### Author Topic: Piston ring end gap calculator/formula?  (Read 10165 times)

#### SFRT - Frenchy

• Platinum Member
• Posts: 5180
##### Piston ring end gap calculator/formula?
« on: June 26, 2011, 07:41:38 PM »
78 Ford 2.3L standard bore 3.78, the book says end gap between 0.010 0.020

Mine is bored 60 over, so it's 3.84, I have Sealed Power rings
>Top compression ring gap is 0.014
>Bottom compression gap is 0.016
>Oil catchers gap is 0.016

I find a formula on Wiseco's website that says strip/HP
>Top Ring gap = bore * 0.0045 which gives gap 0.017
>Bottom ring gap = bore * 0.0055 which gives 0.021

So I have three questions

>Do anyone has a different formula?
>Given the wide gap range of the stock engine, are my gaps fine (surely doesn't want to hand file them and jack them up).
>I measured each ring in the same cylinder, is that ok or should I really measure each ring in their respective cylinders just in case the machine shop didn't bore each cyl exactly the same?
Dat jugs bro.

Terror flieger since 1941.
------------------------

#### icepac

• Platinum Member
• Posts: 5123
##### Re: Piston ring end gap calculator/formula?
« Reply #1 on: June 26, 2011, 09:17:41 PM »
Wider gaps are used when higher heat is applied to the rings.

This is usually an adjustment for nitrous oxide or turbo/supercharging.

Are the rings the same material as stock?

Is this the turbo 2.3?

#### SFRT - Frenchy

• Platinum Member
• Posts: 5180
##### Re: Piston ring end gap calculator/formula?
« Reply #2 on: June 26, 2011, 09:35:36 PM »
The gap is a matter of application like u say, but also the bore diameter. Wiseco's site provides a formula : bore * multiplier. The multiplier is a function of the application.

ill call the machine shop tomorrow see if those gaps are ok, guess ill finnish that engine next week end. I recalled the shop computing something saying 14 & 16 as a result.

It's just a NA 2.3 with a hot cam and headers. Probably 100HPish

Here
http://www.wiseco.com/PDFs/Manuals/RingEndGap.pdf
« Last Edit: June 26, 2011, 09:41:49 PM by SFRT - Frenchy »
Dat jugs bro.

Terror flieger since 1941.
------------------------

#### Captain Virgil Hilts

• Platinum Member
• Posts: 5950
##### Re: Piston ring end gap calculator/formula?
« Reply #3 on: June 26, 2011, 11:46:30 PM »
Use the Speed Pro formula.

I'll let you in on a secret. The \$600 metric Total Seal Diamond Advantage ring package I run in my Stock Eliminator engines has the same gaps you get with the Speed Pro formula. But my bore size is 4.310"! I've never butted a set of rings, even with the water jackets full of machine grout.

I fit my rings to a particular cylinder and piston, putting the rings on the pistons as soon as I finish the rings.
"I haven't seen Berlin yet, from the ground or the air, and I plan on doing both, BEFORE the war is over."

SaVaGe

#### Megalodon

• Persona Non Grata
• Gold Member
• Posts: 2272
##### Re: Piston ring end gap calculator/formula?
« Reply #4 on: June 27, 2011, 10:39:28 AM »
Okay..Add 2 Country's at once, Australia and France next plane update Add ...CAC Boomerang and the Dewoitine D.520

#### Captain Virgil Hilts

• Platinum Member
• Posts: 5950
##### Re: Piston ring end gap calculator/formula?
« Reply #5 on: June 27, 2011, 11:11:44 AM »
Keith Black and Silvolite have nothing I'd want in any engine I build, including their advice. Anyone who builds a cast hypereutectic piston that is so poorly designed that it requires a 0.026" or larger top ring gap in a near stock replacement engine with a 4.040" bore size has nothing to offer me.
"I haven't seen Berlin yet, from the ground or the air, and I plan on doing both, BEFORE the war is over."

SaVaGe

#### Shuffler

• Plutonium Member
• Posts: 17541
##### Re: Piston ring end gap calculator/formula?
« Reply #6 on: June 27, 2011, 11:17:28 AM »
Use the Speed Pro formula.

I'll let you in on a secret. The \$600 metric Total Seal Diamond Advantage ring package I run in my Stock Eliminator engines has the same gaps you get with the Speed Pro formula. But my bore size is 4.310"! I've never butted a set of rings, even with the water jackets full of machine grout.

I fit my rings to a particular cylinder and piston, putting the rings on the pistons as soon as I finish the rings.

Blueprinting always assures the best fit. It takes in account the acceptable tolerances used when the block or crank were originally machined.

I recall hearing of some factory engines coming out of mexico with one cylinder sleeved...... that was quite awhile back.

S.A.P.P.- Secret Association Of P-38 Pilots (Lightning In A Bottle)

#### icepac

• Platinum Member
• Posts: 5123
##### Re: Piston ring end gap calculator/formula?
« Reply #7 on: June 28, 2011, 11:44:20 AM »
The targetmaster GM engines maybe?

#### morfiend

• AH Training Corps
• Platinum Member
• Posts: 7991
##### Re: Piston ring end gap calculator/formula?
« Reply #8 on: June 28, 2011, 04:39:03 PM »
Blueprinting always assures the best fit. It takes in account the acceptable tolerances used when the block or crank were originally machined.

I recall hearing of some factory engines coming out of mexico with one cylinder sleeved...... that was quite awhile back.

Rgr that shuff,certain engine codes tell the tech when he must mic the bore for proper piston/ring sizing.I've heard of as many as 3 different sized pistons in a single 4cyl.engine,2 of the bores required special fitting.

Oh and Hilt's I used to have 1 of Keith's pistons hanging around,came outta a nitro funny boat,made a great ashtray!

One expensive ashtray but a good 1 none the less!!!!!

#### SFRT - Frenchy

• Platinum Member
• Posts: 5180
##### Re: Piston ring end gap calculator/formula?
« Reply #9 on: June 29, 2011, 09:24:18 AM »
Thx Virg,

I did find that formula, gave same for first ring, bigger for second. I asked the machine shop, he said 0.003 per inches of bore. Which for me brings the gap to .0135 -> '014, them he said add '001 to compensate for unleaded fuel . Second gap 18. He said ill be just fine with 14/16. The hell with this crap   anyway, everyone has it's own little recipe, they are all different.

Heck I had the worst experience with that engine.

First machine shop specializes in circle track 2.3s, so I brought my 2.3 to him. He blueprinted aster boring 30 over, ordered the short block kit for me to assemble it. Since it was blue printed I didn't bother checking bore/piston sizes, ring gaps ... Plastiguaged bearing clearances.

... Off course ... Big mistake, but man if you can't trust professionals anymore

Had 120 compression, 12ish man pressure, 40% blowby to the crankcase. So I open the thing again, measure the bore and it's 40 over ... With 30 pistons.

Bring the block to machine shop #2, have it bored to 60 over because cylinders are scared... Plus order 60 piston kit ... Yay. They bore it, I bring the block home measure like '053 over. So:huh so I bring it to machine shop #3 to get it checked, the guy measures 40 over! Go back to machine #2, they measure 53 over, show obvious embarassment, and bore it right to 60 over this time.

Meanwhile I ordered a set of complete heads from machine shop #4, and they are leaking. Turns out they reused the same valves with an odd guide. Had to bring them back to get them done right.

My 72 Dodge, I bring it to an ex-Dodge dealership mechanic from the 70s, who now owns his shop for the last 30 years, and is famous for drag racing. I ask him to adjust my valve lash, and his answer is 'u don't need to, they are hydrolic lifters they self adjust'.

Got a dual exhaust installed by a muffler shop, and as I roll out I cannot shift gears. Ko look under and the guy didn't put the safety pin back into the gear selection linkage ... Which he has the nerve to say ' I didn't touch that'. Turns out that the rear defroster is not working either. On my dodge it's an electric fan that takes hot air from around the muffler, but since the muffler got relocated, he just removed and junk the whole freacking system.

Hi mean REALLY?! Does anyone freacking care of what they do anymore? All those 6 places are owned/operated by caucasians, that sure talk the talk and pride on the ' made in America'. So called specialists highly recommended by local racers all of them ... Clowns.
Dat jugs bro.

Terror flieger since 1941.
------------------------

#### Captain Virgil Hilts

• Platinum Member
• Posts: 5950
##### Re: Piston ring end gap calculator/formula?
« Reply #10 on: June 29, 2011, 10:17:46 AM »
I have more bad news for you. I did a few 2.3 Ford engines not long ago. None of them had thick enough cylinder walls to bore 0.060" safely, more than a few of them would not go past 0.030" safely. Unless you get very lucky, the cylinders in that 2.3 won't stay round, so the rings will leak, and the engine will also run hot.

Yes, the second ring gap should be larger than the top ring gap. The top ring gap will close up more than the second will due to heat, and any gasses under pressure that pass by the top ring must be vented by the second ring, or they will unseat and lift the top ring, making the top ring leak even worse. Ring gap is not affected by lead in gasoline.
"I haven't seen Berlin yet, from the ground or the air, and I plan on doing both, BEFORE the war is over."

SaVaGe

#### SFRT - Frenchy

• Platinum Member
• Posts: 5180
##### Re: Piston ring end gap calculator/formula?
« Reply #11 on: June 29, 2011, 10:30:53 AM »
I heard that too ... Eiichhhh  ... I guess I ll find out. It's a daily driver, hopefully the lack of abuse will male it last. How do I measure wall thickness, and what number am I looking for?
Dat jugs bro.

Terror flieger since 1941.
------------------------

#### Captain Virgil Hilts

• Platinum Member
• Posts: 5950
##### Re: Piston ring end gap calculator/formula?
« Reply #12 on: June 29, 2011, 02:26:11 PM »
I heard that too ... Eiichhhh  ... I guess I ll find out. It's a daily driver, hopefully the lack of abuse will male it last. How do I measure wall thickness, and what number am I looking for?

The best way is to sonic test it. I prefer at least 3/16". You can get by with 1/8", but I think that's asking for it.
"I haven't seen Berlin yet, from the ground or the air, and I plan on doing both, BEFORE the war is over."

SaVaGe

#### SFRT - Frenchy

• Platinum Member
• Posts: 5180
##### Re: Piston ring end gap calculator/formula?
« Reply #13 on: June 29, 2011, 03:27:25 PM »
A bit too late for that. Ill research online an another way to measure if any, I'm done with the short block already minus 1 cylinder. Thx.
Dat jugs bro.

Terror flieger since 1941.
------------------------

#### Captain Virgil Hilts

• Platinum Member
• Posts: 5950
##### Re: Piston ring end gap calculator/formula?
« Reply #14 on: June 29, 2011, 04:50:35 PM »
A bit too late for that. Ill research online an another way to measure if any, I'm done with the short block already minus 1 cylinder. Thx.

You could have it sonic tested before putting the head on. At least if it develops problems, you'll know why and not spend a ton of time/money trying to fix what can't be fixed.
"I haven't seen Berlin yet, from the ground or the air, and I plan on doing both, BEFORE the war is over."

SaVaGe