The Stovebolt Site Forums The Shop Area Engine Shop somethings missing? ** Update**

I've got the old 235 running. It has sat for 15 years.

I've done a bunch of work so far just replacing fuel system parts really.

It now starts & runs well - no smoke at all.

The problem is there is 1 cylinder that has a miss.

I installed new plugs & don't think I have any vacuum leaks. I had a nice one on the line from the carb to the wipers, but have plugged this (I plan on electric wipers). This actually did help it idle better, but didn't cure my problem.

I popped off the valve cover expecting to find a broken valve spring or something. They all work, move freely and appear adjusted well and in good condition.

The truck only has 53k miles.

What is next? Replace the plug wires? points?

Could be wires, or possibly a cracked or carbon scored cap. Try swapping the wires, see if the miss changes to a different cylinder. If so, change the wires. I would suggest going ahead and doing the cap, rotor, points, and a condensor as well.

First thing I would do is see what condition the basic engine is in.
I'd warm it up and do a compression check with a good screw in type compression gauge. Run her thru four or five compression cycles with the cylinder dry then wet her down with a couple of good healthy squirts of 30w and run her thru four or five cycles wet. If your compression doesn't change then my guess is that you've got a bad valve on #1. Most likley the exhaust valve.
If all of that checks out within spec, than I'd go looking at the ignition.
Denny Graham
Sandwich, IL

Do you know which cylinder?

Neat trick I heard of is to use a timing light to diagnose the wire.

(works better if you can do it in the mostly-dark)

Hook a timing light up to each plug wire in turn, and compare the flashes against a wall (or the side of the truck, or something . . . ). Missing cylinder should show up as a weaker/inconsistent flash, compared to the others, I think.

I've also heard of people spraying water mist over the plug wires while the truck runs in the dark, to reveal shorts in the plug wires.

If the timing light doesn't reveal the trouble, maybe Denny is correct, and it's not ignition-related.

don't know if I'm barking up the right tree, but hope it helps.

-Michael

When I encounter a miss, I just pull one plug wire at a time with the engine running. Once you get to the wire that makes no difference in how it runs, you are at your missing cylinder. Hopefully it's just a bad wire.

54tow - I like it. Since I don't have a timing light this will be a good way for me to find the offender.

How much does a good compression checker cost?

I don't know - I always used my father's compression gauge. I got the one I have now at a swap_meet for $5. Hopefully there's someone you know that can loan you one. You may even be able to borrow one from a parts store through their loan-a-tool program.

If its been sitting that long I would warm it up good and check the valve adjustments. I'd bet you'll find that you need to do some adjustments. Just make sure that when you warm it up that you get the oil hot, not just the water temp up. It makes a difference. Then as Denny suggests, do a compression test. You can get a cheap compression tester for less than 20.00 if you look around.
Good Luck
Don

Be sure and pull the plug wires from the distributor end. The plug boot is attractive becaues its easier to grasp.
But then you're holding something that really, really wants to put out a 20,000 volt spark.
If you pull it from the distributor cap, you're holding something that's disconnected from the high voltage.
Guess why I remembered this advice and thought it useful to pass along.

regards,
Leon

OK - I got it good & warm - then pulled (from the plug end) each wire. Turns out cyls 1 and 2 had no effect on the engine at all. While 3, 4, 5 & 6 all made it run even worse. I had good spark coming out of each wire to the plug 1-6.

So I have a 900lb 4 cylender with a brand new carb!

I'll get a compression tool tomorrow or Friday & check.

I'm thinking the best I can hope for now is to rebuild the head right? I will need to pull the intake & exhaust manifolds - yank the head & have it rebuilt. - that is best case

Worst case the valve broke & poked through the piston. I guess I'll find out when I run the compression test.

Make sure you are not leaking vacuum around the intake manifold to number 1&2 cyls.

That is what I would do to Wrenchbender I would spray a little Chemtool B-12 around the intake manifold and if the engine make a different sound or speeds up you have a gasket problem as the B-12 is being sucked into the # 1 & 2 cylinders.
Don

Wrench / Don

Thanks for the advice. I'll give that a try before I do anything drastic.

I still haven't gotten the compression tester. It's been kind of crazy around here the past week or so.

Anything I can try quick and dirty to find a problem helps.

My gut tells me that this thing sat for 15 years with one or two of these valves open & they rusted up or got some kind of gunk on them keeping them from sealing. I won't know for sure until I test the compression.

I may get to it next week. Then again if next week is like this week I probably won't.

I started the truck today & shot some b-12 carb cleaner at the intake manifold 1/2 port.

Both cyls immediately came to life!!!!!!!!!!

So My guess is I need to get a new intake gasket & seal it up really well instead of a complete overhaul of the head.

I am tickled.

I've done these on a SBC but never on an engine this old.

Should I use the heat wrench on the bolts before I tighten them down or buy new bolts?

I'm thinking I'll pull the intake all together & take it in to be tanked & blasted. Just in case there are wasp nests in there from 15 years in the field.

Once again it takes a village to raise a truck!

Thoughts?

I like to use new grade 8 bolts & put a grade 8 SAE flat washer under the head.

I changed mine over to studs and nuts. I also took out the 2 dowells for the ends of the exhaust manifold out and replaced them with studs, too. Makes it much easier to install the manifolds.

While you have it apart,i would replace the gasket in between the intake and exaust manifold.

Yes LB55 that makes it sooooooo much easier for sure when installing the gaskets. I also like to use Copper Cote on my gaskets too. Another source for leaks is the fiber block between the intake manifold and the carb.It's called "Fennalic"?not sure of the spelling for it. I would also use some Blue Locktite on the nuts or bolts that waw when you go to remove them they will not stick but will keep the nut in place and backing out.
62blue
Don