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Follow up question. I always press the post button and then remember...
Rick- you suggested it was very important that I do not use any sealer on the gaskets. Is there a reason? Since I might be faced with installing new gaskets on the manifold itself I need to understand the right and wrong. I would, by past practice, put Permatex on the main manifold gasket whan I put things together.Thanks, Jon |
he means the gasket under the top part of the carb,i test for leaks with some carb cleaner .I had an idle that would go high and then drop ,checked with some cleaner spray the bottom of carbs and then around the manifold with the motor running found the leaks ,redid the intake and now no leaks.bump up the timing a deg or to and balance the carbs.got my webers from red line called ingeles and got a jet kit made 1 change to the idle jet..
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The base gaskets are made of a material that has the ability to conform to minor irregularities in the sealing surfaces. Each mating surface of the carb, top, main body (top & bottom) is machined flat during production, thus negating the need for sealant on any gaskets associated with the carbs or their mounting surface. That's my story and I'm stick'n with it.
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I stand corrected,Howed i do on the leak test.....lol
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Good explanation.
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Jon,
Try this: Back out the throttle speed screw for the carb for cylinders 1 & 2. Place each cylinder in turn at BDC of the inlet stroke. Use your leakdown tester to inflate the cylinder with low pressure say 10psi. With the inlet valve open and the carb butterfly closed, you should only hear a tiny loss through the "closed" butterfly and the idle circuit. If you hear loss through the oil cap, the intake gasket has been sucked in from under the manifold. This would then explain your low airflow measurements for 1 & 2 and associated misfiring. |
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I had some surprises when removing manifolds and seeing the gasket on some runner just displaced quite a bit.That can be an air leak and is the cause of high oil consumtion. Also check if your carburetor fixing screws ae not bottoming out in the hole and you not really getting them tight enough. Also check that the distributor is not interfering with the carb body. I had to grind down some of the intake manifold there in order to fit the dissy. |
With the engine running you can use carb cleaner to find air leaks. Use the extension tube that comes with can so you can spray in small area. check gaskets, throttle shafts and so forth. Rise in R.P.M. shows air leak. You won't be able to get everywhere but will be a good start. Small camera with extension like some have referred to would help. Someone said they found them at home depot I think.
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This forum is amazing. I feel as if I'm getting help from a vast pool of experience. Thanks so much. I have my work cut out for me but greatly appreciate all the guidance. I'll start with the carb cleaner and then pull that carb.
Right now the east coast of the US is getting pounded with storm. I'm fortunate to be getting only medium rain and some wind. Maybe by Wednesday I'll report back. Thanks again, Jon |
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Z. |
O.K. My report back. Carb that was not drawing is now on the charts. I think the linkage had it positioned with throttle plate totally closed. The backfiring issue, however, Is NOT doing just fine thank you.
I tried the starting spray and can get no localized area where the rpm rises. So, do you think it would be better to continue trying to localize the fault OR just tear the top off and start over making sure the gaskets are sealing??? I'm leaning toward dismantling the top to start over with new gaskets on the manifold to heads. Thanks Jon |
ok now look for this on you tube weber tuning part 2 and part 3,some one posted this on here ,this will show how to sync your carbs
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Cab, I wish it were that simple but I THINK I am dealing with other issues - at least, I think I am-the backfiring .If sinking the carbs will remove the backfiring I'll be so happy but I don't think it will.
Eljaro- I added a photo for you. I removed the four carbs in anticipation of removing the intake BUT when I look at the gasket edge on the manifold and down all the intake runners the gasket seems to be seated and shows no damage. My "problem" carb, when removed had the rear gasket slightly wet. Could the leak be here? The off side bank is the one that seems to be backfiring the most at this point and that's where this carb sits. Finally- Is it acceptable to reuse the gaskets under the carbs? Say yes. They look fine just showing the compression of the carb bottom. Regards, Jon .http://www.clubcobra.com/photopost/d...carbthroat.jpg |
i did ,what is your timing set at.
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Jon,
As I have already recommended in a previous post, swap the carbs around then you'll know if the fault is carb related or engine related. Gary |
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