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Author Topic:   Crazily Hot Exhaust Manifold
Stonewall
Dirt Full Roller

Total posts: 44
posted July 02, 2002 09:52 AM UIN: 10024185
I just watched the video tape of my last race and this is what I saw...

My exhaust manifold (corvette 2-1/2" outlet center dumps) on the RH side was glowing blue on the back half of it. I freeze framed a very good picture of it and it is obviously the manifold (seen thru the RF wheel well). Any ideas why it would be doing this or does it happen to anyone else? I've also got an intermittent miss in the engine that I've been chasing all year.

Possible Relevant info...
Ignition: MSD HEI Module & Coil, No vacume advance and welded mechanical advance, timing set @ 36 deg. BTDC.

Solid lifter CAM with valve lash set @ manufacturers recommendation of .022" intake and exhaust.

355 c.i. engine, dart iron eagle heads, dual plane intake manifold, Holley 2 barrel built by KB Carburators (a Carb builder in our area with a VERY GOOD reputation) right now jetted at 78.


340duster
Dirt Full Roller

Total posts: 70
posted July 02, 2002 01:28 PM
I would say one of the cylinders feeding that area wood be running leaner than the rest of the engine.

WesternAuto17
Dirt Freak

Total posts: 248
posted July 02, 2002 01:48 PM
You are lean on that cylinder probably because the intake gasket is leaking and sucking air at the manifold. Just a guess. Whatever it is, you can burn a piston pretty easy, so you need to figure it out.

BayouGent
Dirt Forum Racer

Total posts: 87
posted July 04, 2002 12:35 AM
It sounds like the # 6 and 8 cylinders may be running lean. Look at the spark plugs on these 2 cylinders and compare them to the rest of the engine. 78 is a decent size jet to use but the engine may want a fatter jet (because the other side may have been glowing too and just not seen). If the problem is isolated to just that area of the engine look for a vacuum leak where the intake seals against the head. Get a can of WD-40 and spray some where the intake runners meet the head for cylinders 6 and 8. If you hear a change in sound of the engine you have a vacuum leak right there. If not the vacuum leak could be pulling from the same place in the lifter valley. That would also explain your intermittent miss on occasion as well. If you do find a leak you can try to tighten the intake a little, but replacing gaskets is the way I'd go. If you don't have any luck finding a vacuum leak you might want to replace the intake gaskets just to be on the safe side. Like WesternAuto said you can burn a piston pretty easily. Hope this helps.

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