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Author Topic:   red hot exhaust manifolds!
rogracer2
Dirt Maniac

Total posts: 119
posted June 11, 2005 01:10 AM  
I pulled out my new distributor last week and put in the old one because of a problem with the pickup coil. The motor ran a little hot in the feature, and I checked the ignition timing and it was a mile off. So, this week I I set the ignition timing, went back out, and this time the exhaust manifolds turned hot during the 8 lap heat race! The engine sounded like it was really turning a lot, but I was a mile behind everyone on the track. The temp only went to 210, so I didn't realize the manifold issue.

One guy said it could be timing, one the distributor itself, another said the carb...

Any thoughts or ideas will be appreciated!!!

nine finger
Dirt Forum Racer

Total posts: 76
posted June 11, 2005 03:43 AM  
your timing is still way off. are you trying to time by ear? if not buy a good (craftsman) timing light. your timing is so far off the fuel is burning while the exhaust valve is opening.

rogracer2
Dirt Maniac

Total posts: 119
posted June 11, 2005 03:32 PM  
I checked the ignition timing again this afternoon - it was 8 BTDC. The distributor has welded advance, so I checked the timing up to like 45000 rpm, and it retarded slightly to maybe 6 BTDC. I hear a hissing noise coming out of the top of the quad-jet carb - that I don't remember hearing before. I don't see of feel a vaccuum leak under the car - the noise is coming out of the top of the carb. Could that be the problem?


rogracer2
Dirt Maniac

Total posts: 119
posted June 11, 2005 08:01 PM  
Here's another question: Last week when I pulled one distributor out and put the other one in, I didn't make any marks, but just eyeballed how one came out. If the rotor was turned too far one way or the other, could it still show 8 degrees BTDC with the timing light but actually be a lot more off from misplacing the rotor? I'm going to pull the valve cover and line up the rotor again Sunday...

Gomer T
Dirt Full Roller

Total posts: 36
posted June 11, 2005 08:07 PM  
Had the same problem with a distributor a couple of years ago. The gear was worn causing the timing to be off. Installed a new gear and no more red exhaust manifolds.

DangerZoneRacing
Dirt Maniac

Total posts: 176
posted June 11, 2005 08:08 PM  
With the car running spray carb cleaner all around, like around the base of carb and around the edges of the intake. if you hear a change in the sound of the engine...you have a vacuum leak. I had this problem 2 years ago. People in the stands thought i had red lights under the hood of my car, They told me they looked "satanic red". lol. I literally climbed out of the car after a race and lit a cigerette off of the exhaust manifold. I was told by a engine builder to go runs some hard hot laps and shut it down (shut motor completely off) on the front straight and coast into the pits. Then pull the back 2 plugs on the drivers side and check them to see if your leaning the engine out, in other words if you have to small of jets. I did this and it was fine. We ended up checking the timing and it was dead nuts on. Here we had the wrong timing tab for that balancer so the engine was extremely reatarded. I found this out by the guy pitting next to me that said he had the same problem when his balancer spun! Another thing to maybe look at. Hope this might help you.

eenfield
Dirt Maniac

Total posts: 116
posted June 12, 2005 08:23 AM  
6 deg at 4500 is way low. It should be at 30-40deg, depending the engine and combination.

It not uncommon to hear a hissing noise from the top of the carb. It is just air being sucked in. Still to be safe you should check for vaccum leaks. I my self wouldnt use something like carb cleaner to check though. WD-40 or similar would probably be safer.

petordragon
Dirt Maniac

Total posts: 167
posted June 17, 2005 11:38 AM  
advance timming to about 35 deg with engine reving at 4000. the hissing your hearing is prob idle mixture screws you hear as long as the hissing is comming out of the carb and not from base of carb or intake your ok.

crazyhorse
Dirt Roller

Total posts: 15
posted June 17, 2005 01:03 PM  
did you check to see if the inside of the balancer spun?throwing off your timing.

ispin
Dirt Full Roller

Total posts: 48
posted June 17, 2005 03:02 PM  
I agree with crazy, I fought a car for two days putting in a new dist. Balancer rubber rotated. Set it to tdc made a new mark ran like a dream!

rogracer2
Dirt Maniac

Total posts: 119
posted June 17, 2005 03:34 PM  
I'm guessing that setting ignition timing at 8 BTDC with a welded/locked distributor is the wrong thing to do! Should have been something like 36?

I'm going to put in a new distributor and redo timing next week.

DangerZoneRacing
Dirt Maniac

Total posts: 176
posted June 17, 2005 03:46 PM  
Change the balancer while your at it just to be on the safe side.

o5racer
Dirt Freak

Total posts: 402
posted June 19, 2005 11:29 PM  
For years now I have took a center punch and put a dimple on the inner and outer ring of the balancer right in line with the timing mark. That way Ican look at and instantly tell if the outer ring has slipped. as long as the inner and outer marks line up everything is good.
Nick

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