It`s rare ,but check dist cap for carbon tracking. it will rob spark strength but not 100% . Just enough to let cyl pressure blow out the candle. Good Luck
I Just went through all of this on my 389 pontiac. #8 was dead, had a lot of people scratching there heads. all i can say is check and re-check firing order.....
Funny you mentioned a 389 with a wrong firing order. Back around 1969 a guy from out of state was visiting a cousin here and was driving a 67 GTO. I did not know squat about cars then but knew it sounded strange. I messed with it and found 2 wires crossed. It never backfired or whatnot, it just sounded weird through the glass packs.
Good call Groucho on the lifters and possible spring issues. Still, the fuel for that hole is going somewhere. Too bad you can't "sniff" that header for raw gas.
relax dude...im getting to it..like i said one thing at a time..and i only have 3 or 4 hours after work and its hot as hell out im not worried about 2 thru 8..they are pulling their weight.. at this time im putting my time and efforts into the one that dont play well with the others..trying to smack it to life
It sounds like a vacumn leak on that port runner. The best way to confirm that is get the motor to some one who has a engine anylizer that will run a "Vacumn Wave Form". Some of the Snap-on machines will do this and I am sure there are other brands that do too. Once confirmed it will probably take a visual(tear down) to find it but it is likely to be on the inside sealing surface of the intake manifold. I trust you are NOT using the rubber seals for the ends of the intake that are supplied in a gasket set ?? I also had an intake doing this several years back and it turned out to be aluminum casting flashing blocking the port. So I would say at this point you are going to have to do a visual. Sorry. By the way nice looking motor.
if autolights worked in 7 out of 8 holes i doubt thats the issue..and that plug that was in #1 hole has now been in every other hole and it works fine in them.. no cap tracking either..its new, and yes its been checked checked and re checked
Man do i wish i knew someone with a machine like that.. I didnt build the engine, so im not sure on the gasket choice, but i will be checking after i rule out the pcv issue , if there is a manifold leak.. but 16 as a vac check on idle engine sounds pretty good eh? and 20 at about 2grand rpm?
Hey , i want to go out to all you guys that came to my help on this thread..really its places like this and people like you that make things like this worth fucking with to start. Thanks again all you HAMBers
I'm watching this, one of the better diagnostic posts in a while. I'm going with leaky intake port. Bob
16 is good vacumn but that is the total of 8 cylinders so you need to have a way to isolate the bad cylinder and see what it is actually doing. Maybe someone here on the board knows a way to do that with out the electronic equiptment. Any open or leaking vacumn port such as the one that runs to the trans. modulator will cause the same problem
VRF Is the needle steady at idle, I mean at 16 lbs?? If it is then I think all cyl are working fairly well. Also Does it idle with out any problems? Normally if you have a vacuum leak it will eventually lean the motor out and it will die. How is the throttle response? If you zing it a bit does it cough or backfire?? As far as the plugs being clean the ones in my Ranchero after a run to the swap meet will look just like the ones out of the box. But all in all you may want to pull the intake just for piece of mind. I also have seen them crack under the metal plate in the center of the intake.
yeah she stayed fairly steady, and at 2ooo steady at 20.. throttle response is good..i havent went WFO yet. i can see on the other 7 plugs some light tan showing..#1 looks like a new plug. after i do all the sypherin on all the possibilities that dont involve too much tear down, if they dont produce a result, than off with its intake, and possibly head..but not so soon. gee i really wish i knew someone with a scope and the ability to pin point this issue with technology..worth some $$ to some one in SE michigan?
Hey I was serious about taking the header off and starting it. I guarantee you at 2000 or so you'll see fire. It won't hurt it. Get a buddy and a beer and turn the lights out in the shop. Lippy
It may have been mentioned before, but you can do a backyard cylinder effiency check by pulling one plug wire at a time and note the RPM drop on each hole.
I know you got enough suggestions to send your head spinning . But 1 more that may be over analyzing this thing, but something to think about. I also have a 3 X 2, but on a 292 Y-block and because of coolant passages the center carb is not centered between runners. It's cheated forward causing the right rear runner to be longest because intake design and offset of heads for rod alignment on crank. Now, when at idle if mixture screw on the side with this longer runner is set just a hair too lean it could cause a lean condition at that cylinder possibly because volume of available fuel is to low. Situation could be worsened with a slight design flaw in intake runner design. These old intakes weren't usually computer designed and 98% of folks may not notice what you have discovered. Will not effect off idle and WOT operation because of higher fuel/air flow through boosters. If you have 150 compression, and you have spark, which you do. And you eliminate the possibility of vac leak. May have to find some way to fatten that one side up at idle to balance fuel charge to all cylinders. Don't know, just thinking outloud here. May just be idiotic rambling and probably is. On a side note as a tip for folks without a thermal sensing gun. When roundy round racing if heard a funny idle we tested headers for a miss similar to using a heat gun, only we just dribbled a few drops of water on them. Water sizzle and not stick, hitting good. Water stick and slowly evaporate, not hitting good. Of course won't work on manifolds.
funny you should say that..thats on the easy list for tonight..after i see if the pcv elimination did the trick or not.. those headers are easy to remove
Spray a little carb cleaner or brake cleaner in the pcv hole of the intake if the engine reacts to it you have a leaking intake port!
Ok, I have followed this all the way through. Go buy yourself a $2.00 spark plug. I had one the that the Insulator by the tip was broken. It would fall down and block the spark until you reved the engine up. Cylinder pressure would push the insulator up and it would fire when you got on it. This one took a while to find. If you have compression, spark and gas is will fire. CJO13
My point excactly !!! New don't mean shit and everybody that throws their 2-cents in on this thing assumes everything is perfectly done. If you go to the basics and eliminate them 1 at a time you'll find the problem. I recomended to check the valve lash back on the 2nd page. And if a leak down test was done it would eliminate alot of variables >>>>.
#### That was why I made the comment as I AGREE WITH YOU> Hey Randy I don't think anybody asked you and I appologize if they did and I missed it But does this thing blubber and miss-fire when it idels or are you just concerned about the temp reading on the header. Reason I say this is Lippy hit on this and nobody really listened. If the rings are a bit glazed in this cylinder and it hasn't seated yet you'll need to give a gulp of atf and a couple of good hard throttle loads to seat the rings back in. And when I say hard throttle loads I mean with the car pulling in gear. Just like being on the dyno under a LOAD not free-wheeling >>>>.
yep, im going at it one step at a time,, i will get to these other ideas as i go ..process of elimination..one at a time ..no shot gun shit here.. i want to know what it was..not what it might have been.. if you do too many things at one time..you dont know what one thing made the difference. im also going at it at the path of least resistance ..do the easy shit first.. oh and BTW thanks Eng pro for coming on and checking out my problem
Not that I think it's your problem,I think it will end up being a vacuum leak but a spark plug to a ground in atmospheric pressure does not really indicate spark intensity. The plug must be under compression to achieve voltage high enough to fire a mixture. It does indicate spark presents which in this case I think is sufficient. Good luck and let us know what it turns out to be.A good investment for all is an inductive spark probe. Snap On makes an excellent one that is reasonably priced
no bud she sounds great..no blubber or popping.. steady as she goes..smooth. I cant put her under a load yet..still a chassis..and not enough help to hold her still safely in gear
every one of these plugs have been in a different hole on this engine in the past 2 days..#1 hole is dead no matter what plug i put in it this was determined a long time back in the diagnosis..its not a plug not the dizy, not the wires, its fuel related or vac. and fuel related i believe..all the ignition stuff has been ruled out..completely with no descrepencies
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