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MG TD TF 1500 - carb vent holes

On a resent post regarding damper oil, I wrote the following message. Since I didn't get any response at the time, I've decided to repost as a new post.

This is what I wrote: On a related topic (I decided not to start a new post), regarding the vent hole in the brass damper cap. I quote the following write-up from MGAguru.com:

"Some carburetors have the top vent hole, but not all. Some carburetors have the lower vent hole, but not all. The trick here is that you need exactly one of these holes but not both."

And, "If you have both vent holes the engine will run really bad as it spoils the chamber vacuum, and the piston may only rise a little or non at all (always lean under power."

In checking the carbs on my '54 TF, I have both vents on each carb. Should I now seal off the vent hole in the damper cap? The engine seems to run well after rebuild (although it does have an annoying miss I'm trouble shooting), but then, I haven't had it out on the road for a full test.

I did receive a personal e-mail from LaVerne regarding this topic, but thought this might be a topic of interest a broader audience who visit and contribute to this BBS.

Regards, John
John Brickell

My car has damper holes in both of the tops, mine has the brass pistons in the carb and not the aluminum ones with the spring. Someone told me once that if the carbs have the brass pistons, damper holes are correct in both carbs.
Tom Maine (TD8105)

I seem to recall that we thread on this not too long ago. There were images of both types of carburetors. Let's see if I can find it. Bud
Bud Krueger

Look in the archives for:
daspot (sic) dampers vent
and
Carburretor Damper Top Nut

Bud
Bud Krueger

Thanks for the responses Tom and Bud. I will check the archives as you have suggested Bud. Would have responded earlier, but was out with some good friends at one of our local micro breweries. One of the rewards of living in the Pacific North-wet.

Cheers -- John
John Brickell

John - Our Pacific North-wet has been pretty dry this month, particularly since this is also a La Nina winter. Cheers - Dave
David DuBois

Correct as usual Dave, but will it last?

I have looked at the archival posts that Bud suggested and they were quite helpful. One thing I learned is that just because your carb cap has the angled ridge running down from the top of the cap to the wider top section does not necessarily mean that there is a vent hole there as well. I will check for the hole today, as I have just been assuming (silly me, eh?) that the presence of this ridge automatically implied a vent hole. Apparently not.

Cheers -- John
John Brickell

Yep, upon investigation, there are two vent holes for each of the carbs. Since it will be much easier to fill-in/plug the top vent holes on the damper caps, are there suggestions of how best to do this. Like just solder over the holes? Suggestions?

John
John Brickell

Try placing a piece of duct tape over the holes in the dampener caps first and see if this changes or solves your symptom.
If so, then a piece of solid copper wire that fits the diameter of the hole could be soldered into the hole; or a little JB weld; or just get some solid caps and save those for other carbs.
Dallas Congleton

Good suggestion on temporary closer Dallas and will do -- John
John Brickell

Some good reading on the carbs. Mike

http://www.jcna.com/library/tech/tech0006.html
Mike Hart (52 TD 16378)

This thread was discussed between 17/12/2011 and 19/12/2011

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