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A little help diagnosing please

Go through the igntion and plugs, etc., and then run a compression test on all cylinders; with a steady miss like that, it is either ignition on one cylinder or a leak in a cylinder or instake runner. Is there any miss at idle?

Even your 4.5 power valve should have cut in with the pedal floored; changing from a 4.5 to 6.5 power valve won't change/cure a flat miss on one cylinder.

I had an issue with plug wires earlier and went threw all of that, wires, plugs, etc. That problem (rough idle) was caused by a bad set of wires that would push the connector into the boot instead of plugging in. I pressure tested each cylinder for leaks already but haven't done a compression test (that would be really rough on a few cylinders). No miss at idle, in fact after fixing the wire issue it smoothed out so much that it now sounds very mellow.

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I was going to say something in "ignition, my 1st wild as guess" {like your cap &/or rotor or even air gap if it has one} or advance curve even, or initial timing maybe,

valve-train somewhere {I know you don't want to think it's a bad rocker adjustments too tight/too loose, sorry},

possibly bad wire arching {need ultra-low resistance wires with a hot ignition system like less than 100-ohm's per ft loss, you could be getting cross arching between wires if not separated, adequately/properly}, wrong heat range plugs ??,

also with an aftermarket cam, they generally like allot more initial timing like 16*-20* BTDC easily,

do you have a vacuum advance & if so, is it adjustable ?? {a little allen head screw in the center of the pod thru the vacuum line port, limits the amount of added advance}, if so limit the amount of advance & time it to have between 32*-38* max total timing, usually towards the lower side...

Fuel pressure/supply, Jets, accel. cam & squiters could be lean/too small, if it was the acc. pump charge it should go away after initial hit, but if it's lean {jets or even wrong or bad power-valve} it will surge kind of, under a light load or when your on it hard, under a load... what kind of fuel pressure & pump etc. ??, is it "flowing 5-7psi" everywhere ??

sorry I'm not much help guessing here

I'm not allot of help either, I haven't had allot of time to trouble shoot it yet and can't even answer all of the questions being asked. I really started this thread to get all the idea's I can before I get back in the garage. Checked for arching the other night in the dark with a water mist like suggested and nothing, I'm running the stock recommended plug (for now), wires are Taylors (recommended for hot ignitions), already checked the air gap and I'm fairly confident that it isn't the carb now (idles great, responds well but stumbles threw the whole rpm range as long as it's under a good load but doesn't miss a lick if you accelerate very very gradually). I'm not a pro but I would think if it was the carb it would be more isolated to a particular circuit like idle, off idle, mid or wot but it's everywhere but idle. Thanks, I'll take note of all because even if it is the cap like I believe it is I still need to get it dialed in once this is resolved.
 
I had an issue with plug wires earlier and went threw all of that, wires, plugs, etc. That problem (rough idle) was caused by a bad set of wires that would push the connector into the boot instead of plugging in. I pressure tested each cylinder for leaks already but haven't done a compression test (that would be really rough on a few cylinders). No miss at idle, in fact after fixing the wire issue it smoothed out so much that it now sounds very mellow.

I'm not allot of help either, I haven't had allot of time to trouble shoot it yet and can't even answer all of the questions being asked. I really started this thread to get all the idea's I can before I get back in the garage. Checked for arching the other night in the dark with a water mist like suggested and nothing, I'm running the stock recommended plug (for now), wires are Taylors (recommended for hot ignitions), already checked the air gap and I'm fairly confident that it isn't the carb now (idles great, responds well but stumbles threw the whole rpm range as long as it's under a good load but doesn't miss a lick if you accelerate very very gradually). I'm not a pro but I would think if it was the carb it would be more isolated to a particular circuit like idle, off idle, mid or wot but it's everywhere but idle. Thanks, I'll take note of all because even if it is the cap like I believe it is I still need to get it dialed in once this is resolved.

Good luck & let us know what you find or if something else or some other symptoms, that isn't obvious...
 
Hmmm, timed it by ear. Follow Budnicks instructions on initial timing and see what happens.
 
Hmmm, timed it by ear. Follow Budnicks instructions on initial timing and see what happens.

I knew I was in trouble, I guess I always toyed with the timing until I found the happy spot then put a light on it and took note. I am curious to check the total because I've never ran a brand new distributor nor have I ever had to mess with one. I'm here to learn and will get back to you guys tonight but with the rain I doubt I'll get much testing done tonight. I'll do as Budnik suggested
 
:head_smack: What can I say I'm an idiot, after comparing caps it was obvious that something happened to the button but once everything was installed....no start, blubber, blubber. So I checked the wires (all good) then pulled the cap and there was the rotor with it's tip cranked sideways (wonderful). I noticed they looked a little different and compared the tips and sockets for a match but never compared the height, they sent the wrong one and it hit above the brass. I put the old one back in (it was fine) and took it out, same crap. Then I put a light on it and this is where the "I'm an idiot comes in" turns out even though I've gotten away with it with good results in the past timing by ear is a thing of the past now.............35 btdc at idle. Alright go ahead I've got it coming.......So I start pulling it down and thinking it's going to stall at any minute but turns out it's happy at 15 btdc. By then it was to dark (no headlights yet) for a joy ride but it seemed to really rev allot cleaner.

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Now, what's the best way to optimize the timing? Vacuum gauge? Couldn't check the advance yet (can't reach the carb from where I have to hold the light) but with any luck I'll get my dad to help this weekend.
 
Just thinking out loud.

Fine setting of your timing, by the light, keep in mind your carb idle speed will have an effect. To get the timing in place, idle speed needs to be right.
Set initial timing, then dial in your idle speed on the carb, and re-check timing.

If your idle speed is too high, the timing advance will try to kick in, throwing the timing set off.
 
Just got home, beautiful outside so I fired it up and picked my boy up from school in it..............not so much as a spit, sputter or miss just pure rumble. Now I guess I have a starting point to work from, with it set where it is (16 degree) on the initial it now rumbles allot more (rough idle) but doesn't struggle at all just sounds like a healthy cam but I noticed the power brakes aren't working as well at idle in gear now. Thanks for pointing out the obvious even though I feel like the biggest jackass for my ignorance, Oh well that's one more thing I won't ever do again. Now once I get someone to help I'll check the total. Thanks guys
 
No big deal, LOL I think we've all done something pretty stupid we've truly regretted from time to time, we're human,
we live & learn, by our mistakes sometimes too... such if life
I get mine to fire by ear sometimes also, if it's close !!, then get the light out & make it right, then double check...
have fun
 
Thanks for all the input. I invited a buddy out for some garage thrashing today and had huge progress, here's what we did. We settled on a timing of 16 initial and 36 total all in @ 2,500. The next test drive showed little improvements and reading the plugs showed a very lean condition. After some reading I decided the 4.5 was probably not richening the circuit early enough and put the 6.5 in, the next drive showed a much smoother running motor while cruising but still weak in my book. With it still reading lean we jumped from the .78s up to 82s, the next drive resulted in a big improvement in acceleration. Plugs still reading lean so we figured it would be safer to go allot bigger and work our way down instead of continuing to run it lean and jumped up to .88. This change turns it into an animal, it runs like a scalded dog pulling really hard threw 2nd now. The plugs are still reading lean but it's running like I expected now which is a huge relief. Here's where everything checked out or was set to, 7 lbs of fuel pressure, jumped up to the 6.5 power valve, .88 mains, 16 initial 36 total al in @ 2500, 10 lbs of vacuum @750 rpm in gear and the cranking compression showed all cylinders @155-160 lbs.
 
Yeah, I tuned up a Vega 4 cylinder once by ear at idle and when we got a light on it, it was at 32* BTDC at idle.......that idea never works! Not surprised at the power brakes not as good at idle; vacuum is very likely down now. A check valve in the booster vaccum line will help that; it just needs to be as large as the line...large.
 
"I love it when a plan comes together". been following. ya gotta feel good about the results. congrats!!

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Yeah, I tuned up a Vega 4 cylinder once by ear at idle and when we got a light on it, it was at 32* BTDC at idle.......that idea never works! Not surprised at the power brakes not as good at idle; vacuum is very likely down now. A check valve in the booster vaccum line will help that; it just needs to be as large as the line...large.

BWAHAAAH. had a '73 vega with a fried engine harness. wired the coil into the heater blower motor term. if you turned down the blower motor, it would start missing (not that it really mattered). had to run the fan on high.... all the time. needless to say chicks dig that.
 
"I love it when a plan comes together". been following. ya gotta feel good about the results. congrats!!

Yeah, especially after the embarrassment of being a jackass. Oh well you live and you learn and I learned nothing beats going threw it all one step at a time correcting everything as you go.
 
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