[footjoy]

Originally Posted by 242177P

IIRC, your MPG was down before. Did you ever get that straightened out?
And their heat range.

Never got milage straightened out. Autolite 89s are whats in it.

Thanks

Greg

[footjoy]

Originally Posted by footjoy

Never got milage straightened out. Autolite 89s are whats in it.



Thanks



Greg

Correction auto lite 86


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[ta man]

Can we get a better picture of the groundstrap? I'm thinking your plug may be hot enough to stay clean but you are actually running rich leading to the carbon buildup.

[footjoy]

Originally Posted by footjoy

Never got milage straightened out. Autolite 89s are whats in it.

Thanks

Greg

Mistake they are Autolite 86s.

[shaker455]

Originally Posted by AG

Oil by the rings or carb mis-calibration or both. And maybe mix in some crappy ignition or some valve guide leakage.

X2 AG

Also treat with Seafoam

[Schurkey]

Originally Posted by footjoy

the plugs were white.

Means nothing. Unleaded gasoline doesn't color plugs like leaded did.

Originally Posted by lust4speed

Well, those chambers don't have any quench surface to begin with - basically an open chambered head so deck height doesn't mean anything.

Am I hallucinating? I see a sizeable quench pad on the chamber opposite the spark plug. Appears to be about four times the size of the pad on an Oldsmobile head.

[lust4speed]

One of us isn't seeing what's there, and it could be me . My eyes aren't what they used to be and I could be wrong, but I believe that what we are looking at isn't flat but a curved portion of the chamber roof. All the soot makes the details hard to define.

["QUICK-SILVER"]

How many of the 2000 miles were with the distributor that only had 10° centrifugal advance? And where was initial set during that time?

Little lower on power than expected.
Porcelain snow white like the engines been running without enough timing. Or the 86's were just too hot a plug for driving conditions.
Sooty cylinders like timing was off, carb just a little rich, restrictive air filter maybe.
And very well could be from reversion. Caused by cam timing, restrictive exhaust system, heat riser valve staying shut too much, etc...

Could be a number of things going on here
Clay

[footjoy]

Originally Posted by "QUICK-SILVER"

How many of the 2000 miles were with the distributor that only had 10° centrifugal advance? And where was initial set during that time?

Little lower on power than expected.
Porcelain snow white like the engines been running without enough timing. Or the 86's were just too hot a plug for driving conditions.
Sooty cylinders like timing was off, carb just a little rich, restrictive air filter maybe.
And very well could be from reversion. Caused by cam timing, restrictive exhaust system, heat riser valve staying shut too much, etc...

Could be a number of things going on here
Clay

Lets just put some of it on ignition timing, some on carburetor some on a quench of 63.

No heat riser 2.5 inch mandrel bent exhaust with H pipe

[amcmike]

How's your oil smell?

[Half-Inch Stud]

Whats that guy sayin in Post #6, reversion or something. What do you think about that?

Looks like Reversion on the Chamber"s Scallop portion, and the rest is rich running as if Q-JET was dripping from wellPlugs

[footjoy]

Originally Posted by Half-Inch Stud

Whats that guy sayin in Post #6, reversion or something. What do you think about that?

I don't think the exhaust is insufficient and backing up if thats what it means

[Will]

Originally Posted by lust4speed

One of us isn't seeing what's there, and it could be me . My eyes aren't what they used to be and I could be wrong, but I believe that what we are looking at isn't flat but a curved portion of the chamber roof. All the soot makes the details hard to define.

Every Pontiac chamber I've ever seen, except #061 and some of the HO/RA heads, that area is flat.

That's a crappy picture so it's hard to tell for sure, but I'd be shocked if that area isn't flat. It would mean someone's been at it with a die grinder.

[steve25]

Your plugs are one heat range too hot as seen by the color change over point on the ground strap being so far up near the main body of the plugs!

Also if those plugs have been run in the motor for 2000 miles they should not look white like they do, they should be a light tan in color which means your also running too lean atleast at rpms above a idle.

Your center Carb on your tripower was jetted for 389 cid motor and now your asking it to properly feed fuel to near 19 more cid and better flowing heads then the 389!

["QUICK-SILVER"]

Originally Posted by footjoy

some on a quench of 63.

Quench shouldn't have anything to do with carbon buildup.

Unless you were running ignition timing low for a ping/detonation problem?
Low timing would make for incomplete fuel burn (bad mpg) and overheat the porcelain (bright white) on the plugs. Super heated porcelain will cause preignition and make for ping/detonation noises that a 8.5 SCR engine shouldn't make even on 87 octane fuel.

Need to get all your threads and info rolled into one spot somehow. It's all too scattered out now and makes it hard for people to figure out what's going on and what your final goal is.

I wouldn't have pulled the head untill you got the tuning straightened out and seen what you had was really capable of. That's better MPG and RWHP.

Clay

[jonmachota78]

I would expect the exhaust valves to be a lighter color if it was not running rich.

[65sport]

If it's an automatic transmission with a modulator valve, look for oil being sucked from there into the intake manifold. If the connection is oily, it's likely a bad modulator valve leaking into the vacuum.