Heads
#1
Posted 15 May 2004 - 10:10 PM
thanks, Rob
#2
Posted 15 May 2004 - 10:43 PM
Siggy
#3
Posted 16 May 2004 - 07:33 AM
When you do port a head, you want to aim to take the shoulder off that the valve stem comes thru, so that it is one nice smooth flowing curve around that corner. I normally aim to take the neck of the port out to the size of the exhaust gasket or the manifold, tappering in so you dont break thru the push rod holes, then opening out again int to big area behinde the valve. The back of the valve seat can be shaved off a bit to give it a nice smooth curve too. When you are happy with you finnished head, then you need to make sure all the ports are the same volume...
The pics in the 'Bible' are the best way of figuring out what to do, or try and get a look at a head thats allready been done. There is loads of metal that can be taken out of the head, but it needs to be in the right places. Dont rush doing it either, the last one I did took my about 3-4 days solid to finnish using a die-grinder and diamond tipped burrs.
#4
Posted 16 May 2004 - 08:19 PM
Siggy
#5
Posted 16 May 2004 - 10:18 PM
When I did this I had to keep the std cam because of cost. I was literally swapping heads. In my case the std cam didn't have too much lift. If you are keeping the std cam then there is a pretty good chance that the 12G940 head will go straight on however I suggest you check to see if you have enough clearance as tolerances of the rockers etc are poor and the amount of actual valve you get varies. I did this by attaching a lump of blutack to each exhaust valves and bolting the head onto the block with no gasket and 0 valve clearance. Then I turned the engine over by hand and pulled the head off and looked to see how much the blutack had been squashed. The other way to do it is again bolt the head on with no gasket and 0 valve clearance then turn the engine over until an exhaust valve us fully open then winding the adjuster until the valve touches the block. If it takes about 1mm of extra valve lift then you will be ok.
#6
Posted 17 May 2004 - 10:00 PM
Siggy
#7
Posted 18 May 2004 - 07:11 AM
1 user(s) are reading this topic
0 members, 1 guests, 0 anonymous users