day Last Week Tree View    Getting Started Formatting Troubleshooting Program Credits    New Messages Keyword Search Contact Moderators Edit Profile Administration
Model T Ford Forum: Forum 2018: Holley n h leak
Top of pagePrevious messageNext messageBottom of page Link to this message  By Don Sandberg on Sunday, July 22, 2018 - 02:34 pm:

I have seepage at rim of the bowl and body of the carb. changed the gasket twice still have seepage. I have not backed off the drain valve plug while tightening the drain valve body and gasket to the bowl. I assume that the valve plug does no function except the drain the carb. as necessary Is this correct? Would backing off the plug allow more "tightening" of the valve body and stop seepage?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Strange - Hillsboro, MO on Sunday, July 22, 2018 - 02:40 pm:

Sounds like the float level is too high, adjust as needed.

https://www.google.com/search?q=holley+nh+float+level+mtfca&rlz=1C1CHBD_enUS737U S737&oq=holley+nh+float+level+mtfca&aqs=chrome..69i57.6759j0j7&sourceid=chrome&i e=UTF-8


Top of pagePrevious messageNext messageBottom of page Link to this message  By Corey Walker, Brownsboro TX on Sunday, July 22, 2018 - 04:03 pm:

Sometimes the middle of the bowl will get sunken in over years of tightening the bowl nut. The bowl should hit the carb body first. You can set the bowl flat on a piece of wood then put a socket the right size in the bottom of the bowl and hit it with a hammer to flatten it out. That way when you put the bowl on it will sandwich the gasket there first and when you tighten the nut it compresses both gaskets.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jim Patrick in Florida on Sunday, July 22, 2018 - 04:16 pm:

Can you lay a piece of 180 or 220 grit sandpaper on a very flat surface and sand the rim of the bowling the sandpaper?

I learned from this forum that, right out of the package, the bowl rim gasket is too small to fit into the rim flange and must be soaked in water prior to installation. If you try to install it without soaking, it will either tear, or will be distorted to the point of not sealing properly. Jim Patrick


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Jelf, Parkerfield KS on Sunday, July 22, 2018 - 04:42 pm:

Another possibility is a leaking float valve. That will let the bowl overfill. It can be caused by the needle not seating properly, due to an irregular surface of the needle or seat. Another cause can be fuel leaking from behind the seat due to a rough surface in the hole and a gasket too hard to seal well. The seat gaskets sold in kits are notoriously too hard, and I always make my own. Some make the gasket of lead, but so far thick gasket paper works for me.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Sunday, July 22, 2018 - 05:10 pm:

I think gas is leaking past your float valve. Four possible causes: 1. float too high.
2. gasket under needle seat not seated. 3. Needle not properly seating in seat. 4. A spot of dirt between the needle and seat. See Steve's post above.
Norm


Top of pagePrevious messageNext messageBottom of page Link to this message  By Doug Keppler, Fredon NJ on Monday, July 23, 2018 - 06:32 pm:

I love how it says to check the float valve for leakage in the Ford service manual...turn the carb upside down and suck on the fuel inlet elbow, if needle is properly seated, the tongue or lips will stick to the elbow. Imagine a modern car service manual telling you to put the carburetor on your mouth to check it? By the way after reading that I ran right out to the garage to suck on my newly built carb and my lips stuck! Doug


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Monday, July 23, 2018 - 09:32 pm:

How does it taste? Yuk!
Norm


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Jelf, Parkerfield KS on Monday, July 23, 2018 - 09:37 pm:

About like siphoning, only less.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jerry Davis Houston TX on Tuesday, July 24, 2018 - 09:05 am:

I had the same leaking problem. It turned out the float pin was too short which allowed the float to get stuck in the open position. A trip to ACE and a brass rod that could be cut to the right length fixed it.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Duey_C west central, MN on Tuesday, July 24, 2018 - 11:26 pm:

For checking needles and seats, we can create a tremendous amount of negative pressure (vacuum) to test for sealing on valves.
I've tested this with a gauge. :-/ Slip the tongue or a lip over the port and you'll soon know.
Tastes terrible no matter how much you clean the port. Tried it last on an IH Diesel return fuel check valve. Yuck. Spit. Spit. Yuck.
Leaks like a sieve. No prob tho.
:-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tony Bowker, Ramona, CA on Wednesday, July 25, 2018 - 02:41 pm:

If the NH is set correctly, the fuel will not reach the top of the float bowl and therefore the gas cannot leak out. If the gas leaks out, then the level is too high. Either the float is set too high or the gas is leaking past the cut off valve.
For an NH I believe the float level should be set to 15/64. Just how you get it that accurate on a rough casting is another matter. The needles with a rubber (?) seal seem to fail with modern gas, so the all metal ones are preferred. However modern ones are too rough and need to be smoothed before use. IMHO


Top of pagePrevious messageNext messageBottom of page Link to this message  By Doug Keppler, Fredon NJ on Wednesday, July 25, 2018 - 05:43 pm:

Tony, where are you getting these metal ones, seeing how the venders say they are no longer available? Inquiring minds want to know. Doug


Top of pagePrevious messageNext messageBottom of page Link to this message  By Arthur Babitz on Wednesday, July 25, 2018 - 07:47 pm:

I can answer Norm's question about the taste of the carburetor. I rebuilt my NH last week. Since everything was freshly cleaned and painted, I decided, in the interest of science, to try the "suck" test (see figure 440 in the manual!) It tasted like... fresh paint. My valve was well seated. I followed the advice of sanding the surface where the float valve gasket sits using a dowel with a disk of emery cloth glued to it.


Add a Message


This is a private posting area. Only registered users and moderators may post messages here.
Username:  
Password:

Topics Last Day Last Week Tree View    Getting Started Formatting Troubleshooting Program Credits    New Messages Keyword Search Contact Moderators Edit Profile Administration