1968 Ford Mustang Carb. Problem?

Tiny
ITALYDIRTRAMP5
  • MEMBER
  • 1968 FORD MUSTANG
Engine Performance problem
1968 Ford Mustang V8 Two Wheel Drive Automatic 105k miles

Hi, my name is Josh, I am 17 and need some help with my car. It's actually a 68 fairlane 500, but it has the same engine as a mustang. My question is why is my engine backfiring inconsistantly? It idles fine, but when I goin gear to about 2k RPMs sometimes she'll pop, and backfire out either the carb, exhaust or both. Or when I gunn it it will pop, and when i'm going down the highway it will pop decellerating. Sometimes even sounding like a missing issue at the higher RPMs. This has a '68 302 bored.40 over, HO cam (firing order 351 w), msd blaster coil, points and condencer(gap at 020) an edlbrock 289 intake man. With 2" spacer, and a holley 4160 600cfm with vacum secondaries. I also have long tube headers as well. I really appreciate your time reading this and hope that you can certainly help me out. Thanks again, --Josh
Friday, August 29th, 2008 AT 9:18 PM

3 Replies

Tiny
MHPAUTOS
  • MECHANIC
  • 31,937 POSTS
Hi there,

Check the ignition timing and make sure the distributor is in good order (no shaft wear or worn bushes) check the ignition leads for excessive resistance, and get the exhaust checked on an analyzer for it may be running to lean. Start here.

Mark (mhpautos)
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Saturday, August 30th, 2008 AT 2:12 AM
Tiny
ITALYDIRTRAMP5
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Alrighty mark thanks a lot, i'll give it a try this weekend, I appreciate it
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Saturday, August 30th, 2008 AT 7:40 AM
Tiny
ITALYDIRTRAMP5
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New info. I found out that when the motor was rebuilt, the HO cam was put in with hydrolic lifters, and adjustable rockers, to accomadate for the cam because the motor is NOT an HO motor. I'm pretty sure now this is the problem with the carb. Backfiring up through, my valve timing is off. Should I get new rockers? Re-adjust them? Or try and find HO heads for the 302, or are there any alternative heads, (351W heads; are they the same as HO 302?) Thanks, again, all and any imput is greatly appreciated
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Wednesday, October 1st, 2008 AT 9:15 PM

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