Topic: Head Gasket Selection Help?

[BenelliSEI]

I have a large bin of gasket sets. I am not buying anymore. Pulled out head gaskets for the Sandcast project engine. The original is the dark one and measures 1.2 mm thick (approx). Two are marked “Victor Reinz AFM” and are about 1.2 mm thick. Only one has the smaller stud holes and the tin reinforcement ring around each cylinder bore hole are so poorly made they are not even round. I have a few more that are for later engines, with bigger holes around the studs for rubber inserts.

There is one head gasket marked “Perman...?? Metal Industries” that has really nice copper rings around each bore (they are round and symmetrical) and a grey film coating on a nice, firm material. It is only 1 mm thick. It seems a very high quality and I am inclined to use it. Any comments or suggestions appreciated!

[BenelliSEI]

Head gasket pictures. The one I like is next to the original.

[BenelliSEI]

Bump. In the hope of some input?

[HondaMan]

I have a large bin of gasket sets. I am not buying anymore. Pulled out head gaskets for the Sandcast project engine. The original is the dark one and measures 1.2 mm thick (approx). Two are marked “Victor Reinz AFM” and are about 1.2 mm thick. Only one has the smaller stud holes and the tin reinforcement ring around each cylinder bore hole are so poorly made they are not even round.

A couple of observations:
- The cylinder holes should NOT be round in these head gaskets. They should have occlusions where the valves are in each chamber, so when the metal ring spreads upon torque, it won't end up inside the bore. This issue has happened to me with the red-colored "Made in Japan" gasket sets, a no-name headgasket, and one from a now-defunct (ah, justice?) gasket maker in the past. The latter actually hit the piston crown with its excursion into the bore of an engine I put together, then wouldn't turn (?).

- That 1.2mm thickness is of concern. The OEM gaskets were 0.80-0.84mm thick, with asbestos, and when the asbestos went away in the 1990s they thickened up to 1.00-1.04mm on all that I measured (and wrote down, to remember). The quench band and compression ratio depends on the old 0.80mm thickness, and will be less with thicker gaskets. For this reason (and also because of the lack of seal pressure on the oil passage O-rings when using thicker gaskets with stock O-rings of 2.4-2.5mm thickness) I always mill off the top of the cylinders according to the head gasket I will use. Mostly this comes out to 0.010", though I have gone twice that much on the late K4 and the K5 engines when the cylinders grew longer to make the engines run on lower-octane gas during the Carter Oil Embargo nonsense here in the States that cut off our gasoline supply for about 18 months. While it wasn't published then, the compression ratio of those engines was 8.8:1 instead of 9:1 so they could drink Regular gas instead of Premium.

[HondaMan]

Hmm...could that "Perman..." gasket be an asbestos-based one? It looks it.

[Terry in Australia]

I don’t know if I can be of much help John, when I built my K0 I ratted thru a box of gaskets that were probably as old as the bike (NOS) and found one with the smaller holes for the studs and used that. I think the cylinder holes weren’t round from memory. I didn’t bother measuring the thickness as I am running oversized CB77 pistons which upped the compression ratio quite significantly, but nothing touched so I was golden, and my K0 goes like a rocket. Well, it will again when I swap in some better coils.

[BenelliSEI]

Hmm...could that "Perman..." gasket be an asbestos-based one? It looks it.

Thanks for the detailed response. I think that gasket may contain asbestos. It has that feel and sheen. It’s old enough to be, I’ll check the wrapper today.

[BenelliSEI]

I don’t know if I can be of much help John, when I built my K0 I ratted thru a box of gaskets that were probably as old as the bike (NOS) and found one with the smaller holes for the studs and used that. I think the cylinder holes weren’t round from memory. I didn’t bother measuring the thickness as I am running oversized CB77 pistons which upped the compression ratio quite significantly, but nothing touched so I was golden, and my K0 goes like a rocket. Well, it will again when I swap in some better coils.

h

Pretty much what I am doing, hopefully with similar results!

[PeWe]

My K2 got a stock gasket from a Vesrah gasket kit last time. It was rather hard fiber that did not compress much. Retorqued the day after.

Even Cometic has the fiber type. Before very shiny graphite gasket that usually compressed, nuts a little loose the day after.



Large oil return holes on old cylinder can use additional o-rings. I ordered o-rings for next, 1.5mm thick, 14mm ID
I have used too thick earlier.

It would be nice if 0.8mm thick head gasket were available, or 0.030".
Stock oil feed o-rings will work better and more compression.

Hondaman the man that must have seen most stock head gaskets around here

[BenelliSEI]

Thanks for the info PeWe. I think this one has a graphite coating. It measures 1 mm. The copper rings are round, but well back of the bore holes. With the dowels in place, it sits perfectly symmetrical on all holes. The label reads “Best Gasket, Cycle Division, Gardena, California”. It came with a very nice, blue base gasket which I think I will also use. I have 4 X “0” rings sent to me by Mark P.

I want to use up some of my supplies! Any reason against? Really appreciate the replies. Thanks all.

[BenelliSEI]

Both ends of the gasket have this little cut out. Good place to pry the head off (hopefully in another +50 years)?  Interesting idea.

[Terry in Australia]

Yeah use it John, why not? I torque my heads to 20 foot pounds, (in 4 stages, 10, 14, 18, then 20) leave them overnight, loosen them off and re-torque them, and they don’t leak.

[Don R]

 Is there a decent sandcast gasket or does everyone just trim off the loop?

[BenelliSEI]

Yeah use it John, why not? I torque my heads to 20 foot pounds, (in 4 stages, 10, 14, 18, then 20) leave them overnight, loosen them off and re-torque them, and they don’t leak.

Terry.... I hope to get it down, before we leave, then retorque in 5 weeks!

[BenelliSEI]

Is there a decent sandcast gasket or does everyone just trim off the loop?

Don.... probably, but I’ll trim.

[Terry in Australia]

Yeah use it John, why not? I torque my heads to 20 foot pounds, (in 4 stages, 10, 14, 18, then 20) leave them overnight, loosen them off and re-torque them, and they don’t leak.

Terry.... I hope to get it down, before we leave, then retorque in 5 weeks!

Good idea John, you’ll be surprised at how much more it pulls down when you re-torque it.

[denward17]

When you re-torque, do you loosen the head nuts/bolts, or just go again from their current status?

[BenelliSEI]

When you re-torque, do you loosen the head nuts/bolts, or just go again from their current status?

I don’t but it appears most people do. May have to change my habits!

[PeWe]

I test first if nuts will move when continue with same tourqe when I want to know how much gasket has compressed.
Nut by nut from inner to outer.

Next is to loosen 1/2 turn followed by tighten again.

The thin M6 as last ones. 4 under rubber coins + 2 on each side of cam tunnel.
The earliest have only 1.

If the nuts sat loose, I'll redo the day after again. No hurry when working at home for myself

[BenelliSEI]

I test first if nuts will move when continue with same tourqe when I want to know how much gasket has compressed.
Nut by nut from inner to outer.

Next is to loosen 1/2 turn followed by tighten again.

The thin M6 as last ones. 4 under rubber coins + 2 on each side of cam tunnel.
The earliest have only 1.

If the nuts sat loose, I'll redo the day after again. No hurry when working at home for myself

Thanks Per. Will give this a try. J.

[Terry in Australia]

Yeah, I back them all off a full turn or two and go through the “4 phase” torque sequence again and I’m always amazed at how much further they pull down.

[Phoenix]

The four 6mm under the coins are torqued after yhe 8mm.  I thought their purpose was to locate the jugs.  If that's the case, shouldn't they be tightened first?  Also, if the head and jugs are decked, do you still need to oversize as Mark says?

[HondaMan]

Yeah use it John, why not? I torque my heads to 20 foot pounds, (in 4 stages, 10, 14, 18, then 20) leave them overnight, loosen them off and re-torque them, and they don’t leak.

+1

[denward17]

Terry, HondaMan,

You indicated "I torque my heads to 20 foot pounds, (in 4 stages, 10, 14, 18, then 20) leave them overnight, loosen them off and re-torque them, and they don’t leak."


Just so I am clear, when you loosen them off, I assume you perform this in reverse order from torqueing?
Thanks
Dennis

[HondaMan]

The four 6mm under the coins are torqued after yhe 8mm.  I thought their purpose was to locate the jugs.  If that's the case, shouldn't they be tightened first?  Also, if the head and jugs are decked, do you still need to oversize as Mark says?

I do both. The modern head gaskets are all differing thicknesses, so it seems best [to me] to both deck the cylinders 0.010" and use the thicker O-rings, as the thicker O-rings would work even if it was a genuine Honda (0.8mm thick) head gasket.

Like Terry: I torque in multiple stages (sometimes 4 steps, sometimes just 3 steps if the head-cylinder has no tightness on the locating dowels). After the nuts are all torqued, then torque the 4 sealing bolts (6mm bolts) to 90-100 in-lbs and don't ever loosen those again until the next teardown. The next day I loosen all the 8mm nuts in reverse of torquing order, then torque them all back down, and they usually go another 1/2 turn or so further than the first time. Finally, I re-check the 6mm bolts by just trying to torque them a little more (no loosening first).

Since I started doing this during the last century, I've not had any leaks.