64, 327/365hp cuts out at 4000 rpm - any clues?
05-15-2017, 07:53 AM
#21
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Thread Starter
Thanks everyone for some awesome suggestions.
Although I'm not a mechanic, I've tinkered for years (which means I'm dangerous), but I'm a quick learner and want to know more so I can keep my ride running at it's best... and I know, things are going to happen. With that said, if I feel I'm over my head, I'll go to a mechanic in the heart beat.
The good news is the engine was totally redone a few years ago and very clean, no leaks and many newer original replacement parts that was all done by an east coast Vette shops... So I'm not dealing with years of abuse. I'm pretty sure I'm dealing with today's gas and the previous owner just didn't drive it enough. In my experience, cars don't like to sit in a garage and do nothing.
My best guess is it's the fuel pump... but I'm going to check the plugs and cap to see if there's anything unusual there first since thats an easy check.
More to come once I get the plugs out.
Michael
Although I'm not a mechanic, I've tinkered for years (which means I'm dangerous), but I'm a quick learner and want to know more so I can keep my ride running at it's best... and I know, things are going to happen. With that said, if I feel I'm over my head, I'll go to a mechanic in the heart beat.
The good news is the engine was totally redone a few years ago and very clean, no leaks and many newer original replacement parts that was all done by an east coast Vette shops... So I'm not dealing with years of abuse. I'm pretty sure I'm dealing with today's gas and the previous owner just didn't drive it enough. In my experience, cars don't like to sit in a garage and do nothing.
My best guess is it's the fuel pump... but I'm going to check the plugs and cap to see if there's anything unusual there first since thats an easy check.
More to come once I get the plugs out.
Michael
05-15-2017, 08:18 AM
#22
Team Owner
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2015 C2 of Year Finalist
There is nothing wrong with today's gas. In fact it's better then it was 40 years ago. So get the chicken little the sky is falling out of your head and do a basic tune up first. Check fuel pressure and check valve lash. Report back after all that is done
05-15-2017, 10:05 AM
#24
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If it runs out of fuel due to a clogged filter or weak fuel pump, it feels like the ignition was turned off. If it just starts missing, it's probably ignition and could be fouled plug due to too cold installed plugs.
Check distributor shaft end play - how much?
Attach a dwell meter and free rev the engine to 6000. If dwell drops off more than 2 degrees there is a problem in the distributor like a wobbly breaker plate or weak point breaker arm tension. As previously mentioned you need the high breaker arm tension points. Search for a post started by me for more info on all the different available point sets.
You should be using a spark plug equivalent to AC heat range "5", like the AC R45. Non-resistor plugs equivalent to the out-of-production AC 45 are the NGK B4 and Denso W-14U.
Duke
Check distributor shaft end play - how much?
Attach a dwell meter and free rev the engine to 6000. If dwell drops off more than 2 degrees there is a problem in the distributor like a wobbly breaker plate or weak point breaker arm tension. As previously mentioned you need the high breaker arm tension points. Search for a post started by me for more info on all the different available point sets.
You should be using a spark plug equivalent to AC heat range "5", like the AC R45. Non-resistor plugs equivalent to the out-of-production AC 45 are the NGK B4 and Denso W-14U.
Duke
05-15-2017, 10:20 AM
#25
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People! Always look at the plugs first. They tell all. Best possible would be to drive it into "the condition", do a clean cut (push in the clutch, switch off the ignition, coast to a stop) take out a plug or two and have a look. Sooty or wet=bad ignition, dry and or white = inadequate fuel.
OR next best, just take 'em all out and look. Post a picture. A lot of us can tell you a lot by looking at them. If some look just right and some not, look into the wires, condenser, points lead, evidence of arcing in the cap.
OR next best, just take 'em all out and look. Post a picture. A lot of us can tell you a lot by looking at them. If some look just right and some not, look into the wires, condenser, points lead, evidence of arcing in the cap.
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jerry gollnick (05-16-2017)
05-15-2017, 10:49 AM
#26
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St. Jude Donor '12
I second this because I've experienced point bounce and loss of power due to (unknowingly) having the low spring tension points in my racing engine. At 5000 RPM the engine would just lay down. It would NOT rev any higher. Sounded like I was bumping up against a rev limiter.
I replaced my Delco 106Ps with the supposedly superior D112 HPs back in the day. It would fall on its face at about 5000. I chased that round and round before finding it.And I carried an extra set of plugs around in the glove box, because after a month or so of ******* it around town, they would crap out and misfire.
Last edited by vettsplit 63; 05-15-2017 at 10:51 AM.
05-15-2017, 10:55 AM
#27
Race Director
I like to see the old plugs and install and test with new ones, but they are not the OP's problem as he has now described it. But new plugs with the correct heat range and gap should be installed for peace of mind at this point........and the condition of the old ones that were removed will help tell the overall health of the engine.
Larry
Last edited by Powershift; 05-15-2017 at 10:56 AM.
05-15-2017, 10:59 AM
#28
Race Director
I replaced my Delco 106Ps with the supposedly superior D112 HPs back in the day. It would fall on its face at about 5000. I chased that round and round before finding it.And I carried an extra set of plugs around in the glove box, because after a month or so of ******* it around town, they would crap out and misfire.
Larry
05-15-2017, 12:05 PM
#30
Plus, check the strainer attached to the fuel sender located inside the fuel tank because it can clog from debris in the tank.
05-15-2017, 12:16 PM
#31
Safety Car
Put the trans in 1st gear and see if it revs past 4000 RPM. Do the same in 3rd.
If it doesn't rev past 4000 in first gear, chances are it's either points bounce, or a weak coil. If it revs past 4000 in first gear, but not if in a higher gear, then it's fuel starvation.
If it doesn't rev past 4000 in first gear, chances are it's either points bounce, or a weak coil. If it revs past 4000 in first gear, but not if in a higher gear, then it's fuel starvation.
05-15-2017, 12:27 PM
#32
Burning Brakes
Check carburetor bowls that they are at proper level. Loosen side sight plugs on both primary and secondary side, fuel should just be at the lower edge of the plug hole. If its too low when you get on it it will empty the fuel from bowl faster than pump can put fuel back in, especially if the fuel pump is on the weak side.
Also my 64' 327 365 does not like AC 45 plugs and I'm a die hard GM guy, it loves Autolite "85" Plugs.
Also my 64' 327 365 does not like AC 45 plugs and I'm a die hard GM guy, it loves Autolite "85" Plugs.
Last edited by mjdart; 05-15-2017 at 12:45 PM.
05-15-2017, 12:28 PM
#33
Drifting
Pop,
From my experience, if it a fuel related problem, the car just lays down and quits revving, without sputtering. If it sputters, I would look for an ignition related issue (or wide spread valve float, which I would doubt is the case).
The point set you want to use is NAPA #CS89 or #CS7860 (cheaper but same specs)
Verne
From my experience, if it a fuel related problem, the car just lays down and quits revving, without sputtering. If it sputters, I would look for an ignition related issue (or wide spread valve float, which I would doubt is the case).
The point set you want to use is NAPA #CS89 or #CS7860 (cheaper but same specs)
Verne
05-15-2017, 01:01 PM
#34
Racer
Shooting in the dark
I don't really have time to read the entire thread, so I'll take my shot:
If that 327/365 is totally stock, it has 11:1 pistons and [B]NO[B] current pump gas will work efficiently with that kind of compression. If you're burning premium 93 with ethanol, I would quit the alcohol habit and fill with 90 octane ethanol free with a shot of 104+ additive to fight preignition. This may be a bit labor intensive but I'd open up that carb and check for sediment and rubber residue from any original fuel lines and replace any flexible lines with ethanol resistant fuel line. If you've been burning that 93 octane "moonshine", you could have a water separation issue somewhere in your fuel system.
As for ignition problems, a points type system will start to break up before your engine completely falls down.
Hope that's at least some help. If not, then
If that 327/365 is totally stock, it has 11:1 pistons and [B]NO[B] current pump gas will work efficiently with that kind of compression. If you're burning premium 93 with ethanol, I would quit the alcohol habit and fill with 90 octane ethanol free with a shot of 104+ additive to fight preignition. This may be a bit labor intensive but I'd open up that carb and check for sediment and rubber residue from any original fuel lines and replace any flexible lines with ethanol resistant fuel line. If you've been burning that 93 octane "moonshine", you could have a water separation issue somewhere in your fuel system.
As for ignition problems, a points type system will start to break up before your engine completely falls down.
Hope that's at least some help. If not, then
05-15-2017, 03:07 PM
#36
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05-15-2017, 03:09 PM
#37
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05-16-2017, 01:31 PM
#39
Melting Slicks
This post is indicative of so many here. You ask a question concerning one issue and get bombarded with a zillion, maybe it's this or, try that's.
Bottom line, I would begin by starting with the easiest, most logical, diagnostic suggestions first. Then, report your findings each time you've eliminated (or found) something that relates to the issue at hand. My.02
Gary
Bottom line, I would begin by starting with the easiest, most logical, diagnostic suggestions first. Then, report your findings each time you've eliminated (or found) something that relates to the issue at hand. My.02
Gary
Last edited by Gary's '66; 05-16-2017 at 01:34 PM.
05-16-2017, 05:09 PM
#40
Burning Brakes
Gary, You are exactly right.
GTO Guy, with deference to your professionalism, to discount plug condition as an indicator of possible causes of misfiring is ridiculous.
GTO Guy, with deference to your professionalism, to discount plug condition as an indicator of possible causes of misfiring is ridiculous.