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#1 | |
Registered User
Join Date: Nov 2015
Location: Colfax California
Posts: 1,644
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Re: Diagnosing a misfire
Quote:
This guy got mad too. I must just sound like I'm not taking advice or something, although I assure you I'm listening to everything you guys say. I might not be correct when I take a shot at what may be wrong, but I am still learning. As far as I knew, the carb settings were all good to go. Mixture screws were exactly where member Hugger said to put them, idle speed was set wherever it needed to be after I set timing, and the rest of the carb stuff I don't know about yet. |
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#2 |
Registered User
Join Date: Aug 2006
Location: Redmond, WA
Posts: 6,334
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Re: Diagnosing a misfire
MRTurner, you have sort of the right idea on valve lash, but remember oil is NOT compressible, it's not a "soft landing" for the lifter, nor a buffer. When the lifter goes down into the bore and the bleed hole is covered, that lifter is as hard and solid as a mechanical steel unit.
That's how I understand it, anyway. So if they're set too tight, it's not like the hydraulics "absorb" it, it'll still wipe the cam once overset.
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1970 GMC Sierra Grande Custom Camper - Built, not Bought 1969 Pontiac 2+2 427/390 4-speed Coupe 1969 Pontiac 2+2 427/390 4-speed Convertible |
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#3 |
Registered User
Join Date: Sep 2016
Location: lompoc ca
Posts: 228
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Re: Diagnosing a misfire
you got some good advice for your carb you say its running rich. fix that problem and move on. try to focus on one problem at a time
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#4 |
Registered User
Join Date: Sep 2016
Location: lompoc ca
Posts: 228
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Re: Diagnosing a misfire
and dont adjust your valve train into oblivion Im getting a bald spot from scratching my head
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#5 |
Registered User
Join Date: Sep 2016
Location: lompoc ca
Posts: 228
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Re: Diagnosing a misfire
1you are running rich.2 you have wrong power valve 3your float might need adjustment i dont know holleys im not sure4 check fuel pressure 5 put the other carb on and see if it still runs rich and stops smoking
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#6 | |
Registered User
Join Date: Nov 2015
Location: Colfax California
Posts: 1,644
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Re: Diagnosing a misfire
Quote:
Now, someone mentioned float levels, and only supposed to be able to see fuel in the sight Windows if you rock the truck, but I can see fuel halfway up the sight window. So that needs adjusting still. Went through all my wiring and it's tits, I replaced everything with heavy gauge wire when I put the Powermaster alternator in. |
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#7 |
Registered User
Join Date: Nov 2015
Location: Colfax California
Posts: 1,644
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Re: Diagnosing a misfire
Well boys, it may be time to throw in the old towel and get started on my project short block.....just pulled this puppy out of the #5 cylinder.....I had a hunch
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#8 |
Registered User
Join Date: Sep 2016
Location: lompoc ca
Posts: 228
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Re: Diagnosing a misfire
in my limited experience weak spark usually shows up at highrpm good luck
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#9 |
Registered User
![]() Join Date: Nov 2007
Location: Hermiston, OR
Posts: 947
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Re: Diagnosing a misfire
That wire needs replaced. It's designed to lower the voltage so the points don't burn up. Hei needs full 12v, I recommend a relay.
No amount of valve train adjustment is going to make those plugs look good. You need to get the carb off of there and get those floats adjusted, and inspect the needle and seat. You have 4 pages of pretty good advice so far, might be time to take some of it. Posted via Mobile Device |
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#10 | |
Registered User
Join Date: Nov 2015
Location: Colfax California
Posts: 1,644
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Re: Diagnosing a misfire
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#11 | |
Registered User
Join Date: Nov 2015
Location: Colfax California
Posts: 1,644
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Re: Diagnosing a misfire
Quote:
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#12 |
Registered User
Join Date: Sep 2016
Location: lompoc ca
Posts: 228
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Re: Diagnosing a misfire
hey dave thanks i actually forgot about that now mrturner gets to use his multimeter
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#13 |
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![]() Join Date: Nov 2007
Location: Hermiston, OR
Posts: 947
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#14 |
Registered User
Join Date: Sep 2016
Location: lompoc ca
Posts: 228
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Re: Diagnosing a misfire
Ijoined cause my drum brakes stumped mechanics and me took only one day to get a handle on them but I was all ears good luck
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#15 |
Registered User
Join Date: Aug 2006
Location: Redmond, WA
Posts: 6,334
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Re: Diagnosing a misfire
Remember you can't just measure voltage, you need to measure resistance.
__________________
1970 GMC Sierra Grande Custom Camper - Built, not Bought 1969 Pontiac 2+2 427/390 4-speed Coupe 1969 Pontiac 2+2 427/390 4-speed Convertible |
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#16 |
Registered User
Join Date: Sep 2016
Location: lompoc ca
Posts: 228
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Re: Diagnosing a misfire
sorry webfoot thankyou too was making fun of my age I am suffering from early onset of oldtimers disease
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#17 |
Registered User
Join Date: Sep 2016
Location: lompoc ca
Posts: 228
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Re: Diagnosing a misfire
cool jetting is important but if your floats need adjusting and or psi is too high they should be tended to first. to create that much smoke its unlikely jetting.Sides didnt you say carb ran fine at one point?
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#18 |
Registered User
Join Date: Aug 2006
Location: Redmond, WA
Posts: 6,334
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Re: Diagnosing a misfire
I still wouldn't pour money into an expensive motor project until you've SUCCESSFULLY built a budget one and it's run for a few thousand miles.
You're still new at this, as we all were at one time. And you're going to make mistakes, as we all did. But make cheaper mistakes. Make them on an old vanilla 350. Otherwise, all of the mistakes you will inevitably make will be made on expensive parts. Don't think that just because you pay more for the parts that you will somehow rise to the occasion and do flawless work because the parts are expensive. It doesn't work that way. Try to get your truck to go FAR before you go FAST.
__________________
1970 GMC Sierra Grande Custom Camper - Built, not Bought 1969 Pontiac 2+2 427/390 4-speed Coupe 1969 Pontiac 2+2 427/390 4-speed Convertible |
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#19 | |
Registered User
Join Date: Nov 2015
Location: Colfax California
Posts: 1,644
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Re: Diagnosing a misfire
Quote:
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#20 |
Registered User
Join Date: Sep 2016
Location: lompoc ca
Posts: 228
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Re: Diagnosing a misfire
nice what do you think caused that?Btw I said powervalve not jets good idea to write down carb adjustments in a log in case you need to go back
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#21 |
Registered User
Join Date: Nov 2015
Location: Colfax California
Posts: 1,644
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Re: Diagnosing a misfire
My rings are old and worn...it's been on its last leg for a while I'm sure. That's what happens when you throw some bigger heads and a choppy high rpm cam at an old factory short block. I did change the power alive but it needed a primary jet change as well. No matter now I suppose.
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#22 |
Registered User
Join Date: Sep 2016
Location: lompoc ca
Posts: 228
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Re: Diagnosing a misfire
mr turner your thread is very interesting to say the least. did you determine the problem with leak down test and or compression test?Hows your valve guides?
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#23 | |
Registered User
Join Date: Nov 2015
Location: Colfax California
Posts: 1,644
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Re: Diagnosing a misfire
Quote:
I didn't do the leak down or compression tests today. I've had a feeling that the rings were bad for a while now, and wet oil all over the plugs is proof enough for me. I've been plotting a very low compression turbo build for months now and just needed a reason that would justify starting it, and it appears I have the reason now. I'm thinking that Davepl is on to something though and this first self built short block needs to be real cheap, because if/when I make a mistake I don't want to ruin a 2000 dollar Dart block and some nice AFR heads. |
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#24 |
Registered User
Join Date: Nov 2015
Location: Colfax California
Posts: 1,644
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Re: Diagnosing a misfire
I suppose the extra cheap way would be to buy the 100 dollar long block, strip it down to just the crank and rods but leave those in it. Then buy a decent set of new pistons and rings, install those and put all my top end stuff on it. I'd probably be in it for closer to 400 bucks that way, but I'd be putting a lot of faith in the crank and rods and rod bearings that are already in it.
Man what a bummer this is |
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#25 |
Registered User
Join Date: Sep 2016
Location: lompoc ca
Posts: 228
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Re: Diagnosing a misfire
cam beatings? yeah i bet your cam gets beat!im gonna share my secret engine building technique. make friends with a good machine shop bring them coffee donuts lunch DONT DATE THEIR DAUGHTERS.
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