I’m disassembling my dual ZS carbs to clean and rebuild them. The rear carb is fully disassembled and partially cleaned and I’m now working on the front one. They are ZS 3165’s.
The spindles and bushes are showing wear and I can also see some light around the edges of the butterflies with the throttle fully closed. I’m considering sending them to Joe Curto for a re-bush.
In the meantime, my question for the group - I’m assuming the spindle in the picture below disassembles further but I can’t tell how. There’s a lock tab over the faceted “nut” on the end but even if I undo that the “nut” doesn’t seem to want to turn. With some muscle it felt like the spindle was twisting (deforming) so I didn’t try too hard. It just didn’t seem right.
I let it soak in some PB Blaster for a while and ended up using a little heat to break it free. Thanks again!!
On another note, one of the four screws that hold the carb cover on was really tight and after several attempts, I was beginning to goober up the screw head. I ended up using my Dremel and a cutoff wheel to cut a notch and use a flathead screwdriver. That worked well and I got the screw out. I had previously considered replacing the screws since what’s in there are Phillips head and not the “proper” Pozidriv ones, and had decided against it since the Phillips were working just fine. I may change my mind now.
I had to use my rubber mallet to “moderately tap” the carb cover loose.
I hit reply on that last message on accident - I wasn’t done!
I had to use my rubber mallet to “moderately tap” the carb cover loose after removing all the screws. The picture below shows why. It looks like the carb was dropped or hit with something sometime in the past. The cover is fine, but you can see an ever-so-slight indentation marked by the red arrow on the carb body. That’s just enough to keep the cover from fitting nicely. I considered trying a hammer and punch of some sort to tap it back into shape, but I think using some coarse grit sandpaper with square-ended instrument may be a better idea. Any thoughts on a best approach?
Also, I’ve seen other discussions on the proper installation and orientation of the carb cover. There is no doubt in my mind that the proper way is with the writing toward the rear of the car, which places the “tubular protrusion” near the dashpot cap facing toward the air cleaner. That’s how all the diagrams I’ve seen show it and that lines up the predrilled holes in the cover and the body for the emissions(?) tags that were wired on. That said, after looking at the design, I can’t see why it would matter, functionally. That “tubular protrusion” is an air passage from inside the top of the dashpot opening that routes into the top of the carb cover, opening into a “common” volume above the carb diaphragm. The red arrows in the picture below show the two ends of the passage. Maybe I’m missing something.
No comments on what you have done regarding the carbs but did you know you can edit your posts? There should be a small pen on the lower right hand side which takes you back into your post.
Rob: Since you have these apart for refurb I would strongly recommend two additional items:
Install the Joe Curto adjustable jets with the needles that Joe recommends for you. It is transformational as to your ability to tune the fuel/air mixture.
Remove the secondary butterflies at a minimum, and better yet remove the secondary butterfly shaft and plug the holes. This will help with engine response. Or you could go full-Monty and sleeve the secondary manifold and get a straight-thru flow path for the air/fuel mixture. Looking down the throat of one of my Stroms you can see the result:
I didn’t do the mods in steps, I did them all at once so I can’t say how much difference each of the mods has made by themselves. I would guess that the sleeve would help with initial throttle response since it eliminates the rather significant volume of the secondary manifold/crossover (if your car has the crossover). When you open the throttle the intake vacuum needs to evacuate the secondary manifold before max vacuum/intake flow can be achieved. This takes time (not much though). A secondary bonus is that the sleeve eliminates the sharp edges/expansions/contractions that slows the flow.
Just a word about eliminating the effects of the secondary manifold. I made up a metal plate and gaskets that fit onto the crossover located on the top LH side of the secondary manifold trying to eliminate the effects. However, seems to me that if you, me in this case, do this then there is still a connection between the two branches of the manifold due to the hole between them where the secondary shaft passed though where vacuum can be “stolen” from one side to the other. So, if you do this it seem to me you almost HAVE to sleeve the two throats, which I am about to do just as soon as I get the cooling system sorted out (idler pulley problems).
BTW, sleeving the throats makes the throat diamter slightly less, so, does this mean faster airflow and so possibly slightly richer, or, does it mean a more rstricted airflow making it harder for the engine to produce full power??
The very slight reduction in internal diameter caused by the thin-wall sleeve is a small percentage of the blockage presented by the original secondary butterfly and shaft. Also, the Strombergs are 1.75" diameter and the secondary is 2" diam, so even after sleeving the secondary is a larger diameter- the main restriction is in the carburetor. IMO the sharp edge transitions and volume changes in the stock secondary manifold cause far more pressure drop than the slightly smaller diameter of the sleeve. It would be interesting to put one of each on a flow bench and measure the difference.
Thanks Doug. I am definitely keeping both of those suggestions in mind for the future. For where I’m at now with the car (seeing if I can get it running), and the structural work ahead of me (sills and frame(s) at least) I currently intend to stick with the stock setup. I’d like to get the secondaries functioning properly and see what that setup feels like, and then remove them to feel the difference for myself.
Another part of my rationale is I kinda wanna start with an as-close-to-a-known configuration as I can, evaluate things, and go from there. If I throw in too many variables up front, before firing it up for the first time, I’m afraid I could create more potential troubleshooting paths than I’d like to.
Les, you make it sound like that is undesirable. I cannot speak of the particulars of this manifold, but many manifolds do have a connection, sometimes called a compensator tube/passage. The 4.2 with the Triple SU’s have a connection from the factory.
Tom
Even with sleeves the mixture makes a 90 deg. turn into the “log” manifold, then another 90 into the port. So I wonder if the small holes into the duplex manifold make a difference that far “up stream”. I can see and understand eliminating the torturous route of the ridiculous duplex manifold. No offense intended Doug.
I agree that it would be interesting to take an S-2 to a dyno and see what actually the ROI is on all the classic “fixes”: SU’s, K&N’s, headers, big intake valve, cams, and my fav…the advance curve.
Myth Busters!
Yes, it would be. Clearly, many of the performance items you mentioned, cams, etc., would be expected to increase performance. But I often wonder about the stock S1 4.2 versus the stock S2. We know the HP and torque have been dropped by the Stromberg setup. Many have understandably touted the duplex manifold issue, and, as above, have followed various methods to defeat it. But how much difference does make in regaining what was lost to the 4.2 triple SU setup? That, to me, would be interesting. I found an article in Car & Driver from 1969. To me, overall quite interesting. It somewhat discusses the evolution of the E-Type and its changes. To me, helping to reinforce the reasons I often strongly suggest considering an S2 over an S1. This article was at a time when the car guys felt they were under assault, and this article does point out the obvious we have discussed on the forum. Open headlights, marginal taillights, etc. But the section on the engine emissions is, to me, exceptionally interesting. It is on the second page, first full paragraph. They mention the detuning and loss of hp and torque. But, surprisingly, they mention that in their testing, it is actually quicker in the quarter mile than the triple SU’s, and actually has better performance in the speeds that it is typically driven in the US. I do not know what that specifically means- up to 65 mph, more? Now that does not mean defeating the duplex manifold would not make it better than the stock S2, but it sounds like with the duplex manifold, it is for all practical purpose, equal to the S1 in most ways.
I noted that estimated top speed is down from the likely untrue 150mph to 119mph. Of course this is with the 3.54 diff, which also helps a lot I imagine with the 0-60 time of 6.7secs. I changed out the 3.54 to the much nicer 3.07 around 20 years ago.
I guess we’ll see if we have “improved” the running of the car with our crippling of the duplex manifold. Shade tree mechanic logic says it should but those Jag guys were pretty smart one way or another…hmmm, yes, we’ll see.
Tom, there is no way an S2 is as quick as an S1. I have an extremely small sample (1of each). So my results may not be within the margin of error.
But as an S2 owner, I remember the day I got a ride from the old guy in a well built stock 65 ots. It was an epiphany. “So this is what an E type is supposed to be!” It was religious to me. But it started an unholy wallet emptying exorcism of the emission demons.
Les, in that C&D article the author mentioned a 2.9 rear gear for 150 versus 3.54 and a 110 max@5000. I have no doubt my 3.07 will run to red line in 4th.
