Mark Maras

I agree with Patcon, . Jalex, IMHO, YOU should be the one tuning these carbs. You don't need no freak'in "expert" or even a "mechanic". You'll be glad you learned how. Let me try to convince you with a trip in my WayBack Machine. 1973, The first thing I worried about when I bought my first Z was the horror stories I'd heard about British cars with SU duel carbs and constantly having to tinker with them. I didn't know anything about them, sooo, I took it to a "sports car garage" for it's first tuneup. $76.00 (a fair amount of money in 1973) later I drove the car home and realized that the tune-up hadn't changed the way it ran, which was good, before and after. I realized that I couldn't afford frequent tune-ups at that price. (Thought it would need them) I bought a Uni-Syn and a repair manual and started cleaning and checking the carbs when I tuned it up. They were always fine. It wasn't until I took a suction chamber off, out of curiosity, that I realized how simple the whole thing was. I already knew about float chambers and had read the tune-up manual. It was the EUREKA MOMENT. There was little to them. Not as complicated as a downdraft carb. To this day I'm amazed at how simple and effective the SU's are and still don't understand where the fear factor came from, unless it was the British aspect. You can do it. Give it a try. All it takes is a balancing gizmo, a screwdriver, a tune-up manual and a beer.

He may have changed the pivot points but that doesn't guarantee the float level is correct. Why does he have the front carb mixture screw one full turn richer than the rear carb if the float level is correct in both. Well anyway, when he's done playing with the carbs, and hopefully it's running to your satisfaction, I still strongly suggest that you grab a screw driver, pull the chambers and pistons and verify that the float levels are correct. Remember, your goal is 2 1/2 turns down on both carbs with the fuel level (determined by the float level adjustment) just below the tops of the nozzles.

That's the way the 3 screw carbs were designed. The one with the short ears (left in the pic) is for the rear carb.

That 1/2 turn is probably the difference in the float levels of the carbs unless the needles weren't installed properly.

@Chickenman In post #11 you mentioned dropping your E88 needles .020" to lean it out at idle and it worked great. Do you think this would work for Jalex's SM's? Seems like he's having the same problem you had.

Yup, just remove either the 3 or 4 screws, remove the suction chamber and piston. According to Bruce Palmer (ZTherapy) with the mixture screws 2 1/2 turns down. the fuel level should be 1/16" below the top of the nozzle. It's an easy way to verify the float levels are right.

The float pivot points (ears) that hang down from the cap on 4 screw carbs were long on both carbs, Three screw carbs used long ears on the front carb and shorter ears on the rear carb. To my knowledge, the float setting is the same. Someone correct me if that's wrong. Remember that you can double check the float setting (fuel level) by verifying the fuel level is just below the top of the nozzles with the mixture screws 2 1/2 turns down.

Did you ever take a look to see if the tensioner is in place?

A couple of questions. How does the engine run when it's warmed up? Have you done any work on the carbs such as tuning? Having to crank the engine a little longer could be considered normal if the car sat for a few weeks but having to prime the carbs is "abby normal". Fuel lines and or connections sucking air is a good possibility. Choke cables that aren't pulling the nozzles all the way down is another. A fuel pump pressure and volume check would eliminate the possibility of a weak (as in going bad) pump, which could give you the symptoms you've described.

I agree with Patcon. An electric fuel pump, with or without the mechanical pump, would be a cheap fix. Personally I'd run both pumps.

I've run both. I was watching for any change when I went to the stamped impellers the first time. I thought the stamped impeller pump looked cheap and flimsy. No change. IMO, they're both satisfactory for the street.

If different jiggly bits don't cure it, it could be a clearance issue between the pistons and chambers. You might try swapping the pistons from one carb to the other and see if things improve. The pistons and chambers aren't the same and they do get switched accidentally. I remember a test in ZTherapy's "Just SU's" that calls for removing the chambers and pistons. Tape up (seal) the holes in the bottom of the pistons. Invert the chambers and pistons, then holding the needles, release the pistons at the same time and compare the drop times.

Not just you. I'm sure a clean original set would run great. It's been done countless times.

My ancient radio wiring notes mention a blue/white wire going to the antenna switch, red wire was switched power from the ignition. Presumably both going to the radio. I hope.

A couple of years ago we had a discussion about softening old rubber. Someone (I think it was 240260280) came up with a formula that softens and keeps the rubber soft after the solvent has evaporated. The formula was 1 pt. xylene and 2 ozs. of wintergreen oil. I mixed some up and soaked some old cracked, crusty hood bumpers for 24 hours. I tried flexing one as soon as it came out of the mix. It was nice and soft but crumbled when it was flexed. I waited 24 hours for some of the solvent to evaporate from the rubber and tried the flex test again. The results were much better. No crumble and a lot more flexibility. I found wintergreen oil to be very expensive however. In my notes on the subject there is a reference to "Thor Tire Prep #12". As I recall it is a tire conditioner (softener) used for racing. Might be worth looking into.

Did you check for continuity? I sold one that had continuity but much of what I assume to be protective coating was gone. It looked like the one on pic #2.

When removing the rear panel clips I noticed that they look like the clips inside the Series 1 (sorry) hatch. I believe the ones I'm referring to are the ones that connect to the duct work. Sorry, I haven't been inside an early hatch in a number of years. Anyway, is it possible that the rear panel clips are the same as the internal hatch clips?

You're right. It's the spirit of giving, be it info, moral support or parts, that makes this club a shining star of goodness in a universe of sucking black holes.

You're welcome. Glad they were usable. Pics would be great. Personally, I enjoy knowing that some of the collection (hoarded parts) will live on in another's Z.

If burns are badges of honor, I've got more than Gen. MacArthur. Even had one that burned a small hole in my eardrum. But I regress. I've found that it's very difficult to make a quality, good looking weld when one is flinching from pain and wondering where and when the next one is going to land. Reviewing the suggestion above, I'd suggest a bit better coverage of one's important bits.

I too bent a drive shaft yoke some time back. Upon reassembly the clip wouldn't seat in the groove. Having nothing to lose I smacked the bent piece with a hammer until the clip would fit. Surprisingly, it worked. No vibration, even at high speeds.

Also, enough protective gear (leather) to protect you from sparks when you're welding overhead.

I agree with Cliff. IMO, If one likes screwing around with suspect electrical components, EFI is the answer. If, however, one is more mechanically inclined and wants to move on to other parts of the project, SU's are the answer. They are the most reliable, trouble free carbs I've ever dealt with. Fantastic for the street. I might add that RossiZ swapped to SU's after refurbishing the entire EFI system. He loves SU's on his 280 daily driver.

I agree, anything can be reworked to look new or even better depending on one's desire, time, talent and or monetary resources. If you want it to look original, the best way, with the least amount of work (time) IMO is to replace it, if you can find one.

He's probably thinking the same thing.