Help with engine misses!

[Blazer79]

My old (20 years old) HEI distributor was missing under high RPM when the engine got a little hot, so I just replaced the whole thing with a Summit $149 one, which is supposed to outperform the one in a ZZ4.

I was happy because I thought the problem was gone. Well, today I just came back from the first long trip (100 miles) with the new distributor. It didn't miss during the trip, but when I was near home, I parked at my girlfriend's for about 7 minutes, and then drove 3 more miles home. That's when it started missing again. Now it happened even at lower RPM than before.

I'm desperate and mad now. I spent the $149 hoping to solve any problem (module, coil, cap, rotor, bushings) once for all, and I'm at the same place as the beginning. Any help greatly appreciated. The spark plug wires (Accel Super Stock) and spark plugs (Accel U-groove) are about 1 year old and about only 6000 miles on them. Has a new gas filter. Is it possible that it might be the carb and I'm confused? It happens when I want I need a little more power, like when passing a car.

Thanks

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What the heck!...Drive it like gas is $0.50/gal!!!</font color=black>

 

[cityfarmer2]

If you have an adjustable Vacume advance that could be your problem or you may have to adjust the curve. You should first contact summits tech line I use them all the time even if the don't have what I want to buy. They are generally real cool about it.. Gary...

 

[Blazer79]

Does anybody know where the wire that feeds the distributor comes from? My guess is that maybe it's getting too hot or maybe cut somewhere. Do you think the spark plugs or spark plug wires could be causing this? They are only about 1 year old and about 5K miles. Any other ideas?

<font color=black>//////
What the heck!...Drive it like gas is $0.50/gal!!!</font color=black>

 

[CBLAZER81]

Just a past experience.My other truck was missing and couldn't figure it out.Turned out the plug boot was fried from my headers.It didn't look bad until close inspection.Good luck.

Yes,I have driven over a F*&d lately!

 

[Waxer]

I had the same symptoms and it turned out to be a stretched timing chain. I replaced it with a double roller from Jegs and that cured all my problems. Hope this helps. BTW, I did purchase a new HEI Dist from Jegs as well thinking it would fix it but I had more problems to fix it turned out.

 

[BlueKnight]

check your plug wires and check your plugs. They usually tell the story. I had miss once that was only once in awhile. Come to find out my exhaust burnt a hole in the spark plug wire on the back side. Never would have found it if I didnt physically grab the plug wires and inspect them

 

[AIRBORNE]

Could be a sticking lifter. Ever had a bad cam lobe? Does it feel like that? Try changing your oil to 15W-40 like what is used in diesel motors, it has a detergent to keep the inside cleaned.

 

[79Cheyenne]

I recently had a similar problem I replaced the ignition to no avail. If you have a quadrajet carb look there next. It seems mine was slightly out of adjustment so I was told. (even though I havent got a clue how a misaligned carb would make the engine miss) I replaced it with an edelbrock and have had no problems since.

<font color=blue>Happy Trails

<font color=orange>1979 BLAZER Cheyenne

 

[Zack]

Okay I have a question for all you experts..
The other day I was coming home in my rig and I was doing bout 65 mph.. I was near home so I mashed the gas and got her up to 85 and when I let off the throttle to return to 65 I heard a blup like a flame coming out of the drivers exhuast! I actually saw a little orange in contrast with the dark night sky too! Is this a backfire? How can I prevent this? Also when my baby is cold I can't hit the throttle without it stopping dead then going. Its kinda hard to explain. I bought a brand new qjet from Autozone and my motor is a FRESH rebuild.

Need more info? post

<font color=red>Zack Carlson</font color=red>
<font color=yellow>[email protected]</font color=yellow>

 

[SVBlazer]

The flame is caused by the high vacuum on deceleration. Happens with race cars all the time. Raw fuel is drawn through the carb, past the engine and ignited in the exhaust system. There are a couple of hazards here: blown exhaust system and potential fire. Sounds bad but really not an issue if your exhaust system is sound. This should only happen when your twisting the motor hard and getting off of it equally hard.

Second issue sound like an ignition problem associated with Q-jets. When nailing the throttle the ignition has a hard time lighting off the rich air fuel mixture completely. The result is the bog or quenching of the flame and a stall.

Hope this helps. (sorry for spelling errors..it's late :-/ )

 

[Blazer79]

Thanks for the help. I've never had a bad cam before. The engine is stock with 104000 miles. The only mod is the new Edelbrock intake and Q-jet. I'm currently using Exxon 20W-50 oil since I'm in hot weather. I'm not sure if this one comes with detergents. Correct me if I'm wrong, but I've heard that detergents in the oil are harmful to the engine, I don't know why though.

Would a sticking lifter cause any noise in the engine (like clicks or stuff like that)? How do I determine for sure if a lifter is sticking?

<font color=black>//////
What the heck!...Drive it like gas is $0.50/gal!!!</font color=black>

 

[Blazer79]

79Cheyenne:

I already have a new Edelbrock Q-jet (installed it only 3 months ago). The only way I can imagine the carb causing misses is by lack of gas, and that could only point to the gas pump, since the carb, fuel filter and hoses from pump up are new.

Anyway, I'm installing new spark plugs and wires just to be completely sure about the ignition.

Does anybody know if a bad fuel pump could be causing this? Also, can a too large gap on the spark plugs be causing this? I don't trust the gapping sleeves I have.

Thanks again guys.

<font color=black>//////
What the heck!...Drive it like gas is $0.50/gal!!!</font color=black>

 

[CBLAZER81]

I put an Edelbrock on a while back and the float adjustment was all wrong.That would be my 1st check.The next is the spring choices for the metering rods.check your install manual,it has a lot of ideas on what to do for a lot of problems.If you don't have one try www.edelbrock.com to get
an install manual(tried to find the right url page but couldn't find it)Mine still isn't perfect but it's geting better.Hope this helps.

<font color=green>Yes,I have driven over a F*&d lately!</font color=green>