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

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txstang84 said:
Those gaskets also require a retorque after the first heat cycle..
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That would be a pain in the ***. I'd have to pull the headers to gain access to the lower row of head bolts! That alone would be enough to deter me.

Regarding the advise to NOT use the steel shim style with aluminum heads, I have heard that. I've also heard/read from others that claim to have done it with no problems. May not be worth the risk though, just to save a few bucks.
 
I love the pushing the compression deal. He!!, I've even posted on other threads that I thought guys were leaving some power on the table. With that said, your issues have made me rethink my position. I thought you were trying to lower your cranking compression? If that's still the case, use the thicker gaskets you already have. I used some steel shims on a couple resto Pontiac engines with good results and they were iron on iron. But, that was in a era of decent pump quality fuel. I can't imagine using them with aluminum heads unless it's a race only application that would get torn down quite a bit. As you've said, the thin gaskets will jack your compression back up...:banghead:. Quench, no quench,.....I don't really know at this point, but you need to decide which way you're going to go, and just get her done.
 
I wanted to lower my cranking compression because I thought that it was the only way to stop this engine from knocking. I still think that thicker head gaskets would get me there, but I keep thinking of the many smart engine builders that tout the benefits of a quench engine.
The way I see it, nothing is permanent. I am thinking that I could try the .027 Cometics first. The theory is that even though the compression does go up, the quench effect is supposed to MORE than offset that while providing a more efficient burn.
If the engine runs fine with the thinner gaskets, I will gladly admit that I was wrong about it and beg for the forgiveness of all that suggested it. :prayer:

IF the engine still knocks, I have the .075 gaskets to use. I was all set to just jump in and use the .075 gaskets, but the idea of quench keeps calling me......
 
Frankenduster said:
I wanted to lower my cranking compression because I thought that it was the only way to stop this engine from knocking. I still think that thicker head gaskets would get me there, but I keep thinking of the many smart engine builders that tout the benefits of a quench engine.
The way I see it, nothing is permanent. I am thinking that I could try the .027 Cometics first. The theory is that even though the compression does go up, the quench effect is supposed to MORE than offset that while providing a more efficient burn.
If the engine runs fine with the thinner gaskets, I will gladly admit that I was wrong about it and beg for the forgiveness of all that suggested it. :prayer:

IF the engine still knocks, I have the .075 gaskets to use. I was all set to just jump in and use the .075 gaskets, but the idea of quench keeps calling me......
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quench created turbulence which lessens hot spots and improved mixture as well as flame travel = less ping
 
okay, I just finished reading the whole thing, if you were detonating, you'd see some evidence in the pistons, at least, I'd think.

You mentioned running one stage colder plug, I'm wondering if you need to go one more step. My runs a 68 cuda with a 472 stroker, talked to him about your issue, he said he has something similar happening and dropped plugs he said were at least 2 steps colder and the problem went away

probably a cheaper shot than pulling heads over and over...
 
What's the static compression difference between the .027 and .075" gaskets? Is that enough to make an appreciable difference?
 
It's big - almost a point because it's the full gasket bore losing the volume.
 
With your cam degreed in at 106 when is the intake valve closed on your degree wheel? Do all the open close events on the cam card match the wheel events?
 
mderoy340 said:
With your cam degreed in at 106 when is the intake valve closed on your degree wheel? Do all the open close events on the cam card match the wheel events?
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I should have the numbers that I got. I scribbled them on the instructions included in the degree kit. ( The only paper I had nearby at the time)

I plan to recheck the cam timing as I reassemble the engine.
I agree that the pistons show no physical signs of detonation, yet I clearly heard something knocking. After starting several threads, receiving thousands of views and hundreds of responses, I can only say that I still do not have any proof of what is happening.
I have stated several times that the knocking sound only came on once I got past 1/2 throttle. This is where the secondaries feel the most effective. The engine really picks up power at this point.
Is the knocking coming from inside or from somewhere else?
I mentioned that the only times that I was able to drive at WOT without knocking were the following:
Using 110 octane fuel.
Timing retarded to 6 initial, 20 total.
One time after changing a leaky valley pan, I made 3 full throttle blasts on 91 octane fuel. The first 2 were with an engine not quite up to operating temperature and the engine did not knock. The 3rd pass it did, so I continued looking for the problem. I'll add that while the temp guage is original, it seems to be working okay. The engine rarely ever gets past the middle of the guage, never smells or feels hot and has never boiled over.
To understand the problem, I look at what else occurs at WOT. The air cleaner is close to the hood, but I haven't seen any evidence of them making contact since I'd expect to see scratches or chipped paint somewhere. The engine knocked before and after I installed the fan shroud, so that is a NON issue.
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In May, I replaced the K member with a welded and reinforced unit I had modified. When I removed the original K, I found that the RH motor mount was broken, so I replaced it. This raised the RH side and as a result, the LH header sometimes now made contact at the steering box. I found dimples and scratches in the ceramic coating. The tubes were undamaged prior to changing the K member. At rest, there was about 1/4" of clearance.
As I understand it, under power, the engine lifts on the left side and goes down on the right. This would mean that any header interference shouldn't actually occur at WOT, right? The headers had no other points of interference. The transmission mount is a spool design that is in good condition. The cross shaft for the shift linkage was secure.

Looking at the numbers, I made a few mistakes in calculating the CR. The pistons were only .012 in the hole when I thought they were .017. I had been using an 84 number for the combustion chamber size when they could have been smaller due to the times I've had the heads resurfaced. Anyhow, at this point, I come up with a 10.94 with a Fel Pro .039 gasket. That is with a .051 quench distance. The .027 gasket bumps it to 11.21 with a .039 quench. The .075 drops me down to 10.07 and quench would be a non issue at .087.
 
You can add shims to adjust where the engine sits in the K frame to make small changes and clear the steering box.
 
airwoofer said:
You can add shims to adjust where the engine sits in the K frame to make small changes and clear the steering box.
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The point of contact was some raised casting numbers on the steering box. I took a file and a grinder to the steering box and dimpled the headers.
 
I expected to work all day, but the boss wanted to leave early... BONUS! I'm heading out to the shop to begin reassembly!
 
I hear about how some guys can R&R heads or entire engines in record time, but I have had mixed luck doing so. Maybe some of it is because of the car.....
I have to say that having 2" headers makes this sort of job a real pisser. To get the heads off, the headers have to come out. To get them out, the center link gets unbolted, the trans linkage too. This of course requires lifting the car to what feels like an almost unsafe height so the angle is right for installing or removing these headers. I'd never switch to manifolds, but I can see why many people stick with them.
Going back together, most of the header bolts are easily reached except near #1 and #2 tubes. I sometimes forget to tighten down the starter leads before bolting the starter in place. They are almost impossible to reach afterwards with the headers in place.
I'm almost there, just a few things on the top side to finish. I have both the Fel Pro intake paper gaskets and the thicker Mr Gasket ones. I figure that the thicker head gaskets may require thicker intake gaskets to manitain proper intake port alignment.
 
Take your time,take it slowly F.D. ...Too expensive and frustrating, to rush it guy. Degree the came,with the heads off ,mandatory. I never saw a post ,about a harmonic balancer. Degree it,to top dead center,number one.(using a dial indicator). Check your balancer's timing mark ,against the actual top dead center reading. If it doesn't line up,with the timing marks......
 
I may have not mentioned it before, but I actually did verify TDC when I degreed the cam before. I bought a robust solid brass piston stop and did the deed using a dial indicator. The timing marks on the balancer are spot on. The balancer was bought new when I first built the engine in 2004.
The heads are on already. I bolted them on Dec 31st. Today I got the headers in and bolted up. The steering linkage and trans linkage are in place too.
 
Wahooooo! Its running again! :cheers:

Nothing about the reassembly was too difficult but it would have been nice to have a helper with a few things. My brother in law moved back to AZ so I lost my gopher.
The headers smoked off some of the fresh paint as the engine warmed up. No leaks anywhere so far. I washed the car for the first time in several months. It sounds great and idles about the same as before. Timing is set to 19 initial and 33 total. I'm sure it can take more timing but I'm going to have to run out the 110 fuel or pump it back out, then run 91 exclusively to see. I understand that most guys run between 34 and 37 degrees of total timing. Don at FBO ignition said that running at 30 or 31 degrees total timing instead of 36 degrees could have cost me between 35 and 50 HP.
No, I did not recheck the cam timing. My reasoning was that I degreed it twice before and came up with the same numbers, so I figured that it should be right. Besides, as a timing chain stretches, the cam timing retards, right? I have seen quality chains stretch even after only a few hundred miles.
I have a Rev-n-nator ignition ECU that I might try using. I tried it before when I had the 509 cam and nearly 11.0 to one compression. It detonated worse even though I retarded the timing per their suggestion. I like the idea of having a rev limiter.
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To the guys that felt that the thicker head gaskets would make the car run like a mid 70s 440 with 8.0 compression:
While I appreciate the many, many responses to the multiple threads I've started over the internet, to compare a smogged out 440 to my engine isn't really a direct comparison. In 1976, every American car I know of had a catalytic converter and single exhaust. The Chryslers of that era had closed element air cleaners, milder cams, air injection exhaust manifolds, EGR, lean running Thermoquads and those cars weighed almost 4800 lbs!
How many Mopar guys are running open chamber 906, 346 or 452 heads on their engines? Plenty, I'd guess. They often run quite well even though they have no quench going on.
 
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