TOPIC:

VTEC wrote: I then measured the ID of a Cometic and OEM 1100 gasket and got 72.12mm and 73.42mm respectively. Do you see that extra 1.3mm causing any problems?
.

That equates to the gasket sitting back only 0.65 mm which will then be reduced slightly when compressed..
It will cause no issues.

As for the pistons. Are these new ?
All the newer ( for many years now ) MTC and Wiseco pistons are forged and the band around the dome is machined flat to correspond with the head.
Earlier pistons of both manufacturers were cast and may have a slight slope but I have no examples of these to compare.
All my MTC and Wiseco are forged and have a machined flat band .

gpz1170 wrote: are you sure you have the correct pistons ? the MTC catalog only lists a 1075 kit for a KZ ( 2mm over stock ) not for a J motor.

No. They do make a J kit also. 10.5:1 part #MTC-J1075

zed1015 wrote:

VTEC wrote: I then measured the ID of a Cometic and OEM 1100 gasket and got 72.12mm and 73.42mm respectively. Do you see that extra 1.3mm causing any problems?
.

That equates to the gasket sitting back only 0.65 mm which will then be reduced slightly when compressed..
It will cause no issues.

As for the pistons. Are these new ?
All the newer ( for many years now ) MTC and Wiseco pistons are forged and the band around the dome is machined flat to correspond with the head.
Earlier pistons of both manufacturers were cast and may have a slight slope but I have no examples of these to compare.
All my MTC and Wiseco are forged and have a machined flat band .

You may have caught me in a quick look scenario again. I'll look at the band again later.

Just thought that if I take a significant amount off the block deck I'd also have to deepen the o-ring grooves to use the OEM gaskets. Otherwise they may be too tight.

Right again Zed. Pistons are straight on the edges. You know theses engines well.

So it's looking like using the 1100 gaskets is becoming more and more problematic. What's your experience with the Cometic.

This engine cannot Leak. I'm rebuilding after someone else rebuilt it and everything was a disaster. Including the Cometic gaskets leaking oil at all 4 corners. Of course I discovered that both decks weren't flat, but I've read lots of stories about them leaking regardless.

I don't really see a problem with the 1100 gaskets.
Personally I have never had problems with Cometic graphite head gaskets
They are all I use now especially as 99% of my builds use Wiseco or MTC pistons.
Cleanliness , head torque and re-torque sequence is key.
Always use the head gaskets dry.
Never use spray on sealer.
The only area to apply sealer as insurance is a light smear of RTV for and aft of the camchain tunnel as this area gets hammered by oil spray.
Other paper gaskets. base, cam cover etc I grease both sides .

But say have I to take .020" off the block for squish, plus the previous .006" to get it flat. Wouldn't I have to deepen the o-ring grooves?

So you've never had oil get by a Cometic at the 4 outer studs? I was thinking possibly enlarging the stud holes and using o-rings would be a good idea.

sorry on the 1075 kit for "J", I stand corrected

don

VTEC wrote: But say have I to take .020" off the block for squish, plus the previous .006" to get it flat. Wouldn't I have to deepen the o-ring grooves?

So you've never had oil get by a Cometic at the 4 outer studs? I was thinking possibly enlarging the stud holes and using o-rings would be a good idea.

Never had a problem with oil leaks at the studs.
If using HD studs I run a 12mm drill down the corner holes in the block to straighten them out as the casting tapers around half way through and as well as causing possible restriction also ups the pressure in that area.
You can use a counter bore and fit 'O' rings if you think it necessary .
That is what I do when using copper head gaskets and no top end oiler.
Pretty sure I showed that done in the Orient Express Drag bike thread.
As for the squish. as mentioned, I would just get zero deck height and leave it at that.
I think you are getting a bit obsessed with getting the squish tight at the detriment of other areas of the build when It won't really make any measurable difference.
The width of the band created by the overbore isn't wide enough to create significant turbulence and if you want to build an engine with effective squish you need to start with the 83 onwards 1100 Unitrack with the bathtub twin swirl combustion chamber as these have a substantial squish area machined in with pistons shaped to match.

You're right. I am getting obsessed about the whole job. It's more than a build, but a rebuild catching and correcting everything the last guy messed up.

I asked APE about drilling out the outer stud holes due to the oversized studs. They said it wasn'the necessary but maybe I'll do it any way. Just the block, not the head?

I have all the other gaskets in OEM. They're thicker with a sealant coating.

Got all my parts in and will assemble the lower end this weekend. Followed by checking squish and I'll let you know where the numbers come in.

Thank you.

Just the two rear outer ones which act as oil galleries.
Not the head.
The casting varies so some can be worse than others.
The later motors are better but always worth checking.

Let me hit you with a trans question before I get to work.

Is .025"end play at 1st gear on the countershaft normal?

No spec in the book, but they say if it doesn't turn use the thinner trust washer at the needle bearing. This sounds like it should be a tight end play, but it's not. And the gear against the needle bearing on the mainshaft with the same select-fit thrust washer is about .005".

Note the clay shape in the pic below, which shows the actual squish area/combustion chamber relationship of the bathtub head and Std. J-pistons as it exists in my engine.