why are my headers glowing on my blower motor ??

Old 10-18-2010, 04:07 PM
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bigray
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Default why are my headers glowing on my blower motor ??

we have a 355 sbc with a mega blower { the big one ]. it has 8.5 to 1 blower pistons, it is set at 3% under, it has two 750 holley Mech carbs,. timing is set at 20 then max at 34 total. IT DOES NOT HAVE A VACUUM LEAK. it holds 9psi of fuel pressure the whole way.it leaves great, but it never really pulls, it weighs about 2350 leaving at 4000 shifting at 6400 and at a idel it will start to make the headers glow,,its only running like 10.40 to not much better,, is it fuel ?? is it timing ? what is it ?? HELP
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Old 10-18-2010, 04:36 PM
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blowninjected540
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Exhaust pipes get red hot for two basic reasons. Either the ignition timing is incorrect or the engine is running extremely lean. There are other causes but these are the two most common, ignition timing is extremely critical. Blown motors love advance. Without enough initial timing advance, blown motors will run hot and the exhaust pipes will glow in the dark. Blown motors should run as little as 16 degrees or as much as 26 degrees initial advance with the total advance of about 32-36 degrees at 2500 RPM to 3000 RPM. Specific timing requirements depend on compression, blower drive ratio, engine load, camshaft, and fuel octane.


That answer was copied and pasted from BDS wed site blowerdriveservice.com I didn't become a master mechanic overnight :lol: But learning everyday.
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Old 10-18-2010, 04:45 PM
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bigray
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thats what we have been looking at.. how can we make it fat at idel ?? the last run we had 82 front and 89 rear, then for the heck of it we took 1 front jet completly out, and still no change ??
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Old 10-18-2010, 04:52 PM
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blowninjected540
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Check out blowerdriveservice.com under tech questions /frequent ask questions.

Is your distributor locked out ? do you have a set of blower carbs ?
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Old 10-18-2010, 04:59 PM
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bigray
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dist is not locked out, it just maxs at 34 degree. nope the carbs are not set up blower carbs, just 2 good holley 750s we had,
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Old 10-18-2010, 05:47 PM
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kwkracing
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If your drag racing this engine lock out the timing and then start trying to tune the carbs. What model carbs?
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Old 10-20-2010, 04:04 PM
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billhendren
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If you are using 23 deg non fast burn heads lock the timing and set it at 36 deg. buy a MSD boost retard to back the timing off as boost comes up. the power valve circuit must be referenced to the manifold under the blower to keep the engine from leaning out. this is normally done by blocking the existing p.v. vacuum source and milling a groove in the metering block to the vacuum advance port which is then plumbed to the manifold side of the blower. Bill
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Old 10-20-2010, 04:13 PM
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fla1976
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Here is a website that shows you how to modify the power valve circuit.
http://www.motorsportsvillage.com/modifycarb.html
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Old 10-21-2010, 05:59 PM
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bigray
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JUST A UPDATE... we did lock the Dist out and set it at 36, and i also forgot to mention that it also has 2'' carb riser plates, that are the 4 hole desdign. so we also milled them out to make them all open. this seems to have helped alot,, gonna try to go out this weekend, but they are calling for rain, i will keep everybody updated as to weather this fixed the problum,
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Old 10-22-2010, 06:07 AM
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billhendren
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Originally Posted by bigray
JUST A UPDATE... we did lock the Dist out and set it at 36, and i also forgot to mention that it also has 2'' carb riser plates, that are the 4 hole desdign. so we also milled them out to make them all open. this seems to have helped alot,, gonna try to go out this weekend, but they are calling for rain, i will keep everybody updated as to weather this fixed the problum,
Be sure to modify your carbs for below the blower boost reference before you try to race it. if you dont it will run lean under boost. If you have been running it without below the blower reference and haven't melted it down you are WAY rich. Bill
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