htr
Well-Known Member
- Posts
- 1,515
- Location
- Central Otago, Southern New Zealand
OK heads off and yes there are bent valves. 2nd cylinder form the cam belt, bent exhaust valves. That problem may have stemmed from a leaking oil seal on the exhaust cam itself.
The motor has been fitted with a MLS HG at some stage. In dismantling things I found that the cam belt drive cog on the crankshaft has had the crank pulley locating peg sheared off, most likely done when the former owners attempted to fix the problem, another expense!
Ive stripped down the spare head in prep for some head work. Even an inexperienced person like me can see that there is potential for some improvements
Namely on the inlet side. Smooth out the radius going down to the cylinder, match the ports into the head itself, smooth out casting seams in each throat. There is quite a lip when you look at the valve seat [below the actual valve] next to the spark plug. Ill see it this can be filled and smoothed out too.
The exhaust ports are very similar to the inlet in the work that could be done. Ill open up the exhaust ports but leave them a bit smaller than the manifold ports. Apparently this aids gas extraction and helps prevent any pulses going back to the head.
The spark plugs protrude through a small raised area in the cylinder head. Would there be any benefit in removing that raised area?
The coolant holes in the head are very uneven so they will be cleaned up too. Interesting to note that the head gasket has two different sized holes for those coolant galleries. 5.5mm on the inlet side and 11.5 on the exhaust side. Would it be useful to enlarge those inlet ones to allow greater coolant flow?
The inlet manifold will get a clean out as there is a lot of moulding flash protruding. The exhaust manifold will be cleaned up too [lots of excess weld] especially at the ports and where the 4 go into 2, theres some manufacturing crimping that can be eased out I feel.
Aiming to finish off with 52mm throttle body, a better air filter box arrangement with a raised air intake and a strengthened oil rail. Im keen to explore cam timing. I may do a simple mod to the pulleys so that they can be adjusted slightly to enhance cam timing.
Exhaust front pipe and sump off tomorrow to see if a strengthened oil rail has been fitted.
More later.
HTR
The motor has been fitted with a MLS HG at some stage. In dismantling things I found that the cam belt drive cog on the crankshaft has had the crank pulley locating peg sheared off, most likely done when the former owners attempted to fix the problem, another expense!
Ive stripped down the spare head in prep for some head work. Even an inexperienced person like me can see that there is potential for some improvements
Namely on the inlet side. Smooth out the radius going down to the cylinder, match the ports into the head itself, smooth out casting seams in each throat. There is quite a lip when you look at the valve seat [below the actual valve] next to the spark plug. Ill see it this can be filled and smoothed out too. The exhaust ports are very similar to the inlet in the work that could be done. Ill open up the exhaust ports but leave them a bit smaller than the manifold ports. Apparently this aids gas extraction and helps prevent any pulses going back to the head.
The spark plugs protrude through a small raised area in the cylinder head. Would there be any benefit in removing that raised area?
The coolant holes in the head are very uneven so they will be cleaned up too. Interesting to note that the head gasket has two different sized holes for those coolant galleries. 5.5mm on the inlet side and 11.5 on the exhaust side. Would it be useful to enlarge those inlet ones to allow greater coolant flow?
The inlet manifold will get a clean out as there is a lot of moulding flash protruding. The exhaust manifold will be cleaned up too [lots of excess weld] especially at the ports and where the 4 go into 2, theres some manufacturing crimping that can be eased out I feel.
Aiming to finish off with 52mm throttle body, a better air filter box arrangement with a raised air intake and a strengthened oil rail. Im keen to explore cam timing. I may do a simple mod to the pulleys so that they can be adjusted slightly to enhance cam timing.
Exhaust front pipe and sump off tomorrow to see if a strengthened oil rail has been fitted.
More later.
HTR
