Technical 5,8 cylinder not firing, valve train noise

so here is what I got, 5 cylinder not burning, plug is white (new nkg plugs). It is a little grayish white. I check spark on 5 with a Allen wrench to ground and saw spark. I tested is with my multi reader on ohms and got resistance in according to its length. 5 Header pipe is still chrome while others are yellow/blue

Valves move in accordance. I have new lifters. Just bought new pushrods and rocker that I haven't installed. I do have lifter noise that doesn't seem to go away, if I tighten my rockers too much it won't start. So I back em off but it still clatters when I accelerate only, never at idle.

99 Vortec with points distributor Holley 650. Roller lifter. 1931 ford truck, T5

Any ideas guys..

 

Run a compression test

 

dumb question, but do you have 5 & 8 mixed up on the cap?

 

Cam going flat ?

 

I fought two cylinders not firing a couple of months ago. Same as you, valves are moving and I'm getting spark. I replaced all the ignition parts anyway (throw money at it) and kept scratching my head.

Someone on the HAMB suggested looking for a cracked intake, so I poked around there - and found a pretty big pipe threaded port I'd left unplugged in an intake runner. I capped the hole and voila, the engine ran perfect.

Interestingly, the wide open vacuum leak was on the opposite side of the engine from the cylinders that were not firing.

Good luck!

 

That's why I thought, but there not, but I did think about swapping them in firing order. But I don't think that's a good idea.

 

I kinda did, what I mean is I used a napkin inside the spark plug hole and it popped it out, bout as much pressure as other cylinders, I am planning on a leak down test, maybe my intake valve is closing

 

I wondered that, but how can I tell

 

Yeah vacuum leak is what I'm going to look for tonight, thing is the engine ideals good and a vacuum leak would show mainly at idle right? Gonna have fun with carb spray tonight. I'm wondering if my valve train noise is related to this misfire.

 

Never seen it with a roller cam.

 

Measure the movement of the rockers with a dial indicator. The intake should move the same amount on all cylinders. Same for the exhaust.

 

i like that, gonna try it after i inspect the valves and put new pushrod and rockers.
you think dwell could be an issue, maybe points staying closed too long or vice versa?

 

Ohhh that's not going to get you anything. Where to start ?

You need compression first and FAST
fuel air spark timing - at the right time and the right ratios

Then it's a process of elimination.
Compression test first!
One way to eliminate the ignition system as a culprit is to move the distributor 1/8 turn then move all the plug wires back one terminal. See if the problem moves. Takes a few mins and proves it. I'll bet you'll find no problem and know it's fine.

If there's no heat on the exhaust and no fuel on that plug id chance down the fuel delivery and intake valve.

 

if you have a auto trns check your modulator valve

 

Look for a vacuum leak most sbc the 5 -8 intake runner is the one with the big vacuum port.

 

X2 on a vacuum leak
Mine did that and had a carb adaptor issue plus a leak between the carb and base plate

 

It's a 99 vortec engine it only has 8 dead vertical intake bolts.

Why dit it get new lifters?

Pictures of #5 valves might show some variation one of these eagle eyed guys can spot.

 

This most likely isn't your problem but it's an example of how strange things can be. The company I worked for bought a couple of trucks at auction to use in the yard. One had a dead miss on number 5 cylinder. The spark plug looked clean. Grounded the plug, good spark. Compression was about 15 psi lower. The intake, valve covers and timing cover appeared to have been removed.

While checking the motion of the valves, something didn't look right. The intake valve opened and closed then the exhaust valve opened and closed when the cylinder should have been coming up on compression. The camshaft had obviously been changed recently as the gaskets, timing chain and gears were new. Somehow, the number 5 cylinder exhaust lobe on the cam was ground 180 degrees off from where it should have been. I have no idea how one lobe of a cam could be ground wrong. It was very easy to see compared to another camshaft and the truck ran great with the new cam. It was definitely the strangest thing I've seen.

 

The exhaust pipe does get hot, what does that mean? Also the plug has a white ash, not clean. I just switch it around with number 7 plug and ran it. Will check it when it cools down, then I'll do a compression check, my gauge wasn't workin well.

 

Mine are plugged. Sprayed carb cleaner around the base and manifold but got no change.

 

I switch over to a new carb and it did idle better, my Holley was off. The eddy works better but the #5 plug is still white/ash

 

It got new lifter because I rebuild it and didn't want to run old rollers, also got new push rods and rockers. Unfortunately I didn't get a pic of the valves.

 

^*Well what does this mean ? ^^

Not burning ?
Is getting hot?
Is it not burning ?
It is getting hot but "not burning"
Is it not discolored ?

White ash is lean, and lean is hot HOT HOT.

 

With a dial indicator, I measured the rockers travel and didn't get a difference between #5 and #7. I'm thinking maybe my cap is off somehow, producing spark just not at the right time??? Compression is the only other thing, maybe. wouldn't I have excessive blow by/crank case pressure. That plug isn't firing at all, low compression is still burning fuel, but no compression means it's goin pass the rings into the crankcase. For that to happen I would have forgotten the rings on rebuild. Or a huge gape?

 

I'm sorry I used two different words that are misleading. What I meant to say is that #5 is lean and so is 6,8. The rest are brownish. I meant to say not burning right. I have chrome headers. At initial start up the pipes started to change color to eventually turning red hot literally, except #5. I had some ngk plugs I run in my BBC Brodx heads when that happen so I went and bought new ngk for this specific make/model and year. No red hot pipes just lean plugs. Sorry I confused you

 

Wouldn't that just put everything back to where it was? I wouldn't expect a change, unless you think it's a bad cap?

 

The entire distributor,
Pick up coil, module, or points cam , bushing wear, cap, rotor.

 

Red hot pipes are not good at all.
They aren't supposed to turn blue immediately either.
Blueing is a symptom of severely out of time and or lean,,,
Funny thing is #5 didn't turn,

 

Yeah I know what you are saying.
My timing is at 10 initial. 16 or 18 with advance. No ping and fires right up, no sputter at high rpm. It's not kicking back at start up.

 

I lowered the gap to 32-35 from 40. Interestly my white plugs were a little high than the rest. I'll drive it later and report.