Mr Hoodjacks wrote:blue74l wrote:Ahh - so they are a good thing. OK maybe time to bump up the CR and a bit of a port job and 3 angle grind !:bounce
Nah, don't. You will kill your old bottom end
Hoodjacks - read Dave Beckers post above - he's got it right.
Lets consider - you have a 1600 dual relief case which has a good bottom end and so you decide to rebuilt the top end. Any problesm with that?
Now you also have a 1300 dual relief case in good condition and decide to rebuilt the top end into a 1600. This case is likely to last LONGER than the rebuilt 1600, as the bottom end in both cases is identical but the 1300 only made 44hp (the 1600 makes 60hp), so the 1300 case has had an easier time of it.
The 1600 P&C are a drop in replacement item - same sized outer diameter, sot hte conversion is easy.
You CAN use the original 1300 heads but will end up with about 8.8:1 compression and the slightly smaller valves of the 1300. 8.8 is a bit high for comfort (even Shell optimax 98 octane would be marginal), and of course the smaller valves would reduce the benfits of the higher compression ratio anyway. Yo'd also be limite to using the 30 of H30/31 sized carbs, which would limit any increas in hp.
So it's better to get a set of 1600 heads to go with it, for a more normal 7.5:1 compression ratio (use normal unleaded petrol). You can use 1600sp heads and stick with the 30 or H30/31 carbs if you wish. Or with the 1600dp heads you can also use the larger 34PICT/3 carby if you want to for a few extra hp, or you can use the 30 or H30/31 sized carbs if you prefer (more choices).
Rob
Rob and Dave's aircooled VW pages
Repairs and maintenance for the home mechanic
http://www.vw-resource.com