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Author
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Topic: i'm really in trouble!! cam/ ignition??
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Stang72
Journeyman Posts: 55
From: Arkel,Zuid-Holland,Holland
Registered: Jan 2003
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posted 05-25-2003 10:55 AM
   
Hi Guys,Im having trouble with my 302. Since i've put on a set of World heads (Windsor junior) it's been backfiring all over the place.. intake or exhaust backfire, you name it , i've got it.... before the heads it has done it also but less...
if it's running now (at idle ...) and put it in 1st ,it stalls. also with raised idle (2000 rpm). When you floor it from idle it backfire's (intake) , when it's running at say 2500 rpm it backfire's thru the exhaust.... now we've tried almost anything except setting the whole car on fire (we are saving that for last ;(...)
Now here are the layout of the engine, '71 302 , 0.030 overbore. all new bearings and so. speed pro flattop pistons 10,2 to 1 compression with 54cc cambers (i have 58cc so lets say the comp is 9.4 to 1) the camshaft is from Ford Motorsport partnumber M6250/A312 with the following specs Adv. dur. 290-300, dur. 214-224. intake opens at 0 bdc, closes at 34 abc, exhaust opens 49 bbc and closes 5 btc. lift at valve 472 i- 496 e. the intake is and weiand stealth with an holley 4bbl 600cfm, the ignition is from Mallory Unilite, and an upgraded coil also Mallory. Now it has never run properly with the Unilite and now its at its peak...so i really need some help about what to do or change... thanx in advance Ben
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N266fords
Gearhead Posts: 1039
From: Spokane ,WA USA
Registered: Apr 2003
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posted 05-25-2003 12:30 PM
whats the firing order on that cam is 15462378..? are your wire good ? and not touching each other ? Could it be your distributor is 180 out.? Give us some more to work with here you say it did it before the head change! But was it doing it befor the cam change? You could have a flat lobe on the cam. You could have a bent pushrod have you had the valvle covers off..If you have guide plates on the heads you have to run harded push rods ,you are if thats the case right? Bruce
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Stang72
Journeyman Posts: 55
From: Arkel,Zuid-Holland,Holland
Registered: Jan 2003
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posted 05-25-2003 12:38 PM
the engine has hardend pushrods/guideplates and are new. The backfiring started with the new cam( when the engine was rebuilded) and when i think about it, also before, when i put in the Mallory.checkings the lobes is worth a shot i guess
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Stang72
Journeyman Posts: 55
From: Arkel,Zuid-Holland,Holland
Registered: Jan 2003
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posted 05-25-2003 12:40 PM
Bruce , i have 9 volts on my coil if that's what you mean??? im using the original ballast resistor
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Hemikiller
Gearhead Posts: 421
From: Clinton, CT
Registered: Feb 2002
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posted 05-25-2003 12:48 PM
First, the firing order is 1-5-4-2-6-3-7-8....Check the firing order
Check the plug wires, spray them with water and see if idle changes. My guess is plug wires have a problem.
Check the carb, it may be too lean with the new heads.
You may also have a vacuum leak somewhere. check around gaskets with spray carb cleaner.
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N266fords
Gearhead Posts: 1039
From: Spokane ,WA USA
Registered: Apr 2003
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posted 05-25-2003 01:13 PM
Unless you are running points no ballast...Bruce
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Stang72
Journeyman Posts: 55
From: Arkel,Zuid-Holland,Holland
Registered: Jan 2003
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posted 05-25-2003 03:24 PM
So no ballastresistor is required????.12 volt straight on???
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69 Sportsroof
Gearhead Posts: 1421
From: Valley, Alabama, USA
Registered: Mar 2002
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posted 05-26-2003 01:25 PM
From the Summit website concerning the unilite distributor...Mallory recommends the use of a MAA-700 Ballast resistor and MAA-29351 Power Filter in order for the Unilite to operate efficiently. Are you using mechanical only or vacuum advance?
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