GPz11 top end, dry build

[moizeau]

Just lapped the valves in and going through my selection of shims. I'm thinking choose the smallest ones, chuck the cams in then measure? This will be with the head not being bolted on. Any advice or different opinions?
Cheers

[z1bman]

I think you've answered your own question

[Al]

Based on my own recent experiences with mine and the fact that this isnt the original head (?) i would definately torque it down. Pistons at half mast, chain in the tunnel and toruqe the cams in and check that they rotate completely freely and you can activate the end float as well. Before you put the cams and perhaps the shells; put a steel straight edge across either the vacant half moon bearing cutouts or the top face of the cam cap seats and measure with a feeler guage underneath the rule to see if any of the four cam bearing locations are below or above any other. You would be looking to see if the two in the middle were high or low for example. You may be able to rock the straight edge back and forth and that would be a give-away. If the cams wont rotate freely or the straight edge shows up a curve you will need to address this before the shim process or you wont get it right. (easily)
AL

[moizeau]

Thanks both of you.
Yes Al, this is Rob's head. I've had the cams in (no valves etc.) they spin freely with end float. Checked will plastigauge and all was good. It's difficult to torque the head down because the engine is still in bits. Barrels, sump,rocker cover and cyl. head are painted but I've still got to finish the upper and lower cases.
I was trying to get an idea of whether or not I have enough shims in the right ball park.

So I guess now that I'll have to wait until the rest of the engine is done before I continue with the head.
Cheers for the advice.

[zed1015]

That head is straight and was going to go on my turbo build.
The only reason i didn't use it is that i got a deal on some new pistons that wouldn't work with it's steeper exhaust valve without messing about recutting the pockets so used a J head instead.
I would bench shim it to 0.20mm to allow for the fresh ground seats to bed in.
Just use the thinnest shims that's there so you have a clearance to measure.
Only fit one cam at a time though and make sure the head is spaced off the bench.

[moizeau]

Thanks Rob.
To spin the cams, is it OK to use a cam sprocket bolt?
Cheers

[Al]

That head is straight and was going to go on my turbo build.

Thats a great place to start. At some point you will torque the head down and it would be an opportunity to check if it went down completely flat.

To spin the cams, is it OK to use a cam sprocket bolt?

Doesnt make it right but i do.
I have renewed mine recently so feel reasonably comfortable with that. If there are any signs i would replace them though. For a couple of quid it would be un-thinkable to have one break.
AL

[moizeau]

Thanks Al. I'll use some sacrificial M6 bolts then and put a nut on the back and keep the originals for the final build.

[moizeau]

Specs for inlet and exhaust (FSM) are 0.08 to 0.18. Rob's advised 0.2 which I'm trying to achieve.

I've got 2 x 0.22 and 1 x 0.17 and 1 x 0.2.
Should I bring the 2 at 0.22 down to 0.17 or the 1 at 0.17 up to 0.22......or am I good to go? These are inlets if it makes a difference to bedding in.

Put another way, with 0.2 being the target is 0.22 or 0.17 the preferred number if 0.2 is unobtainable?
Cheers

[zed1015]

The figure to get close to is obviously 0.18mm but i always set them slightly wider to allow for settlement with newly ground valves etc and most times they end up where they should be without further adjustment.
Either way you are most likely to be re-shimming a few when it comes to re-checking after a few miles anyway so your choice but .22 is a little on the wide side if that one decides it's staying where it is.
0.17 gives you plenty of room for manouver and if that settles to 0.15 you can go size thinner and if it stays put it's close enough bang on for stock cams..

[moizeau]

Thanks very much Rob. I'll bring the 2 at 0.22 down a size then.
Cheers, much appreciated

[moizeau]

These are the results

Guess which shim I have none of?
I have loads of 240 if anyone wants a swap.
The shims from the seized engine, the spare engine and then Rob's head, with all the extra ones he chucked in and not one 230. Bugger
Yes I have nicked your code, very good it is

[moizeau]

Will post also in the wanted section but......
I'm in need of 4 x 2.3mm 13mm shims, I have the others required.

Have a look in the box and see if you need any?
One other option is to pull my spare 650 engine to bits but I doubt I'll have 4 x 230s in there.