Carb differences between Tillotson HT3A HT5A HT7A carbs for 084 088 and MS880

[rynosawr]

Hello all,

I have been posting some but feel like I haven't added much to the forum, so I haven't seen any pics of the differences in these carbs and I thought I would document the similarities and differences.


I have the HT3A, HT5A, and HT7A carbs here for this documentation.

All have the same butterfly bore of 27mm, the same Venturi and choke opening and butterfly design as well.

As for the differences in the jetting/fuel circuit,

The HT3A has approximately a 1.10mm hole and a smaller hole in thebrass jet plug approximately in the center of the carb body

The HT5A has approximately a .75mm jet (not numbered)

The HT7A has a numbered .90mm jet and has a brass insert for the filter compensation circuit that is drilled into the Venturi bore (marked in red)


I will have to edit my photos because many are sideways.....

:-E

 

[rynosawr]

Ok, as promised.....

The pics and differences....

 

[rynosawr]

 

[rynosawr]

I see no differences on this side

 

[Dixiepipes]

I'm having the same questions sorta. I have a few of these different models and need to know which one is the better? Their has to be a model better than the other or they would not have different numbers. I am referring to better as a race carb though.

 

[RedneckChainsawRepair]

I'm having the same questions sorta. I have a few of these different models and need to know which one is the better? Their has to be a model better than the other or they would not have different numbers. I am referring to better as a race carb though.

HT 1 2 3 5 7 = Race HT1

Had the same question years ago. DC hotsaws gave me the info.

me = Which one of these carbs has better circuity for opening up for more fuel flow or are they the same?

Dennis Cahoon = One thing about the newer HT's, they have a Hi speed jet that's in the way when you want to round slot (T-slot) the fuel area. You can do it but it's annoying to work around. When I have time, I'll take a look at the HT's I have and try to answer you question better. I would go with the HT-1.

 

[backhoelover]

from what the tech bulletins say you want a ht11 they went to a ht 11 to help with performance

 

[backhoelover]

or a ht 12. only different is the ht12 has limiter caps