What... AGAIN???

[Robert Smith]

Ok gents, tell me if this sounds right; I had a valve job late '06... the car has been runin' swell over the year and had very little trouble with it.

Last time I had the car in for my guy to take a look at the carb (was acting up) he noticed #4 was acting weird... wasn't fierin' right... low compression. So, I take it to the guy who did my valve job at Derffey Auto... he takes a look and listens to it a little... checks it out, and comes to the bitter realization that the motor needs another valve job! It's only been a year since I got the last one!

He told me that the reason for this is because the valve seats weren't hardened... and that the unleaded fuel today is ruinin' my motor. I was told when I bought the car that the seats were hardened... so much for that. So, here I am drivin' thinkin' everything is fine and now I have to get another valve job... does this sound right? I mean, I do drive the car daily... and I do put it through some tough tasks from time to time... but, only a year since the last time I had it in??? Wouldn't I need an adjustment? And not a complete valve job?

Any thoughts?

=Rob ( 1946 P-15 owner)

[BobT-47P15]

Rob.....that doesn't sound right to me, anyway. The valve seats in all

these old MoPar sixes were hardened at the factory. Everyone is using

unleaded gas and it doesn't do what he said. Sounds as if the mechanic

is NOT famailar with these engines. Might be some other trouble with

the valves.

I'm sure others with more knowledge than me will eventually chime in.

Are you still wearing the vintage clothes and all that?

Good luck.

[Don Coatney]

Sorry to hear of your problem. If the valve lash was not set correctly (too close) you will burn a valve. The exhaust valve seats are hardened and running unleaded gas has nothing to do with valve failure. I do not think I would allow the same mechanic to do another valve job on your engine as he apparently did not know what he was doing the first time.

[Guest rockabillybassman]

I'm with Don Coatney.

[james curl]

Yes the shop that did my michine work tryed to tell me that my exhaust seats were not as hard as the new ones are and would need to be replaced. When I picked up the block only one exhaust seat had been replaced, I asked him why and he said that the original are a whole lot harder and better than the new seats. Besides that he broke his tool trying to remove the first one.

[Plymouthy Adams]

if the grinder of the valve had to reface the existing valve and ground it without leaving ample amout of material on the surface the sharp edge that is left tends to get very hot very fast and will erode..that is why valves are replaced frequently, because there is not sufficient material to face and have integrity/reliability left. If there is insufficient solid metal between the top of the valve and the angle cut..your grider should be responsible for the fix..while the head is off verify condition of all valves in regard to this..this could be a repeated fix down the road...exhaust valves are the main culprit..specification for this is in the book and should be known to anyone cutting a valve..and the comment of the hardened seat says he is not familar with your engine..assumption/comment regarding seat is already an excuse to lay blame..and just an excuse...if he knew of this why did he not point this out when he did your head..do not let this guy try to fool you..your seats are hardened..there should be material between the top of the valve and ground face..also as these valves are ground the stem is enlongated..a performance engine would get shimmed for correct installed spring height and the end (lash adjust) would be ground for correct length also..but that is almost a mute point on these low compression low rpm engines with mechanical adjuster...however..as far as DO IT RIGHT..it is part of a proper done job.

[greg g]

How did he determin you needed new valve job??? Look in his cashdrawer??? What test did he perform to make his determination? Vacuum, compression, or the old open the hood and listen? Did he even pull the spark plugs and look at their condiditon or did hesimply lay onhands and decide you needed to pay him for another poorly done job?

Before doing anything I would want to see the results of both a compression test and a vacuum gauge reading. Both will tell you a lot about the engine's condition.

What symptoms is it exhibiting? Could be as simple as a bad spark plug wire of points or condensor going bad.

I would definately get a second opinion before doing anything else.

[Robert Smith]

Hey guys, thanks for all the input and opinions!

Well, Derk at Derffee Auto has rebuilt many flat heads, he owns a ’42 Plymouth coupe… I have a friend who highly recommended him to me after he rebuilt his flat head in his 51 Chevy.

I’m not sure where I’m going to take the car… there aren’t too many places around here I can take it to that understand old flat heads. I’m in Monrovia CA and there’s a few little shops here and there, but, I’m not sure how many I can trust.

Anyone here in LA County know of a place that would find out what the real problem is?

Thanks,

=R

[Reg Evans]

Well....I hope Derk didn't use flat head specs on the 51 Chevy too.

[Normspeed]

I agree, a valve job properly done should last for years of normal service.

Robert, the weather outlook this weekend looks pretty crummy for car work without a garage, but if your car is still driveable and you can wait til next weekend, you could drop by my place and I'll be glad to run a quick compression and vacuum check and take a look at the plugs and points for ya. Might be something simple.

The laying on of hands, however, would require the passing of the collection plate!

Rev. Normspeed

[Don Coatney]

Hey guys, thanks for all the input and opinions!

Well, Derk at Derffee Auto has rebuilt many flat heads, he owns a ’42 Plymouth coupe… I have a friend who highly recommended him to me after he rebuilt his flat head in his 51 Chevy.

I’m not sure where I’m going to take the car… there aren’t too many places around here I can take it to that understand old flat heads. I’m in Monrovia CA and there’s a few little shops here and there, but, I’m not sure how many I can trust.

Anyone here in LA County know of a place that would find out what the real problem is?

Thanks,

=R

Robert;

Did you ask him how often he does a valve job on his own 42 Plymouth?

[Captain Neon]

For a valve job to go bad in one year, it seems suspicious to me. My father drove a 1962 Falcon 6 cylinder almost every day every where through out the early 90s on unleaded gasoline, and then a few more years before selling it after replacing a couple of burnt valves and adjusting a few more. One year of normal use should not burn out a valve properly installed in less than a year even if they aren't hardened seats.

Just for the record, I use tetraethyl lead additive and CD2 lead substitute (sodium) in my P15 with premium E10 base fuel (91 octane in CO, 93 in the Midwest, 92 most every where else). I have been running E10 since 2003 after a move back to Minnesota.

I'll never understand why mountain regions like Colorado sell low octane fuel (85, 87, 91). It would seem to me that 90, 92, 94 would make more sense here. The moving van this summer experienced a noticeable power loss on 87 octane fuel upon entering the higher altitude of Colorado.

[TodFitch]

<snip>

I'll never understand why mountain regions like Colorado sell low octane fuel (85, 87, 91). It would seem to me that 90, 92, 94 would make more sense here. The moving van this summer experienced a noticeable power loss on 87 octane fuel upon entering the higher altitude of Colorado.

My old 82 Plymouth TC3/Turismo always got 87 octane. Except on my first trip with it to Colorado. Filled the tank with the low grade without noticing (or caring) that it was 85 octane. The car did not like that at all. Barely ran. Once I nursed it long enough to add more gas to the tank I added some high octane and things got a lot better.

Since that incident I have paid close attention when driving to Colorado and when the economy gas octane changes from 87 to 85 somewhere near the Utah/Colorado border I shift up a grade on gas. At least in the modern car. The 1933 will run just fine on 85 octane.

Back to the original topic: My guess is the valves were set too tight and the adjustment was not re-checked hot. If that is the case then refacing/replacing the one valve and adjusting them all should be enough to fix the problem. I have burned valves on my 1933 but the fault has always been mine (too tight or mixture way to lean). On my car at least, the valve seats have always been good.

Of course the earlier offer by Normspeed to help with a compression check and vacuum analysis should be taken: The problem might be something else entirely.

[Captain Neon]

We run the wife's '92 Acclaim on 85 octane. The car almost never leaves town and only briefly gets to 55 mph on her way to work. It also has fuel injection and a computer to adjust timing. All of the other vehicles get 91 octane. When we go on a significant trip, I fill-up with premium. I also fill-up with premium and add a bottle of fuel injector cleaner at every oil change.

The Neon Expresso needs 89 octane or better. I did some experimenting to see if blending 50% E85 with the lower octane gasolines would give me any savings as I commute 30 to 45 minutes one way to work every day and my Neon is OBDII (?) compliant. The only cost savings was when I ran 100% E85 otherwise the cost/mile was almost the same or even cheaper with 91 octane E10.

[YukonJack]

Am I missing something here? Chevy didn't have a flathead in 51.

Hey guys, thanks for all the input and opinions!

Well, Derk at Derffee Auto has rebuilt many flat heads, he owns a ’42 Plymouth coupe… I have a friend who highly recommended him to me after he rebuilt his flat head in his 51 Chevy.

I’m not sure where I’m going to take the car… there aren’t too many places around here I can take it to that understand old flat heads. I’m in Monrovia CA and there’s a few little shops here and there, but, I’m not sure how many I can trust.

Anyone here in LA County know of a place that would find out what the real problem is?

Thanks,

=R

[Normspeed]

It was a trick question!

[JerseyHarold]

Another possibility for a burnt valve is too lean a mixture in that cylinder. Could be a bad manifold gasket or a restriction in the intake runner.

Just my two cents' worth.

Harold

[mackster]

The laying on of hands, however, would require the passing of the collection plate!

Rev. Normspeed

HA HA That's funny. I know some overrightous mechanics claim that they can just hear all troubles but I will want test results if they tell me they need to operate on me!

[wayfarerstranger]

that must be a rare bird .. chevy never had a flat head engine ??

[Don Jordan]

Robert Smith this might be a little far away for you but it would be worth the drive for peace of mind. I knew I was in the right place when I walked in and they were working on a V 16 Lincoln. They rebuilt my 218 and knew all the little things you would hope they would know.

At least give them a call:

Adams Metallizing & Grinding

44632 N. Trevor Ave.

Lancaster, CA 93539

661 942 9538

Hope this works - I've been pleased.