tube80z Posted January 23, 2009 Share Posted January 23, 2009 EDIT: I called someone else who was at the testing to refresh my memory. The issue with the triple SUs was that cylinders 3 and 4 ran lean compared to the other cylinders (based on EGT and spark plug reads). Later they shined a strobe light down the middle SU at various rpms and noticed the piston fluttering up and down while the outer two SUs had the piston rock solid. What were they using for a balance tube? Because we never saw that on my motor. Then again I had a cam that had a lot of duration. Steve at ZTherapy talked to Dave Rebello and they mentioned the same thing when they tried tripples but they didn't have a balance tube. So my data point of one is probably skewed. And I would agree for the money I'd opt for EFI. Cary Quote Link to comment Share on other sites More sharing options...
SHO-Z Posted January 23, 2009 Share Posted January 23, 2009 I don't think he'll mind, so here's some triple-SU candy for you, built by Steve Epperly (ZTherapy)... . . Here is the tripple SU set up by Ztherapy. I really do not know what the problem is with the center cylinders, Jag ran tripple SUs on thier engines with no problem. Thier runner length is about the same, maybe a little longer. Inline 6s all have the same firing order from what I have seen. Quote Link to comment Share on other sites More sharing options...
back-to-zcars Posted January 23, 2009 Share Posted January 23, 2009 What were they using for a balance tube? Because we never saw that on my motor. Cary Are you still running yours with the triples? I am glad mine has a proper balance tube. Quote Link to comment Share on other sites More sharing options...
johnc Posted January 23, 2009 Share Posted January 23, 2009 What were they using for a balance tube? It had a balance tube, which kind I don't recall. Efforts to richen the center carb were not very successful. The center two cylinders were either too rich or too lean and it seemed as if the center carb was not very sensitive to adjustment. FYI... all of the testing I described above was basically done at WOT. Part throttle operation was fine with the triple setup unless things got too rich and then there was a stumble on throttle takeup. Quote Link to comment Share on other sites More sharing options...
tube80z Posted January 24, 2009 Share Posted January 24, 2009 Are you still running yours with the triples? I am glad mine has a proper balance tube. My engine is the one above in the white Z. Steve used it for some time and is looking to change the cam to one less radical. My new car will have a V8, which we've joked somehow needs to have 4 SUs. Cary Quote Link to comment Share on other sites More sharing options...
eec564 Posted January 25, 2009 Share Posted January 25, 2009 Here is the tripple SU set up by Ztherapy. I really do not know what the problem is with the center cylinders, Jag ran tripple SUs on thier engines with no problem. Thier runner length is about the same, maybe a little longer. Inline 6s all have the same firing order from what I have seen. The Jag's have nice cross-flow DOHC (still 2-valve per cyl) heads with three nearly identically shaped and spaced intakes. The large angles in that manifold could very well create turbulence with that size SU, causing the piston to misbehave. Quote Link to comment Share on other sites More sharing options...
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