clearance for egge pistons in 32 block?

[jambottle]

I have a set of egge #122 pistons for my b engine. they are .100 over size.
lost instructions .i think egge says .025. looking at the troubles with #4 cylinder on here. Should i go to .030 or maybe .035.touring cam,2 carbs ,5.5 steel head.Thanks

[Patrick L.]

I would have to say that .025" would be a bit too much. A bit way too much.

A general rule of thumb is .001" per inch of bore. Manufacturer specs would trump that though.


How about making a call to Egge. 1-800-866-3443

[Jim Brierley]

you are probably thinking .0025", not .025"? i usually bore to .003" clearance and then give it a light hone, .0035" finished size.

[BRENT in 10-uh-C]

Maybe this is redundant in saying this but I think it bears mentioning. The .003" - .0035 size that Jim and others are mentioning is the actual size of the piston PLUS the .0035", --NOT the bore size.

Using the O/P's bore size as an example, many machinists will unknowingly look up that as .100" over on a Model-A engine would be 3.975 and bore it to that size plus add the additional .003" - .0035" ...which is a little much IMHO.

[tbirdtbird]

"Manufacturer specs would trump that though."

Not necessarily, since the mfg may not know or understand the application. Meaning they prolly do not know that #3 and #4 run hotter, at least 20* or more when I use my temp gun. Many many Model A owners do not even know this.

I am in Jim Brierley's camp all the way

[Mark DeRoseau]

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I've heard this a few times that number 3&4 will run hotter, and not to Open up a can of worms, but how does one know this. I agree theyre the furthest away from the radiator so the water will be a few degrees warmer. I mean taking a reading of the outside of the head with a digital infrared thermometer, says nothing of the true temps of the combustion chamber, bore surface, crown of piston. Which is what will truly tell the thermal expansion rate of the bore size / piston. Right? You'd need to put EGT sensors in a manifold for that no?

[d.j. moordigian]

There is some wrong information in this thread,....personal opinion.

Things you should know before boring and honing.

1. Piston material..
2. How much "cam" is ground in the piston..
3. How much "taper" is ground in the piston..
4. What does the manufacturer recommend for clearance..
5. Where does the manufacturer want you to measure it..
6. Each piston is measured for a specific hole..period..

When I was younger,...forged pistons had a clearance .007" to .0085".
Now, for forged pistons, they run around .0025" to .0035".

[Patrick L.]

Originally Posted by tbirdtbird

"Manufacturer specs would trump that though."

Not necessarily, since the mfg may not know or understand the application. Meaning they prolly do not know that #3 and #4 run hotter, at least 20* or more when I use my temp gun. Many many Model A owners do not even know this.

I am in Jim Brierley's camp all the way

I tend to run a bit more also. But, I always look at what the manufacturer wants first.

[jambottle]

Yes my bad; .0025 or .0035. Thanks

[tbirdtbird]

"but how does one know this. I agree theyre the furthest away from the radiator so the water will be a few degrees warmer. I mean taking a reading of the outside of the head with a digital infrared thermometer,"

who is measuring the head temps? Look closely at the construction of a Model A engine. The cyl walls are out in plain sight for all to see on the driver's side of the car. Get your own IR temp gun and shoot away and report back to us.

Consider that Jim Brierley races As. Think he knows anything? As far as wrong information, this forum is loaded with wrong information. There is no shortage of supposition, speculation, and inexperience, tho.

My suggestion to all is to set the clearances up however you believe and then get back to us in 1000 miles

Why exactly are we rebuilding motors in this shop that were set up too tight? Are we imagining that the pistons are heavily scored?

Is this how you want your pistons to look?

I call'em like I see'em, sorry

[Mark DeRoseau]

Not saying motors aren't built to tight. Just don't agree with a 20 degree hotter temp on the head or outer sleeve closing up the gap and changing tolerance of the bore that much. Pistons grow I get it.. If people have they're engine builders trying to eek out every last pony by building their motor so tight, they risk that score in the hole. Better off running them on the loose side @.0038 - .0042 and spending some time properly gapping rings.
And a fresh motor, sealled up nicely with usually a new Snyder 5.5 and fresh sharp edges on everything isn't prone to a heavy left hand and a little detonation? That melts Pistons as well right. I think 2.5 / 3.5 grand is too tight. And can/probably will score a hole. Just wasn't agreeing with a hole running 20 degrees hotter will close up the steel that much, maybe a tenth or two. Built with sufficient gap at the start, that's not the problem.

[Purdy Swoft]

Originally Posted by tbirdtbird

"but how does one know this. I agree theyre the furthest away from the radiator so the water will be a few degrees warmer. I mean taking a reading of the outside of the head with a digital infrared thermometer,"

who is measuring the head temps? Look closely at the construction of a Model A engine. The cyl walls are out in plain sight for all to see on the driver's side of the car. Get your own IR temp gun and shoot away and report back to us.

Consider that Jim Brierley races As. Think he knows anything? As far as wrong information, this forum is loaded with wrong information. There is no shortage of supposition, speculation, and inexperience, tho.

My suggestion to all is to set the clearances up however you believe and then get back to us in 1000 miles

Why exactly are we rebuilding motors in this shop that were set up too tight? Are we imagining that the pistons are heavily scored?

Is this how you want your pistons to look?

I call'em like I see'em, sorry

Times two !!!!!!! Dave is right !!

[tbirdtbird]

Mark we might be closer that it initially seemed. I thought you wanted less clearance, but you are seeking more.
".0038 - .0042 and spending some time properly gapping rings."
I have no problem with this at all.
And the hole expands with more heat; it is the piston that creates the problem (I have written this so many times I can't stand it) since the piston expands more than the hole does....aluminum expands way more.
When it does it binds in the hole and scores. The sides of the holes look as bad as the pic of the piston I posted. That scoring represents a lot of local heat. Abused as such, when the piston finally cools it shrinks (its been planished!!) to a lesser diameter than it started and now you have piston slap, along with bad scoring. Time for an overhaul which could have been avoided

I am really tiring of typing the same thing week after week. As soon as I post .0035 clearance, or .022 top ring gap, a bunch of know-it-alls jump on here and promise the world will end. They never explain exactly what will go wrong, they just say things like, "that is too excessive", which is a chicken's way out of an explanation.

So, in the future, y'all set your engines up however y'all desire, maybe use you Ouija board to get you specs, and just for kicks, post back after 1000 miles (if you get that far) and tell us how it all went. And throw away you IR temp guns, after all, you don't want to collect too much data, now do y'all, and who needs feeler gauges anyway, just shove'em in there

I call'em like I see'em, sorry

[George Miller]

Originally Posted by tbirdtbird

Mark we might be closer that it initially seemed. I thought you wanted less clearance, but you are seeking more.
".0038 - .0042 and spending some time properly gapping rings."
I have no problem with this at all.
And the hole expands with more heat; it is the piston that creates the problem (I have written this so many times I can't stand it) since the piston expands more than the hole does....aluminum expands way more.
When it does it binds in the hole and scores. The sides of the holes look as bad as the pic of the piston I posted. That scoring represents a lot of local heat. Abused as such, when the piston finally cools it shrinks (its been planished!!) to a lesser diameter than it started and now you have piston slap, along with bad scoring. Time for an overhaul which could have been avoided

I am really tiring of typing the same thing week after week. As soon as I post .0035 clearance, or .022 top ring gap, a bunch of know-it-alls jump on here and promise the world will end. They never explain exactly what will go wrong, they just say things like, "that is too excessive", which is a chicken's way out of an explanation.

So, in the future, y'all set your engines up however y'all desire, maybe use you Ouija board to get you specs, and just for kicks, post back after 1000 miles (if you get that far) and tell us how it all went. And throw away you IR temp guns, after all, you don't want to collect too much data, now do y'all, and who needs feeler gauges anyway, just shove'em in there

I call'em like I see'em, sorry

I think most of the know it all's never built any engines. That goes for a lot of the other things we talk about. You are right on.

[jambottle]

I called egge ,they recommended .0025. From what i can take from the replies here, i`m thinking .0035 clearance and .020 to .022 top ring gap.everybody agree ? Thanks

[Patrick L.]

Originally Posted by jambottle

I called egge ,they recommended .0025. From what i can take from the replies here, i`m thinking .0035 clearance and .020 to .022 top ring gap.everybody agree ? Thanks

I think I would agree. I like to add a little extra room. I think a little loose is 'more better' than too tight.

[ABento]

Check the cam on those pistons I ended up with some from EGGE that were camed incorrectly and scored 2 or 3 of them and we had 3.5 thou of overbore,this was on a 6 cyl White engine.

[Bob C]

Originally Posted by tbirdtbird

Mark we might be closer that it initially seemed. I thought you wanted less clearance, but you are seeking more.
".0038 - .0042 and spending some time properly gapping rings."
I have no problem with this at all.
And the hole expands with more heat; it is the piston that creates the problem (I have written this so many times I can't stand it) since the piston expands more than the hole does....aluminum expands way more.
When it does it binds in the hole and scores. The sides of the holes look as bad as the pic of the piston I posted. That scoring represents a lot of local heat. Abused as such, when the piston finally cools it shrinks (its been planished!!) to a lesser diameter than it started and now you have piston slap, along with bad scoring. Time for an overhaul which could have been avoided

I am really tiring of typing the same thing week after week. As soon as I post .0035 clearance, or .022 top ring gap, a bunch of know-it-alls jump on here and promise the world will end. They never explain exactly what will go wrong, they just say things like, "that is too excessive", which is a chicken's way out of an explanation.

So, in the future, y'all set your engines up however y'all desire, maybe use you Ouija board to get you specs, and just for kicks, post back after 1000 miles (if you get that far) and tell us how it all went. And throw away you IR temp guns, after all, you don't want to collect too much data, now do y'all, and who needs feeler gauges anyway, just shove'em in there

I call'em like I see'em, sorry

Just cut and paste, it will save a lot of typing.

Bob

[Egge]

The clearance on the Egge pistons (E122) is .0025.

[d.j. moordigian]

T-bird,

Let me ask you this,.....did you understand what I wrote?
.....................................do you have a question about what I wrote?