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Dellorto phf 32 carbs for 850-T

Discussion in 'Loop & Tonti' started by cragar, Jul 28, 2010.

  1. cragar

    cragar Just got it firing!

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    Hello everyone, I'm new here, just bought an old 850-T. I have a spare set of PHF 32 carbs leftover from my Duc and I was thinking about fitting them to the Guzzi. anyone out there have any experience with that mod? if so was it worth it and what's a good starting point? Jets?slides?neddles? etc...thanks
     
  2. guzzibob

    guzzibob GT Reference

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    I have a T3 (very similar to your T) that I mounted 32PHF's from someone's Duc, oh, maybe 20-25 years ago. As it came the jetting was terrible. I managed to get it pretty close without too much effort, but it took a good bit of time & experimentation to get the last little bit (meaning, a sag just off idle when the throttle was rolled up slowly) sorted. It runs beautifully now, way better than stock from about 4500 rpm out to readline, with little to no loss below that. Maybe 5-10% lower gas mileage, for me very well worth it. I think the 32 PHF's are a very good match for the small valve big blocks like the T & T3. Part of the way through this jetting evolution my 850 became a 1000 (more or less), but I don't feel that made a whole lot of difference in the jetting. What I came up with should be close.
    Can't do it right now, but I will get back & post the details within a few days, including what you have to do to mount the things, which turned out to be not so simple, but doable.
     
  3. Tonerjockey

    Tonerjockey High Miler GT Contributor

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    Here's how I did it.

    Gotta increase the ID of the manifold. Get some nylon and cut 2 bushings to fit. Contact Gordon at MG Cycles and tell him what you want to do and he will set you up with cables. Make sure you get the bendy tubes.... you'll need 'em.
    I haven't figured out the jetting yet.

    2 -32's ready to install on a V7 Sport:
    [​IMG]

    Close up of the nylon bushing:
    [​IMG]

    Good luck. Post your results so I can copy 'em .... :eek:

    Alex
     
  4. cragar

    cragar Just got it firing!

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    nice! Did you just use Nylon tube? where did you get it? and was there a lot of machining involved? can I just use LM1 intakes (if I could find them)? and sorry to ask so many questions but I'd still really like to know what you guys are using for jets and slides.
     
  5. Tonerjockey

    Tonerjockey High Miler GT Contributor

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    Hey Cragar,

    Dunno about jets yet. Picked up an assortment of mains, got a bucket of pilot jets. Gunna try em at Bonneville in a couple of weeks.

    The nylon was a 2" stick 12" long I picked up from a supply house. I used a lathe to cut the bushing. The bushing is not a straight tube but has a lip on it. Check out the VHB's.... those are basically the same.

    I imagine you could use Lemans manifolds depending upon what 32's you have. Do your carbs mount with a clamp like the ones in the picture or do they use a rubber sleeve to mount to the manifold? The model number of the carbs will tell you but I forget which are which.

    Generally speaking, Lemans' stock manifolds use a sleeve. 850T's and older use the clamperz (give or take models that don't heh heh ). Lemans (stock) use 36mm carbs and you have 32mm carbs. There probably is an ID difference between correct intake manifold sizing for these two different carb sizes (called choke size in some circles).

    Then there are other intake port and manifold inside diameter issues. My head ports are enlarged. I opened up those intake manifolds you see in the pictures to match the 32mm carbs. Also I Dremeled the head/manifold gaskets for smooth flowage.

    The stock manifolds for VHB30's have inside diameters smaller than 32mm. Seems to me ya gotta open up the ID of the intake manifold... it was kinda tricky. Lots of hand work.

    The reason I did all this is to try to increase my top end performance. The bike these carbs I intend to run with is a race bike and only runs at wide open throttle (WOT). I run at top end, I am less concerned about how the bike takes off from a stop light or how (IF?) it will idle and overheat.

    If I can dteremine which jets work best for my application I'll post the data.

    Good luck on whatever you wind up trying. I think this forum is a great place to share the experiences.

    Alex
     
  6. guzzibob

    guzzibob GT Reference

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    OK, here is jetting & other info on my T3 30 VHB to 32 PHF carb conversion. Should be same for T as far as I know. A couple of notes:

    1)I like Tonerjockey's use of plastic sleeves to adapt the stock metal intake manifold. Seems a lot easier than what was done on my bike, namely welded up then turned down to match larger aperture on 32's. Also, LM I or any other manifold I am aware of used to mount 36 or 40's as on various Guzzis such as LM I-V & others will not work cause the mounting is different, namely the male/female is backwards from how the VHB's & 32 PHF's mount. That is why the conversion to 36's is easier than to 32's, there are off the shelf manifolds that work. Also, in order for the PHF's to clear the starter selenoid on the left side, you need to use 2 rather than 1 gasket between the intake manifold & the head-on the left side only. Though it doesn't hurt if you use 2 on both. With both gaskets in use, the reservoir at the bottom of the float bowl clears the selenoid by, oh, the width of a piece of paper. Since these manifolds are rigid unlike the rubber ones used elsewhere, has never been a problem or issue. Except that to change jetting on the left side you have to either pull the 3 bolts attaching the manifold to the heads or drop down the starter. Annoying, but not really difficult. No such issues on the right side. Do take it easy with these 3 bolts, easier than you would think to strip, require helicoils.
    2)Looks to me like Tonerjockey has correctly identified cables from MG Cycle that should work without the need to have someone make up custom cables like I did. These bikes did come with the 2C Tomaselli throttle. The stock cables do not work because the PHF's require a different end than the VHB's do.

    (EDIT-called MG Cycle, spoke to Gordon who knows all, & cables described above, part # "cable1" if standard bars, or "cable2" for the high wide police bars, are not exactly "bolt on," cause they assume PHF or PHM carbs that come with a metal "elbow" attached to the top of the carb that makes a curved 90 degree turn in the cable. The 32 PHF's have no such elbow, the cable goes straight in through the top. So you need to also buy the elbows from MG Cycle, part # 3698 to make everything work. So if you want the MG Cycle cables, just call & tell Gordon exactly what you want, ie Tomaselli 2C throttle to 32 PHF carbs, with whatever bars, & he'll be sure you get what you need.)

    3)Unlike Tonerjockey, my application is strictly street, & jetted accordingly. That said, when I went from 850 to 950/1000 cc (whatever it was) I went from 122 to 150 main jets, without any other jetting changes. That 150 seems way too fat, since on my 1000S with 40 PHF carb's & the big valve engine I went from the stock 145's to 128 main jets, & that bike runs like the proverbial "raped ape" at high throttle/rpms. The 145's were clearly way too fat on that bike. When I get around to it I'll try some smaller mains on the T3, after all they are cheap. That said, the thing runs way, way better than stock at anything over 4500 RPM or so.

    So here it is, copied from my notes:

    My bike runs very well, except for a very slight, usually subtle just off idle hesitation when I bring the throttle down almost to idle, then bring it slowly back up. (SEE BELOW-SOLVED BY REPLACING K6, OTHERWISE FINE, WITH K1) It is most noticeable in top gear at freeway speeds, not noticeable at all when ridden hard. Compared to the square slide 30's the bike came with, I lose 10 mpg (more recently, more like only 5 mpg) & a little low end, say below 3500 RPM. I think it is about even 3500-4200, then all plus from there on up, esp 5000-6500 RPM. Below is the jetting I have, & have tried. This bike retains stock cam, exhaust & heads, except for being lightly ported. It has been twin plugged-but that did little except put money in Charlie Rice's pocket-truly an evil result. I do have K&N air filters (the big oval cans, not the much smaller cones often used on various LM) & Dyna ignition (not relevant to jetting).

    Idle jet-55 (have been as high as 62)
    Main jet-150 (was 122 before I converted from 850 to 1000cc)
    Needle-K-1, middle slot. (Replaced K6 with K1, solving remaining off idle hesitation problem.) This was really the big thing. Carbs came from bevel drive Ducati with K-16-almost unrideable, no low end whatsoever with the K16. Also tried K3, K5, then K6 for a long time until 8/04. Also tried other slots in K1.
    Needle jet-AB265 (tried 264)
    Choke jet-75
    Spray needle-38 (tried 35)
    Float Weight- 10.5
    Float position-18mm
    Float level-65cc
    Slide-60/3 (tried 70/2, 50/3, made 65/3)
    Float needle-250
    Idle screw-short, pre-EPA

    So at the end of the day the items that were changed from how it came off the Duc were idle & main jets, needle (by far the most important change), & maybe the needle jet.

    By all means lay your hands on the Dell Orto tuning manual to better understand what you are doing, & what you might need to change if my jetting needs a bit of modification for your bike. The thing is very, very helpful.

    Good luck
     
  7. cragar

    cragar Just got it firing!

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    That is an awesome bunch of information! Thanks for your time everyone! I'm sure these posts will be very apreciated by many a Guzzi fan.
     
  8. Tonerjockey

    Tonerjockey High Miler GT Contributor

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    Hey Guzzibob,

    Great stuff! I have 142 mains in my 32's and have yet to try em. Dunno what needles I have!!! Guess I better look..

    Thanks all,

    Alex
     
  9. Tonerjockey

    Tonerjockey High Miler GT Contributor

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    Just checked my32's and they had K16's. I'll see if I can get some K1's.

    [​IMG]

    Thanks for the info's.

    Alex


    BTW I have a new mascot for the race bike... Porco Rosso :p
     
  10. guzzibob

    guzzibob GT Reference

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    Note the edit to my earlier post re: use of the MG Cycle cables on the conversion.
     
  11. Tonerjockey

    Tonerjockey High Miler GT Contributor

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    I recommend not dropping a carb with the bendy tubes attached. They break very easily.

    Happy Trails,

    Alex
     
  12. Chris R

    Chris R Cruisin' Guzzisti

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    Believe me I would love to bad mouth Charlie - the scurvy dog never made good on a order I sent against a large credit and then farked off to europe - but twin plugging is IMO a good thing IF the engine is built to take advantage of it.

    1. Twin plugging of itself will not add any power.
    2. It will allow you to run higher compression without detonation which will add power- with T3 pistons you are unlikely to be detonating.
    3. If the engine is breathing through anything less than 36's the effective compression won't great enough to cause detonation as well.
    4. It will allow you to retard the ignition about 6 degrees which will give more power IF you recurve the distributor to suit.

    So on a more or less stock T3 it isn't going to do much, on a Lemans most definitely unless you live in an area with super octane.

    This isn't caused by the carbs - they pretty much provide a constant air-fuel ratio with minor variations - this is caused by you using your wrist more!

    And thanks for the detail - maybe we should have a sticky devoted to jetting?
    Ta,
    ChrisR
     
  13. guzzibob

    guzzibob GT Reference

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    Since the bike in question is in fact "a more or less stock T3", twin plugging in fact didn't do much as we both stated, with or without more advance. Did not mean to imply that would be the result in every application, especially one with a much more contorted combustion chamber than a stock T3. As for the mpg thing, seems to me we are quibbling about what is meant about "causation." All I know for sure is that after the carb change performance went up & mileage went down, though less so after I got the jetting finally squared away. On the one hand there is clearly more motivation as you suggets to twist the throttle more when I want to get moving in a hurry, since I get so much more result now at higher rpms & throttle settings. On the other hand there are also some times when I just want to get a certain result somewhat less than max, & it takes a lot less effort shifting/throttle twisting etc now than it did before, because it runs so much stronger over most of the range. Whatever, point is the end very, very much justified the means. I just love the way this bike runs now, & never miss an opportunity to say so.

    Oh, & a big plus one on the Charlie Rice as scurvey dog thing. You were by no means the only one cheated by him, as I suspect you know.
     
  14. Tonerjockey

    Tonerjockey High Miler GT Contributor

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    Installed the 32's in my V7 Sport and did 3 runs at Bonneville.

    Best run was 124+ MPH. A 10% + improvement over stock. VHB30's.

    GuzziBob.... wow great needle / ject combination! Thanks.

    Now setting up PHF36's to try. Measured my heads and they're ported to 36mm. Made some 8 to 6mm step studs.

    just FYI.

    Al
     
  15. guzzibob

    guzzibob GT Reference

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    Glad to be of help. It took quite a while & lots of experimentation to get to the final street result, though probably 75% came quickly just from getting the stock K16's out of there. Anyway, no reason everyone should have to reinvent the wheel, right? You get that 10% top end improvement strictly from the carb swap? Do you have any idea how much of a HP bump it would take to get that much more top end? Just curious. Hope you get a similar or even greater bump from the 36's.
     
  16. Tonerjockey

    Tonerjockey High Miler GT Contributor

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    I dunno about the HP. Seems I am always in a rush getting ready to race and can't seem to get to the dyno enough. Also, I would rather blow it up on the salt or dirt instead of the dyno... :eek:

    Pair of PHF36's ready to mount on V7 Sport. Made up some 8to6 studs. I need to test run this set up before leaving for Utah.

    [​IMG]

    I hafta run VHB30's for the record but nothing sez I can't try stuff out long as I'm there eh?


    Alex
     
  17. Rafael

    Rafael GT Reference

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    Great thread.

    The aftermaket (black) manifolds shown in Alex's pic above are available at MG Cycles http://www.mgcycle.com/index.php?cPath=178 these require a 8mm to 6mm step down stud on T-3 heads (8mm stud holes).

    The other manifolds shown are the original 850 LeMans style with 6mm mount bolts, the stock rubber part of the manifold is still available at many retailers.

    My T-3 has the 1000SP NT two part manifold. The aluminum portion mounts with a 8mm countersunk bolt. But, alas, the rubber (elbo with vacuum plug) portion is no longer available.
     
  18. contractor20

    contractor20 Cruisin' Guzzisti

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    Raph I might have what you are missing. I scored a set of 30mm dells with those damn rubber elbow things on the motor side of the carb and even modified a set of short straight stubbs (long story)to suit but the carb kept hitting the starter. So i bought some black plastic things and as I couldn't find any stepped studds turned down the outside top of 8mm allen heads and removed the brass eyelets and eased some material from around them. Its a tight fit but works.

    :idea: Reply if your interested in the rubber manifolds ....
     
  19. klinkhammer

    klinkhammer Just got it firing!

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    First post!
    I have a V7 sport with PHF 32's. When I bought the bike it came with some needles and jets but I never got it sorted out. Lately I've been running it with K18 needles. Revs great from about 2500 but nothing under that... It works but I really use the clutch.
    Just got back from a test drive with K1 needles. What a difference, pulls like a steam engine.
    Thank you guzzibob!
    /Johan
     
  20. klinkhammer

    klinkhammer Just got it firing!

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    Did some further testing today. Moved the needle clip and tried some different jets but ended up very close to guzzibob.
    K1, middle slot. Idle jet 55. Main jet 130.
    For the record; except for the phf's, my bike has (to my knowledge) no modifications. The cylinder barrels got sleeved way back, but everything else is a stock V7 sport 1972.
    Thanks again guzzibob.
     

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