440 headgasket to lower compression

[BLK 68 R/T]

Didn’t realize it has had a different dist. In the past. I would agree with everyone else then on a timing issue.

 

[BSB67]

I guess I don’t understand how a timing chain impacts ignition timing if the engine’s ignition has been timed properly.

Maybe folks are inadvertently being unclear and are actually referring to the balancer mark being off.

 

[RemCharger]

I guess I don’t understand how a timing chain impacts ignition timing if the engine’s ignition has been timed properly.

Maybe folks are inadvertently being unclear and are actually referring to the balancer mark being off.

I think some of the references are possibly the cam is over advanced.

 

[BSB67]

I think some of the references are possibly the cam is over advanced.

Sure. But still only blows 150 psi.

 

[RemCharger]

Sure. Still only blows 150 psi.

Static.

 

[kaj750]

Your timing chain doesn't even need to be off a whole tooth. If it's a set with multiple keyways for camshaft degree-ing, it might be really advanced, or retarded, using the wrong keyway
.
Curious. Do you have a degreed balancer, or a timing tape on it? If not, I'd put a tape on it before I took anything apart.

For the avgas, I just drive on the airport grounds, put a credit card in the machine, enter my license number in place of the aircraft number, and self pump. (Into five gallon cans, NOT the truck!)I do it at my tiny az airport, but I think I could do it in a small airport in california...... but it wouldn't be cheaper than california pump 91

Balancer only has paint marks. Adding tape on the reinstall would be simple enough.
Not sure I have any airports that small, around me. I'll check, just for the heck of it.

 

[33 IMP]

Balancer only has paint marks. Adding tape on the reinstall would be simple enough.
Not sure I have any airports that small, around me. I'll check, just for the heck of it.

Fresno Chandler executive has a self serve 100LL , 24/7.
I use a steel can, so I ground the filler to that. Normally, a pilot would ground the plane. If you use a plastic can, you'll need to ground it to your car/truck. .

 

[kaj750]

Fresno Chandler executive has a self serve 100LL , 24/7.
I use a steel can, so I ground the filler to that. Normally, a pilot would ground the plane. If you use a plastic can, you'll need to ground it to your car/truck. .

I forgot about Chandler. Heck, why not? Maybe it'll get me a chance to drive the crap out of the car before I tear it apart.

 

[Curiousyellow71]

With the heads off my reference of down was measuring from the deck to the top of the piston. You need that to know where your at or its just a guess.
This compression calculator is simple enough to use.
Compression Calculator

 

[kaj750]

With the heads off my reference of down was measuring from the deck to the top of the piston. You need that to know where your at or its just a guess.
This compression calculator is simple enough to use.
Compression Calculator

Noob question, but with piston at TDC, yes?

 

[BLK 68 R/T]

Noob question, but with piston at TDC, yes?

Yes.

 

[kaj750]

I have not read the responses, some may have made sense and a few are probably well intentioned but wrong.
Here is my experience, a real world situation that actually happened:
I had a 440 based 493 that knocked at anything over half throttle.
Compression ratio was 10.8 to 1 with Edelbrock aluminum heads, a Mopar Performance '509 cam, Demon 850 carburetor and 4.10 then 3.91 gears and a 727. I had to pull back total timing to 31 degrees just to keep it from knocking at half throttle. I joined this forum almost entirely to get advice on how to correct this problem and a LOT of well intentioned members stepped up to help.
Some advice was excellent and I didn't follow any of it. In summary, the predominant theme suggested was to pull the engine and swap in dished pistons to get below 9.5 to 1. I just did not want to pull the engine out for what seemed like a problem that should be fixable without a piston change.
Some advice was wrong but was an easier way to go. One was....Install a bigger cam to bleed off cylinder pressure. Yeah, in theory that sounds good......except that BIG cams do sort of bleed off cylinder pressure at low RPMs...(more accurately, the overlap doesn't allow as much cylinder pressure to build at low RPMs)......while then going WAY bigger in pressure at higher RPMs. Yeah...the bigger cam made it knock worse at wide open throttle.
I was also advised to:
* Slow the advance rate of the timing curve.
* Add an air/fuel meter to ensure the engine isn't running lean.
* Adapt some manner of a cold air intake.
* Check for oil migration through the valley pan.
* Try using a colder spark plug.
* E 85
* Methanol injection.
* Water injection.
* Use 1.6 ratio rocker arms to make the cam "bigger".
* Install thicker head gaskets.
That last one was met with equal amounts of support and criticism. I saw it as a crutch that might just work. Several critics swore that it would make things worse because I'd lose quench. I was .017 in the hole with the Ross pistons and with the .039 head gasket I had, I was already on the outer edge with quench anyway so screw it...I bought a set of Cometic .075 head gaskets and while the heads were off, I had them ported. With the thicker gaskets, I was now down to 10.17 to 1.
Guess what? The engine did not knock anymore! I was able to move the total timing to 34 degrees too. Power increased and the knocking stopped at full throttle. It only hinted at knocking a few times in really hot weather but 99% of the time, it just scrammed.
The big cam annoyed me (idle quality) so I swapped in a milder cam that was better for street use. That combination resulted in higher cranking pressure but even then, no knocking.......until that cam started going flat. I took that as a cue to go ahead and pull the engine and go through it.
In 2022 I went ahead and switched to dished pistons and thinner head gaskets. I'm now at 9.6 to 1 with great quench. The engine makes more power than ever and actually runs great even on mid grade 89 octane!

Looks like I forgot to reply to your post. All of those suggestions are in this post. Your solution happens to be what I planned to try.
I'm going to go ahead and swap heads next weekend.
I will check the head gaskets that came with the heads. Maybe I will be lucky and they will be the 0.051" version. If not, I will order a set.
I have all the stuff here, may as well try.
I also may pull the timing set off and redo it myself so I can confirm it's accurate.
I will scour YouTube for a how-to video, to make sure I do it right.

 

[kaj750]

Yes.

Pulling the heads next weekend. Will check. Thank you.

 

[1KoolBee]

.020 down with .039 head gasket will kill your quench. That and potentially too much timing is going to create problems. You could go with thick or thin head gasket, but either way you’re going to have to tune your way out of it. Personally I’d go thin head gasket, maybe find an .030 MLS if they exist? Not sure if .020 shim gasket would work with AL heads. Drop thermostat to 165, very carefully recurve the distributor, then jet the carb with an o2 sensor in exhaust. Rinse and repeat ignition and carb fine tuning as necessary.

 

[Mariposa Mike]

Off topic but to the OP, have you found a machine shop in the Fresno area you can recommend? Yellow pages and internet does not come up with anyone. Seems no machine shops left in Central Kalifornia.