Anyone here ever have their pistons machined?

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Kern Dog

Kern Dog

Build your car to handle.
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With all of the various issues that I have dealt with trying to stop the detonation in my 440/493, I am considering all options.
I spoke with Dwayne Porter several months ago. One method he suggested to reduce compression was to have the combustion chamber sides of the pistons milled and to deck the block to zero. The pistons would allow more combustion chamber volume to reduce compression and the cut in deck height would increase quench.
Anyone have an idea on how much it would cost to have pistons milled? Mr Porter thought a .040 cut would be enough to lower compression about 1/2 a point.
NEW dished pistons from 440 source are $600 plus rings, then I'd need to have them swapped onto my rods. Cutting my pistons seems like a cheaper and easier way to go.
 
Wont you have to completely disassemble the block ie new gaskets and added labor pluss the decking.I would think new slugs would be cheaper. Should be cheap to have pistons installed
 
I don't think you would have to deck the block. Just mill the pistons. This is assuming you have domed pistons that stick above the deck. You would mill the pistons down to deck height.

***Edit*** I just read the op again and see where he mentions milling the deck. First, if you mill the pistons to lower compression you will gain it back, at least partially, by milling the deck.

How about more info on your build, such as timing, deck height, pistons, heads, current quench, gasket thickness, and current compression ratio. Thanks.
 
You can swap pistons on the rods in a shed with a small pick. What about balancing with new or even cut pistons?
 
I have seen forged pistons milled to lower compression. Assembly will need to be rebalanced. I'd look for diff slugs and sell yours. Jmo. Either way, will need to be run down.
 
I have milled my pistons twice since the 70's,, and about to do it again,.. I can't remember what it cost then,, but have been quoted $100, about an hour.. He will weigh each piston first, and remove equal weight from each piston.. They started out at 12.5 to 1..
 
/6 Matt said:
Hey frankenduster, what is your quench area. .35" is a good target neighborhood.
Click to expand...

.035"

we no nothing about your combo, weight, gear, converter, timing curve, fuel octane, compression, heads, pistons, head gaskets, plugs.

list all that out and you may just need a different curve in the dizzy...
 
Have had a coupe sets of dome pistons milled, last set were 360 Diamond pistons, had .125 cut off the dome....

If they are domed, need to check to the pistons to see if the dome is solid or not...

These were done about 5 yrs ago, cost 100 bucks...
 
Yep, that is another question, how much meat is under them? The type of milling you want to try for IMO is basically connecting the valve reliefs and making one continuous wedge and leaving the rest of the piston alone to retain your quench. Cant find a pic but they are out there. I think some of the older KB's had this style of VR's.
 
805moparkid said:
.035"

we no nothing about your combo, weight, gear, converter, timing curve, fuel octane, compression, heads, pistons, head gaskets, plugs.

list all that out and you may just need a different curve in the dizzy...
Click to expand...

Search through his posts-there's another thread about 4 pages long about his problem...ignition and cam timing have been discussed at rather great length. Oh, and grab a cup of coffee...
 
I've cut the domes off forged Pistons, without looking, the $100 ballpark sounds right. No pockets underneath, so just reballanced the crank and away I went.
 
So you'd rather tear the engine slam apart than try to optimize the ignition curve. I'm lost.
 
I think he asks questions, then waits until he finds an answer that agrees with the one he already is thinking of.....
 
72BBSwinger said:
I think he asks questions, then waits until he finds an answer that agrees with the one he already is thinking of.....
Click to expand...


I read that many times. I don't even think I understand it. lol
 
RustyRatRod said:
So you'd rather tear the engine slam apart than try to optimize the ignition curve. I'm lost.
Click to expand...


I have not made up my mind on anything yet. I like to know what options are available.
For the record:
What do you think I've been doing? I have asked numerous times about the ignition curve and the most helpful suggestions have been...you need to delay full advance until 3500.....
Great. Now how in the world am I to do that? Stiffer springs? NOBODY has stepped up to suggest what springs, where to get them or anything else on that matter. I am dealing with an engine that knocks at anything over 25 degrees of total timing. It USED to detonate at 31 with the old cam, NOW it knocks long before that. I mentioned in the other thread that the Lunati cam swap resulted in worse detonation than I had with the 509 cam. This was with 91 octane.
It may be annoying for you to read all these threads on the same problem. Despite some members opinions, I am not waiting around for people to approve my own ideas or what I have already decided. I'm not co-dependant to the point where I need validation of what I do. I ask when I truly do not know.
 
Frankenduster said:
I have not made up my mind on anything yet. I like to know what options are available.
For the record:
What do you think I've been doing? I have asked numerous times about the ignition curve and the most helpful suggestions have been...you need to delay full advance until 3500.....
Great. Now how in the world am I to do that? Stiffer springs? NOBODY has stepped up to suggest what springs, where to get them or anything else on that matter. I am dealing with an engine that knocks at anything over 25 degrees of total timing. It USED to detonate at 31 with the old cam, NOW it knocks long before that. I mentioned in the other thread that the Lunati cam swap resulted in worse detonation than I had with the 509 cam. This was with 91 octane.
It may be annoying for you to read all these threads on the same problem. Despite some members opinions, I am not waiting around for people to approve my own ideas or what I have already decided. I'm not co-dependant to the point where I need validation of what I do. I ask when I truly do not know.
Click to expand...
Okay man, here ya go. What distributor are you running? I'll get you the delay you need. I just dont have that info.
 
Why go thru the trouble of milling the pistons down .040"? If thats what you want to do, just put a thicker head gasket in. I have run head gaskets up to .165" before, MLS Cometic. Hell of a lot cheaper and easier than pulling the whole engine down and milling pistons.

Anyhow, just so some of us dont have to read for 2hrs, give us your basic combo so we can help

What stroke
What pistons, p/n and specs
What is your piston to deck clearance? Under, even, or above? How much?
What heads, known chamber cc, no guessing here
What cam and where is it installed, what ICL, again no guessing
What exhaust
What intake
What size carb
What dist are you running, Known Curve or unknown?
 
Pretty sure 5 gallons of 110 per tank would cure it. The people making our gas these days are f-ing us 6 ways from Sunday Frank. The 91 of today ACTS like the 87 of yesterday in my last engine. I ran my engine for 19 yrs and the 91 octane in 1998 was head and shoulders better than what they call 91 today. I really think an affordable fuel tester would sell like hotcakes if one exists. I would love to call out the people filling the pumps around here with one.
 
MRL Performance said:
Why go thru the trouble of milling the pistons down .040"? If thats what you want to do, just put a thicker head gasket in. I have run head gaskets up to .165" before, MLS Cometic. Hell of a lot cheaper and easier than pulling the whole engine down and milling pistons. This is exactly where I have been heading. The piston milling idea is just something I may consider in the future.

Anyhow, just so some of us dont have to read for 2hrs, give us your basic combo so we can help

What stroke 4.15
What pistons, p/n and specs Ross 94998 Flat Tops with 6cc valve reliefs
What is your piston to deck clearance? Pistons sit .017 below deck
What heads, Edelbrock with 84 cc chambers
What cam and where is it installed, what ICL, Lunati 316/326 solid Degreed to 106 as per cam card.
What exhaust 2" TTI headers, 2 1/2" pipes, Flowmaster 42451 mufflers, tailpipes.
What intake Edelbrock Performer RPM
What size carb Grant 850 VS with 86/94 jets and a 3.5 PV
What dist are you running? MP electronic, Chrome box. 2 Brown springs, 16 initial, 30 total. Idle @ 1000. Curve begins at 1350, all in by 2350.
Click to expand...

Here we go....
 
I have told you TIME AND TIME AGAIN. You need to DISASSEMBLE the distributor. You need to use the Mallory keys to limit the mechanical advance. The keys are numbered according to the amount of advance. I don't know how to make it any plainer. Yet, you keep wanting to go back to major engine work to try and solve your problem. I HAVE stepped up to the plate SEVERAL TIMES and told you what to do and how to do it. You have REFUSED to listen. I don't know what else to do. If you lived close by, I would come by and fix you up in less than an hour. It's not hard to do, you do have to follow instructions though.

Frankenduster said:
I have not made up my mind on anything yet. I like to know what options are available.
For the record:
What do you think I've been doing? I have asked numerous times about the ignition curve and the most helpful suggestions have been...you need to delay full advance until 3500.....
Great. Now how in the world am I to do that? Stiffer springs? NOBODY has stepped up to suggest what springs, where to get them or anything else on that matter. I am dealing with an engine that knocks at anything over 25 degrees of total timing. It USED to detonate at 31 with the old cam, NOW it knocks long before that. I mentioned in the other thread that the Lunati cam swap resulted in worse detonation than I had with the 509 cam. This was with 91 octane.
It may be annoying for you to read all these threads on the same problem. Despite some members opinions, I am not waiting around for people to approve my own ideas or what I have already decided. I'm not co-dependant to the point where I need validation of what I do. I ask when I truly do not know.
Click to expand...
 
We've been through ALL this. Each time, someone new recommends something different, he jumps in that direction. Look how quick his timing comes in. THAT'S his problem. He will NOT listen. Good luck. Maybe you can get through.


MRL Performance said:
Why go thru the trouble of milling the pistons down .040"? If thats what you want to do, just put a thicker head gasket in. I have run head gaskets up to .165" before, MLS Cometic. Hell of a lot cheaper and easier than pulling the whole engine down and milling pistons.

Anyhow, just so some of us dont have to read for 2hrs, give us your basic combo so we can help

What stroke
What pistons, p/n and specs
What is your piston to deck clearance? Under, even, or above? How much?
What heads, known chamber cc, no guessing here
What cam and where is it installed, what ICL, again no guessing
What exhaust
What intake
What size carb
What dist are you running, Known Curve or unknown?
Click to expand...
 
so you bought a cam that makes more cylinder pressure... retard the cam and that will help or put the 509 back in it.

or better yet go to wallace racing calculators and figure your DCR, get it below 8.5
 
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