a 25 I think
will check
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| 390 Holley Jet size https://slantsix.org/forum/viewtopic.php?t=37074 |
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| Author: | 68barracuda [ Thu Sep 17, 2009 2:45 am ] |
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a 25 I think will check
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| Author: | SV162 [ Mon Oct 05, 2009 7:07 pm ] |
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Just adding a bit more info to this thread. I'm using a 600 Vac Sec Holley temporarily while I have my 390 repaired. Yes I broke the number 1 rule, "never over tighten....anything" I cracked the base plate through the PCV port.  Anyway, this 600 I'm using is a standard setup, 25 shooter, 66 primary jets, 64 secondary jets and 65PV. Now believe it or not, but I'm getting surging at cruising speed, and there's a massive bog off idle. Interesting that if my little Slant was to use a 600 Holley full time I'd need to jet it up and put in a bigger shooter. Unfortunately I can't try this out as it's a loaner carb and I promised I wouldn't pull it appart.  Another bit of info for you which you may or may not find interesting. I ran my car down the track last week with the 390, before I broke it. I got there late, and in a hurry to get to the staging lanes I forgot to swap the purple secondary spring(which I use on the street) for the short yellow spring(which I use at the track). After my first dissapointing run and wondering what was wrong I realized I hadn't swapped springs. So a quick spring change and what a difference!! The up shot from all this is I got some real world figures on how much difference it makes having the secondarys open earlier. 1/4 mile with purple spring 16.04 @ 86mph 1/4 mile with short yellow spring 15.73 @ 88mph |
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| Author: | SV162 [ Mon Oct 12, 2009 6:02 pm ] |
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Got my 390 back all fixed up and had a play with it on the weekend. Put in some 53 jets which caused surging at cruise and a huge bog off idle, so I put in some 55's which didn't surge at cruise but still had the off idle bog although not as big as the bog with 53's. So I swapped the 25 shooter for a 28 and the bog is totally gone. Stomp it at any speed and it just goes. If I get on the throttle just slightly under load there's just a barely noticable surge which goes if I give just a bit more throttle so I might change the power valve from the 4.5 to a 6.5 and see what happens. So to answer my own question Quote: if I decrease the size of the primary jets can I up the size of the accel pump shooter to cover the lean spot, or doesn't it work that way?? Yes, yes you can 
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| Author: | SV162 [ Mon Oct 19, 2009 8:08 pm ] |
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Another update for those following. I'm still running with the 55 jets and all is well. I swapped the 45 PV for a 65 PV and that has improved things. I did some driving around with a vac gauge hooked up and I think ideally an 85 PV would be better because my vacuum at cruise is around 15 to 16"Hg, but my vac at idle in gear is around 8 to 9" so the 85 PV would be opening at idle........not good. I think I've finally got this carb dialed in...........well almost
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