Edelbrock heads on a 340 with KB243 pistons

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BTW, those Felpro 8553PT's are just stone stock Felpro SBM Permatorque head gaskets..... you should be able to find tham all over Louisville in just about any auto store.

The Felpro 1008's compress to .039"
 
70aarcuda said:
https://www.summitracing.com/parts/fel-8553pt/overview/make/dodge

.053-.018= .035......
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That 8553 head gasket crushed is actually .046 crushed.
519sd is actually thicker when crushed even though summit says its .043 ... that's bull.There is a serious problem with sites posting false specs.
One 340 I did used kb243 with ported iron closed chambered heads and those pistons were .024 out of the block on that motor after getting the decks true/square, I ended up taking a few thou off the quench side of the piston to make .029 quench W/ 519sd head gaskets, .051 ish thickness If my memory serves me right..
I remember ordering 3 diff sets of head gaskets, torquing them with clay on the pistons to see the real crush and quench distance and laughing seeing how diff they were not only from advertised..but from hear say on sites. Eddy head gaskets are said to be .050 on summit, they showed up and were nothing but 8553 pt which are .046 crushed...so now that's two diff stated thicknesses on the same site...who are you gonna believe?
 
I guess I'll have to believe the clay! I have one set here, I'll try them and see where they come out and take it from there. Thanks for all the help.
 
rumblefish360 said:
I have read anything above .050.
I liked the "Cometic" post! I have them do me up a custom set.
I have run a quench as close as .028. There were signed that there was rod stretch and the slug was getting to close.
Current quench is .038.
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?
nm9stheham said:
A local shop here experimented with quench gap and when the gap got down to .025" the pistons would juuust kiss the heads under circle track racing conditions, revving to around 7-8k RPM. Pistons rock and expansion rates vary between engine parts, so I take that as an absolute racing minimum. For most folks, I'd recommend the .035" minimum.

I agree with Crackedback..... .050" quench gap still gives some benefit from all I have read on the subject for 40+ years.

As for the benefit of quench: I like to run CR as high as possible to extend the torque band down as low as I can; that is all due to my street use and rally experience. Quench just gives some margin against detonation, and thus some margin against things going wrong as one drives around with variable gasoline, etc. It also contributes to a small amount of combustion efficiency, and thus power and mileage.

But, I can see others deciding to forego it.
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I would re write that.
Quench/squish keeps mixing the charge, faster burn, less fuel dense spots in the combustuon chamber, more resistance to pre detonation, gain in mileage due to those things as well as torque because the resistance to pre det allows more dynamic cyl pressure. Tighter the quench...the better the benifits.
As for compression, dynamic ...just divide by two and thats about the octane you need to keep it happy @ optimal timing.
 
MOPAROFFICIAL said:
?

I would re write that.
Quench/squish keeps mixing the charge, faster burn, less fuel dense spots in the combustuon chamber, more resistance to pre detonation, gain in mileage due to those things as well as torque because the resistance to pre det allows more dynamic cyl pressure. Tighter the quench...the better the benifits.
As for compression, dynamic ...just divide by two and thats about the octane you need to keep it happy @ optimal timing.
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And yet, Chrysler said they went to the open chamber design for emissions and detonation resistance.


Hmmmmmmmm.
 
yellow rose said:
And yet, Chrysler said they went to the open chamber design for emissions and detonation resistance.


Hmmmmmmmm.
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Last to implement a smog/air pump too.
The wedge chamber is good, coming from that era, but then then someone brought the chamber back to a rendition of the earlier 273 stuff and brought the open side to a more squarish shape and then called it a magnum. I wonder but then don't...which was cheaper, then, making a new piston shape or casting a new head...they answered that already I guess, 3 head designs later!
 
MOPAROFFICIAL said:
?

I would re write that.
Quench/squish keeps mixing the charge, faster burn, less fuel dense spots in the combustuon chamber, more resistance to pre detonation, gain in mileage due to those things as well as torque because the resistance to pre det allows more dynamic cyl pressure. Tighter the quench...the better the benifits.
Click to expand...
That all sounds very good to me....I was just too lazy to write it all....LOL
 
yellow rose said:
And yet, Chrysler said they went to the open chamber design for emissions and detonation resistance.
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Easy to 'splain:
1. Lower CR for lowering NOx emissions.
2. Lower CR for less detonation propensity with the hotter t'stats to lower HC and CO emissions.

It was just a workaround to cure problems caused by the early emissions tactics. But of course, it is Marketing's job to turn everything into a selling point LOL
 
MoPar official, you left a "?" About my post. What can I explain for you?
 
According to Fel-Pro the manufactured thickness is .046 - .057. That is uncontrolled manufacturing of the material and you don't know what you have till you buy it and measure it! Then you take off .005 for compressing when bolted together.
I just went through this on a big block I built over the summer, got Cometic .060 stainless gaskets, no crush, no retorque,
and gave me .040 quench.
 
MOPAROFFICIAL said:
I actually asked what signs you saw, the rpms you were turning, piston skirt/cyl wall clearance and how you measured the qd...but it only left a ? instead.
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Whew! Ummm, 25+ years ago... whew, well, what I remember is the tops of the pistons were deformed and had speckled spots of missing metal.
I do not know what "qd" is.
I can not answer anything else, sorry.
 
hemichuck said:
I just measured the set going on my magnum stroker and they were.050 so they compress about .005?
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It would be a big help to people if you stated what part number gasket that is.
Aside from that, if you ever tear one down after some miles ...measure the gasket for fun.
 
Quench distance was .028. OE rods, Hyper slugs @ zero deck, cast crank.
RPM's were on the high side @ 6700 max. How high did it spin on a missed shift is anyone's guess.
 
MOPAROFFICIAL said:
It would be a big help to people if you stated what part number gasket that is.
Aside from that, if you ever tear one down after some miles ...measure the gasket for fun.
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I don't know the brand, it's the ones that Edelbrock recommends for the Performer Magnum heads that I put on my 408. I have several other sets in the garage I'm gonna check out tomorrow. I'm going to get some clay so I can check the distance after I torque them.
 
hemichuck said:
So those Felpro Permatorque Blue gaskets compress to .053? I always thought they went .040
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They go to .040 not .053. I ran my 340 with the 484 cam, open chamber Eddy heads with the .028 thin Mopar gaskets and 3.73 gears and it was perfect on the street using pump gas. So if I were you that would be a good way to go for your dad.Get the quench at a comfortable number and dont use the smaller 441 cam and he will like it just fine!!
 
If dear old Dad puts it in Drive, and the engine never gets past 3500/4000..........I don't get the big cam idea. And if you stuff a smaller cam in there then you will get into DCr issues. Sooooo, why worry about walking the thin line? I'm a little late to the party, but I'd have to agree with post#27, as to milling the pistons to set the quench, AFTER the Cr has been established, to work with the application specific cam. If the cams ICA calls for a chamber size that can be achieved with a gasket thickness, that simultaneously hits the squish zone then Ba-da-boom you are done. Conversely, if you select a gasket thickness that hits the squish target and then determine the Scr to be compatible with such and such a cam with an appropriate ICA, again you are golden. If that cam then is suitable for dear old Dad ,then you are Triple-Golden.
FWI; I have been running about .033 for around 100,000 miles, withKB107s, Eddies,factory 340 rods,and shifting stick at around 7000. Yeah it's been higher,often, and a lot higher.
 
AJ/FormS said:
If dear old Dad puts it in Drive, and the engine never gets past 3500/4000..........I don't get the big cam idea. And if you stuff a smaller cam in there then you will get into DCr issues. Sooooo, why worry about walking the thin line? I'm a little late to the party, but I'd have to agree with post#27, as to milling the pistons to set the quench, AFTER the Cr has been established, to work with the application specific cam. If the cams ICA calls for a chamber size that can be achieved with a gasket thickness, that simultaneously hits the squish zone then Ba-da-boom you are done. Conversely, if you select a gasket thickness that hits the squish target and then determine the Scr to be compatible with such and such a cam with an appropriate ICA, again you are golden. If that cam then is suitable for dear old Dad ,then you are Triple-Golden.
FWI; I have been running about .033 for around 100,000 miles, withKB107s, Eddies,factory 340 rods,and shifting stick at around 7000. Yeah it's been higher,often, and a lot higher.
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Dear old Dad probably wont ever get to 4000 RPM but my Viper driving speed demon son I'm sure will test its limitations. My dad will fill it with regular gas but at least my son will use premium. After everything Ive seen on here I would put my best guess at buying the gaskets and some modeling clay and seeing what I come up with. As with almost any post you really have to read between the lines to come up with a definate answer. I have a buddy who builds small blocks and is more than a little anal about clearances and Im sure that he can probably give me an hour long lecture on the different gaskets and what they will actually compress to. I guess its time to go by and tell him Merry Christmas.
 
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