above deck ?

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j par

j par

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I've heard of zero deck . But so far I haven't heard anybody talk to above deck? I just went to the machine shop to check on the progress of my stroker motor and this was what I saw. They said something about checking the open chamber heads and making sure I had clearance.View attachment 20150202_121735.jpg

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I added a few extra pictures that I took while I was there today I mean really who doesn't want to look at pictures of eye candy like that?
 
early 340s were positive deck, meaning the piston comes up out of the bore. If yours do also, you better have them calculate the compression ratio. Most "street" strokers will have dished pistons to get down to a comfortable pump gas ratio.
 
replicaracer43 said:
early 340s were positive deck, meaning the piston comes up out of the bore. If yours do also, you better have them calculate the compression ratio. Most "street" strokers will have dished pistons to get down to a comfortable pump gas ratio.
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I didn't know that about the 340. The higher compression is fine with me as far as race fuel and stuff I'm trying to build more of a drag motor than a street motor. Not to say I won't drive it on the street of course, but if I have to add 5 gallons of race fuell to it each time I fill up no big deal.
 
By the time it has a head gasket it won't be above anything.


Why is a freshly machined short block leaning on a random piece of metal??
 
SpareParts said:
By the time it has a head gasket it won't be above anything.


Why is a freshly machined short block leaning on a random piece of metal??
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Well, it will still be a "positive deck" motor, now matter how thick the head gasket is, but most head gaskets are .040 or so, so piston to head clearance shound not be a issue here. Machine shop is doing the correct thing by measuring, and, yeah, whats up with the engine laying on a piece of scrap? I am sure they own a engine stand or something?????
 
I can't answer as to why the block is held up by that piece of metal ? But i can say it was the perfect hight to keep the block firmly on it's opposite four cylinders. The shop seems to use an assembly bench with overhead cranes as apposed to a motor stand like I'd use in my garage. Well i think I should save any more defending the shop til after i get the motor back ! Lol Portland Engine Rebuilders is a very large shop that's has a good reputation and has been around a long time. As a matter of fact my High School auto shop went there on a field trip 30 years ago.
 
replicaracer43 said:
Well, it will still be a "positive deck" motor, now matter how thick the head gasket is, but most head gaskets are .040 or so, so piston to head clearance shound not be a issue here. Machine shop is doing the correct thing by measuring, and, yeah, whats up with the engine laying on a piece of scrap? I am sure they own a engine stand or something?????
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Correct. I was trying to say that he should not have to worry about hitting the head once the gasket is there.

Multiple opinions on that I know for a fact that Dave from Hughes likes the piston to "kiss the head" .... I'm not that ballsy with mine.

Lol I have a few extra stands I would lease out
 
Well they measured and it was .010 out of the hole and with a .039 gasket. Only left .029 clearance and they want .035 clearance and so they're going to cut out the heads a little bit to give room that way?
 
I would use a thicker gasket and leave the heads alone. Stock rebuild felpro's seal good and are around .050 compressed.
 
mderoy340 said:
I would use a thicker gasket and leave the heads alone. Stock rebuild felpro's seal good and are around .050 compressed.
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of course when he called that was pretty much the first thing that I ask and I was told that I would lose a lot more compression that way and a lot less if I just had the heads touched up...
 
Demand a thicker gasket. They're just wanting some more $$$ on the deal. Machine work in house pays better than ordering gaskets in my opinion
 
SpareParts said:
Demand a thicker gasket. They're just wanting some more $$$ on the deal. Machine work in house pays better than ordering gaskets in my opinion
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Agreed, an extra $120. but as it was explained to me (with machine shop prejudice of course) the .011 thicker gaskets on all 8 cylinders would lower the compression much more than just spreading the whole out a little bit on each one of the heads openings?
 
How much compression are you willing to LIVE WITH?????

My 408 has flat top pistons and a "0" decked block. I do have a closed chamber head, and my compression is Over 12.5:1....................
 
work the head, and set the distance at .035.
 
Cudafever said:
How much compression are you willing to LIVE WITH?????

My 408 has flat top pistons and a "0" decked block. I do have a closed chamber head, and my compression is Over 12.5:1....................
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I have 596heads so there probably 70-72cc ?
live with as far as race fuel ?
 
I don't know about availability where you are , but I love me some E-85.
12.85 : 1 compression with about 70/30 street to track use.
1.69 a gallon right now and I haven't priced 110 octane lately , but I bet it's a whole lot more than that.
 
I assume you have had the same shop do a valve job and resurface the heads. Ask what the head CC is or measure it yourself. CC the piston volume and calculate the Dynamic Compression ratio based on the intake closing event of the cam you plan to run. Select the head gasket thickness to match the compression ratio, and piston to valve clearance you can live. You don't build a quench motor with open chamber heads.
One other thing I would do to the chambers is smooth out the chambers to prevent detonation and even up the chamber CCs.
 
Its not a big deal, my 440 has them out .069 the chambers were cut and use a Felpro gasket no problem.
 
Purple Haze said:
Its not a big deal, my 440 has them out .069 the chambers were cut and use a Felpro gasket no problem.
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yes the machine shop didn't sound worried they just like to keep me informed of exactly what's going on and that's why I like to use them.
 
Using the OP's flat top pistons and a closed chamber heads I could see going through the process of building a quench motor. With an open chamber and a flat top piston the squish to the exhaust valve just isn't there. I'm not a pro engine builder but have built a few in my day and this is my opinion of why you need a closed chamber for a quench motor.

read this article
https://www.rbracing-rsr.com/squishcalc1.html
 
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