Topic: Sealant on 750 head gasket or not ?

[754]

 Using a fiber gasket from a Vesrah kit.  Should a run dry, or thin smear silicone  ?
Head and cylinder have just been cleaned up not machined.

[BPellerine]

I have never used silicone on a headgasket frank,I have used coppercoat before,worked ok,a little harder to get off later though.bill

[Stev-o]

No silicone, ever!  (Except on the bathtub). 

I also use copper spray, but that is on the Kawasaki with a copper gasket. 

[scottly]

Dry.

[seanbarney41]

Copper spray worked great for me...I would not use a Vesrah gasket without it.

[disco]

Dry & no problems at all.

[Jerry Rxman Griffin aka MuthaF'er]

Dry

[HondaMan]

I use mostly Vesrah head gaskets, They need 2 things:
1. Most important: use a thicker-than-normal O-ring on the 2 oil journals at the center rear of the cylinders. ALL of today's head gaskets are thicker than Honda's were, so the old spec of 2.4x12mm O-ring at that site is too thin, and most of the leaks I fix are caused right there. If you can't find the 2.62 x 10.77 O-rings (aka 7/64" x 27/64") at your local Ace Hardware, PM me for a pair, you need them.
2. Smear a LIGHT coating of non-hardening Permatex#2 or Hondbond #4 around this same site. If the engine is the post-K2 variety with the 8 rubber dowels (and steel center dowels) then consider smearing an even thinner coat along the front edge holes. Also, if your cylinders DO NOT have these dowels, make sure the head gasket has the small holes at those 8 sites: if it has the big holes you also need 8 of the 2x11 O-rings, one in each hole, to prevent weeps (I have those, too...). And, vice-versa: if your head has the 8 rubber dowels and the head gasket holes for them are not 14mm size, you need to punch out the holes, or get the other head gasket (I have THOSE, too...).

[754]

I am running a 72 cylinder with a 75 ish head.
I have a vesrah, Ibco, and maybe Cometic gaskets, so I have choices. 
Either way it goes together tomorrow or next day.
 I measured the depth of tge puck hole, there was about 20 thou difference across the head.

[scottly]

Frank, the TRW pistons are known to have valve clearance issues on the exhaust side.

[754]

Really that would throw a wrench in the plan!
The 315 cam has about .375 lift.. i got an Andrews A kicking around  that should fit.
I was going to semi tight the head nuts then lift the rocker with a dial indicator on the valve collar.
Wish I had a extra week.

[scottly]

Notice the crescent shaped indentation at 6:15, where the valve pounded into the piston. This was with a cam with only .312" lift.
 

[754]

Here is the piston,bad pic.
Looks like if you measure of the sharp corner the cutout would be about 90- 100 thou deep.
Problem is, I dont know deck height.
Maybe I got to dig out that A grind.

[scottly]

My pistons are 65mm, aren't yours 61?
When I cut the reliefs, I wasn't very precise. I basically removed the witness marks, plus a little bit more...

[754]

Mine are 61 mm. I WONDER WHY they had the trench on the cutouts.
A grind had  .345 and .350 lift.  The 315 says .365, but my cam card may have said .375
 Hmmmm

[scottly]

Do you mean the notches in the OD of the crown, at 12:00 and 6:00 in my pic? They seem to be a signature of TRW pistons. My best guess is that they were used to index the forged slug before final machining?

[Jerry Rxman Griffin aka MuthaF'er]

Surely you are bound to have a spare set of stock pistons sitting around? Are those 12.5:1? Big head.

[754]

10.5 to 1   .oo4 clearance, stovk would rattle.
I can always go stock cam, not how it would be with high compression.

[Jerry Rxman Griffin aka MuthaF'er]

Frank, those domes sure look a lot taller than all the alleged 10:5:1 I've seen??

Get er dun! Godzilla wants to see who is most frightening in person! 

[754]

 Well Jerry  it's back to stock pistons.  Top chrome ring was a bit tight in the TRW,s.
One stock set of used are actually pretty tight  in the bores. Needed lots of cleaning.
Running out if things to surprise me pretty soon.

[scottly]

What about the F motor you just picked up? When are you planning on leaving?
Here are a couple of pics of 10.5:1 TRW pistons jaguar posted a while back, which was how I figured out that I had TRWs in my engine.

[754]

I am trying to avoid engine swap for A few reasons.
After all, just a top end right, should be easy ..right.?
Got stock pistons cleaned up ready to go but got a slightly oval sleeve spigot,  must have got bumped or dropped.
So I either bump or press it, or hone the spigot part. .. .003 sideways, about .0012 the other  I would be happy if I can get it to . 002....... without cracking it.    No shortage of frustration on my plate.

[HondaMan]

I am trying to avoid engine swap for A few reasons.
After all, just a top end right, should be easy ..right.?
Got stock pistons cleaned up ready to go but got a slightly oval sleeve spigot,  must have got bumped or dropped.
So I either bump or press it, or hone the spigot part. .. .003 sideways, about .0012 the other  I would be happy if I can get it to . 002....... without cracking it.    No shortage of frustration on my plate.

Do you mean on the head, inlet spigot? The hose will usually seal those OK.

[754]

No the cylinder sleeve end one. The forged pistons were a bit smaller  and fit., but with the stock piston , I got 1/2 thou or less on spigot of the sleeve , it's oval.
I can't remember how forcthe pistons go down,   also have not done a motor in ages.

[scottly]

Why not just swap the motor, Frank? Geeze, between busted cooling fins, the rod damage, and now the messed up sleeve, that motor has a hex on it!
I'm going to be VERY disappointed if you don't make it to Delores...
BTW, I don't care how you get there.