FL,FLH Panheads heads.

[Tom Barlett]

What is the difference between FL and FLH heads?Is there different number of fins?Are the heads the same casting but one is polished and ported more?I have a 61 FL and 63 FLH and want to make sure I have the right heads.Also a friend of mine has a 57 FLH and he would like to know.Thanks

[bmh]

Supposedly it was polished intake ports. On pans anyway, I've never seen a set of shovels with factory polished ports. The only other differences I'm aware of are the cam and higher compression pistons.
Brian

[cdndewey]

I think you'll find the main difference is the valve springs. If you look in a parts book or a service manual you'll notice different part numbers and different specs for FL's and FLH's. As far as the physical aspect of the heads, that is mainly a year thing, ie: fin size, porting, outside oilers. I hope this sheds some light.

[Rubone]

FL and FLH castings are the same. The only heads I have ever seen that were truly factory ported were '55 and '56 heads, only on the H models. It seems the factory gave up on the porting early on and just depended on the cam and as mentioned the heavier springs to control it, also the pistons which were higher compression ratio. Otherwise the engines were the same, when castings or features changed it occurred across the board. By the way, I have seen several factory ported heads where the casting broke out between the valve seat and port where it is quite thin, with pieces missing. Possibly why the practice was discontinued.
Robbie

[portagepan]

On this topic. Is the correct compression ratio for a 1965 FLH 8:1?

[bmh]

I thought that all FLH motors were 8.5:1 C.R., but in looking in my panhead service book I see it listed as 8:1. But I must note that the specs in this book are wrong on the C.R. for 48-54. It lists FL's as 7:1, Yet all the period factory literature says 7.2:1. Maybe someone knows for sure as I see only one piston listed for FLH's 55-73.
Brian