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TR6 TR6 with Su HS carbs

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hughv

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I Have been working on my Brothers 73' TR6 he installed rebuilt SU HS Carbs i'm not sure what car they originally came from, has anyone done this conversion and if so what needles and damper springs did you use? i had the car running today after resetting the mixture and idle i took it for a spin it has very poor acceleration and sluggish (i have a TR4 and it would have blowned the door off the 6) The gas is quite old and i plan on draining the tank and adding fresh gas next week could that be one of the problems? Hugh
 
hughv said:
The gas is quite old and i plan on draining the tank and adding fresh gas next week could that be one of the problems? Hugh
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Absolutely! Definitely get some fresh gas in there and then reset the mixture.

Also check what's in the dampers. IMO if it's not at least 20 weight motor oil, you should suck it out and replace with 20W or heavier. The dampers are what give the mixture boost for good acceleration; otherwise you'll have a lean bog when you open the throttle.

And double-check that someone hasn't set the timing to the book value of 4 ATDC. That figure applies only with the vacuum retard operating; but the HS6 carbs will almost certainly not have the proper vacuum retard port (and for sure you don't want the retard connected to the vacuum advance port). With the retard disconnected, you want the initial timing up around 10-12 BTDC.

I didn't find the TR6 listed in my SU manual, but they show NZX8002 needles and AUC1167 springs for a 75-76 2500 converted to HS6 carbs. TR6 should be similar.

PS, while I certainly don't mean to impugn your brother, it has been my observation that most of the folks who convert a TR6 to SU carbs are trying to solve a problem that turns out to not be carburetion at all. In spite of "all that emissions crap", the original ZS carbs actually work pretty good. So don't be surprised if your lack of performance turns out to be something else.
 
Thanks for your imput i will check the timing, actually i found a rebuilt distributor. After i get the fuel delivery sorted i will install the new distributor. Do you know of a scorce for the su needle and spring? Thanks Hugh
 
Google "Joe Curto" or "Paltech" either one will have both the info and the parts.
 
Still having issue with the hs6 for some reason i am unable to get the mixture on the rear carb correct i have gone through the standard mixture setting adjust nut all the way up then down 2 to 2 1/2 turns engine idles fine, reset float level, when i lift the piston to check mixture engine speed stays the same i can lift the piston all the way up still engine speed stays the same i have tried moving the mixture nut up and down with no change in engine speed i have noticed a popping sound from the exhaust any suggestions? Hugh
 
Have you checked the synchronization? Sounds like it's not sucking through the rear carb at all, or at least not very much.

With the piston all the way up, it's not contributing any fuel at all, unless the fuel is literally running out of the jet on its own. Fuel running out on its own might indicate a bad float (Burlen has recently started offering "unsinkable" floats in response to all the troubles with original ones) or fuel pressure just a bit too high. Or even just a bit of crud caught in the float valve.
 
i have checked float levels and reset them the floats themselves seem to be ok i did balance the carbs to get the correct suction .Because i don't know the condition of the engine i plan to do a compression test, just a theory there may be a problem with valves or rings (low compression) the engine will idle fine but when i rev it doesn't rev freely kind of flattens out any suggestions would be appreciated Hugh
 
You have never written why the change to SU's was done. Was it for this same issue? If Yes then I'd be looking for the problem elsewhere. If No then look for vacuum leaks or mechanical issues like the butterflys are not opening all of the way. Also did you change needles to the ones Joe Curto would recommend or the ones Randall suggested?
 
Might not be the issue, but if the carbs are from a Volvo, then the float bowls might not be at the correct angle - are they tilted on the car? That could be part of the problem if so.
 
I worked on the car today the float bowls are tilted, i tuned the carbs as best i can. the engine seems to be missing when revved the plugs are either sooty or wet with gas not sure what's going on there the engine idles but not smooth looking for suggestions. Hugh
 
See TR4nut's post ? No use fiddling with the carbs until you get the float chambers vertical... Joe Curto can fix you up with the part you need.
 
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