hs-50 d shaped intake port.

#1
when looking at this port at fist glance it looks pritty hopeless from a performance standpoint. i though get rid of the casting flash and break the sharp edges on both left and right sides of the port. after a while i came to realize the casting was thick enough to get a nice smooth transition the length of the port on both sides. then i started to adress the sharp step on the floor of the port. again came to realize i could get a nice smooth transition from the floor to the valve guide stem. now time to do the exhaust port. anyone out there hav pictures of a ported hs 50. i would like to see how others have approached this. anthony.
 

Attachments

delray

Well-Known Member
#2
you got couple options on how to address hs-50 port. I personally think type of intake,cam(rpm your going to be turning,carb, application...etc. will dictate your porting. seen guys epoxy the port and bowl area get a better flow. need to use a good epoxy for that. maybe welding some aluminum may also be a option.
ole4 another member here can maybe chem in. he is more knowledge then me on porting and what parts may benefit the most for your project. he also has done some bench flowing with clone heads. not sure if he has setup a flathead yet?
also if you decide to make this into a engine build maybe you can post the engine project under the Tecumseh engines.....
 
#3
you got couple options on how to address hs-50 port. I personally think type of intake,cam(rpm your going to be turning,carb, application...etc. will dictate your porting. seen guys epoxy the port and bowl area get a better flow. need to use a good epoxy for that. maybe welding some aluminum may also be a option.
ole4 another member here can maybe chem in. he is more knowledge then me on porting and what parts may benefit the most for your project. he also has done some bench flowing with clone heads. not sure if he has setup a flathead yet?
also if you decide to make this into a engine build maybe you can post the engine project under the Tecumseh engines.....
delray. that sounds like a good idea. the engine is a new build. its completely torn down again. iv done the intake port, so if i got the shape wrong i screwed. i might not gain as much as i could have but i believe its got to grow a bit better than stock. i will wait for input before i do the exhaust port. i really don't navigate the forum very well as i typed in hs50 porting and nothing came up. thanks for the response.
 
#4
Never bothered with flow testing the flathead. This was a late model HS50 with the small exhaust valve. I opened up the cast seat to take a old larger hs50 valve. I made the port a constant cross section filling in the d shape with jb weld as the manifold I made was round. I had the reground mech advance cam reground by isky looks like a BM JR with a 108 LC. With a 22mm chikuni and the cam plus valve job it ran OK but nowhere near the performance of some of my built clones. When I ran into ignition issues I replaced the coil with a hot coil and I have to say that made it come alive. Unfortunately it is on my old atlas with a tc88 converter and it is almost unrideable unless you are used to it. until it starts shifting up it will just flip over, once over about 8 MPH it drives nice.
 

Attachments

delray

Well-Known Member
#5
just not a lot info when it comes to porting a hs-50 port or crazy builds on flathead hs-motors. I thinks the best knowledge your going to get from this site might be someone like ole4 I mention earlier or do your research on flathead racing motors...briggs...Hblock tecumsehs....


I see ole just chem in as I was typing this....thanks ole...…..
 
#8
my hs50 is an early one. 1972 so big valve for rings. my ports have the deeply sloped walls behind the valves. you say the pictures you sent are of the small valve hs50? that would mean they changed the port shape behind the valves no ramp. is there and advantage to the newer stile block besides the thin ring pistons. i chose the early block for the esthetics. bigger bore and it had a lighted coil. this was in 2010 and did not do a lot of research. between that and my impulse buying,its come back to bite me in the ass. again guys thanks for the input. anthony
 
#9
I have a thick ring piston in an earlier Hs50 (big bore, big valves) with Dyno 245 cam and 18lb valve springs Chikuni carb etc. and it revs right on up to 7000 rpm like nothing. So just because the piston has thicker rings doesn’t mean it won’t perform well IMHO and in my experience.
 
#10
I have a thick ring piston in an earlier Hs50 (big bore, big valves) with Dyno 245 cam and 18lb valve springs Chikuni carb etc. and it revs right on up to 7000 rpm like nothing. So just because the piston has thicker rings doesn’t mean it won’t perform well IMHO and in my experience.
massacre. my 1/32 exhaust valve came today. intake came a day or two ago. tomorrow my rupp hs45 will be hear. i can't wait to see that lighted aluminum flywheel. now im waiting for the tecumseh factory pilot ream. still have to find a shop to cut the valves and seats. i see no reason for this engine to not be a decent runner. and theres always the hs 40 to fall back on. anthony.
 
#15
Well I know I have posted pics but not sure if I ever started an official build thread.
massacre. i don't know wate a official build thread is. i can barely navigate this forum. and if i did figure out how to start an official thread i don't have the experience to give advice. but i will keep posting even if my build looks silly to the pros out there. its entertaining and i will learn a thing or to. tomorrow when that hs40 comes om gonna rip the blower cover off and post a picture of the elusive lighted aluminum flywheel. to me that piece is the holy grail. anthony.
 
#20
Never bothered with flow testing the flathead. This was a late model HS50 with the small exhaust valve. I opened up the cast seat to take a old larger hs50 valve. I made the port a constant cross section filling in the d shape with jb weld as the manifold I made was round. I had the reground mech advance cam reground by isky looks like a BM JR with a 108 LC. With a 22mm chikuni and the cam plus valve job it ran OK but nowhere near the performance of some of my built clones. When I ran into ignition issues I replaced the coil with a hot coil and I have to say that made it come alive. Unfortunately it is on my old atlas with a tc88 converter and it is almost unrideable unless you are used to it. until it starts shifting up it will just flip over, once over about 8 MPH it drives nice.
ole. i looked at your pictures carefully. at fist i could not see where you filed in. tig welding half me life killed my eyesight. they are some big ports. they probably flow good. hear is my problem. its getting a reground dynacam 245 and ark billet rod so i need decent flow. but i need to youse a stock tecumseh carb for that vintage look. so im stuck trying to make that d port flow. thanks for the input. anthony.
 

Top