That points to high CR which probably explains why you had both spacers under the barrels AND gaskets in the heads. Strange. You most certainly want to do some head cc-ing and deck height measuring.
Most odd. Heads with steps and gaskets and shims suggest a low CR. 160psi cranking compression suggest a high CR.
Just been out and measured the seal, shim and head lip. Top mating seal with head about 0.75mm measured with digital caliper. This mates up to my AMC head with lip. Not sure what height lip is... measured with feeler gauge as about 0.60mm Bottom spacing shim about 0.23mm, measured with digital caliper. So not super accurate, but near enough to about 1mm with just seal and shim together which is less than 1.6mm suggested replacement shim. But if lip is part of equation then it looks about right at 1.6mm. Any thoughts on this would be appreciated. I think I'll be doing compression chamber sizing/concave piston/deck height measuring once case etc is back just to see what my compression ratio is or could be.
I may be misunderstanding but the measurements are the thickness of the shim and seal which relates, I think, to the VW bulletin.
It does and would apply if you had the original non-stepped heads but the standard way to fit the stepped AMC heads the head gasket is replaced by the step in the head with no need for the shim under the barrel. What you appear to have is the step and the shim (mixture of shim and gasket, same result) and yet you still have high cranking pressure. We all look forward to you measuring everything because until you do you and the rest of us are guessing. My logic says the case must have been decked and the shims/gaskets are trying but not entirely managing to readjust the deck and CR back towards stock.
IMO you should aim for a deck of 1.0 to 1.6mm and a static CR of about 8:1 – assuming a standard spec hydraulic cam. Include the lip in the head in the deck height measurements, so for instance, if the lip is 0.60mm and the piston is down the cylinder 0.20mm, the deck is 0.80mm and you’d need to add a 0.20mm base shim to increase the deck to 1.0mm. If the resulting CR is too high increase the thickness of the base shim, but try to keep the deck below 1.6mm. Looking forward to your combustion chamber/piston/deck height/CR measurements. And just for interest can you measure the length of the cylinder from where it locates in the crankcase to the top face?
Cheers Zedders, below is a photo of my head mid clean (not touching the value seats). Out of curiousity, does this looked decked, if it is possible to tell from a photo?
You can’t tell by looking, you need to measure it but AMC heads are supplied with a step and that head has a step. The decking zedders refers to is on the crankcase. Something is odd with the bits you have – stepped heads, dished (bus) pistons, head gaskets and base shims should mean you have a very low static CR. But you have a very high cranking pressure.
If you mean the distance between the two spots, about 127.11mm being the total length of the cylinder....not slanted as shown The carbonised top of the cylinder is about 8mm The beveled end is about 2.5mm
Sorry, I mean between where the cylinder fits on the crankcase (where the base shim is) to the top where it fits in the head. It should be around 90/92mm, but it’s not very easy to measure.
Just picked up my case after being worked on by the people at Formhalls http://www.formhalls.com/ I now have an aligned case for my new bearings (overize 0.5mm). They also sorted my stuck dowel pins, knackered cam plug seat and opened up the oil chambers and threaded them for me to clean. Guess what I'm doing over the Xmas period Really great people to deal with and they are happy to take on VW work if people need it.
Sounds like a good job any pics? What was the cost for the align bore etc? Worth knowing as handy people to know.
I'll put some photos up once I've cleaned the cases up a bit, but there is not a lot to look at really. As for cost it is a bit difficult to separate the various bits and pieces done but it was similar to other estimates I received. The type of company they are is shown by their really generous loan to me of a crank pulley to help me get off my extremely tight timing gear
Latest update and small favour to ask. Cleaning and lapping valves ongoing and all piston ring gaps measured and all fine....all within new ring measurements. Looking at parts and was wondering if somebody knows if the case bolt across the top of the cam cap is a 8.8 or a 10.9 strength? And now the small favour.... I managed to snap one of my lower compression rings. Does anybody have a spare 94 mm ring before I go and buy a new set? Thanks
If you mean the bolt that holds the strainer it’s part number N 0103732, M8X72. I don’t know the grade but I’d use 10.9. Used rings go in the bin and with the engine stripped you might as well hone the bores and fit a new set – Hastings rings are pretty good.
