Stopping the knock: Lower compression and ported heads...

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Hey Dude, if your going to start fuckin around with people that are honestly trying to help you, and that are my friends you can pound sand... Were probably at 1000 posts between all your threads of ONLY trying to help. If your going to turn around and pull this **** close your account and go to moparts.com

http://board.moparts.org/ubbthreads/ubbthreads.php

you'll fit in better with the class of people... YOU NEVER BITE THE HAND THAT FEEDS... Especially in this family, my family...
 
I didn't start threads to alienate people. I asked for help in an area that I had little understanding.
I understand brakes, suspension, body and paint. I've restored numerous cars, rebuilt several engines and resurrected cars that were long dormant.
My experiences of trying to run a high compression ratio engine on the street are well documented here and elsewhere. This is one area where I really need help. I have learned some new things and read stuff that never occurred to me.
Jokes? I can appreciate them as well as anyone. What I do not like is to be openly ridiculed or insulted. When I make insulting comments that are NOT a personal attack, I make great efforts to let others know that I am not serious.
I got pissed and made an impulsive response. I saw my mistake and tried to correct it. Dont care to forgive? Oh well. I suppose I'm the only one that is capable of making mistakes.
 
OK folks-seriously-let's knock off the bullshit...I just want to see this thing go back together and see if it treats him better. I'm not offering any more advice...I just want to see how it runs...no dog in this fight.

And what's with the moparts link?
 
txstang84 said:
And what's with the moparts link?
Click to expand...

I didn't click on it, but I am also a member on Moparts under this same screen name. I have started threads here, there, on FBBO and Dodgecharger.com. Yeah, I know, I know..."Cast a wide enough net, you'll find the advice you are looking for..."
I am tempted by some good ideas that I read. I've PM'd some sharp tech guys now and then. There are many ways to skin a cat and some are better than others. All have some degree of compromise.
I am moving ahead with the .075 Cometics as previously planned. What HP I will give up in quench I'll gain back (and more) in a better ignition timing setting. To some naysayers, I suggest you continue to pop in to check the progress. Hopefully by the end of the Thanksgiving weekend I'll have some good news to report.
Thanks again to everyone, Greg
 
I ordered the Cometics on Sunday night. The Summit site listed the gaskets as being in stock and ready to ship. I'm in California and the nearest Summit store is 2 hours away. It turns out that the gaskets are shipped from Cometic back east somewhere and they have to be made to order. This means that I will not get them before the middle of next week.
I ordered ARP head bolts too. I figured that since I had 5 or 6 uses from these bolts I should get new ones.
The car has been sitting idle for 2 months. I missed out on the great driving conditions of the early fall. I really should get the heater working in the car once its running again.
 
Correct-most of the time, unless it's a commonly used thickness, Cometic makes them per requested spec. I was fortunate with my 4.6 4V build that Fel-Pro also makes MLS gaskets for that app. Before you lay them down though, is your deck surface machined with the proper RMA to use Cometic gaskets? I'm thinking this has been covered before in previous threads, but I can't recall.
 
During this long process, several people have chimed in. Some suggestions got lost in the mix. I have had a few suggest to have the chambers hogged out and to use a thinner gasket. Not a bad idea. Some liked the idea of going thinner with the heads as is to gain quench. I decided to go with thicker gaskets and ported heads.
Yeah, the port job isn't as slick as some others I have seen recently online. I had no experience having heads ported before so I wasn't knowledgeable enough to know the difference between a passable job and a precise CNC job. I DO know that prices for the expert porting are easily double what I paid, so its not as if my money was totally wasted.
One of the nagging things during all of this is the comments from many that felt my compression ratio SHOULD have been okay on pump fuel. I read from many that had engines with more CR that ran fine. I asked these people for the specifics of their engines and a few did respond. The majority of them used 93 octane which we can't get here in CA. EVERY one of these people with successful high CR engines were east of me where the fuel is a better quality AND higher octane.
This still brings me back to the nagging question: If others were able to run on pump gas, how can I get to that point?
I was under the belief that I was running at 10.73 to one. After cleaning the pistons and REchecking deck clearance, I found that I was .012 in the hole instead of .017. Then I started thinking of how I've had these heads off the engine a few times and had them lightly surfaced each time. The resurfacing surely reduced the chamber size by a measureable amount. This means that my actual compression ratio couls be closer to 11.0 to 1 but I still am at .051 quench distance at best. The 191 average cranking PSI shows that I am over the limits of what I can run with 91 octane fuel.

I asked around about what actual physical signs are visible if detonation is occuring. Some told me that the tops of the pistons will look like they have been hit with an icepick. I looked at mine before cleaning the carbon off and found absolutely no markings like that. After cleaning, the result is the same.
 

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The mark below the exhaust valve notch in piston #1 is from where the flimsy piston stop made contact.
 

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I'm no engine expert, but I solve other mechanical problems for work and otherwise. You gotta measure everything and nail it down, write it down. There's lots of guys here that can help, but without good hard data, they are in the dark. A picture is worth a thousand words, but doesn't give dimensions.

I recommend starting a Word document on your computer that you can copy and paste good info into, as well as keep your own notes.

My gut says get some quench and look to the cam to reduce cylinder pressure...but my gut doesn't count for much.
 
Hey Greg, I've followed your posts on FBBO and now here. Like a previous post said, you have to be reaching 1000 posts trying to help lol. There seems to be a common thread amongst the most knowledgable engine gurus here, "if only I could get the motor in front of me". Well, I think we all applaud your efforts, but maybe it's time to put the motor in front of an expert?
 
Thanks HT, I am closing in on a fix. It may not be the perfect one, but it will improve things.
I'm not sure if you read through every post in the numerous threads, but I think that my situation came down to the simple fact that I had too much compression to run on the 91 octane CA unleaded fuel. I ran 110 leaded and the car ran really strong, actually faster than it ever did before. This told me that the knocking/detonation could be eliminated. If all I ever did was to drive the car locally, I could have just ran the 110 fuel at $10 per gallon.
I decided to lower the compression.
There are many ways to lower the compression. I chose to use thicker head gaskets. Some don't like that method and felt that it wouldn't work in part because my idea takes away whatever "quench" I had. Their reasoning was that the 440s of the mid 70s had no quench and even though they had 8.0 compression ratios, they had detonation problems. I don't dispute that, but I also feel that it isn't exactly a direct comparison. I have aluminum heads with better port design. I have an aluminum intake and headers. This engine runs cooler and breathes better than any stock 440. My cam has a much later intake closing than any stock cam.
When I get to the point where I need to pull the engine, I will probably replace the pistons with ones that have a dish on the valve side and a quench pad on the other. At that time I could also zero deck the block and run a standard .039 Fel Pro head gasket. This would get me quench and a reasonable compression ratio at the same time.
Another thing for the guys against the "thicker head gasket idea": I ran a .060 Cometic gasket in 2006 and the car ran great on 91 octane gas. I was able to set the timing to 35 degrees @ 3000 rpms and had zero knocking of any kind.
The Cometic gaskets came in yesterday but I don't know how soon I'll get to work on the car. As is often the case, the week suddenly got really busy!
 
...don't forget, even after you make the head gasket change, gotta get a good hands on of where your cam is degreed in...and possibly retard it a little.
 
I will check the cam timing again, but when I degreed it, it came in exactly the point called out on the cam card. I'd feel pretty silly if I find an error there.
 
Evidently I misunderstood one of your previous replies where I was almost sure you stated you weren't sure where it actually was, as you may've not measured it correctly...moreover, what I was getting at is that if you do retard it a few degrees, it could help out with your high cranking pressure and further reduce your potential for detonation...but I digress...and I'll resume my position purely as an observer...
 
txstang84 said:
Evidently I misunderstood one of your previous replies where I was almost sure you stated you weren't sure where it actually was, as you may've not measured it correctly...moreover, what I was getting at is that if you do retard it a few degrees, it could help out with your high cranking pressure and further reduce your potential for detonation...but I digress...and I'll resume my position purely as an observer...
Click to expand...

Yer learnin. lol
 
I already have the .075 gaskets here but I am tempted to try a set of the .027 gaskets just to know for sure. That would put me at 11.21 to one though!
Not sure if I mentioned everything, so I'll recap a few things.
4.35 bore.
4.15 stroke
83 cc chambers. ( I thought they were 84, later I figured they were less due to the times i have had them resurfaced)
Pistons .012 below deck. ( Another discovery: I previously thought they were .017 in the hole)
Fel Pro .039 head gasket.
This comes to 10.94 to one. I previously thought I was at 10.73 to one.
Cam degreed in at 106 as stated in cam card.

As I understand it, the Cometic head gaskets can be REused?
If so, I might try using the .027 gaskets. If the engine runs fine, I'll leave them in. If the engine still detonates, I can put in the .075 gaskets I have here and use the .027s in another engine.
I'll bet this idea makes a few of you proud, huh?
 
Cometic head gaskets are reusable to an extent as long as the surface is correctly machined and the gaskets aren't damaged during removal...

And we're not "proud" of anything...yet.
 
I have read of some guys using steel shim gaskets on aluminum head engines. They say to spray with copper coat on both sides. Mancini racing sells a PAIR of the steel shim gaskets for under $40. Might be worth a try. Hell, at $40 it would be silly to NOT consider it, right?
 
It's not advised to use the steel shim gaskets on aluminum heads.
 
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