For a street car (and from my own experience) it is very hard to beat an Offy 4 bbl intake and a vacuum secondary 390 Holley.
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| Intake query https://slantsix.org/forum/viewtopic.php?t=44788 |
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| Author: | AHamilton [ Sat Apr 30, 2011 12:10 pm ] |
| Post subject: | Intake query |
I just purchased a 63 valiant signet 200 convertble. The car has been redone already. The guy put an offenhauser twin single barrel intake on it. Sure looks cool. Being a usually V8 only guy, bought this car strickly for to and from work...much better gas mileage than my 4X4. Is there a better intake to get more HP. I keep hearing about the supersix intake. Is that a better intake? I already know, and want a hyperpak...but don't think good for daily driver. Give me some opinions guys. |
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| Author: | Brussell [ Sat Apr 30, 2011 2:31 pm ] |
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Aussie speed intakes seem to be preferred, also the most expensive and they only come in 2 and 4 bbl. I'd think for a daily driver you'd just want to keep the 1bbl? It would be cheaper to bump up compression than to buy one of these manifolds brand new. |
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| Author: | slantzilla [ Sat Apr 30, 2011 3:58 pm ] |
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For a street car (and from my own experience) it is very hard to beat an Offy 4 bbl intake and a vacuum secondary 390 Holley.
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| Author: | Chuck [ Sat Apr 30, 2011 4:08 pm ] |
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Quote: For a street car (and from my own experience) it is very hard to beat an Offy 4 bbl intake and a vacuum secondary 390 Holley.
I never got mine working right. I had trouble with hesitation off the line. How did you solve that? I tried different power valves.
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| Author: | 2 Darts [ Sat Apr 30, 2011 10:14 pm ] |
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Quote: I never got mine working right. I had trouble with hesitation off the line. How did you solve that? I tried different power valves.
Usually for off-the-line stumble, I check the accelerator pump.Here's what Ma Mopar recommended with this combination (so I'm using it for a baseline setup on the Aussie Speed). Primary jet 49 Secondary jet 52 Power valve 25R-591A-65 PV channel restriction .052" Idle air bleed .078" Hig speed bleed .043" Diaphram spring Yellow |
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| Author: | SlantSixDan [ Sat Apr 30, 2011 11:47 pm ] |
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If you're after MPGs for a daily driver with reasonably snappy acceleration, a 4bbl isn't the answer. A 2bbl ("Super Six") is. |
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| Author: | mfdu [ Sun May 01, 2011 3:48 am ] |
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no no no no no - the dual single-barrel haas real potential on an almost stock 225! (well, i'mnow stating vested interest, since i've got a Speco dual single-barrel jobbie i'm rebuilding, to go on soon) but the dual single is a real even flow - if the carbs are well balanced, each cylinder gets a nice amount of go juice. and the visual balance is hot, too! i'm going dual stock carter bbs's, one of which is stripped and being cleaned currently. i'm planning a dual 2" exhaust with a modified stock manifold (chopping out the heat box to create two banks of three cylinders) equalising thru a 2x2" in/out muffler, well, enough about my build. 
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| Author: | DusterIdiot [ Sun May 01, 2011 8:49 am ] |
| Post subject: | I would... |
Quote: Primary jet 49
Jetting will depend on your altitude and vehicle.Secondary jet 52 Power valve 25R-591A-65 PV channel restriction .052" Idle air bleed .078" Hig speed bleed .043" Diaphram spring Yellow I've always wondered where Mopar got the idea for using 49's, I've always had to jet 51-52 primary then 52 for street or 53-54 "power" in the secondaries. Most moderate builds will want a 10.5 or 8.5 PV. In general it's better to statr with the "Stock" jetting and work up or down from there. -D.Idiot |
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| Author: | Chuck [ Sun May 01, 2011 8:55 am ] |
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I always got a stumble at about 6.5" of vacuum. Tried getting a power valve to come in just before that, but couldn't get it right. Carb was new and did not have an accelerator pump problem. |
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| Author: | slantzilla [ Sun May 01, 2011 2:59 pm ] |
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Carb was probably a touch lean and needed more primary jet. These little carbs are touchy about the air bleeds being plugged too. 
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| Author: | Chuck [ Sun May 01, 2011 5:24 pm ] |
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Quote: Carb was probably a touch lean and needed more primary jet. These little carbs are touchy about the air bleeds being plugged too.
Thanks. Good to know.
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| Author: | Doc [ Mon May 02, 2011 8:46 am ] |
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Also double-check the size of the PV restriction passage... that is a drilled passage in the carb's main body so it is often over-looked and not altered. You can change PVs forever and still have a lean transisition stumble, if the restriction 'passageway' is to small. DD |
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| Author: | wvenable [ Mon May 02, 2011 1:18 pm ] |
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If this is a daily driver and you care more about MPG's than opening the hood to show off - I would follow Dan's advice. I know where I can lay my hands on a cast iron super six intake If you are interested. I would be interested in the Offy dual one bbl and carbs if you feel the need to change it over. Just a thought. Nice daily driver by the way! 
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| Author: | AHamilton [ Mon May 02, 2011 5:04 pm ] |
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MPGs are important, but not the only concern. One or two mpg I don't care about. My truck was getting only 10 mpg, I already am getting 15-16 mpgs with this little car. So far I'm about as happy as pig in poo. I just got a 833OD and when I get it buttoned up, I was told I'll get around 25 mpgs. Eventually I plan on doing a twin turbo/dutra dual exhaust set up, and then HP is my major concern. But for now, if I can get 5+ mpg with a supersix intake, great. Might get 27+ mpgs after the OD. Money in the bank. But to reiterate, it's all about major mpgs, not a few. |
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