Later model US heads
- Thread starter Ronn
- Start date
IIRC the log head made in 1978 and later are the best flowing and have the largest valves. Also IIRC the log it's self is larger on these heads.
Howdy:
Sorry Ronn, the D5 castings were the last to use 1.65" intake valves. It will have the larger 1.75" carb intake hole and slightly larger intake tract volume than CXXX castings ( with the exception of the C9XX-M, flat-topped log castings).
It will likely have the lower CR 62 cc chambers for lower CR.
For 1.75" intake valves and carb hole, hardened seats, and larger volume intake tract, look for a D7XX or later. Some of these later casting had the flat-topped log. There is some indication that the EOXX castings have even larger intake volume. But they do have several EPA taps and bungs cast on that will have to be dealt with.
Adios, David
Sorry Ronn, the D5 castings were the last to use 1.65" intake valves. It will have the larger 1.75" carb intake hole and slightly larger intake tract volume than CXXX castings ( with the exception of the C9XX-M, flat-topped log castings).
It will likely have the lower CR 62 cc chambers for lower CR.
For 1.75" intake valves and carb hole, hardened seats, and larger volume intake tract, look for a D7XX or later. Some of these later casting had the flat-topped log. There is some indication that the EOXX castings have even larger intake volume. But they do have several EPA taps and bungs cast on that will have to be dealt with.
Adios, David
ugh...oh well. Well, should'nt be that bad since theres only like 3/16" difference in valve sizes. That could be made up with induction enhancments 
Ram air? Or what about buying the larger valves and have my nearby machine shop grind the head for them? What part numbers do I need cause I'm interested in doing it. As well as have the guides replaced to bronze exaust etc. Oh and will the stock size guides and retainers work in the larger valves?
Or will the added performance be not to noticable and just to scrap the whole idea?
Ram air? Or what about buying the larger valves and have my nearby machine shop grind the head for them? What part numbers do I need cause I'm interested in doing it. As well as have the guides replaced to bronze exaust etc. Oh and will the stock size guides and retainers work in the larger valves?Or will the added performance be not to noticable and just to scrap the whole idea?
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