Rebuilding SUs?

[m240]

The mechanic who is putting new floorboards in my Z tolld me the carbs need to be rebuilt. They are 71' round tops. He wants about 600 labor and about 200 parts so I am going to try it myself. I've seen posts both for and against using the grose jets from ztherapy. Any opinions either way? I've also seen posts warning against using to wrong tubing on the float bowls. Does anyone know if the float tubing that comes with the motorsort kit is the same grade as the one from ztherapy in case I go with that one instead? I've watched the tape from ztherapy and it doesn't look to hard as long as I go step by step.

any opinions or advice are greatly appreciated!!

[2ManyZs]

I may be mistaken, but I think MSA sells rebuild kits supplied by ZTherapy. I'm not 100% sure but I think the reman carbs that MSA sells are also done by ZTherapy, that is why they get a premium price for them.

Easy way to find it is to call MSA's tech line and ask them who supplies their carbs and rebuild kits. The number is (714) 639-2620 if you don't already have it.

[jcdozier]

Why not just get the kit from ZTherapy? I rebuilt my '71 roundtops with the ZTherapy kit last year - it's not difficult to do and you get the "right" tubing. Plus it's a LOT cheaper than the $800 or so the mechanic wants to charge you. I've also seen the yes/no posts about the grose jets - haven't had a problem with them.

[hmsports]

The SU's have an aura of voodoo.

They are not difficult to deal with. I know that ZTherapy does a wonderful job of cleaning, replacing bushings and the like, but I've found that taking the carbs apart and giving them a nice bath in carb cleaner and a good cleaning with a toothbrush... then replacing the jets (I don't use the grosse jets - just stock ones), adjusting the floats, replacing the float gaskets and fuel hoses (I purchased some aftermarket hose from a motorcycle shop in town) will do wonders.

I purchased the rebuild kits from Victoria British (Ok guys, don't bother flaming me about VB, it's been done before) and just used aftermarket hoses. The rest of the stuff is fine -- and cheaper too.

Just take your time. It's very rewarding.

Rick

[AxtellZ]

I'm with Rick on this one..

I too have used VB, and even Napa rebuild kits on 3 "refreshes" now. (yes, 3 different cars, didn't have to redo one 3 times!)

I agree the fuel hose is not ZT quality, but it serves the purpose quite well....also, you can order just the fuel line fron ZT for 6 or 8$ each if you want.

Just clean off a well ventilated area & get cleaning, it really is quite simple- if you have the video, you're set.

One thing i did was to work 1 carb at a time the first time, so if i screwed something up i had one to reference back to.

Don't be intimidated by the voodoo, its easy and rewarding- spend your $600 on something fun! like a carb synchronizer...

HTH, Jeremiah

[Daniel]

I also vote for -do it yourself.A buddy of mine is a mechanic.When the new cars come out the factory shows how much time is paid for whatever job.He said the first couple you lose money while learning.Then you make money by completing the task in less time.If you pay to have the job done you are no better prepared for the future.Take your time.Take photos,draw pictures whatever it takes to put humpty dumpty back together.I also agree with the one at a time.That way you do have a correct one to compare and you don't mix up parts.Then in the future you won't need that mechanic.You won't be afraid to dig in should the need arise.Myself I would go as close to factory parts as I could get.The last ones lasted 30+ years.Thats cheap! Have fun!! Daniel

[laffeaux]

Ztherapy has a video called "Just SUs" and it's well worth watching. After seeing it, working on your carbs seems very easy. If you live in the SF bay area you can borrow mine.

The mecahanic is way overpriced. $800 for a rebuild is crazy, when for $600 you can buy Ztherapy carbs and install them yourself in about an hour. If you have the ability to check your butterfly valve linkage (i.e. if your carbs are off the car) then you can see if a rebuilt kit will work. If your butterfly vale moves excessively (side to side), air can be sucked into the engine at the back of the carb (that's bad). Thereare bushings that will eventually wear out, Ztherapy replaces the bushings with bearings. If your bushings are shot, I'd order a new set of carbs form Ztherapy, but if they are not, a rebuild is all you need.

The rebuild kits are $150 for two carbs, which seems high. What you really save at that price is leg work. You can find all of the parts for cheaper, but it might take a while to accumilate them all.

The idea about getting the flexible fuel line at a motorcycle shop is a good one. A local shop here sells fuel line made of some material that I'd never heard of that is very thin walled and flexible. It would work fine. It's not standard fuel line like you'd find at a auto repair shop. It costs a bit more than standard hose.

[m240]

I've read that to check the butterfly valve alls you have to do is shoot carb cleaner at the bushings while the car is running and if the idle slows then the bushings are bad. Will this work as well as checking them while off the car?

[skip260z]

I've read that to check the butterfly valve alls you have to do is shoot carb cleaner at the bushings while the car is running and if the idle slows then the bushings are bad. Will this work as well as checking them while off the car?

No. Purpose of using the carb cleaner spray on the bushings of a running car is to detect the change in idle - indicating the leak.

Don't get too hung up on the tiny bit of air leak around the bushings.

Also - as the others have said - the Z SU carbs video explains it all. Do one carb at a time, you have fun, intimately learn all about SUs, and save a ton. If the SUs were any simpler, they'd be wood burning stoves.

[m240]

Thanks for all of the replies! Since I already have the SU video I think I'm going to try either a VB or other stock jet kit( the stock jets lasted this long) and some fuel line from a cycle shop. Looks like this will be next weekends project.:classic:

[mike240]

what's the difference if any, in the cfm output between the stock jets for the SUs and the ZT jets. it would seem that you could just buy a stock rebuild kit (cause $150 for a rebuild kit is ridiculous...i can buy a new holley 4bbl for less than that. i wonder if board members of car part companies get together at meetings and find different ways to bend the average consumer over and have their way with them...with no lube). sorry. i digress. anyway could i just buy a stock rebuild kit and get some bigger jets and needles elsewhere?

[skip260z]

Originally posted by mike240

what's the difference if any, in the cfm output between the stock jets for the SUs and the ZT jets. it would seem that you could just buy a stock rebuild kit (cause $150 for a rebuild kit is ridiculous...i can buy a new holley 4bbl for less than that. i wonder if board members of car part companies get together at meetings and find different ways to bend the average consumer over and have their way with them...with no lube). sorry. i digress. anyway could i just buy a stock rebuild kit and get some bigger jets and needles elsewhere?

I'm not sure of what you refer to as jets... the choke-nozzles that come up thru the bottom of the carb bowls - or the needle/seat assemblies? The GroseJets replace the needle/seats with a spring-loaded ball-berring - no clogging as possible with needles. No real perf gains.

Can't argue the Holley sentiment, but then Holley carbs have a monster aftermarket. Not quite the same for SUs.

Also, stock rebuild kits (from Datsun/Nissan) are NLA from everything I have read. The rebuild kits today range from the "refresh" kits (gaskets, needle/seat and dangerous fuel line) to the more complete parts kits put together by vendors - like ZT, MSA, VB.

No, there is no more aftermarket for 30-yr old rustbuckets. These are Z's, not Z28s. We're SOL.