Missfire /backfire and running hot

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Model T Ford Forum: Forum 2013: Missfire /backfire and running hot
Top of pagePrevious messageNext messageBottom of page Link to this message  By Valtteri Aspinen on Monday, May 27, 2013 - 10:10 pm:

So yesterday I drove my car, first all worked fine. Then suddenly I was getting lots of missfiring/backfiring (I dont know the terms, but I think gas exploted in exhaust) and the car was running very hot. I also noticed that if I advance the spark over half a way, I will get a knocking sound out of the engine. I also noticed some black burn marks at my exhaust manifold gasket, so I think I have a leak there, so probably in intake to? Should I use copper rings and glans? Could this leak cause all the problems? And what size wrench do I need for the exhaust pipe nut?


Top of pagePrevious messageNext messageBottom of page Link to this message  By kep on Tuesday, May 28, 2013 - 03:29 am:

An intake leak can cause the engine to run lean, If the backfiring and knocking/heat goes away with the mixture screw turned out then it is likely leaking.


Top of pagePrevious messageNext messageBottom of page Link to this message  By mike_black on Tuesday, May 28, 2013 - 07:41 am:

You definitely need to fix the exhaust/intake leaks with rings and glands if possible, then go from there. I've used pipe wrenches and big channel locks for the exhaust pack nut, but they are not easy to use with a body on. Nothing works better than the wrench made for it sometimes available at swap meets or through the T vendors.


Top of pagePrevious messageNext messageBottom of page Link to this message  By keith g barrier on Tuesday, May 28, 2013 - 08:05 am:

Leaning the carb out to much will also give the same symptoms, however you do need to fix the leaks. KB


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dave Dufault on Tuesday, May 28, 2013 - 08:43 am:

"And what size wrench do I need for the exhaust pipe nut

Can you borrow one ?
http://www.modeltford.com/item/3061W.aspx

pipe wrenches don't work so well:
http://www.mtfca.com/discus/messages/331880/354841.html?1366058377


Top of pagePrevious messageNext messageBottom of page Link to this message  By Valtteri Aspinen on Tuesday, May 28, 2013 - 01:45 pm:

Okay, so now I have changed intake and exhaust gaskets. Now it runs on idle really nice and adjusting carburetor needle really makes change in motor. But problem is this, when I start giving more gas it start "rumble" back it nice running is away. What causes this? Lack of gasoline?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Valtteri Aspinen on Tuesday, May 28, 2013 - 01:46 pm:

And also engine start running really hot when giving more gas.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Tuesday, May 28, 2013 - 02:51 pm:

It's possible that the fuel line between the tank and the carburetor is partially plugged. Or that you have a filter in that line. Anything which restricts the flow of fuel will run well at starting or idle, but when you open the throttle, the float level will drop and the gas will not be flowing enough to replenish the fuel in the bowl. Hence it will start to run lean. Another possible cause of the overheating and backfiring could be retarded spark. A combination of restricted fuel and retarded spark would cause the exhaust valves to get hot and some of the gas would explode after the valves are opened.
Norm


Top of pagePrevious messageNext messageBottom of page Link to this message  By Valtteri Aspinen on Wednesday, May 29, 2013 - 11:48 am:

Fuel line checked, no affect. Could it be spark plugs?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Scott Conger on Wednesday, May 29, 2013 - 11:56 am:

intake gasket leak is what I suspected in previous thread and that change made the positive result I expected (Tues. May 28 1:45 reply).

my next advice may seem far out, but have seen it before...what do you know about the muffler? Almost sounds like it's blocked or partly blocked. There is some bypass effect with the exhaust pipe not being clamped to the muffler and that may account for the good idle, but when running a volume of exhaust, if the system is partially plugged, it will act as though starved for fuel, and will run very hot. Remove muffler and see if engine will run freely.


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