OHH50 monkeying with jets

jeffe

jeffe

Member
#1
#1
I tried a few different jet sizes on my stock Ohh50, the one that came with my new cheap carb (fits a #69 drill) I thought it was lean ...wouldn't rev up. Turns out it was blowing black which I couldn't see initially.

Then I tried the jet from the original carb which is stamped with 166 and fits between a #64 and 65 drill... really blowing black...

So, I took the smaller one, soldered it closed and redrilled with a #71 drill. It runs better.. revs up and doesn't bog..

If my 'plastic' cam was worn a bit would it cause it to run better on the smaller jet? Or does that not compute..? :shrug:
 
delray

delray

Well-Known Member
#2
#2
i would doubt your cam is worn,even though it is plastic..:doah: for maybe best performance up grade for when it comes to carb's for that engine would be a adjustable idle and main jet carb...:thumbsup:
 
jeffe

jeffe

Member
#3
#3
Thanks, I thought the carb I was buying at least had the adjustable idle air screw..apparently , I didn't look close enough at the picture..
I didn't measure the cam lobes before I put the cover back on...should have, but it looked okay.
 
delray

delray

Well-Known Member
#5
#5
that looks to be a big block carb or H series.
i have good look with the rupp style hs-40 or hs-50 replacement carb they do have the adjustments.
only problem , they don't have the crank vent hookup so i by pass that into a small filter unit and i am not using the correct governor setup.


also i have modified this engine little,advance the timing ,mill the head,header, have a newer style steel cam and 16 pound animal springs and aftermarket automotive style retainers and keepers and even the air cleaner.
 
jeffe

jeffe

Member
#6
#6
Okay, thanks, I'll check out those carbs.
Seems like it's going to run alright for now, so I'll get them to put one on the slow boat for me... :)
 
Dr. Shop Teacher

Dr. Shop Teacher

#7
#7
The one thing you'll need to do is tune this engine with the air cleaner installed. Delray and I have swapped notes a couple of times, and we keep coming back to an HS40 carb with a straight fuel inlet. The intake runner is so long, you'll get that blowback no matter what you do so just expect some. As Delray has done, a new shorter intake (no governor) fixes this problem but you'll have to go to a billet rod.
 
jeffe

jeffe

Member
#8
#8
Dr. Shop Teacher said:
The one thing you'll need to do is tune this engine with the air cleaner installed. Delray and I have swapped notes a couple of times, and we keep coming back to an HS40 carb with a straight fuel inlet. The intake runner is so long, you'll get that blowback no matter what you do so just expect some. As Delray has done, a new shorter intake (no governor) fixes this problem but you'll have to go to a billet rod.
Click to expand...
Thanks Doc. :)
Yeah, my tuning when I ended up with the #71 drill jet was done with the stock filter on. Initially I had been trying it out without a filter, but then I did some reading and found that suggestion on here... :thumbsup:

I ordered a clamp on filter and plan to make or buy an adapter.

I should say that my initial thought of the cam being worn was because of some grey/black stuff at the bottom of the crankcase. Maybe someone put some moly in it or some other additive. I don't know.
 
delray

delray

Well-Known Member
#9
#9
jeffe, here is something to think about too for a air cleaner. works just as good as a aftermarket for what your doing...:thumbsup:
i just took a stock tecumseh air cleaner housing and cut the outer piece off and just save the retainer to hold the air cleaner on.
also purchase a outer wear filter that go's over all of it. poor man's K&N filter...:laugh: hey it work's good.


housing cut off.


outer wear over the stock air filter and cut off housing?retainer
 
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