No - they are the original VW heads, not AMC ones. Thanks again Geoff - looks like I've got a solution.
Bother. Next to impossible to obtain 1mm barrel base shims. Don’t suppose anyone has some lying around they don’t need?
Sorry, I don’t have any 1mm shims. I’ve been thinking about the very low CR and I’m curious why. The engine would originally have had dished pistons, if you’ve changed to flat top the CR must be higher than standard. 2.0l heads should have a combustion chamber volume of around 50cc and plugging that into a calculator: 71mm stroke, 94mm bore, deck 1.25mm gives 9.4:1 CR. If the pistons are not flat top, what is the dish volume? And what is the head combustion chamber volume?
Chuck those^ away Mark. Don't use head spacers, shims, gaskets on a Type 4. EDIT: Before you ask, I don’t know why they are still included in gaskets sets.
I don’t need them Geoff, they’re sat in a box with some other type 4 gaskets. They don’t fit Scooby motors
Thanks for the offer Mork, appreciated very much. I think though that if I used 0.7mm shims by themselves it won't give me enough deck height for comfort - I guess I could stack them with the 0.25mm ones I have but its a bit sub-optimal. Geoff - thanks again for looking in your drawers and for coming up trumps with CSP. I was looking at the Bus Depot in the States and despite them saying 1-3 days delivery on their website they actually meant 3-4 weeks to despatch. I'll go ahead with the 1.07 ones from CSP and suffer the 40 Euro postage. As for the CR - I've given up on web-based calculator as they give me different answers for the same inputs - simple enough to calculate on your own spreadsheet. Here's what I've got; Compression Ratio Calculator Bore 9.4 cm Stroke 7.1 Deck height 0.125cm Head volume 55.5cc Piston dish 9cc CSA=69.3977817 cmSq Deck Volume = 8.67472271 cc Swept Volume=492.72425cc (1970.897001 capacity) Min volume =73.1747227 cc Max Volume = 565.898973 cc CR= 7.73353081:1 Yes - in my limited wisdom I've gone for new dished pistons!
Even more of a reason to throw them away - they’re no use for a scooby and they’re no use for a Type 4.
It's all cm or cc.. think I've got it right! It does tally with one of the online CR calculators I was using. Ugh - CSP won't deliver to UK for anything less that 200 Euros. Luckily I've got a mate in Munich...
I measured it - in the kitchen using vegetable oil and butter as it was too cold to be messing about in the shed!
When I did the head volume I forgot to put a spark plug in and got vegetable oil all over the place - I couldn't work out why it wasn't filling up!
Another quick question - As I'm putting the heads back on without the seals, do I need to lap the mating surface between the head and the barrel? (I think the answer is no but not sure of the pros and cons). Cheers!
It’s impossible to lap an aluminium head square to two different barrels . Machining and measuring is the only way.
The cylinders must be the same height and flat and the object of lapping is to remove the imperfections in the machined surface to obtain as good a metal to metal contact as possible. There are not many that have the skills or the equipment to machine the heads and barrels with sufficient accuracy, especially at home. In an ideal world the cylinder tops would be lapped to a perfectly flat surface and a flat disc would be lapped to the heads but I have neither and I lapped the heads to the cylinders - I also lapped the valves to their seats.
