Missing on one cylinder - 351C

7173Mustangs.com

Help Support 7173Mustangs.com:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
Unfortunately I have no idea what's inside this thing. I only learned yesterday that it had rollers. I basically got the car with no history other than a couple people who knew of the car, but no details. 

All the other cylinders are running at temp. Checked the firing order several times, but I'll triple check as I've love that to be the issue.

 
OK, I'm hooked now, please let us all know how this ends up. Like a good mystery there needs to be a conclusion...

My $0.02: focus on why there is no combustion- its either a mechanical problem or a fuel/ ignition problem.

If you are confident that the compression test rules out a mechanical problem (i.e. the piston/ rings/ valves/ cam/ are allowing the necessary compression to be made at the proper time; and I'd still be curious what the other bank's numbers are, especially the cylinder with the rocker to valve cover interference), then you are on to fuel or ignition issues.

I think the Hyfire is a CD-style ignition, and I'm pretty sure that it can't, but could something in the box affect only one cylinder?

I would swap plugs with a known good cylinder and see if the issue stays with the cylinder or follows the plug. Don't replace the plugs just yet, you might lose some of your evidence...

I think it has already been mentioned, but could there be an intake gasket issue affecting your problem cylinder?

 
Last edited by a moderator:
After that last slew of messages, I was thinking about the firing order. Only had a few minutes yesterday, but sure enough, the firing order was out of whack. Oddly enough, reworked it and the engine runs exactly the same. Still cold on that one cylinder and still not running great. It started easier and wasn't as cold blooded, but still idled and ran the same once up to temp. I had it in my head that I would do this and suddenly a beast I hadn't seen would awaken. I will try swapping out that spark plug later today or tomorrow.

Oh and as an added bonus, I did decide to check the torque on the intake bolts. They were all a little looser than they should have been. Last bolt, just about to click at 25lbs and the bold snapped. If there wasn't a problem before, there may be one now. So that's cool.

 
Last edited by a moderator:
This likely isn't the problem at all, but it seems these engines don't like modern plugs. Some will disagree I'm sure, but I have had zero problems with Autolite 24's. I set the gap at .045" but I have Pertronix Ignitor II and coil, but for normal points set at .035"

Good luck finding the issue, hope it doesn't hit the bank account too hard!

Geoff.

 
Last edited by a moderator:
Dude,                                                                                                                                          Please tell us exactly how the plug wires were messed up.                                                               Did you re check the timing ?                                                                                                         Boilermaster

 
Yes, rechecked timing. Firing order was 1,3,8,2,6,5,4,7. It's currently set to 1,3,7,2,6,5,4,8 (hopefully that's right).

I do need to verify where #1 is though. I am basing #1 on what was previously set as #1. If that's not correct, than obviously none of the rest of this matters.

 
Thanks. This is a Mallory distributor with no markings on the cap and I think #1 can be anywhere, so I need to check and see where it's pointing. Time for me to stop making assumptions about this engine.

 
Ok, a little more to report. Doing this in 15-30 minute chunks so going to take a whole to get this sorted.

Finally actually swapped the plug with cylinder #2 and the problem didn't follow, so I think it's safe to say it's not the plug. Validated the location of #1 so my firing order is correct.

I think I've finally come to the conclusion that I need to bite the bullet and park this thing and dig in. After spending months in the driveway getting the trans installed, converted from auto to manual and a million other little things I just wanted to drive the thing and not do anything that would take it off the road for any length of time until I've gotten some seat time. I don't have a good place to work on it day to day and it's a bit of a production to get it parked longer term so it's something I've been avoiding.

Along with getting it running right, I have a laundry list of things I need to get done that are going to take more time, like new carpets and rebuilding just about everything in the dash that will need more time off the road.

So at the very least, I'm going to park it, pull off the intake and see what's going on a little deeper. I've wanted to replace the intake gaskets anyway and may swap out the intake itself with something a little more street-able. It'll also give me a chance to clean off more of the old rat turds I keep finding all around the top of the engine and fix a couple broken bolts.

Thanks for all the ideas and help. It's helped me get to the point where I stop dicking around with it and start trying to make it right and not just make it work.

 
Well Dude,

You can look at the snapped off intake boil in this way,

You needed to cross off leaking intake manifold gaskets off of your list anyway and with the intake manifold off you can have a better look see at the lobes of the camshaft and condition of the lifters.

Suggest you start compiling information needed to be ready to adjust the valves (solid ) or check and adjust lifter preload (hydraulic).

My way of thinking is that if you have a bad cam lobe or collapsed lifter there should be quite a bit of noise associated with that.

You have never mensioned any valvetrain noise while running the engine with the valve covers off.

you could bring # 1 cylinder to TDC on the compression stroke and see if you can spin the pushrods of that cylinder between your fingers/

Another possibility that exists is that perhaps a rocker stud has come loose under the rocker arm (although that should make noise too.

When you go to install the valve cover back on what valve does the marks on the cover point to?, looks like # 1 intake valve to me ?

Boilermaster

 
So, I don't know the source of your problem, but I would pull the valve covers and verify that you don't have a bent pushrod or a lobe on the cam that is wiped out.

I pulled the intake of a BBC looking for "a screw that fell down the carb" per the PO and when we started looking it was a big old hunk of plastic wedged up in the intake port.

If you can't find an electrical demon, then it is time to pull the valve covers and possibly the intake.

 
Last edited by a moderator:
Just trying to come up with a way where you can show compression on a compression test, but not have valve seal on a running engine. It would require a combination of problems. I can think of two scenarios, both that involve a collapsed or bled down lifter when the valves were adjusted. In one, the rocker was screwed down too far to compensate for the lifter, and in the other, the valve has recessed. Then, when the engine is started the lifter pumps up enough to keep the valve from closing all the way.

It appears that the spark plug is not the problem, and it would take a really big leak on the intake manifold to lean that cylinder out enough for that cylinder to not fire, or suck enough oil to foul the plug.

Be interesting to find out what the problem is, file it away for future reference.

 
As a "Hail Mary" if it has double springs, check to see if the outer spring is broken. I had it happen once. The inner saved the engine. It was missing because the valve was bouncing off the seat. As I said a very long shot. I hope you get it sorted out with minimal drama. Chuck

 
Pulled off the intake. The one thing that jumps out at me is that one port around the problematic cylinder. There isn't a bunch of gasket stuck to that port in the intake, so I have to assume it's blown out. Ran out of light to do anymore today

In nothing else, looking forward to cleaning this up and replacing those nasty valve covers. 

https://lh3.googleusercontent.com/cnmkXNPigsSCmyvO8Bbxo_t-LPr0k_zkMFpw2_THCtGXs4Zr-aSlt-6WbmM1RyxPg-7W75rJK4VxWeb8hxZZQeSN6EPG7TSyXuXRFX7T2J3PdHSOqE7vXdS0F0YRlzSIgn4jdxLvSgA=w1250-h937-no[/img]

https://lh3.googleusercontent.com/X9zFSi9PATbTKvVDdhwaTVRU5_c6C10Zh-U3Iv05tdZ5JeiTwk6MxgANag6jA1PHUzqBYOoUXCcu27e_-0h14dUKhOclBo-klWP2D8pCpw29VMB2zH0nmn2MfEMCH5OkORaA97Ts1Tw=w1250-h937-no[/img]

 
Last edited by a moderator:
Hey Dude,

That is sounding like a best case scenario

What of the broken bolt? were you able to remove it with the manifold off ?

Kind of sounds like the previous owner did away with the valley pan (turkey pan)

Could you please tell us what intake manifold you have, aluminum or cast iron and manufacturer.

I prefer to use Felpro sfl1228 with no valley pan if the intake does NOT have the heat crossover.

Typically, I will NOT use the end seals, I instead like to use permatex grey.

Unless you know if your engine block has been decked and or if your cylinder heads have been shaved, this can be a safer route to prevent oil leaks.

Please bear in mind that the intake manifold, could have been machined to fit a machined block and or cylinder heads.

The standard rule for clevelands seems to be no more than 0.030'' taken off of the block and or heads as a total will still seal with thick aftermarket gaskets such as the Felpro I listed ( 0.060'')

Now that you have the intake off you can easily do a much better inspection of the valve train.

with a cheap dial caliper you can measure your camshafts lobe lift on that #1 cylinder and compare it to the lift of the other cylinders.

That will tell you if the cam is good or not and give some kind of idea as to how much VALVE LIFT your cam is supposed ho have.

To measure camshaft lobe lift you simply need  to measure the height of the lifter at it's lowest point and again at it's highest point while rotating the engine by hand and do a little math.

How about some pictures of your lifters of that #1 cylinder at their lowest and highest lift with some measurements ?

Some here will also be able to tell you a lot about the state of your valve lash with some good pictures of the lifters at the valve fully closed and fully open positions.

Dude, it is my opinion here, that you not move too fast or haste fully, look, measure, report and get opinions here and proceeded slowly.

Sorry I am so anal, but I only want you to get this problem repaired properly and have great results.

If I were in your area, I would gladly lend a hand free of charge.

P.S. there are a few members here that think you may have a collapsed lifter on that # 1 cylinder , I myself would not rule that out just yet, but let's make sure that your cam is not wiped out before we get into valve lash adjustment.

Boilermaster

 
Dude, I literally just went through all of this if you’re going through with my Cleveland. Come to find out I had a wiper lobe and a solid roller lifter had disintegrated and messed up a piston skirt. I needed to go through my engine anyway so I’m in the current process for a rebuild.

I would strongly encourage leak down test. I am surprised that no one has recommended this yet. You can get a testing device off Amazon for less than 100 bucks. This will really help you narrow it down.

You can also use it to test the health of all other seven cylinders.

It will isolate your issue hopefully.

It can, but not always.

I had 150 pounds Compression on my bad cylinder. Anyway, I hope you don’t have the same issue that I did. My prayers are with you. Keep us updated

Mike

Sent from my iPhone using Tapatalk

 
Last edited by a moderator:
Boilermaster, great info as usual. 

You can probably see the end of the bolt in the pic below. The end of the bolt is sticking out past the end of the thread so I'm hoping I might be able to grab the bottom of it to work it out. Either way, it looks like I can go try to work it either direction which should make life a little easier. Haven't been back out to it since last night. 

You are correct, there is no pan in there. Manifold is an Edelbrock Torker 2. Thanks for the tips in gaskets and sealing. 

I'll have to look at what it would take to measure the cam like that. I certainly would like to have that info, but not sure how to go about doing that. I'll get some more pics once I get going on this. Very time limited lately so this will be a bit here and a bit there. Now that I've parked it, I'm going to take my time and go through this and do my best to do it right and learn as much as I can while I'm here. 

And Mike, you really had to go there?  ;) If this engine needs a rebuild, so will my marriage. Here's to hoping I don't follow along your path. 

https://lh3.googleusercontent.com/Wtigg_95qBCYehIdMlSv3_H2G8f1PEyFGg2WowXJfhNW_GLU0ZMU4F39vhwAK85f4zEEA4CSxaWkNYhfDsgewvKjsEU7M1LFRhQyTGilcd7At7qq5mj-JmMrNBucVb-fotAY1Xb8ezk=w1208-h889-no[/img]

 
Last edited by a moderator:
Sorry to mention it.

I can relate with the wife!

Sent from my iPhone using Tapatalk

 
That's definitely a big enough leak to cause enough oil to quickly foul the plug, as well a making it too lean to fire before it starts sucking in oil.

With that much of the gasket missing I would want to make sure it isn't stuck in one of the valves.

I think Chuck (c9zx) also had this kind of failure.

 
Last edited by a moderator:
Back
Top