The Ford Barn

flatjack9 · 08-13-2018, 02:14 PM

Does anyone make a big bore head gasket for a 21 stud engine? I've got a 36LB that is going to 3 3/16 + .020.

Ol' Ron · 08-13-2018, 02:49 PM

made mine from a 239 24 stud gasket. Just punch in the 4 stud holes

Kurt in NJ · 08-13-2018, 02:51 PM

What are you doing to keep the rings out of the water jacket?, LB blocks get thin at 0.060

Ron talks about using later gasket and making needed holes

swedishsteel · 08-13-2018, 03:33 PM

Will be interested to see if it works for you. I bought a '36 sedan that came with a '36LB block that was made into 3 3/16: cylinder walls bored completely out and machined for sleeves. New cam and valve train was already installed. i assembled the rest of it and put it in my '36 coupe. Got hot right away and spit water out the left header. thought it was a head gasket so tried a couple snake oil "fixes", that didn't work. Tore it down and one of the sleeves was split top to bottom. Bad sleeve??? I don't know, but I later found some info on boring 221 blocks to 239 and it was done with later blocks that had thicker cylinder walls. Good luck. Rod

flatjack9 · 08-13-2018, 07:13 PM

This engine was already bored to 3 3/16 +.010 with very little wear. Sonic testing showed that with a slight shift in a couple bores, it is doable. I'm not doing the work, just suppying parts. Where do you find a LB block these days? Too bad, I had sold one last month and my other one didn't pass the pressure test.

JM 35 Sedan · 08-13-2018, 08:35 PM

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I've often heard of '37 to E'38, 21 stud, 221 blocks going to 3-3/16" + some over, but never would have thought a '36LB block would go anywhere near that without doing something out of the ordinary using special sleeves.

In the last five or six years, 36LB engines, with good blocks, seem to be coming out of the woodwork for me, and another local friend. I've stumbled over four, and a friend has found at least three. Prior to that, I couldn't find one good enough to rebuild, or buy one at a reasonable price. Two of mine were basically gifts, and two were in cars I bought.

flatjack9 · 08-13-2018, 08:39 PM

I'll see if I can get the sonic test results.

Brian · 08-13-2018, 09:53 PM

Cometic can do 21 stud gaskets 3.188 bore Part number : H2428SP2040S That is .040" thick, but they can make any desired thickness.

Brian · 08-13-2018, 10:00 PM

With my 3 3/16 bore 21 stud engine, I'm using gaskets that were as big as I could get- not 3 3/16 but...I think from memory I had something like a .007" overhang around top of cylinders. I chamfered the pistons a tad; sufficient to clear, and it works; have not blown any head gaskets. Possibly, using those Cometic gaskets, you'll have in the region of .010" overhang, judicious relieving of edge of piston crowns could get you outta trouble. What are the existing gaskets with the +.010" bore?

Kahuna · 08-13-2018, 10:11 PM

Brian is correct with Cometic

JM 35 Sedan · 08-13-2018, 10:49 PM

Quote:

Originally Posted by Brian

With my 3 3/16 bore 21 stud engine, I'm using gaskets that were as big as I could get- not 3 3/16 but...I think from memory I had something like a .007" overhang around top of cylinders. I chamfered the pistons a tad; sufficient to clear, and it works; have not blown any head gaskets. Possibly, using those Cometic gaskets, you'll have in the region of .010" overhang, judicious relieving of edge of piston crowns could get you outta trouble. What are the existing gaskets with the +.010" bore?

Which year 21 stud engine have bored to 3-3/16"?

Brian · 08-13-2018, 11:06 PM

John, It's a 37 block. According to the sonic test performed, it'll go another .020" yet [safely]. Running pump in head heads on it.

JM 35 Sedan · 08-13-2018, 11:31 PM

Quote:

Originally Posted by Brian

John, It's a 37 block. According to the sonic test performed, it'll go another .020" yet [safely]. Running pump in head heads on it.

Okay, thank you Brian.

flatheadmurre · 08-13-2018, 11:43 PM

With MLS gaskets everything has to be dead flat or they leak so surfacing block and heads is a must before using them.
Solid copper and a waterjet cutter maybe...probably cheaper then the MLS from Cometic.

Brian · 08-14-2018, 02:33 AM

Murre, Have you such a machine?- waterjet cutter

flatheadmurre · 08-14-2018, 03:14 AM

Nope but there is a company in the next town with one.
I just send them a CAD file and they cut what i need.
Best would be to O-ringing the engine going for solid copper but that takes CNC macining both head and block...and pinning the head to block for keeping it centered.
Been a lot of questions about bigbore 21 headgaskets lately...wonder what kind of order it would take to make some of the big dragons do a custom gasket run...probably more then hundreds of gaskets...

Yoyodyne · 08-14-2018, 08:44 AM

Quote:

Originally Posted by flatheadmurre

Been a lot of questions about bigbore 21 headgaskets lately...wonder what kind of order it would take to make some of the big dragons do a custom gasket run...probably more then hundreds of gaskets...

I need some for .100 over, was planning to repunch 24 stud gaskets.

lotsagas4u · 08-14-2018, 06:50 PM

We need Tod to cast a run of these blocks, where is Tod?

08-13-2018, 02:14 PM	#1
flatjack9 Senior Member Join Date: May 2010 Location: Oshkosh, Wi Posts: 4,525	21 stud big bore gasket Does anyone make a big bore head gasket for a 21 stud engine? I've got a 36LB that is going to 3 3/16 + .020.

08-13-2018, 02:49 PM	#2
Ol' Ron Senior Member Join Date: May 2010 Location: Chester Vt Posts: 8,855	Re: 21 stud big bore gasket made mine from a 239 24 stud gasket. Just punch in the 4 stud holes

08-13-2018, 02:51 PM	#3
Kurt in NJ Senior Member Join Date: May 2010 Location: on the Littlefield Posts: 6,156	Re: 21 stud big bore gasket What are you doing to keep the rings out of the water jacket?, LB blocks get thin at 0.060 Ron talks about using later gasket and making needed holes

08-13-2018, 03:33 PM	#4
swedishsteel Senior Member Join Date: Jan 2011 Posts: 342	Re: 21 stud big bore gasket Will be interested to see if it works for you. I bought a '36 sedan that came with a '36LB block that was made into 3 3/16: cylinder walls bored completely out and machined for sleeves. New cam and valve train was already installed. i assembled the rest of it and put it in my '36 coupe. Got hot right away and spit water out the left header. thought it was a head gasket so tried a couple snake oil "fixes", that didn't work. Tore it down and one of the sleeves was split top to bottom. Bad sleeve??? I don't know, but I later found some info on boring 221 blocks to 239 and it was done with later blocks that had thicker cylinder walls. Good luck. Rod

08-13-2018, 07:13 PM	#5
flatjack9 Senior Member Join Date: May 2010 Location: Oshkosh, Wi Posts: 4,525	Re: 21 stud big bore gasket This engine was already bored to 3 3/16 +.010 with very little wear. Sonic testing showed that with a slight shift in a couple bores, it is doable. I'm not doing the work, just suppying parts. Where do you find a LB block these days? Too bad, I had sold one last month and my other one didn't pass the pressure test.

08-13-2018, 08:35 PM	#6
JM 35 Sedan Senior Member Join Date: May 2010 Location: Near Rising Sun, Maryland Posts: 10,858	Re: 21 stud big bore gasket Sponsored Links (Register now to hide all advertisements) I've often heard of '37 to E'38, 21 stud, 221 blocks going to 3-3/16" + some over, but never would have thought a '36LB block would go anywhere near that without doing something out of the ordinary using special sleeves. In the last five or six years, 36LB engines, with good blocks, seem to be coming out of the woodwork for me, and another local friend. I've stumbled over four, and a friend has found at least three. Prior to that, I couldn't find one good enough to rebuild, or buy one at a reasonable price. Two of mine were basically gifts, and two were in cars I bought. __________________ *John* *"Never give up on what you really want to do. The person with big dreams is more powerful than one with all the facts". Albert Einstein*

08-13-2018, 08:39 PM	#7
flatjack9 Senior Member Join Date: May 2010 Location: Oshkosh, Wi Posts: 4,525	Re: 21 stud big bore gasket I'll see if I can get the sonic test results.

08-13-2018, 09:53 PM	#8
Brian Senior Member Join Date: May 2010 Location: Masterton, New Zealand Posts: 3,828	Re: 21 stud big bore gasket Cometic can do 21 stud gaskets 3.188 bore Part number : H2428SP2040S That is .040" thick, but they can make any desired thickness. __________________ Unfortunately, two half wits don't make a whole wit!

08-13-2018, 10:00 PM	#9
Brian Senior Member Join Date: May 2010 Location: Masterton, New Zealand Posts: 3,828	Re: 21 stud big bore gasket With my 3 3/16 bore 21 stud engine, I'm using gaskets that were as big as I could get- not 3 3/16 but...I think from memory I had something like a .007" overhang around top of cylinders. I chamfered the pistons a tad; sufficient to clear, and it works; have not blown any head gaskets. Possibly, using those Cometic gaskets, you'll have in the region of .010" overhang, judicious relieving of edge of piston crowns could get you outta trouble. What are the existing gaskets with the +.010" bore? __________________ Unfortunately, two half wits don't make a whole wit!

08-13-2018, 10:11 PM	#10
Kahuna Senior Member Join Date: May 2010 Location: NorCal Posts: 2,617	Re: 21 stud big bore gasket Brian is correct with Cometic

08-13-2018, 11:06 PM	#12
Brian Senior Member Join Date: May 2010 Location: Masterton, New Zealand Posts: 3,828	Re: 21 stud big bore gasket John, It's a 37 block. According to the sonic test performed, it'll go another .020" yet [safely]. Running pump in head heads on it. __________________ Unfortunately, two half wits don't make a whole wit!

08-13-2018, 11:43 PM	#14
flatheadmurre Senior Member Join Date: Apr 2015 Location: Sweden Posts: 3,045	Re: 21 stud big bore gasket With MLS gaskets everything has to be dead flat or they leak so surfacing block and heads is a must before using them. Solid copper and a waterjet cutter maybe...probably cheaper then the MLS from Cometic.

08-14-2018, 02:33 AM	#15
Brian Senior Member Join Date: May 2010 Location: Masterton, New Zealand Posts: 3,828	Re: 21 stud big bore gasket Murre, Have you such a machine?- waterjet cutter __________________ Unfortunately, two half wits don't make a whole wit!

08-14-2018, 03:14 AM	#16
flatheadmurre Senior Member Join Date: Apr 2015 Location: Sweden Posts: 3,045	Re: 21 stud big bore gasket Nope but there is a company in the next town with one. I just send them a CAD file and they cut what i need. Best would be to O-ringing the engine going for solid copper but that takes CNC macining both head and block...and pinning the head to block for keeping it centered. Been a lot of questions about bigbore 21 headgaskets lately...wonder what kind of order it would take to make some of the big dragons do a custom gasket run...probably more then hundreds of gaskets...

08-14-2018, 06:50 PM	#18
lotsagas4u Senior Member Join Date: Apr 2011 Location: Plainview, Texas Posts: 757	Re: 21 stud big bore gasket We need Tod to cast a run of these blocks, where is Tod?

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