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.030 or .036 head gasket?

Started by adayrider, December 13, 2019, 01:58:40 AM

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adayrider

December 13, 2019, 01:58:40 AM Last Edit: December 13, 2019, 02:38:29 AM by adayrider
What should the piston to head clearance be?
I bought a 128" 11 to 1 kit from FM, I put pistons and cylinders on and measured. Sent heads and cylinders out, cut cylinders for 0 deck (-.008 on front and -.011 on rear)  and he ported heads and cut .002 from heads to get 88 cc. Kit comes with .030 gasket but guy that did the heads said to use a .036 or .038 gasket to get at least .035 between piston and head.

I'm no motorhead so what do the experts say? If I known this I would have less cut from cylinders. Either way I don't want contact.

Edit - 2019 SGS

Ohio HD

If the pistons are at 0.000" deck now, they 0.035" to 0.038" is fine for a street motor. 

adayrider

Quote from: Ohio HD on December 13, 2019, 03:02:06 AM
If the pistons are at 0.000" deck now, they 0.035" to 0.038" is fine for a street motor.

That is exactly what he said. .036 it is then and an extra $50
Thanks for the help and reply.

Mag19

My builder likes it to be 0 checked with old gasket. When assembled use .30 gasket.

Ohio HD

You don't need to put the head on to check. Just use a zeroed dial indicator. A lot more accurate than clay or soldier. Saves time as well.


[attach=0]

Mag19


Ohio HD


Mag19

Nice, thanks. I already have the dial indicator so I may use the stand from summit for checking mine. Getting back to OP's original question. Do you check with gasket as well as rings on piston and what value are you going for on an 11:1 compression application

Ohio HD

I don't install the rings until I'm ready to assemble for good. I make a shim from 0.020" thick plastic shim stock and wrap the ring lands on the piston to stabilize it. Measure directly over the pin, both sides. The measure was 0.035", no base gasket. So I used an 0.031" base gasket and a 0.040" head gasket, gives me 0.036" squish.

Squish is more directed at motor / head style / design and intended use, not compression. That motor in the picture is 11.3:1.

 

Mag19

Yes squish is over my head at this point. I did ask the builder that's porting and cc'ing my SE heads for my build about squish and he replied with squish isn't even a thing. He decks the heads for clearance and sends them to me with recommendations of decking the pistons/cylinders to 0 and using a .030 base gasket. Not sure what the head gasket is. Thanks for the info on tour process

adayrider

Quote from: Ohio HD on December 13, 2019, 04:49:36 PM
I don't install the rings until I'm ready to assemble for good. I make a shim from 0.020" thick plastic shim stock and wrap the ring lands on the piston to stabilize it. Measure directly over the pin, both sides. The measure was 0.035", no base gasket. So I used an 0.031" base gasket and a 0.040" head gasket, gives me 0.036" squish.

Squish is more directed at motor / head style / design and intended use, not compression. That motor in the picture is 11.3:1.



Does this mean if you have 0 deck with base gasket  and .036 head gasket you still get .036 squish?

Ohio HD

Quote from: adayrider on December 13, 2019, 06:05:51 PM

Does this mean if you have 0 deck with base gasket  and .036 head gasket you still get .036 squish?

yes

Herko

With a high level of success, Sheffer Performance of Evansville Indiana targets a net squish of .030 when ever heads are removed. This is normally done via zero decking and using a .030 MLS head gasket. The .030 squish is employed on his 124/128 M8 builds as well other cubic inch configurations and including Twin cams.

"Net" squish examples:
Deck height of .000 use a .030 thou head gasket
Deck height of .010 out of the hole use a .040 thou head gasket
Deck height of .003 in the hole use a .027 thou head gasket

His in-house tuning research and data compilation has shown .030 to work well to balance optimum power and rideability with mitigation of spark knock (ping).

Based on these findings, adjusting static compression ratio with head gasket thickness is of poor design.
Achieve desired static CR via net combustion chamber volume incorporating head and piston volumes with a gasket thickness based on a targeted net squish.

Avoid assumption.
Always check deck height.
As a minimum, use a true straight edge and a good feeler gauge set.
Front cylinder often differs from the rear.
Check with the pistons installed that will be used in the build. Or, at least measure the compression height of the new pistons (stated and actual can differ) and compare to the compression height of the old pistons using math factoring in the deck height before disassembly. Variances in cylinder height (block height) and rod length do happen.

Above all else, don't shortchange your build with a mediocre tune. Do the research and vetting process to get a professional and competent tune. Travel the distance if necessary. Too often guys travel the short local path which ends up being the heartache highway of an expensive incompetent tune. Max power Dyno graphs are only a small part of the story. Wide open tuning is the easy part. In the tuning arena, what separates the men from the boys is the knowledge, process and implementation of tuning procedures that are applied to all of the part throttle areas.

Cheers
Considering a power upgrade?
First and foremost, focus on your tuning plan.

Mag19

I think that that is the best advice I've seen someone put out there yet. Really nice clear concise explanation there. Thanks for that.

Cheers to you

adayrider

Quote from: Herko on December 14, 2019, 08:21:43 AM
With a high level of success, Sheffer Performance of Evansville Indiana targets a net squish of .030 when ever heads are removed. This is normally done via zero decking and using a .030 MLS head gasket. The .030 squish is employed on his 124/128 M8 builds as well other cubic inch configurations and including Twin cams.

"Net" squish examples:
Deck height of .000 use a .030 thou head gasket
Deck height of .010 out of the hole use a .040 thou head gasket
Deck height of .003 in the hole use a .027 thou head gasket

His in-house tuning research and data compilation has shown .030 to work well to balance optimum power and rideability with mitigation of spark knock (ping).

Based on these findings, adjusting static compression ratio with head gasket thickness is of poor design.
Achieve desired static CR via net combustion chamber volume incorporating head and piston volumes with a gasket thickness based on a targeted net squish.

Avoid assumption.
Always check deck height.
As a minimum, use a true straight edge and a good feeler gauge set.
Front cylinder often differs from the rear.
Check with the pistons installed that will be used in the build. Or, at least measure the compression height of the new pistons (stated and actual can differ) and compare to the compression height of the old pistons using math factoring in the deck height before disassembly. Variances in cylinder height (block height) and rod length do happen.

Above all else, don't shortchange your build with a mediocre tune. Do the research and vetting process to get a professional and competent tune. Travel the distance if necessary. Too often guys travel the short local path which ends up being the heartache highway of an expensive incompetent tune. Max power Dyno graphs are only a small part of the story. Wide open tuning is the easy part. In the tuning arena, what separates the men from the boys is the knowledge, process and implementation of tuning procedures that are applied to all of the part throttle areas.

Cheers

Well this contradicts what has been posted doesn't it? If I use .030 head gaskets that is .030 between piston and head.
I'm no machinist, motor head, mechanic or head porter, could someone tell me which head gasket I should use. I have both .030 and .036

PoorUB

Quote from: adayrider on December 14, 2019, 12:46:19 PM
Well this contradicts what has been posted doesn't it? If I use .030 head gaskets that is .030 between piston and head.
I'm no machinist, motor head, mechanic or head porter, could someone tell me which head gasket I should use. I have both .030 and .036

I would use the .030", BUT, use what ever the guy that is helping you build the engine recommends. He might have a reason to use the .036" that we are unaware of.


Fuel Moto kit? Call them and ask!
I am an adult?? When did that happen, and how do I make it stop?!

adayrider

Quote from: PoorUB on December 14, 2019, 01:56:45 PM
Quote from: adayrider on December 14, 2019, 12:46:19 PM
Well this contradicts what has been posted doesn't it? If I use .030 head gaskets that is .030 between piston and head.
I'm no machinist, motor head, mechanic or head porter, could someone tell me which head gasket I should use. I have both .030 and .036

I would use the .030", BUT, use what ever the guy that is helping you build the engine recommends. He might have a reason to use the .036" that we are unaware of.


Fuel Moto kit? Call them and ask!

I did ask and and I shared the answer in first post. Now I'm looking for other opinions and an understanding of why. You can't hang a guy wanting to learn can you.

skunk

I've always shot for .030 in my builds and have not had any issues. Street motors, mostly in street baggers rode hard, twisted tight. My opinion only, YMMV

PoorUB

Quote from: adayrider on December 14, 2019, 02:39:30 PM

I did ask and and I shared the answer in first post. Now I'm looking for other opinions and an understanding of why. You can't hang a guy wanting to learn can you.

I'm confused! Did you send the cylinders and heads back to Fuel Moto to get cut? Your post says you sent them out, but not to who. You stated where you bought the kit, but not who cut the cylinders and heads.

Do what Fuel Moto said to do. They have a fairly good idea what is going on!
I am an adult?? When did that happen, and how do I make it stop?!

adayrider

Quote from: PoorUB on December 14, 2019, 04:27:54 PM
Quote from: adayrider on December 14, 2019, 02:39:30 PM

I did ask and and I shared the answer in first post. Now I'm looking for other opinions and an understanding of why. You can't hang a guy wanting to learn can you.

I'm confused! Did you send the cylinders and heads back to Fuel Moto to get cut? Your post says you sent them out, but not to who. You stated where you bought the kit, but not who cut the cylinders and heads.

Do what Fuel Moto said to do. They have a fairly good idea what is going on!

I wasn't going to get in to all this so I'll make it short. I didn't buy from FM. I went their porting guy and bought through them do to lets say lack of communications. And the fact FM didn't seem to care about details such as 0 deck. I'm not bad mouthing anybody though, to each their own. I'd rather not go into any of that.

So after buying some parts I reached out to my preferred tuner and he recommend a different cam the RS 552 instead od wood 408.. So I decided to go with the RS 552 cam and send my heads, cylinders and intake out to be ported, new valves, springs, and cylinders cut for 0 deck. I told porting guy what cam I was using and all. So in the end the parts are done, I pay the man and he ships them and emails me saying it was going to be tight and he prefers .035-.038 piston to head clearance and I should use a .036 HG

I don't have a problem using the .036 except it will lower compression. I was just wanting to know why .036 clearance all of sudden when I have always thought .030 was optimal for squish. The 552 is 550 lift vs the 408 at 520 but the concern seemed to be piston to head not valve.







PoorUB

Well, there you go, your preferred tuner that helped you build the combination recommends a .036". I would go with his opinion, especially if he is tuning it too.

You have enough faith in him to change cams and so on, trust his head gasket recommendation.

That is one thing bad about coming here, you will get many differing opinions. None of them wrong, but with the combination you are running your tuner most likely has the best opinion.
I am an adult?? When did that happen, and how do I make it stop?!

adayrider

Quote from: PoorUB on December 14, 2019, 05:33:58 PM
Well, there you go, your preferred tuner that helped you build the combination recommends a .036". I would go with his opinion, especially if he is tuning it too.

You have enough faith in him to change cams and so on, trust his head gasket recommendation.

That is one thing bad about coming here, you will get many differing opinions. None of them wrong, but with the combination you are running your tuner most likely has the best opinion.

Tuner is not the one that recommended it, it was the porter. Your right about the bad part. LOL
I was worried about piston hitting the head with .030 but I don't feel that is the case now.

PoorUB

The piston will never hit the head with a .030" or even a thinner head gasket. The problem arises a few miles down the rod when carbon starts to build up on top of the piston and in the combustion chamber. Thinner head gaskets and the carbon starts hitting the head or the piston sooner.

Most here will recommend a .030" head gasket, but I would still run what the guys, who ever they are, recommend. .030" or .036" or .006" difference probably will not make much difference. Most guys ask about the stock head gaskets which I believe are .045"
I am an adult?? When did that happen, and how do I make it stop?!

yobtaf103

What size is the base gasket, seen no mention ?

adayrider


adayrider

Fed ex delivered my .036 this morning I ordered from FM ans wouldn't you know it they sent me .030  :banghead:

Ohio HD

If you're sure that the pistons are no more than zero (not above the cylinder at all) use the 0.030" gasket. 0.006" one way or the other won't make or break the motor.

rigidthumper

Ignorance is bliss, and accuracy expensive. How much of either can you afford?

FXDBI

Lift @ TDC needs to be considered when doing all your math has well.  Bob

rigidthumper

552 has .183"  TDC lift on the exhaust lobe, so he should have .270" ish to be safe.
Ignorance is bliss, and accuracy expensive. How much of either can you afford?

Txwezl

Quote from: adayrider on December 15, 2019, 07:36:33 AM
Fed ex delivered my .036 this morning I ordered from FM ans wouldn't you know it they sent me .030  :banghead:

Denniskirk has the .036

adayrider

Quote from: Txwezl on December 19, 2019, 01:56:26 PM
Quote from: adayrider on December 15, 2019, 07:36:33 AM
Fed ex delivered my .036 this morning I ordered from FM ans wouldn't you know it they sent me .030  :banghead:

Denniskirk has the .036

I can't/couldn't find them. They do have 4.205 bore .036 but not 4.25 .036. Maybe I'm missing them?
I think I'm going with .040 now because I can't find .036 without special order. I had cylinders decked .008 and .011 so that puts me right where I would have been if I just bolted them on with .030   According to BB calc I'm still at 10.97-1
Mr. Rick Ward took time out of his day to call me because he seen this and took shot that it was me posting. He explained to me how it works and I could use the .030 but .036 would be best for what I was doing and .040 wouldn't hurt. So since nobody can source a .036 without special order I think I'm going with .040. I'm just a backyard hack and don't have all the top shelf dial indicators, micrometers special tools to be that precise. And even though I like to think and ride it like a race bike, it's still my riding and touring bike and I'll never miss the 1 lb or 1 hp I'll get from the extra squeeze. And I always have the .030 on the shelf if needed. LOL

Thanks for everyone's input and help.


kd

If Cometic has a gasket pattern and they don't list what you want but have the dimensional materials to stack or build a gasket they will do it at the cost of the same gasket they list.  No extra fee.  You may call that special order but when I spoke to them there was no extra time to build and ship the gasket.  It's a great service from a great gasket supplier.  Did you give them a call?
KD

No Cents

  give Cometic gaskets a call as kd stated.  :up:
Give them your bore dimensions and desired thickness of the head gaskets you want and they should be able to help you out.
(800)752-9850
08 FLHX my grocery getter, 124ci, wfolarry 110" heads, Burns pipe, 158/152 sae

yobtaf103

Quote from: yobtaf103 on December 15, 2019, 02:18:02 AM
What size is the base gasket, seen no mention ?
Apparently the 0.014' base crushes to 0.013" in reality

kd

Quote from: yobtaf103 on January 05, 2020, 08:53:24 AM
Quote from: yobtaf103 on December 15, 2019, 02:18:02 AM
What size is the base gasket, seen no mention ?
Apparently the 0.014' base crushes to 0.013" in reality

I tested a .020 Cometic base gasket.  It was .020 crushed (no change) and with a light smear of aviation cement between 2 gaskets you could not even measure the added sealer because it squeezed out under pressure.  I needed to stack a .003 linen paper gasket to the .020 base gasket to achieve 0 deck. They couldn't come up with that dimension material to make them for me.   Cometic told me this is what I would find and I should have listened to them and saved my time and trouble. I guess I just needed to know.  :embarrassed:  FWIW, they sealed perfect and still live dry.
KD

Nutoy

I did a 107 tc and the piston out of the hole .002 and a .030 gasket and after 5000 miles and some carbon build up on the pistons and pistons would hit the head when motor was cold. swapped the .030 gaskets with a .035 and no more problems.

adayrider

Quote from: Nutoy on January 05, 2020, 11:36:07 AM
I did a 107 tc and the piston out of the hole .002 and a .030 gasket and after 5000 miles and some carbon build up on the pistons and pistons would hit the head when motor was cold. swapped the .030 gaskets with a .035 and no more problems.

So what happens in the extra .005? In other words if carbon build up causes contact in 5000 or 10,000 or even 50,000 miles with a .030, why doesn't it build up even more in 6000 or 15,000 or 60,000 and hit then? Or does it? I know there are bikes out there that have 100,000 miles and more and never been apart. Factory gasket is what,.042 or something? Why don't their motors build up and eventually make contact?

Ohio HD

Quote from: adayrider on January 05, 2020, 01:13:56 PM
Quote from: Nutoy on January 05, 2020, 11:36:07 AM
I did a 107 tc and the piston out of the hole .002 and a .030 gasket and after 5000 miles and some carbon build up on the pistons and pistons would hit the head when motor was cold. swapped the .030 gaskets with a .035 and no more problems.

So what happens in the extra .005? In other words if carbon build up causes contact in 5000 or 10,000 or even 50,000 miles with a .030, why doesn't it build up even more in 6000 or 15,000 or 60,000 and hit then? Or does it? I know there are bikes out there that have 100,000 miles and more and never been apart. Factory gasket is what,.042 or something? Why don't their motors build up and eventually make contact?

Most OEM TC gaskets are about 0.045" when crushed. Most OEM TC motors the piston is down the hole 0.010" to 0.013" ish.

Most motors that see much carbon build up in the squish area (irregardless of squish) is due to poor tuning / oil burning. The smaller squish is to help prevent detonation with higher dynamic cylinder pressures and advanced ignition timing. 

Mag19

Quote from: Herko on December 14, 2019, 08:21:43 AM
With a high level of success, Sheffer Performance of Evansville Indiana targets a net squish of .030 when ever heads are removed. This is normally done via zero decking and using a .030 MLS head gasket. The .030 squish is employed on his 124/128 M8 builds as well other cubic inch configurations and including Twin cams.

"Net" squish examples:
Deck height of .000 use a .030 thou head gasket
Deck height of .010 out of the hole use a .040 thou head gasket
Deck height of .003 in the hole use a .027 thou head gasket

His in-house tuning research and data compilation has shown .030 to work well to balance optimum power and rideability with mitigation of spark knock (ping).

Based on these findings, adjusting static compression ratio with head gasket thickness is of poor design.
Achieve desired static CR via net combustion chamber volume incorporating head and piston volumes with a gasket thickness based on a targeted net squish.

Avoid assumption.
Always check deck height.
As a minimum, use a true straight edge and a good feeler gauge set.
Front cylinder often differs from the rear.
Check with the pistons installed that will be used in the build. Or, at least measure the compression height of the new pistons (stated and actual can differ) and compare to the compression height of the old pistons using math factoring in the deck height before disassembly. Variances in cylinder height (block height) and rod length do happen.

Above all else, don't shortchange your build with a mediocre tune. Do the research and vetting process to get a professional and competent tune. Travel the distance if necessary. Too often guys travel the short local path which ends up being the heartache highway of an expensive incompetent tune. Max power Dyno graphs are only a small part of the story. Wide open tuning is the easy part. In the tuning arena, what separates the men from the boys is the knowledge, process and implementation of tuning procedures that are applied to all of the part throttle areas.

Cheers


While checking deck height does he omit the base gasket and then do the math for the proper base gasket? Thanks

Barrett

Quote from: kd on January 05, 2020, 09:19:24 AM
Quote from: yobtaf103 on January 05, 2020, 08:53:24 AM
Quote from: yobtaf103 on December 15, 2019, 02:18:02 AM
What size is the base gasket, seen no mention ?
Apparently the 0.014' base crushes to 0.013" in reality

I tested a .020 Cometic base gasket.  It was .020 crushed (no change) and with a light smear of aviation cement between 2 gaskets you could not even measure the added sealer because it squeezed out under pressure.  I needed to stack a .003 linen paper gasket to the .020 base gasket to achieve 0 deck. They couldn't come up with that dimension material to make them for me.   Cometic told me this is what I would find and I should have listened to them and saved my time and trouble. I guess I just needed to know.  :embarrassed:  FWIW, they sealed perfect and still live dry.

Are the Cometic base gaskets a true .020? My S&S base gaskets are .018 and I'm .002 out of the hole. (T/C)
I went with a .040HG.

kd

January 07, 2020, 06:32:58 PM #41 Last Edit: January 07, 2020, 06:44:57 PM by kd
Quote from: Barrett on January 07, 2020, 06:05:23 AM
Quote from: kd on January 05, 2020, 09:19:24 AM
Quote from: yobtaf103 on January 05, 2020, 08:53:24 AM
Quote from: yobtaf103 on December 15, 2019, 02:18:02 AM
What size is the base gasket, seen no mention ?
Apparently the 0.014' base crushes to 0.013" in reality

I tested a .020 Cometic base gasket.  It was .020 crushed (no change) and with a light smear of aviation cement between 2 gaskets you could not even measure the added sealer because it squeezed out under pressure.  I needed to stack a .003 linen paper gasket to the .020 base gasket to achieve 0 deck. They couldn't come up with that dimension material to make them for me.   Cometic told me this is what I would find and I should have listened to them and saved my time and trouble. I guess I just needed to know.  :embarrassed:  FWIW, they sealed perfect and still live dry.

Are the Cometic base gaskets a true .020? My S&S base gaskets are .018 and I'm .002 out of the hole. (T/C)
I went with a .040HG.


The .020 Cometics I used on my 4.060 bore were exactly.020 when I torqued and dummied it up to confirm before assembly.  I was .003 out of the hole on both cylinders and added .003 linen paper to the .020 gasket with a light film of aviation cement to make it 0 deck (.023 gasket width).  The aviation cement squeezed out when torqued and sealed well at o deck and is still dry.  I guess the answer is, in my experience, yes they are a true .020.
KD