madkaw Posted May 28 Author Share Posted May 28 On 5/17/2025 at 2:33 AM, jonbill said: It's a welded p90a. I think the ports are 38mm. I think they must be as big as they can be since the head bolt holes broke through when we drilled them for m12 bolts. Did you have to use the air bleeds to balance ports ? I tried opening one up and didn’t get any response in the air . Quote Link to comment Share on other sites More sharing options...
jonbill Posted May 29 Share Posted May 29 Yes I did on the FAJs, I just about got the amount of adjustment I needed. Quote Link to comment Share on other sites More sharing options...
madkaw Posted May 29 Author Share Posted May 29 14 hours ago, jonbill said: Yes I did on the FAJs, I just about got the amount of adjustment I needed. I don’t need much and it’s just on the first ITB. Maybe really have to crank out the bleeder to get anything out of it ? Quote Link to comment Share on other sites More sharing options...
jonbill Posted May 30 Share Posted May 30 I don't really remember I'm afraid, but I know there wasn't a lot of adjustment available. Have you looked at recentering the throttle plates to see if you can get more consistent air flow when closed? Quote Link to comment Share on other sites More sharing options...
madkaw Posted May 31 Author Share Posted May 31 19 hours ago, jonbill said: I don't really remember I'm afraid, but I know there wasn't a lot of adjustment available. Have you looked at recentering the throttle plates to see if you can get more consistent air flow when closed? I guess I don’t know how that’s done and what it does . I run cable that moves first ITB that moves the rest . The first ITB needs more air but there’s no way I can see to adjust its linkage without moving the others . I hooked up the cable and this engine started and idled great - so no real complaints ! Quote Link to comment Share on other sites More sharing options...
jonbill Posted May 31 Share Posted May 31 (edited) There should be adjuster like this between each, to make each pair flow the same, and the bleed screw is to balance flow within a pair. If the bleed screws don't have enough, then hold the throttle body up to the light with the throttle closed. You'll probably see the butterfly isn't perfectly centered because they weren't assembled very carefully. So they flow different amounts of air. You can slacken the two fixing screws and recenter the butterflies to balance them. But.... Why does the first need more air on yours? That doesn't sound right. Edited May 31 by jonbill Quote Link to comment Share on other sites More sharing options...
madkaw Posted June 6 Author Share Posted June 6 The synchronizer reading will be 5 on the first carb and 7 on the other two . Not sure how much off that really is . If I try and adjust the idle screw on the first ITB , that moves the other two based on how the linkages are overlapped . Quote Link to comment Share on other sites More sharing options...
jonbill Posted June 6 Share Posted June 6 I think thats a significant difference. Adjusting the throttle stop on that carb will move the others. Have you got a pic of how the throttle bodies are linked? I balance them by disconnecting the linkage and using air bypass to get each pair in balance with themselves and the throttle stops to get the 3 three balanced with each other. Then connect/adjust the linkage so they're still flowing the same at idle. They should then stay in balance as you open them. Quote Link to comment Share on other sites More sharing options...
madkaw Posted Sunday at 01:58 AM Author Share Posted Sunday at 01:58 AM The thing runs so good I can’t believe they aren’t very closely synced . First time doing ITBS so don’t know what to expect . I think they have been very good . Alpha N is a bit of a learning curve . I think I figured out I how to get 32 table for VE - but it runs well with 16 . I have a good MAP signal and I can see why some would use or try MAP density . I have a 3/4” log and soon it will be 1” . I will try it sometime just to prove to me - ha . Quote Link to comment Share on other sites More sharing options...
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