Line Boring Side Effects (Chain Housing)

[jkh2cpu]

A day or two ago I reported that I checked the deck
height, and it was about 1 or 1.25 mm less than it
should have been. The other night a lightning bolt
passed through my brain on the way to sleep, and
I began to wonder about how far off are the chain
housings. Well, when the chain housing is mated to
the case, I can just bolt up the aluminum camshaft
flange cover, but I'm not in love with the fit: it's
close, but not touching.

Two solutions come to mind:

1. Go for the gold standard and have the chain housings
milled by maybe 1.25 mm.

2. Add two extra gaskets per side to make up the
difference... two together measure out at a little over
1.00 mm... This might be the eventual leaky standard

I have to add that when the case was being machined,
the machinist (Competition Engineering) thought that I
would be OK. I guess I am when the engine is cold, but
when it warms up, and things move around, I'd hate to
develop an oil leak.

[jkh2cpu]

Never mind. We went to a local greasy spoon for lunch
and afterwards I thought about solutions 1 and 2, and
then realized that 2 would do what I don't want, but
more so. I forgot about option 3: the base gaskets will
make up for the difference.

If all parcels arrive on time, Friday will be an interesting
day in the garage, what with piston to valve clearance
checking.

[Trackrash]

I slightly enlarged the three holes in the cam end plates and that allowed enough wiggle room to ensure the o-rings sealed on my car. I have milled heads and no cylinder base gaskets.

The bigger concern will be the slack in the timing chains...

[cgarr]

Your chain box might be pretty close on the heads, your case was narrowed but the heads were also surfaced this will bring them more inline with the chain boxes. Only other thing is the chain its self and the adjuster so there is enough travel to tension the chain without reaching its limit.

[jkh2cpu]

Thanks, Gordon. I was thinking of enlarging the holes, but
I don't think that will be necessary after I get the deck height
right with the base gaskets: the chain housings should be in
good alignment with the cam towers then.

I just got my SC grind cams, and I'll have the base gaskets on
Thursday late in the day, so Friday is 'check it out' day as far
as the valve / piston clearance goes.

Anything else to look for when I do this bolt-up check?

[Steam Driver]

I'm wrestling with the same thing. If you use cylinder base gaskets to space those back out correctly, then the chain cases will definitely be too narrow. Not sure what to do with this, I guess I will see when I get to that point. You would think thicker gaskets would be available for doing this since it's a fairly common issue.

[jkh2cpu]

I'll report back tomorrow when I build the engine up
again with the thicker base gaskets. I should have a
lot more clearance for the cam tower bolt holes to clear
the opening in the chain housing. As it was the other
day, they, they just fit, but it was a bit too close for my
liking.

If I put thicker gaskets between the case the the chain
housing, I'll further reduce the clearance for those cam
tower bolt holes...

[tharbert]

I had this same conversation with an engine builder here a while back. As it was explained to me, it's common to use multiple cylinder gaskets as spacers to adjust the deck height after machine work. I'm looking at the triple whammy: align bored, spigots decked and heads milled. You can get different sized gaskets from builders like Henry or Steve once you know what you need. PP seems to offer only one size, I'm guessing .5mm. Ollies shipped my case back with gaskets included, presumably to account for what they had milled. They are 1mm gaskets. If I remember correctly, fewer is better. So if you end up needing 1.5mm and you only have .5mm gaskets, go find a 1mm gasket: 2 is better than 3. It was also suggested that once you know what you need, have a single gasket made to fit although that sounds a bit pricey...

[Steam Driver]

I queried Ollie's about the chain case gaskets; they said to use double gaskets or "930" gaskets. I'm going to measure a chain case gasket tonight and see how thick it is.

[jkh2cpu]

Hi, Steam Driver. My base gaskets came a day early today
(Thanks, PP and USPS) It looks like I'm going to need 1.5
to get my deck height. I put some play doh (thanks, grand kid)
on the pistons, and cranked through 360. Heh. No squish, even
with a big wad of the stuff.

I've got to tear down the engine, install the chains, and
put it together again. I'd do it tomorrow, but I'm going
down to Durand, MI to watch and photo the Canadian
National and maybe a few short lines. Priorities, you know.

Friday will be the day to see how it's going to fit together.
So far I've got a good feeling about it.

tharbert: PP offers 0.25, 0.5, and 1.0 mm base gaskets.
I bought the 1.0s and 0.5s thinking that I might need that
much. Lucky guess

[Steam Driver]

For everyone's information I miked the chain case gaskets last night and they were .0355-.0381 depending on where I miked. So using two of them might be an over-correction depending on how much torquing compresses them. I'm just going to get another pair of gaskets and eyeball it during assembly.

Looking at the parts book the P/N for SC's and Turbos is the same, so I don't know where that idea came from.

[Trackrash]

Let us know how it works out.

[Steam Driver]

Be awhile until I get to that point. Meantime all other ideas will be entertained!

[jkh2cpu]

Using base gaskets with a total thickness of 1.5 mm, I'm in
like Flynn: no problems with the cam tower / chain case
alignment. My deck height is 1.5 mm give or take a wobble
or two. I'm going for conservative here.

I'll check the piston / valve clearance tomorrow it it isn't too
hot and humid in Central Michigan.