more dead cylinder questions, all input appreciated

[chariot_chaser]

In an earlier post I explained that my mechanic found that the #4 cylinder was dead in my 86 wagoneer. It had good compression and spark. I took the passanger side valve cover off and the rocker arms looked to be moving just fine. So I replaced the plugs, chased what I thought was a bad plug wire but still #4 didn't respond at idle. I took it back to the mechanic and he did a leak down test, checked the compression on #2, and #4, and checked the vaccuum. He said the vaccuum fluttered and compression was good and close on both cylinders. One thought he had was that maybe the hydraulic lifter was overpowering the valve spring, holding it open a little at idle. He said if it was a weak spring I should replace it before it burns a valve. So I guess my first question is, what is a burned valve? And my more general question is does anyone have any thoughts on what's going on in the black hole I call cylinder #4. If it helps the mechanic said #4 fires at higher rpms, just not at idle. One more queston, I've been thinking about doing the TFI upgrade. Will this help the situation?
Oh yeah, I trust the mechanic, he didn't charge me for most of the stuff he did since he can't lock down the problem so I don't have any reason to think he's anything but honest. TIA

[Don S]

chariot_chaser
This could be quite a few different things. A valve stem could be sticking...I use 2cyc. outboard oil in the gas tank(1/2 pint/20gal) as an "upper lube"..If you will watch it run in the dark sometimes you can see bad wires and/or elec."leaks". might look VERY close in the dizzy cap and rotor for cracks and carbon trails. Also low voltage could cause a problem... Most of the guys here would tell you to up grade to the TFI......Good Luck.......ds..

[Jerk]

don, I've also got a fluttering vac needle at idle, it surges about 1/2 to 1 wholr inch from 14" to 13" and back most of the time, and rpm drops about 100, matching the surge, it is only noticeable at idle and occasionally at 1600 or less rpm, I just changed the oil and filter last week, re-routed spark plug wires( year old solid cores, and year old cap/rotor)- no difference, it runs like a bat out of hell when stepped on though. I smoked the back tires for about 35 to 40 feet the other day on dry ground to see if it still would, actually the left one caught after 5 feet and the right one did the rest. it revved to about 4200 and then shifted, then I backed off and drove around normally. It doesn't seem to be any normal vaccuum leaks but I'm wondering if my spark is crappy or my #8 cylender needs new rings or valves/seals/guides...Matt

[Don S]

Matt W
If I knew what I was doing I'd go back to service writing(40 years ago) :D My guess would be crud in the Carb... But check the PVC & EGR valves first. Compression check on all cyc. for balance is a very good stroke!! Double check all the vacuum lines if your going to Ouray...a leak means your not going over those Passes :eek: ....Don't forget the upper lube..it does alot more than you may think....... ;) ...ds..

[Jerk]

don, no gottem egr -edelbrock perf non emmisions intake manifold. the carb should still be good, 6 month old edelbrock perf carb, all new filters with it- 3 of them actually, 1 single in/out (disel filter) inline prior to mech fuel pump, 1 with return line after fuel pump, one clear, single in/out just prior to carb. all new fuel line except for hardline. I checked the pcv valve and the manifold vac to reservoir that works q-trac/vac gauge, and the one going to the power brake booster, no hisses anywhere, I haven't done a compression check though...I'm kinda skeert at what I will find :(
I'm not going to ouray, I don't really travel that much, gots two wee ones and they are not at all enthralled w/ carseats! 30 minutes and "WAAAAH"! makes it fun getting groceries. :( that plus my running-until-my-wife-drives-it wagoneer is not trustworthy- no gas gauge, gas leak, no mph-o-meter. wiring is a nice mess thanks to p.o.-sherriff's deputy. Oh well, one day the 81 cher wt will be running and the whole -famn-damily will go on excursions...that day is a long-long-loooong way off. :(

[Don S]

Matt W ... I learned not to assume that new parts are good the hard way. It's not just crud in the gasoline..Forward back-fires and air vents can put crud in. Part of AMCs new car make-ready in the '50s and '60s was taking the carbs apart and checking all the settings. I've done so many "vis-flows" I still have night mares :eek: ....if your vacuum gauge movement is kind of slow I think it's a vacuum or carb problem..Maybe the PO put a Rad cam in it if the gauge wiggles alittle faster :confused: ......ds..

[Jerk]

dude, I AM the p.o. sorta it was my dad, I put the engine in, we built it, I paid the machinest, I got the 401 from junkyard, I DID put a cam in it, but its unly a strait replacement- edelbrock performere for old edelbrock performer, the engine is pretty matched to itself, maybe a slightly lumpier cam somewhat later, I might have screwed up the break in period by cranking the dang thing for total of 20 minutes before it actually started and ran. My old Holley had a leaky power valve gasket and was flooding/ hadraulicking number 8 cylinder with raw gas before we yanked the thing off pulled the plugs cranked it to vent all gasoline out of cylinders, and I rebuilt the holley again, and changed the oil and filter, also, I had stabbed the dizzy in 180 off, foundout later and restabbed it. once it started, I broke it in at between 2000 and 2500 rpm for 20 minutes, turned it off, changed oil and filter again and drove it, the holley started acting up again and so I junked it 2 months later for the 1405 ed/ perf 600 cfm.
BTW the vac needle movement is rather quick, I can see it wiggle for every spark, it surges approximately once per second to 1.5 seconds
at like 600 rpm to 800 rpm. The vac line has been plumbed in permanately for over 2 years BTW, but all new lines about 1 year ago. tach is suntune and runs off coil for rpm reading.

[ April 06, 2002: Message edited by: Matt W ]</p>

[Rogue]

fluctuating vacuum readings can be caused by weak/broken valve springs, and or sticking valves in worn out guides

[Jerk]

I was hoping that wasn't the case. still am, could it in any way be related to bad spark system? Actually, I'll just check all that stuff when I get the chance sometime. **** it,now I got my only 2 vehicles that run needing repairs. **** it!!!!!!

[Jerk]

****it-****it-****it!

[ April 06, 2002: Message edited by: Matt W ]</p>

[Jerk]

****, stupid, pieces of ****! **** you , you ****ty, ****ing pieces of ****ing, ****!
a(woops)le, sons of a *****! jeeps!

[ April 06, 2002: Message edited by: Matt W ]

[ April 06, 2002: Message edited by: Matt W ]</p>

[Jerk]

hey, this is fun! :D

[Don S]

Matt W.....HOW HIGH are you......EEerrrrr....at what altitude do you live ?? "whole inch from 14" to 13" and back most of the time, and rpm drops"......At 550' above sea level you should run alittle more vacuum?? :D :D .........ds..

[Jerk]

-4400 ft below sea level heh...heh-heh...heh I can give it more vacuum by advancing my initial advance a few degrees, but the closer to 20* advance it gets, the more it pings at 3000 rpm. I'm at 16 to 17 degrees right now and it idles at 15 to 16" in park, warmed up, at 700 to 800 rpm.

[Jerk]

<blockquote>quote:</font><hr>Originally posted by Matt W:
****, stupid, pieces of ****! **** you , you ****ty, ****ing pieces of ****ing, ****!
a(woops)le, sons of a *****! jeeps!

<hr></blockquote>

my tribute to Happy Gilmore :D

[Rogue]

rotflmao :eek: