don't mess with to many things at one time....sure if you have no basic skills in engine mechanics.
Now that plug is indeed fouled and how ! ... so you found a first problem.Place 8 new plugs and be sure to have the right type for your heads ( taper or flat ring )and temperature grade according your engine , as Marlin explained. And try running the car .See from there. The only thing you risk is fouling another 8 plugs but that isn't THE cost i suppose...
greetz
quote:The engine idles fine, but when I pumped the gas the bang turned out to be blowing out of the carburetor
I'm 90% sure it's carb related. Ignition and valve springs come later. Just had a friend's Pantera that did exactly the same, reason was lack of acceleration pump squirt. Check with engine off and a mirror over the carb (not your face) that you have two strong squirts immediately after opening the throttle. If you don't that's the reason. You can normally adjust it (my friend's Pantera was misadjusted by a mechanic, when properly adjusted the problem was gone). Or it could be dirt in some passages or a loose squirter (big screw holding it down, visible in the mirror).
A paste from my web page:
" it’s critical to adjust end play when throttle is fully depressed. If end play is too much you lose pump action, if it’s to little you end up destroying the pump. End play is determined by opening the throttle fully (engine off) and then seeing how much further you can press the accelerator pump at the are situated on the fuel bowl. You should be able to create a gap of 0.4mm, adjust spring just above to obtain that."
The head is aluminum, and it has SVO stamped on the side. The plug 5754 is holding has a shorter reach. Is this the difference, or is there something on the seal itself that is different. If I get the same plug I have but with a tapered seat, and is there any harm if it should have had the washer?
quote:Originally posted by MARLIN JACK:
...By the way...'What Heads are You running'??
Stock Cleveland heads take a SparkPlug with a 'Tapered' Seat! What head are You using a Plug with a Metal 'O' Ring Gasket, In?? And it looks to Me, that ring hasn't even been Compressed Fully to Seat! Are You running the Wrong SparkPlug? Most All Aluminum Heads take a 'Flat Seat' Ring Gasket, Sparkplug! NO Tapered Seat Plugs in Aluminum Heads; The Seat would Errode and The Taper Could Crack Them!...
My dad built this engine, and he build a lot of engines. As far as the amount of oil required to foul the plugs. Before I installed the PCV valve it had 2 vents, and was leaking oil out of the vent pretty badly. I put the PCV valve in and no more oil, leak. Maybe I am sucking too much oil out of the valve cover? It seams to me my best bet is to replace the plugs and put the leaky vent back on If it runs I will buy an oil catch for the PCV. As far as which plug the plug feels like it is going in all the way. It takes a lot of turns to get it tight, and I would be shocked if my dad who built 7 small and large block American engines, and 4 six cylinder outboard motors that I can remember would put the wrong plugs in.
Thanks Marlin.
It was early in the morning when I wrote that. The PCV valve I installed goes into the manifold, so to get to the carb the oil would have to go up steam. The Plugs are NGK. I know hotter plugs are less likely to foul, but will it resist fouling while burning a little oil.
If the drain backs are clogged would that starve the crank bearings? I did about 100 miles of hard driving before the problem developed, so I think that if I had starved the crank I would already have more serious problems.
I will do the other things, but I am going to try new plugs first. If it runs well with new plugs, then that is a start.
I will have the box checked. The distributor cap looks brand new, and I have another MSD cap in a box, so I know the current one is at least the second one since the rebuild was done 10 years ago. I had it off to get the trans out. The plug wires don't look as new.
It was early in the morning when I wrote that. The PCV valve I installed goes into the manifold, so to get to the carb the oil would have to go up steam. The Plugs are NGK. I know hotter plugs are less likely to foul, but will it resist fouling while burning a little oil.
If the drain backs are clogged would that starve the crank bearings? I did about 100 miles of hard driving before the problem developed, so I think that if I had starved the crank I would already have more serious problems.
I will do the other things, but I am going to try new plugs first. If it runs well with new plugs, then that is a start.
I will have the box checked. The distributor cap looks brand new, and I have another MSD cap in a box, so I know the current one is at least the second one since the rebuild was done 10 years ago. I had it off to get the trans out. The plug wires don't look as new.
Update. I pulled a plug from the other cylinder bank. It looked the same as the one I pulled last night, and it had oil around the end of it. It has been a few years since the plugs were changed. It is possible that it was not running perfectly and degraded slowly until the backfiring became noticeable. The oil level is not any lower than when I filled it 2 weeks ago, so I have not burned enough to notice a drop in the pan level on the dipstick. I am going to do new plugs and plug wires, and I found a cheap home-depot way to make my own oil catch can for the PVC line. I will update you when I get the new plugs and wires.
Ian
Ian
Thanks I had to get the same plugs because the guy at the auto store did not know an equivalent but hotter plug, and the current NGK R5671a-7 is the hottest they make. They do not have 6 or lower, which means higher in NGK world. I found out that the autolite 3935 is equivalent to the 7 but that is there hottest on that plug. If anyone knows similar plugs that would be great. If I find one with the correct thread and shape and an NGK heat rating of 5 or 6 is this all that matters, or are there other factors?
As for the wiring. I am putting the wires on one at a time replacing the old ones one at a time, and as a backup I will label them with tape and a sharpy.
OK My wife had to go out, so I could only drive up and down the street once. It misfired once on a low RPM 2nd gear start, but starting in first ran through one two great. It took this long, because I cross threaded the first thread for the 7th plug I was changing, and had to wait for a back tap tool. I was not able to push too much, because it is stronger now than ever. In first the tires spun, and in second the clutch slipped, so I must adjust the clutch before I try driving anymore. I noticed that the air filter is hitting the two tubes that point out the top of the carb. I think it is meant to dome upward, but has collapsed downward. I am going to fix this too before I drive again.
I don't know if I cross thread it. When I tried to hand tighten the plug it went about one rotation and was stuck. I took it out and put it back in many many times, and it kept happening. I could see with a flashlight that the first thread was damaged, so I got a back tap.
quote:
The two tubes, the cover is hitting, are the Float Bowl Vents! You need a Minimum Clearance of 3/4 Inch over the Top of those, or your going to have problems. The 'Power is Back'! Did 'It' put a Smile on Your Face?...
Does it have to be 3/4" of nothing, because the K&N filter on top of it allows air through, unlike the stock setup with the Aluminum cover.
I have still only driven about 10 miles. It seems to be running better the longer I drive it. in 10 miles I sucked about 3 oz of oil into my catch can. Mind you I drove those 10 miles 1/8 at a time I was WOT or on the brakes the whole time. It is not running perfectly. If I step on it from bellow 2k rpms it hesitates. If I role on the throttle or quicly floor it above 2500 RPM it runs strong. I try to keep the revs below 6500, but it revs so quick from 4000-7000 sometimes I have gone higher. All is good in that high RPM range, and I think the low RPM response was improving, so maybe I need to drive it hard some more if it is nice Saturday. Thanks for all the advise and help Marlin.
Ian
Ian
I drove it all day yesterday. No more hesitation. It is running smooth and strong. I am still sucking a lot of oil into my PCV catch can. I am going to try mounting it higher than the valve cover to see if more will drain back into the engine. It has so much torque that when the tachometer hits 3500 RPM in second gear the tires start losing grip, and I have to let up on the throttle. Before I installed that catch can I must have been burning a lot of oil, but even before I put the PCV valve on it was not running this well, so the plugs and wires probably needed a change anyway. When I have more time I will pull the valve covers and check the oil drain holes. If they are clogged the problem is on both sides, because it doesn't matter which side the PCV is on it is pulling oil out. Of course the harder I drive it the faster it sucks oil, but that is because hard driving causes high vacuum in the intake. Thank you for all of your input.
I bought a better PCV valve from JEGS, and now I am not sucking or leaking oil. Thanks for all of the help.