Piston to deck distance.???? 360

[Josecuda]

I´m in the process of rebuilding a 1975 360 that was taken out of a truck. The thing is that I replaced the 8.6:1 compression stock pistons for a set that are flat tops (Clevite TC-3066) to raise comp. ratio a bit. When piston #1 is at TDC it shows a 0.125 between the piston top and the block deck. Is this normal or I am having some sort of problem around here? I just changed the pistons and rings, not the rods.

 

[lenweiler]

Sounds like the pistons are a stock replacement.

 

[moper]

Yup. You put in stock pistons... they are always that low. You need either hypereutectics or cast or forged performance pistons to fix that.

 

[340sFastback]

The distance between the center of the wrist pin to the top of the piston is "Compression Height". You need a piston with a longer Compression Height so that it comes up closer to the deck.

 

[lenweiler]

Depending on chamber volume, you'd want somewhere near 0 deck height. Lots of formulas out there.

 

[pagilman]

I always thought that 8.5 /1 pistons were about 1/4 of an inch down in the hole. yours are .12 below deck I think those are about 9.5 as '0' deck is about 10 to 1. The factory early 340 were 10.5 and were above deck, some thousanths but I can't remember how many. But i may be wrong.:read2:

 

[dgc333]

A standard bore 360 with zero deck flat top with a typical 72cc open chamber head and 0.039 head gasket has 9.6:1 compression.

 

[lenweiler]

Sorry. I assumed he was looking for optimum cr on pump gas.

 

[340sFastback]

Send those pistons back and get the bigger compression height pistons.

 

[Josecuda]

Cant go to high on compression. My goal is to rebuilt the 360 as cheap as possible while making it reliable. Not that much high performance around here. Going with higher compression and better heads, since I'm running the stock 360 ones, when time is appropiate. Thanks all for the help!!

 

[3404spdvaliant]

Any 360 after like 73' had more like 7.8-1 +/- if you ask me.
The early 71'-73' had flat tops that gave around 8.2+/- or so from what I know, while the others had dish top pistons that gave an average of 7.8-1
Remember 'IF' you turned the crank you 'MUST' resize the rod's.
It sounds like you have replacements for the early 360, good better than late.
Then measure how far the ring package is from the top of the piston then compare with the old pistons ring to piston top, curious to know.

 

[Josecuda]

The rings do get to the exact same point, just not sure about the measurement right now. So, I am suppose to expect an 8.something comp ratio with these flattops?

 

[3404spdvaliant]

Yea, with your average 360 head cut .010[figuring in past valve job/s surfacing]
If you bored it say .030 then it could be more.
But around 8.1-8.5 ,
thick head gasket?

Are you reusing the steel head gaskets?

If the measurements are the same, check the center of pin to the piston top, if the same as well then cool you did what you were trying to do 'raise compression'

 

[Josecuda]

Actually not much of a compression raise but the stock dish top pistons were bad and needed replacement. I found these at good price and bought em. The thing is I had no idea how much the comp. ratio will vary if I used the flat tops instead of the dish pistons.

 

[340sFastback]

If you are going to stay with those pistons run some thin head gaskets and a little head milling would be good too.

 

[dgc333]

Remember 'IF' you turned the crank you 'MUST' resize the rod's.

If you turn the crank you MUST use undersize bearings to match the amount the crank was turned .

Resizing the rods and replacing the rod bolts is a good idea but turning the crank undersize and resizing the rods are not related.

FWIW, the cost of resizing a set of rods and installing new bolts is the same or a little more than just purchasing brand new I-beam rods from Eagle or Dart. Those rods will be stronger and better balanced than the factory rods to boot.

 

[3404spdvaliant]

If you turn the crank you MUST use undersize bearings to match the amount the crank was turned .

Resizing the rods and replacing the rod bolts is a good idea but turning the crank undersize and resizing the rods are not related.

FWIW, the cost of resizing a set of rods and installing new bolts is the same or a little more than just purchasing brand new I-beam rods from Eagle or Dart. Those rods will be stronger and better balanced than the factory rods to boot.

Still up to the same huh?
They don't resize rods just for the sake of 'new bolts' distorting them.
Believe it or not rods distort.
Anytime you turn the crank you should resize the rods so your rods don't fly through the side of your block PERIOD

You and I have been here before.
keep your old rod/new rod argument to yourself. It seems you just can't keep from your worthless bickering crusade.

The 'bearing' thing is a good example of this.. tisk.. tisk..

Let everyone know that if it was dgc333's motor he would throw his stock rods in the trash and buy new ones off the internet, thats his choice.

 

[71DartGuy]

I hope that last post was a joke. Seems a bit condesending to me and I think Dave was merely STATING HIS OPINION just like everyone else does on the site!

 

[dgc333]

Mike, That's his way! His opinion is always right and anyone that disagrees is a jerk.

I will continue to disagree when its appropriate with the hope that folks have enough info to make an informed choice.

 

[moper]

Mike, That's his way! His opinion is always right and anyone that disagrees is a jerk.

I will continue to disagree when its appropriate with the hope that folks have enough info to make an informed choice.

I agree.

 

[3404spdvaliant]

I agree.

You agree with'em thats cool, of corse you build $9,000+ engines so I doubt you would take a 80k + mile engine, tear it apart, grind the crank, press new pistons on untouched rods, bore it, then slap it together and rev 6,500.

I bet for that much money you just throw every thing away and start new.

OH WAIT, YOU DON'T BUILD ENGINES REMEMBER?
YOU SELL PARTS.
YOU TOLD ME THIS IN ANOTHER THREAD WHEN I FIRST JOINED.
YOU WERE SAYING WHAT NOW?

To Everyone ...
Do it your own away if you want, know ones holding a gun to your heads.
I actually really care about the success of anything I've ever offered advise on,
and don't wanna see people make the same mistakes over and over cause some anonymous on the internet say's they lucked out when they did it.
If you got lucky when doing such a thing, sweet.
Good practice? not even close, and I don't have a $9000 engine to sell you, which is what it would cost having to start from scratch with a junk crank,block, and pretzel'd rods.

Dave333, We don't get along and thats fine cause I don't like you, never did.
See no one else knows, but I do, I know why you said your rod bit out of nowhere cause you and I argued this at moparchat where you were pretty much on your own with that one and you wanted to instigate bs on this poor guy's thread, Not cool.


And for the record stock rods with good arp bolts have taken a certain 340 to 9000RPM night after night at el cajon speedway along with the 273 rockers when we were broke with out a dime to spend.:yawinkle:

 

[moper]

340, dude, you got issues.

I was agreeing with Dave that you are first a foremost a punk kid. Then you do prove me dead right.

You don't read detail well or perhaps it's all in comprehending what you read. You don't know jack about me, and I think most of what you know about engines unfortunately comes from regurgitation of subject matter affected by the above mentionned deficiencies. I base that on your posts and your own posted times with the combo you say you built.

So, again to try and educate you more at least on who you're trying to dig... I have sold parts. I've also run dyno shops, custom bent pipe, built any combo you have read about except Hemis and slants, serviced everything on a Mopar muscle or standard cars, fabricated in a 4wd shop, started a 3 state Mopar club that is now 11 years old, and volunteer with Habitat for Humanity.

I currently build engines for a select few customers, but it's not how I pay my bills. I no longer work in the automotive field for my living. I strongly urge you to just relax and give input to these posts. You are right about a lot of things although I'm convinced you can say why. And as for me, I'm not a know it all. I just know more than you.

 

[daredevil]

even with new rods i,m checking the big end and sizing as need be

 

[3404spdvaliant]

340, dude, you got issues.

I was agreeing with Dave that you are first a foremost a punk kid. Then you do prove me dead right.

You don't read detail well or perhaps it's all in comprehending what you read. You don't know jack about me, and I think most of what you know about engines unfortunately comes from regurgitation of subject matter affected by the above mentionned deficiencies. I base that on your posts and your own posted times with the combo you say you built.

So, again to try and educate you more at least on who you're trying to dig... I have sold parts. I've also run dyno shops, custom bent pipe, built any combo you have read about except Hemis and slants, serviced everything on a Mopar muscle or standard cars, fabricated in a 4wd shop, started a 3 state Mopar club that is now 11 years old, and volunteer with Habitat for Humanity.

I currently build engines for a select few customers, but it's not how I pay my bills. I no longer work in the automotive field for my living. I strongly urge you to just relax and give input to these posts. You are right about a lot of things although I'm convinced you can say why. And as for me, I'm not a know it all. I just know more than you.

hee hahh, hee hahh, hee hahh
Thats what you sound like.

Name calling, age discrimination, thats rich.
Must suck being old, no wait old is cool, just your not.
I'll tell you something you know more about then me is chevrolet products and the cover charge/back stage pass to a Barry manilow concert.
Go take a sunday drive in your corvette and maybe a zanex.lol:yawinkle:

Brother we should be so lucky to have young people be interested in this industry/hobby and further advance it, thats 1 of the reasons it has kept evolving as it has. 1 'old guy' did not design every motor they ever came out with.

So take it easy, don't wanna have a heart attack,
I mean you haven't even got to build a slant6 yet. lol

 

[dgc333]

Moper, there is no reasoning with him! He was banned from MOPARCHAT and its just a matter of time he will be from here too.