One Sick Nailhead - Need Your Help

[jerryacheson]

This post has been running a little while on the Nailhead site and I thought I'd give you guys a shot at it. I took the stuff off the top of my 62 401 back in June to clean the engine compartment and engine and freshen things up for the BCA convention in Kokomo. I didn't make it but I do have the car back together now. I also installed a Pertronix III and Flame Thrower coil for HEI like performance. At first, the engine ran really bad. It smoked alot and did a lot of popping out the exhaust. I had the Carter AFB rebuilt and removed the Pertronix and replaced with points and stock coil. A professional mechanic friend of mine tweaked the engine to get a little better performance out of it.

Well; it's not over yet. I took the car on a road trip this weekend to see if highway speeds would clean out the system. No dice.

Since we last spoke I have driven the car over 150 miles. The car still misses and smokes much more than it ever has. I pulled the plugs and they are all fouled with black soot. The drivers side is worse than the passenger. On hard acceleration, the exhaust is black. The following is the result of a dry compression check.

> > 1 = 86

> > 2 = 78

> > 3 = 70

> > 4 = 92

> > 5 = 65

> > 6 = 55

> > 7 = 90

> > 8 = 79

These appear to be pretty low since my service manual calls for a minimum of 160 if we assume this is a low compression engine (9.0 to 1). It's worse if this is a high compression engine. Not only is this low, there is a range wider than 15 lbs between them.

It doesn't look like any adjacent cylinders are low so it's probably not the head gasket. Right?

What are your thoughts on the problem?

Jerry

[rocketraider]

First- what is oil consumption doing, just so we can rule out oil fouling?

Next- what brand and grade of gasoline are you using?

Last- has the timing set ever been replaced? Popping back and uniformly low compression indicate valve timing problems to me. A stretched timing chain can cause stuff like this, as can a worn cam or crank gear.

I don't understand a Pertronix causing all this, since every one I've used on these old high-compression engines has made worlds of difference in them.

[jerryacheson]

I've only had this car a year and probably have less than 1000 miles on it. I haven't noticed any consumption. I changed oil before the 150 mile trip and added Restore. I haven't noticed that any oil was used.

I've been running Marathon or Meijer (department store) brand gas at 92 octane. My first couple of tanks on this car were 87 octane. I haven't noticed a difference in performance.

The guy I bought this car from last September told me the engine had recently been rebuilt. We didn't get into the details (shame on me). The engine didn't look fresh so I really suspected his claim (shame on me again). Any tests I can do to see if the timing set is out of wack?

I don't suspect the Pertronix. I just removed it so I could be sure it wasn't causing the problem. Is it possible that the Pertronix system exagerated an existing problem?

Oh by the way; when I put this together I put Champion plugs in her at .035 gap. Upon recommendation of a friend, I bumped the gap to .040 and saw not improvement. A post on the Nailhead site suggested that we couldn't run Champion plugs in a Buick (seems strange to me) so I converted to Bosche Platinums. I couldn't find someone that could provice a stock AC plug. Of course I didn't check everywhere. Someone else this weekend suggested that the Platinum plugs may be expecting more firepower. I guess I could put the 40,000 volt coil back in. What would that do to my points?

I was also wondering about the cam and timing chain. Any way to eliminate these from consideration or prove they're the culprit?

Jerry

[jerryacheson]

Just a little more info for your consideration. I performed compression checks at operating temperature dry and then with about 3 cc's of oil poured into each cylinder. The following is the result. The first number is the cylinder. The second is the dry compression and the third is the wet compression.

1 - 102 - 105

2 - 94 - 105

3 - 90 - 105

4 - 94 - 103

5 - 90 - 93

6 - 90 - 98

7 - 87 - 97

8 - 94 - 110

These numbers are certainly better than the ones that I reported earlier from a cold engine. What do you think is wrong with this thing. All plugs were fouled with black soot except number 8 which was pretty clean. Number 2 was also fairly clean but did have some soot.

Jerry

[Guest]

It sounds to me like you need a good mechanic. Your engines ran good before you messed with it, right? If so lets assume to did something wrong. Backfiring, smoke will indicate you have your firing order wrong on the plug wires. But start from square one, check point gap. then find #1 cyl on dist cap. Knowing the dist rotation and firing order, follow you plug wires to each cyl to make sure the right wire goes to the right cyl. Having this done right then check timing and see that spark advances are working properly. If your compression tester is from K-Mart or of similar quality your problem with compression may lie in this tester rather than in the engine

Low compression on all cyl is an indication of a jumped timing chain due to wear in chain and gears. If all is well in what I have before mentioned. try advanicing your timing way beyond what is recomended (20-30 degrees) if the engine runs good (smooth) without pinging but lacks the power it most likely is the chain. If you compression tester came from K-Mart or it is of similar quality the proplem with compression may be with the tester rather than the engine>

[Guest brh]

I agree with previous post. Black smoke is an indication your engine is running too rich. Either not enough spark at the right time or the carb is giving the car way too much fuel. I'm leaning more toward a timing problem. Also watch what additives you are using in the oil and the fuel.

[jerryacheson]

More info. Compression tester is a SUN and appears to be good quality. I've never had an issue with it before.

I just turned the engine over to establish TDC for #1. The piston is up; the valves are closed and the mark on the harmonic balancer is pointing to zero. The rotor is pointing about a quarter inch past #1 plug wire toward #2. Timing is actually set at 12 degrees BTDC. Dwell is set to 32.

Interestingly, when I look in at the pistons and several of them look like they have a mark where they have been burnt (probably because of timing issues). I saw this once in a Chevy 235 where it looked like a .022 shot went through the piston.

[65Catvert]

Hi Jerry--My 65 401 timing spec is around 5 degrees. Were the earlier ones like yours that different? Maybe thats the problem.

[Gene Brink]

Jerry,

It sounds to me as though you have given this some careful thought and considered the most likely causes so it is a puzzle. Seems to me that Both Rocketraider and GS400 are most likely correct that the problem is either with valve timing or plug wires connected to the wrong terminals (although the latter would not account for the low compression at all so I tend to think something is either off with the valve timing or your cam/valve train is shot). Just a few random thoughts; 1) black smoke - excess fuel. You mention that the carb was overhauled without any change so I'd be inclined to think the ignition system isn't sparking enough to burn the fuel (or the wiring is off - see below). If this were a problem only during idle I'd suspect the float level was off but if that were the problem it should be okay at speed.; 2) popping - assuming this only happens when the engine is warmed up a bit (?) - probably unburned fuel exploding in the exhaust system; 3) plugs - they will all work. You will find people who swear by every brand - I've used Champions, Autolites (gasp!), AC and even Sears (made by Champion) and they all worked just fine; 4) low compression - only two things that can cause this - restricted air intake (carb not opened, valve not opening/closing at the right time or opening enough) or blow by (rings or valves); 5) the "burnt marks on the piston tops" could be a real problem (not with the compression, at least initially) and one that I learned of only after ruining a perfectly good 322 nailhead by burning a hole in a piston top with only 32,000 miles on the engine. If you wire wrong you can get the ignition spark to arc to ground on the top of the piston. If the mark you see is right below the spark plug (top edge of dome centered between the valve relief areas) this could be the cause.

What I'd do at this point? Check the wiring, distributor cap, pull the valve covers and turn the engine over by hand watching pushrods to insure that they are actuating the valves fully - if not you could have a bad cam, collapsed lifter, bent pushrod or faulty rocker arm.

Good luck, Gene

[Guest brh]

This may be a real dumb question, was the distributor ever removed from the car and then reinstalled without rotor position being indicated. Reason I ask is I had someone pull a dist. not mark its correct position for firing order and wonder why it would not start. He had number 1 firing at 180 degres from its correct position. Just another 2 cents. Make sure when determining TDC both valves are closed and the piston is at the top.

[gungeey]

This sounds veery much like a timing chain at the end of it's life. When you are attempting to start the car, does it spin fast and freely, but doesn't fire up ? That would explain your fouled plugs( by the way, Champion plugs will work just fine in a nailhead)The erratic compression readings, backfiring are all symptoms.What happens id the timing chain stretches over time. The rivets holes enlarge, and that develops the slop you are now dealing with.

[65Catvert]

Re the timing chain--Do you have the famous original nylon coated chain? I did in my 65 and when I dropped the oil pan, I found half of it in pieces in a mound of sludge. Over all this time, they just break off the chain. Although the engine was running OK, when I pulled the cover, the chain was real sloppy and just waiting to jump. Another $.02.

[gungeey]

You're right! ...I remember the same set-up in my '64 Skylark. Chunks of gear at the botom of the oil pan. I remember the symptoms well. The starter could spin like crazy...the valvetrain was far enough out of time that the cylinders couldn't make proper compression. When it did fire up, it coughed , kicked and backfired w/ lurching, no drivability in general.

Sounds like I'm knocking the Skylark? I hope not. One of the best cars I ever had. Was a daily driver that gave me No problems except for the chain. Steve

[Reatta Man]

Jerry,

I don't mean to be insulting, and if you already knew this, please disregard this message.

Did you know that the #1 cylinder on the nailhead engine is the front cylinder on the passenger side? Most people don't know this if they are not familiar with the Buick V-8s of the 50s and 60s or don't have a factory service manual.

Many professional mechanics assume it is the front cylinder (nearest the radiator) on the DRIVER"S side, like it is on most other GM V-8 engines. If your pro doesn't work on a lot of Buicks, and set his timing light on the front driver's side cylinder, your timing will be 30-60 degrees off. If you are not sure where he set it, ask him to check it again, or check it yourself.

Everything else about setting the timing on the engine is the same--set the RPM to the factory recommended setting, remove and block the vacuum line, connect the timing light to the #1 cylinder, and rotate the distributor until you get the correct reading on the timing scale next to the harmonic balancer. After setting the timing, I always like to check the dwell, adjust it if necessary, and then recheck the timing and dwell once more before I tighten down the distributor locking nut.

If you aware of the cylinder placement issue and are sure the timing is set correctly, the only other item I can think of that would cause this kind of lousy performance is a bad condensor.

Good luck. Feel free to e-mail me and let me know how everything turns out.

Joe

[rocketraider]

And once again, the Forum is working- I never knew this about the Nailhead. Of course, when I got my first Rocket Olds, I found out the hard way that they do not use the 18436572 firing order as later Olds and other GM engines use

[Ted "Wildcat65" Nagel]

I think this post is right on, I had the same/similar symptons starting my 65 Super Wildcat before I bought it. A mechanic had wired it so #1 was drivers side front, I had a heck of a time figuring out what was wrong, burned up a starter and so on.

Went back to the MANUAL, like I shouldadoneinthefirstplace, and saw the correct #1 (Passenger side front)and the 50,000 watt light bulb went off...no harm done. I can laugh now, but at the time I was cussin'. The timing mark on the passenger side is a big clue. Super Wildcats don't have that handy firing order imprinted on the valve covers, either.

[gungeey]

I'd say there's a load of great thoughts here, the only thing about the "Timing on the Wrong Front Cylinder Theory" is the low compression readings. Wrong firing order would be of no consequence.

[jerryacheson]

Timing is correct (at least what I can see is.) I've already learned the lesson about #1 on the passenger side. I set this thing up like a Chevy when I first put it together. Never did get it to fire. I'm pretty sure she's correct because I've checked the firing order at least a hundred times. This thing seems to run ok. She just fowls plugs and doesn't have the power I'd expect from this big nailhead.

I think it's fair to assume that the distributor and plug wires are correct at this point. So; why the low compression and the fowled plugs. The compression jumps about 10% when wet over a dry check. I'm no expert but that would suggest to me that the problem is not in the rings. Does that reduce the choices to timing chain or valves? If valves, why are they so even? I'd think they'd fail at different times. Someone has suggested that the heads may have been decked and that the valves are not closing all the way. Possibility? How do I prove it?

What other choices do we have?

If this were your car/engine, what would your next step be? (Gasoline and matches are not an option.)

Jerry

[old-tank]

Two other possibilities: check for blow-by...remove an oil filler and rev the engine, and if smoke shoots out the rings are worn or maybe broken; are your plug wire real wire and not carbon string resistance wire, and are the plugs non-resistance? In my 322 the original AC 44 plugs are not available and the substitute is a 43R which fouled in 20 miles using petronix (replaced with a used set of 44's and it is still running well and the plugs look new at 15,000 miles). Sorry but my guess is a very worn engine.

Willie

[JohnO]

Since you live in Indy, there must be a good mechanic around. I don't concede easy, but there comes a point where it

is beyond you. Ask around, take it to a good mechanic. You have covered all the basics and then some.

[Reatta Man]

Jerry,

Let me kinda think out loud here, and let you know what I would do if it were my engine. I hope some of this helps.

First, before tearing down the front of the engine, I would like for you to check the engine vacuum. If it is lower than normal, disconnect both exhaust pipes at the exhaust manifold and then recheck the compression, or start the engine and see how it runs with the exhaust disconnected. I had a '73 Lesabre that had a nearly completely blocked exhaust system that had no power and ran poorly. While your exhaust system may look OK, it can break down and block passages in the mufflers that will literally choke out the engine. If it starts and runs OK with the exhaust off, and the vacuum comes up, you'll need to replace some or all of the exhaust system. By the way, a plugged exhaust can also cause low compression readings. What goes in must go out, and if you can't get the old air/fuel mix out, you can't compress a new one, right?

Second, as for the compression, lets check the plug seats. Do the area where the plugs seat have a lot of rust? If so, you may have not gotten a good seal with your compression tester. Try seating a rubber gasket on the tester then screw it into the sparkplug hole. If you get a different reading, then your tester was leaking badly when you did the first test. Be sure and use new spark plug gaskets when you eventually put the plugs back in. I also agree with the previous post; make sure you go with non-resistor plugs if that is what your book calls for on your engine.

Next, I think you can check the valves fairly easily and all it will cost you is a set of valve cover gaskets. Remove the valve covers, slowly loosen the rocker arms and see if they are holding a lot of pressure down on the valves. If so, you may have shaved heads. If that is the case, you may be able to get an extra set of push rods from a junk yard, and grind about 20-50 thousands of an inch off of them. Install them, and recheck the compression under the same conditions as the first readings. If the compression goes up, you found your problems. By the way, I would not leave the junk set of push rods in the engine. See if you can get a set of shorter rods from a parts house, or have a good machine shop shorten and polish a new set. If there doesn't seem to be a lot of pressure pushing down on the valves, check to see if the valve stems have a lot of carbon build-up on them that would keep them from moving freely through the head. If they are carboned up, you may be able to remove a lot of the carbon with some Berryman's B-12 carb cleaner. If you use that to remove the carbon, be sure and do an oil change before you start the engine. Berryman's will really thin down your oil. If they have a lot of carbon build-up, there's a more extensive way to get the carbon off without removing the heads, but I'll save that for later if you need to go that route.

Finally, if you are sure the compression test was accurate, the valves are not being held open and fairly sure they are seating properly, and the exhaust system isn't blocked, I would next look at the timing chain. GM didn't do any of us any favors with that lousy nylon-coated chain, and if your engine still has it, you might as well get rid of it now. If you have to go this route, and have the timing chain cover off, check the alignment marks BEFORE you remove anything. If the previous mechanic installed a new chain set on just one tooth off, your engine will produce many of the problems you are describing. If it is the original destruct-o-matic nylon chain, check to see if it jumped one tooth.

Hope this helps. At least you are not doing this in the middle of July during a heat wave!

Joe

[Guest]

One quick question-did you use the metal gasket under the carb? It keeps exhaust from the manifold crossover out of the carb.

Ok, just checking the heat riser is working too?

Just fishing,

[Ted "Wildcat65" Nagel]

Previous post was me, just trying to help!

[jerryacheson]

I installed a new metal plate (the old one was almost rusted through). How do I test the heat riser? I haven't messed with it.

[Reatta Man]

Jerry.

Have you tried any of the suggestions I made earlier? Let me know how it turns out.

Joe

[jerryacheson]

You guys had a lot of interesting ideas about what was wrong with this car. Thanks for sharing them. I thought I'd pop back in and let you know how the saga ends.

I finally gave up and took the car to a pro (builds 1000+ hp engines and does a lot of work on classic cars). His conclusion was that the engine was strong and had no internal issues. It was the carb that was bad. He built an Edelbrock 500 CFM carb with electric choke for the car. He reduced the size of the primaries and opened the secondaries. This is supposed to give me more cruisin' economy and more spunk on accelleration. She's running pretty good right now. Let's go cruisin'

Jerry

[gungeey]

Plus, do us all a favor and put your compression tester under your drivers side front wheel just before your next trip!

[Guest 31tudor]

I'd say passenger side rear tire. Use one foot on the brake and one of the gas.

(Of course, that's coming from a hot rodder!)

[jerryacheson]

Gungee and 31tudor,

What's your point?

[gungeey]

The point is your original post tells us of compression readings as low as 65 and 70lbs. All the new carbs in the world won't fix that! Your compression tester is junk.

No harm done... just sent us off on a wild goosechase.STeve

[jerryacheson]

Took the old girl out for a 300 mile road trip today. I ran her at over 80 mph on the highway and along some rural routes. She ran great. New carb performed perfectly; no smoke; and she got over 15 mpg. Thanks everyone for your support in finding the bugs. The cruise was a pleasant one.

[Guest]

Jerry- you can't <span style="font-weight: bold">do</span> stuff like that with an old car! They're supposed to be slow and unreliable in modern traffic!

Glad to hear the car is back in top form and doing what early 60s GM do best- teawing up the highway wike a big old dinosaur! (Thanx Elmer Fudd; apologies to Bruce Springsteen...)

Rocketraider

At work in the land of high voltage