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Discussion Starter · #1 ·
So I had to go hot rodding my 55 yesterday. (1972 350/5speed, hei ignition, edelbrock 1406 4bbl) Ran it through the first three gears pretty hard. The results were not good. A bad miss at any rpm, will not hardly idle. Thought the float may be stuck, but no! Pulled cap off hei after checking timing to check for cracks or damage, all looked good. Number 1 cylinder lines up with rotor at number one and on timing marks. Pulled top off carb to check for debris and blew out seats. Didn't help! Any ideas??? Could i have floated a valve, and how would I check for that. Also the timing light I have is not inductive pickup. It's just the old clip on to the plug type. Could that be a problem. Any advice would be great!
Thanks, Duke
 

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I was thinking the same thing, cracked porcelain or maybe even bad wires or both.
 

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It might sound a little crazzzzy, but even on my HEI units, i will pull the plug wires one at a time while the motor is running to tell me what plug is not firing, you will be able to hear and feel the miss in the motor when you remove the plug wire, if there is no change in the sound or the idle of the motor, you know that plug is not firing. You can also loosen the wires on top of the D cap, fire up the motor and pull them one at a time so you wont get shocked like you might with puling the spark plug end of the wire.

Also fire up the motor at night time in the dark, if you have a bad spark plug wire, you will see the spark jumping around on the wire looking like X-Mass lights, it could be something as simple as a bad wire also.

:anim_25:
Rick
 

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It might sound a little crazzzzy, but even on my HEI units, i will pull the plug wires one at a time while the motor is running to tell me what plug is not firing, you will be able to hear and feel the miss in the motor when you remove the plug wire, if there is no change in the sound or the idle of the motor, you know that plug is not firing. You can also loosen the wires on top of the D cap, fire up the motor and pull them one at a time so you wont get shocked like you might with puling the spark plug end of the wire.

Also fire up the motor at night time in the dark, if you have a bad spark plug wire, you will see the spark jumping around on the wire looking like X-Mass lights, it could be something as simple as a bad wire also.

:anim_25:
Rick

Thats what I was talking about.....:tu
:gba:
bowtie-trifive
 

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Discussion Starter · #9 ·
Sorry guys, I forgot to say I pulled the plugs. All had a little bit of white tip on them. I will try the running it in the dark and pulling the plug wires one at a time. Would still like to know how to tell if a valve could be the problem?
Thanks for all the suggestions
 

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A Compression test will assist in diagnosing a faulty or sticking valve.
Also a backfire or popping in inlet or exhaust will help.
regs
 

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You could have Broken a Valve Spring. Find out which Cylinder is missing if its not Plugs or wires then pull valve cover and check springs sometimes you can see the broke spring. Can be easily fixed on the car. Hope this Helps
 

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Discussion Starter · #12 ·
Thanks guys for all the advice. Pulled some of wires last night, thought it smoothed out some. So today, I changed dist. cap, rotor, wires. Seems like the miss has smoothed out, but some of the time if I let it drop to an idle it will run good at 1000rpm. But when I hit the petal hard and let completely off it, rpm will drop to nothing and it dies. This is all setting still. If I am driving, it's not to bad till I let up to stop, then it dies. I don't know to chase it as a carb problem or electrical problem. My next step is to pull valve covers and check. To make matters worse, I am suppose to show car to a buyer Sunday. After Sunday I will pull carb off my 57 to try. Any More ideas would be great.
Thanks
 

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Thanks guys for all the advice. Pulled some of wires last night, thought it smoothed out some. So today, I changed dist. cap, rotor, wires. Seems like the miss has smoothed out, but some of the time if I let it drop to an idle it will run good at 1000rpm. But when I hit the petal hard and let completely off it, rpm will drop to nothing and it dies. This is all setting still. If I am driving, it's not to bad till I let up to stop, then it dies. I don't know to chase it as a carb problem or electrical problem. My next step is to pull valve covers and check. To make matters worse, I am suppose to show car to a buyer Sunday. After Sunday I will pull carb off my 57 to try. Any More ideas would be great.
Thanks
Sounds like you have a carb problem going on. What kind of carb are you running? It is kind of hard to explain on the computer, but is sounds like you might have a float issue. With the air cleaner off and the car idling, look down the primary's and the secondary's on the carb and see if you can see any gas dripping out of the ventures down into the carb. BUT, what ever you do, DO NOT touch the throttle with your face over the carb, if you hit the gas it could back fire into your face..... ASK ME HOW I KNOW :sign0020:

Anyway, if you can see fuel dripping out of the ventures into the carb, you either have a piece of crap stuck in the needle & seat for the float, or the float level is to high. Basically your carb is like a toilet, if your float level is set to high, the water or fuel has to go somewhere, the toilet drips all over your floor were as the carb will drip fuel down the ventures causing the car to run very ruff and it will not idle because the motor is getting way to much fuel. It may sound silly, but i can listen to a carb and hear bye the vacuum or the whistle in the carb whether or not there is fuel dripping into the carb.

Rick
 

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Poor running small block

Hey Duke150....Check fuel press at idle. shd be around 6 psi. could be tired fuel pump. install vac guage and check vac at idle vac shd be taken from mnfld port shd read steady... a bad valve or v/spring will show as a vac needle jumping rapidly back and forth. a bad fuel mixture will make the needle sweep slowly back and forth. poss that distrib weights are stuck at no advance or anywhere inbetween or vac adv pot is dead... use your vac guage to set your timing...and fuel mixture....first set idle where you like it. then with vac adv suction line installed to distrib..... adv distr til your vac reading is highest then just bac the timg back a hair......reset your idle and set your idle mix at 1 1/2 turns out from shut off....recheck vac guage .....turn idle screws'[ one at a time] in til eng stumbles and then open up 1/2 turn. if all looks OK shut off eng and try to start...if it labours to start, you may have to back timing off a hair and reset idle RPM and idle mix. I hope this helps... we do not have emission testing here in Tappen so the idle setting may be a wee bit rich but with the crummy gas these days rich is better and you can lean it out if you have to go for testing. This way of setting your timing IFALL ELSE IS GOOD is easier thn a timing lite and actually shows what timing the eng wants with regard to all the wear parts cam/chain/TIMING GEARS etc. and you don't need to worry about damper and timing tab etc. I have set many eng this way including long duration highlift cam setups. With good success Sorry to be so long winded CHEERS TERRY
 

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Discussion Starter · #15 ·
OK guys, Rick and Terry share The winners ribbon today. I decided to throw parts at it. New cap and rotor, no, back to NAPA. New wires and plugs, No!$#%*. Back to NAPA. New timing light. NO!$%#:). OK, I need to eliminate something! New satin Edelbrock Carb. NOOOOOOOOO! Wait a minute, adjust idle mixture on new carb. Runs great. Man am I a great mechanic or what. No, I am not! I did the same thing on the old carb and blew it out at the same time, but I should have adjusted and checked the old carbs idle mixture screws again. I believe the old carb was ok but needed more adjustment. Of course this knowledge after the fact. But all in all, I had to show the car to an interested buyer today and I think it may be sold. So all is good thanks to the people on this site.
Thank everyone for your help! BTW Terry, My 55 is the same color combo as your, but reversed.
Thanks again everyone.
Duke
 
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