Yep, ran the search....found some info beating around the bush of what I was looking for but nothing with my answer. read the service manual for the 2 jet and still didnt find what I was looking for, googled it, still no luck, even went to the library (see my other thread) still no luck. Here's my question. I just put a tripower on with 2G carbs, my primary carb has two idle screws at the base as it should...BUT I cant find anywhere that states what each one does...I believe from the info I did dig up that both needles do the same thing....but the wording is vague....SO my question is, the idle screws...each one affects one venturi? or does each one serve a different purpose? (I believe its the first option) Second, I have my idle screws set up a 1 and 3/4 turns out....(SBC 375HP) from any of you alls experience whats the general consensus of how many turns out you need to be for optimum performance and engine health? It seems to run fine, smooth, not loaded up....but want to make sure I dont run it lean...also I'm running at 3 PSI fuel pressure; should I up it by a half pound? I did read that you can knock the needles off the seats running too high of a pressure.... first timer on a multi system and with the 2G (I've always worked with the Holleys)
My method for fine tuning the idle adjustment is to hook up a vacuum gauge to the manifold and set your idle screws to where you get the best vacuum. This has always worked well for me, but I haven't tried it on a multicarb setup, although it should work the same
yep, thought of that....forgot to mention it in my initial post....(havent done it yet though) but your uncertainty on the multi aspect was my question as well....
The vacuum gauge always works. One other thing to think about, you didnt say if your carbs were made for a tri power or if they are all regular carbs, If they are all three regular carbs, you may get a better idle using the center normally, and open the idle mixture screws about 1/8 to 1/4 turn on all the end venturies. It takes some time , but is well worth the effort.
Each idle screw affects one venturi, both have the same function. Original tripower carbs have idle circuits in the center carb only. I agree with vacuum tuning.
thats what I was looking for....I have the "proper" carbs as secondaries...EG: no needles. cool, so basically, what I do on the left I do on the right, I'll chuck the vac guage up to the primary and get her tuned... thanks for the insight
salty, a good place to start is 1 1/2 turn out on the center carb. Like mentioned before set it at the highest vacuum with a gauge. If you don't have a gauge just set them where the engine starts easily...takes the fuel without bogging...and shuts down without dieseling. The end carbs should'nt have idle circuits in them...they should be plugged. The end carbs are there to just dump gas through. Three lbs. fuel pressure is about right. I'm running a mechanical fuel pump on my sbc (400 h.p.) My fuel pressure regulator took a dump last summer and I have'nt replaced it yet. So now i am running about 6 1/2 lbs. of pressure to the carbs...no problem at all. Can't tell any difference at all in the performance and no leakage. Someone correct me if I'm wrong but the two screws in the center carb....one should be for fuel adjustment and the other air. Hope this helps you out. It took me a while to get my 3x2 setup figured out but I love them now!! Also when people ask you if they all three work??? Tell 'em they would'nt be there if they did'nt!!!!
Thanks A.D. Just got her roughed in on the tune...you are correct in ***uming that the end carbs idle circuits are plugged...no worries there...I got the initial tune with the iming gun and vac guage done then my timing light ****ped out on me...sheesh... once I get the timing light working again, I'll finish the tune...Its just about there, no dieseling on shut down, idles well, starts at one blip but bogs a bit when you blip the throttle...I'll work that out thanks again!
Salty you will probably have to play with the jets a little on the end carbs to find out what your engine likes when they are all open. I think I started with 57's and ended up with 52's in the end carbs. You may need a little more advance in the dizzy too. Sounds like you're almost there.
Hi: I am gathering parts to build a set also. There is a good post on "Clubhotrod.com" that may help as well as "Vintakes.com " if you found any other info I would appreciate you letting me know.
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