question about my 455 buick plug problem

well today i went and changed the plugs in my 455 (from a 71 buick centurion) it was running real rough... took the #7 plug out and found it had no tip on it but the rest of the plug is fine.... what could have done this? they are autolite 26 plugs

 

nobody has any idea?

 

seriously is it because its not a small block chevy that i cant get any help?

 

If they're new plugs,they were probably produced in Mexico. Rather poor quality control. If it was a problem on all eight,I'd venture piston touching it(therefore,wrong/mis-marked plug);seems that problem would have been discovered upon fire-up. I'd get a magnet in that cylinder pronto and hopefully find that missing piece.

 

i hope its a defective plug and not a piston or valve problem... i put a magnet in there and cant find the piece

 

Looks like the ground electrode came off.

It happens, but not often.


I took a look at some Autolite's a couple days back when I was shopping for plugs for my 462" (bored 455) mildly built Buick engine.

Made in China . . . that says a lot right there.

I couldn't find the usual plugs I run - Bosch platinum + - I decided to give a set of AC-Delco's a try.

Made in the US.

They're running just fine and with the timing advanced 4 more degrees over what it was (8* initial and 32* all in) to 12* initial and still 32* all in it sounds and feels a little stronger.
(8* initial and 32* all-in are the stock figures.)

Granted, a subjective thing, but the seat of the pants dyno ain't always wrong.

Hoping for a small improvement in gas mileage, but it's probably just in time for the 5% methanol increase which will negate any hoped for gains....

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Engine's are pretty tough and more than likely the broken piece went through the cylinder without damaging anything.

Fwiw - my old BSA single ate the back half of the carb slide and the only thing that happened was that it ran rough due to being overly rich.
Got me home with no probs and opening up the engine showed no damage and no marks.

A new carb slide had it back in business next day....

 

when it was running good i had to mix half AV gas and 92 so it wouldnt fall on its face and ping..

 

I thought the 455 Buick's went to the 8.7/1 CR in 71.

Perhaps you have 1970 components, engine or the factory stuck in a leftover 10.0/1 CR engine.


What kind of timing curve are you running?

Ever have the head off and taken a look at the piston dish?

A big dish indicates the low comp engine, small dish the 10.0/1 and if you have flat-tops you have an about 12.0/1 CR.

 

Did you install the original plugs yourself? If not maybe the plug was missing the ground electrode when installed. If you have a HEI ignition system the coil would probably fire the plug. My guess is that the ground electrode is embedded in the top of the piston.

 

i put these in myself a couple weeks ago when i got the car the motor was blowing water out the left side exhaust so i put some liquid glass in for a temp fix... the car is a 71 centurion with factory dual exhaust and runs like a raped ape.. still has points no hei and i have never touched the timing

 

This may be a wee bit o/t.

C9;you found AC plugs made here? Most,if not all of AC-Delco's products are made in Mexico now. I won't use their oil filters anymore because of the poor quality. Back when I worked in GM engineering,we could blow the Mexican-made AC oil filters apart upon fire-up with 3800 Buick V-6 motors(up to 70 psi initial pressure);made one hell of a mess(and occasionally a nice fire) in the dyno rooms. All the mechanics,myself included,went searching throughout the building for the last of the U.S. made units. NEVER had a problem with them. Switched to Wix on my personal vehicles.

SpeedRacer,hope you find that piece before it gets intimate with your piston.

 

Yep, made in the US - just went out and looked at the box again.

WIX is the oil filter to use.

They do ok on really cold weather startups where the engine lights off on the choke and oil pressure can hit 85# - 90#

Even summer morning starts around here - where the choke doesn't always engage - depending on how many days since the engine ran - pressure will hit 65# or so.

 

thanks for all the info c9 its not realy that off topic because i am putting the motor in my 53 chevy sedan delivery.. i thought about pulling the intake and lookin for that piece.

 

Looked on-topic to me.

I understand the cast iron intake flows pretty well so you may want to use it for a while.

Quite a bit lower than the Edelbrock Performer or B4B (single 4 bbl) intakes.

So if you're fighting a low hood problem - probably not with your Chevy - it's a usable piece.

I ran one for a while on the 32 and it did ok.