Holley 390cfm Secondaries
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Cranky Old Guy
Joined: Mar 2008
Posts: 3,562
Likes: 6
From: Raphine, Virginia
Holley 390cfm Secondaries
Got about 500 miles on the 203I6 now and while very pleased, starting to tweak it a little. Wasn't getting quite full travel from throttle cable and blamed that for secondaries not seeming to come in. Fixed that, now the last bit of travel actually does nothing, no rpm increase. The vacuum is only running 16hg at idle which I expected to be a bit better with this cam. If there's a leak, I can't find it. Are the secondaries adjustable or need to change the spring/diaphram? It runs strong, burning clean after upping heat range on plugs one step. High gear about 3000/3250rpm and it's wanting more gas. She'll turn higher than I want to push it yet in first and second. Sorry for so long, but wanted to give you enough info to go on. It's still building noticeable power the more miles I get on it.
Postmaster
Joined: Dec 2006
Posts: 3,603
Likes: 10
From: Spokane, WA
There is a secondary spring kit available with a number of different tension springs available.
http://www.holley.com/data/Catalogs/...ce%20Parts.pdf Look through there and you might find it or just check with a parts house...some of them carry that kit and may have it in stock.
http://www.holley.com/data/Catalogs/...ce%20Parts.pdf Look through there and you might find it or just check with a parts house...some of them carry that kit and may have it in stock.
Moderator
Joined: Dec 2007
Posts: 7,987
Likes: 104
From: Boise, Idaho
If you're going to be changing around the secondary springs for tuning, I definitely recommend one of these:
Holley 20-59 - Holley Vacuum Secondary Quick Change Kit
Install it once and the time to change the springs is reduced to about 30 seconds, instead of having to remove the choke and secondary housings every time, and line everything back up to reinstall.
If you get assorted spring kit, I'd recommend putting better marks on them for which one is which. The tips are color coded, and the paint on mine fell off in no time. The only way for me to know which one is which is to feel them by hand, and sometimes that can be difficult.
Holley 20-59 - Holley Vacuum Secondary Quick Change Kit
Install it once and the time to change the springs is reduced to about 30 seconds, instead of having to remove the choke and secondary housings every time, and line everything back up to reinstall.
If you get assorted spring kit, I'd recommend putting better marks on them for which one is which. The tips are color coded, and the paint on mine fell off in no time. The only way for me to know which one is which is to feel them by hand, and sometimes that can be difficult.
Thread Starter
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Cranky Old Guy
Joined: Mar 2008
Posts: 3,562
Likes: 6
From: Raphine, Virginia
Thanks guy's. Been hot the last two day's and putting some miles on it. I hooked up my vacuum gauge and ran it to the cab. Vacuum seem's to be coming up a bit. Running 17.5 at idle on hot engine so think I'll wait till it stabilizes. Still think I have a vac leak somewhere. Idle screw backed off and still idles about 1000rpm. Really need to find that before messing with the springs.
Moderator
Joined: Dec 2007
Posts: 7,987
Likes: 104
From: Boise, Idaho
Just some quick questions, since I've had this issue. When you back the idle screw all the way back, is the throttle cable slack? If you pull on the throttle linkage, do the RPMs momentarily drop? Just asking because I had this problem for a while and it turned out to be all linkage related, not vacuum leak. Not saying it isn't, but they're quick things to check. 
Even when I had a really big vacuum leak on my intake, I was able to finagle my RPMs down to a 700 RPM idle.
Even when I had a really big vacuum leak on my intake, I was able to finagle my RPMs down to a 700 RPM idle.
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Cranky Old Guy
Joined: Mar 2008
Posts: 3,562
Likes: 6
From: Raphine, Virginia
Throttle cable is slack, no rpm drop, instant throttle response. The gaskets that came with this intake really s***. Two piece gasket, one each for three cyl. and they didn't even match ports very well. I was expecting them to leak. If they are, it's on the bottom where I can't check. Not enough room between header and intake. Need to check and see if any improvements have been made in those gaskets. The little engine screams, but I know there is still some more left in it.
Things like this happen when there is only one supplier for a product.
Things like this happen when there is only one supplier for a product.
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