Setting of PHF 32 AD/AS on a 750 GT

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froggie
Mariana
Posts: 30
Joined: Sat Feb 17, 2024 2:42 am

Setting of PHF 32 AD/AS on a 750 GT

Post by froggie »

I am am a bit confused about what could be a correct setting of jets, needles, etc. for PHF 32 AD/AS, as currently fitted on my 750 GT (OEM was Amal 30).
Asking the question because some of my fueling/ignition issues may be related, although I understand that I should beforehand check timing and possible air leaks.

The PHF 32 AD/AS were standard on the 750 Sport .
According to Falloon, the normal settings on the Sport are the following:
main jet - 125; idle jet - 70; slide - 70/2; needle jet - 265AB; needle SK17/2nd notch

The PHF 32 AD/AS were also fitted to the 860 GT with normal settings as follows:
main jet - 122; idle - 60; Slide - 70/2; Needle Jet – 265AB; Needle- K6/2nd notch.

Some users of PHF 32 AS/AD on their 750 GT however indicated on this forum that they used a 60/1 slide instead of 70/2 and also a 65 pilot jet instead of 70. No other indications however concerning the other parameters.

I understand that the Sport has higher compression pistons than the 750 GT, and that the 860 GT obviously has a larger volumetric capacity, so that it is difficult to guess from the data above what could be an adapted optimised setting for the 750 GT.

In the end, what could be the best (or at least a good) setting of all the parameters (main jet, idle jet, slide, needle jet, needle) for PHF 32 AD/AS on a 750 GT, or at least where to start from? (I do not know yet what is my current own setting, not having disassembled the carbs)
Any opinion is welcome!
froggie
Mariana
Posts: 30
Joined: Sat Feb 17, 2024 2:42 am

Re: Setting of PHF 32 AD/AS on a 750 GT

Post by froggie »

Responding to myself.
I just found a very relevant thread here: https://forum.bevelheaven.com/viewtopic.php?f=26&t=4818

Actually it's not that easy to find these threads on the forum, a research often leads to a saturated server unable to deliver. :?
At least this time I was successful :-D

So it would be:
Slide = 70/2; no mention of 60/1 here
Needle= K16 (bottom / richest notch) orK3 (middle notch) or K6 (middle notch); that's still very open... :?
MJ=125; 115 would be too lean
Pj=62 or 65; 60 seems unsuitable and 70 not mentioned
AB 265

Overall, it seems like alchemistry and requiring further tests :lol: .
But at least it gives a starting basis not too far off!
Chasbmw
Cucciolo - the Lil Pup
Posts: 18
Joined: Mon May 24, 2021 8:41 am

Re: Setting of PHF 32 AD/AS on a 750 GT

Post by Chasbmw »

That’s interesting my GT is undergoing a full rebuild but with sport pistons and a slightly hotter cam.

My Haynes manual gives different settings of 125 mj front carb and 122 rear

Anyone know why?

The needles are K6s

Should there be an adjustment for the higher CR. measured at 9.2. And the hotter cam?

Charles
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