Need some opinions on where to go from here...

[mshred]

Looking for some advice and opinions here. 1977 360 in my aspen was removed, cleaned, fresh bearings, new Speedmaster heads and rockers, intake and solid flat tappet cam installed. I reused the pistons and rings, and did not re-hone the cylinders as they looked good as they were. Upon cam break in, it seemed that the longer the engine ran it started having a miss. The car really didn't want to idle once the break in was done, and I noticed the number 4 cylinder seemed cold. A hot compression test revealed equal readings on all the cylinders, except cylinder 4 which was down about 25psi- I assumed this reading was due to essentially having a dead cylinder. I also noticed what seemed to me like excessive smoke out the exhaust on odd cylinder bank. I have since gone over a few things:

-Checked my ignition box settings (Mallory hyfire 6) to make sure the firing was setup for V8 and the limiter was not affecting anything
-Noticed number 5 and 7 plug wires starting to melt, even with heat jackets on them, because of the el cheapo header pipe running right at that level. Planning on replacing with 90 degree boots on those cyl.
-Relashed all the valves, COLD. Some were out a couple thousandths from the suggested spec (not sure if the lash could have been an issue)
-Noticed number 4 cylinder pushrods specifically are almost touching the head in the pushrod holes as they travel up and down the with the valvetrain. I clearanced all the holes before assembly and checked on the stand, but clearly in some spots not enough as when running it may be contacting ever so slightly based on witness marks and the tight clearance cold.
-I performed a cold leakdown test today. All cylinders were under 5% except for cylinder 6- it was 70%. I tried backing up the piston, going forward a bit, just to see if bringing up the air pressure in a slightly different position would help it seal, but got the same reading no matter what. Problem is, I don't hear it leaking out the exhaust, or the carb, or the crankcase when I remove the dipstick. I'm wondering if the valves on that cylinder might have some carbon buildup, enough to keep the valves slightly open, and cause a constant leak.

So I'm stumped at this point. I have attached a picture of the spark plugs- this thing was pig rich on break in, as evidenced from the plugs, but after break in was over I really didn't run it and try tuning it to improve this. You'll notice both the plugs for cyl 4 and 3 are clean- they are opposite banks to each other, and wondering if there could be a distribution issue there, causing some of the misfire? Also wondering if some of these symptoms that occurred on break in are telling of flattened cam lobes? (I've only ever ran roller cams in the past). Honestly not sure what to do. I'm thinking take off the heads on both sides, have the valve job and valve seals checked at a machine shop, open up pushrod holes some more, and reinstall the outer springs while the heads are on the bench so long as all the lobes on the cam look worn in evenly and there is no issue there...or am I missing something else possibly?

Any suggestions or insight, I'm all ears. It's almost winter here and I want to get a plan together for what I need to do so that in the spring I can start to drive and enjoy the car again. Upon break in it seems like I possibly toasted the transmission, so that's why I haven't fired it back up to see what happens again (what happens when you listen to people tell you fill it with 6 quarts and break in cam in park and top up trans after..)

 

[SRT_DSTRHOLC]

Question, did you try putting some oil in the cylinders that were lower and see if or how much it raised the compression numbers?

 

[mshred]

Question, did you try putting some oil in the cylinders that were lower and see if or how much it raised the compression numbers?

I didn't, no. I did that compression test back when I broke in the cam, with the engine hot, about a year ago. Right after cam break in, I was busy packing up to move homes and the focus was on the move and working on the new house up until very recently. Just now having the time to start digging at it all again.

 

[Oldmanmopar]

What intake, carb and distributor? One thing to check is the distributor cap and distributor. 3 & 4 are next to each other on the firing order They don't look like they are firing. 1,8,4,3,6,5,7,2 , That is the only thing that links those two cylinders. If its a dual plain intake they are not on the same runner level so ignition spark ties them together. Cracked Cap?

 

[RedFish]

I'm no hitrodder but I will take guess that speed master aftermarket heads are aluminum. You can guess they are CNC perfectly flat. My knowing cylinders weren't dressed leads me to think the old cast iron block surfaces weren't dressed either. That begs the question, what head gaskets you're using? Pistons can't swap holes but the horses they make can jump poor fences. Good luck.

 

[mshred]

What intake, carb and distributor? One thing to check is the distributor cap and distributor. 3 & 4 are next to each other on the firing order They don't look like they are firing. 1,8,4,3,6,5,7,2 , That is the only thing that links those two cylinders. If its a dual plain intake they are not on the same runner level so ignition spark ties them together. Cracked Cap?

Holley Strip Dominator single plane with a 780CFM Holley Vac Secondary and a factory electronic distributor. I am almost positive we rechecked all the plug wire routing from the cap to the cylinder, but I will check again, as I am truly hoping it was just something simple and silly like that. I actually thought about buying a new cap, just to eliminate that as well.

I'm no hitrodder but I will take guess that speed master aftermarket heads are aluminum. You can guess they are CNC perfectly flat. My knowing cylinders weren't dressed leads me to think the old cast iron block surfaces weren't dressed either. That begs the question, what head gaskets you're using? Pistons can't swap holes but the horses they make can jump poor fences. Good luck.

The deck surfaces were not dressed by me, but this engine was rebuilt at some point before me, as the cylinders were bored .030" over and the crank was turned .010" on all the journals, so its possible they were done before me. Anything is possible, but it seems like the machine work on the block was done well, and it ran fine before I pulled it apart for upgrades and cleaning. I'm running the thin Mopar head gaskets, I believe either .024" or .028" compressed thickness.

 

[furrystump]

It could have flattened a cam, then it sat without running for a year. With all the metal in the oil and now the rings are sticky.

 

[RedFish]

Recommending something like comedic (spelt) gaskets will have to come from someone else. I can't know what the head maker recommends either. Not even certain this is your issue. I've seen others chase their tale.
I can't recall what we poured in where to free up stuck rings. I know it worked though.

 

[Oldmanmopar]

Holley Strip Dominator single plane with a 780CFM Holley Vac Secondary and a factory electronic distributor. I am almost positive we rechecked all the plug wire routing from the cap to the cylinder, but I will check again, as I am truly hoping it was just something simple and silly like that. I actually thought about buying a new cap, just to eliminate that as well.

The deck surfaces were not dressed by me, but this engine was rebuilt at some point before me, as the cylinders were bored .030" over and the crank was turned .010" on all the journals, so its possible they were done before me. Anything is possible, but it seems like the machine work on the block was done well, and it ran fine before I pulled it apart for upgrades and cleaning. I'm running the thin Mopar head gaskets, I believe either .024" or .028" compressed thickness.

The reason I included the firing order wasn't doubting you wire install. It was to show that 3 & 4 are next to each other on the cap. I don't see the strap on the plug burnt back on 3 or 4 So those cylinders are getting washed with fuel and not firing,

Pull those wires 3 and 4 while its running one at a time. Hold your wife's hand while doing it and you won't get jolted. I always tell who ever is standing here to hold me back so I don't fall into the engine while its running. You know a safety reason, LOL works every time. After about 4 times my wife don't care if I fall in anymore.

 

[mshred]

It could have flattened a cam, then it sat without running for a year. With all the metal in the oil and now the rings are sticky.

About 15 mins into the initial cam break in I shut the engine down as I had tried a 1 piece pan gasket, and it did NOT seal...So at that point, I drained the oil, dropped the pan, new pan gasket, then back to break in for another 20 mins. I kinda figured that if I flattened a lobe, the oil at that time would have shown it, but it was clean....I guess I can drain the oil now and have a look, although pulling the intake manifold will also tell the story.

Also, there was only 1 cylinder that was sticky, so I am just hoping that maybe its carbon considering how rich it was running

 

[furrystump]

You could get a cheap bore scope and go through the oil drain back holes in the head. Peek at each lifter and lobe. The filter might have caught a bunch. Cut it open.

 

[mshred]

You could get a cheap bore scope and go through the oil drain back holes in the head. Peek at each lifter and lobe. The filter might have caught a bunch. Cut it open.

Already did that actually, just didn't add it to the post because it was already a novel.

It was quite difficult to get right down there, but from what I could tell, it looked alright. I may try again though and also check cylinder 3 now as well. Good idea on cutting the filter.

 

[mshred]

The reason I included the firing order wasn't doubting you wire install. It was to show that 3 & 4 are next to each other on the cap. I don't see the strap on the plug burnt back on 3 or 4 So those cylinders are getting washed with fuel and not firing,

Pull those wires 3 and 4 while its running one at a time. Hold your wife's hand while doing it and you won't get jolted. I always tell who ever is standing here to hold me back so I don't fall into the engine while its running. You know a safety reason, LOL works every time. After about 4 times my wife don't care if I fall in anymore.

Ah gotcha....well I guess now I am doubting my wire install because i'm hoping its something stupid like that. I also wondered if possibly its so rich that it could be washing out cylinders.

Still trying to figure out why I have excessive smoke out the exhaust on the odd firing bank

 

[PRH]

I’d be trying to nail down what’s going on with the high leak down on the one cylinder.

 

[mshred]

I’d be trying to nail down what’s going on with the high leak down on the one cylinder.

Any suggestions for that?

 

[PRH]

The air is going somewhere.

 

[mshred]

The air is going somewhere.

Yes, but if its not audibly coming from the exhaust, the carb, or the crankcase, could it not just be leaking right at the valve enough to cause the leak but not really have it felt or heard in the usual spots?

 

[Mean416]

That leakdown number is obviously concerning. Post compression test numbers too.

With that kind of leakage it narrows things down. Ask "what could it be?"

1. Something with the valve sealing
2. Something with the ring sealing
3. Something with the head sealing

Based on the deteriorating idle...my bet right now would be blown head gasket. Just a guess though.

 

[mshred]

That leakdown number is obviously concerning. Post compression test numbers too.

With that kind of leakage it narrows things down. Ask "what could it be?"

1. Something with the valve sealing
2. Something with the ring sealing
3. Something with the head sealing

Based on the deteriorating idle...my bet right now would be blown head gasket. Just a guess though.

If I recall the compression numbers were somewhere in the 125-130psi range, but on cylinder 4 it was down to almost 100. This is a factory low compression build with 65cc heads, thin head gaskets, and an Oregon regrind cam with 230/236 duration at .050" and just under 9:1 compression. Definitely wouldn't get the same numbers now doing a cold test.

Its looking like I really don't have a choice but to start taking this thing apart...Just sucks not knowing what exactly to look for really.

 

[dano]

I take it adjustable rockers? Did you do a geometry check and push rod length check?

 

[PRH]

Several rocker options end up with retainer to rocker interference with the SM heads.
Are you sure you don’t have any of that going on?

 

[mshred]

I take it adjustable rockers? Did you do a geometry check and push rod length check?

Several rocker options end up with retainer to rocker interference with the SM heads.
Are you sure you don’t have any of that going on?

Yes, Speedmaster adjustable rockers. They made contact with the spring retainers, so I took some measurements and had a custom rocker geometry kit made for them, and then measured for pushrods with a measurement that gave me the best pattern/lift. There is no clearance or geometry issue going on...My only concern as noted was that the pushrods on cylinder 4, specifically the intake pushrod, seems like it may have been making contact during the actual running of the engine.

 

[middleagecrisis]

Heads were new, but you put the old rings back into their matched cylinder. Did you run a compression check on the motor before you disassembled? The lower #4 cylinder and oil residue on some of the plugs tells me bad ring seal. I've never used the same rings again when pulling apart a motor. A quick hone job and new rings are too cheap to risk having sealing problems. That's just my opinion.

 

[mshred]

Heads were new, but you put the old rings back into their matched cylinder. Did you run a compression check on the motor before you disassembled? The lower #4 cylinder and oil residue on some of the plugs tells me bad ring seal. I've never used the same rings again when pulling apart a motor. A quick hone job and new rings are too cheap to risk having sealing problems. That's just my opinion.

Yes, heads were new, rings were not. Hence my logic for not re-honing. I never did a compression check before, mainly because I was planning to install new rings. But thought I would try re-gapping/checking ring gap, and re-installing back into the same cylinders in the same position, like many of the LS and some Hemi guys do for budget boost bottom ends.

I would agree with you on the ring seal of number 4, except that the leakdown, even cold, showed very good ring seal on all cylinders, except number 6

 

[dano]

Yes, Speedmaster adjustable rockers. They made contact with the spring retainers, so I took some measurements and had a custom rocker geometry kit made for them, and then measured for pushrods with a measurement that gave me the best pattern/lift. There is no clearance or geometry issue going on...My only concern as noted was that the pushrods on cylinder 4, specifically the intake pushrod, seems like it may have been making contact during the actual running of the engine

I had to open and clearance mine quite a bit, and all I had were Hughes rockers and a shim. But that doesn't address the #4 issue unless the push rod bent.