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| Why not use a Holley 4548 450cfm carb? https://www.slantsix.org/forum/viewtopic.php?t=43766 |
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| Author: | drgonzo [ Wed Feb 23, 2011 7:57 am ] |
| Post subject: | Why not use a Holley 4548 450cfm carb? |
I already have one and have experience with holleys. I know a lot of people have reported bad experiences with the 450s but I wonder if they had tunnel ram carbs. This is a Ford replacement carburetor. I am going to try it. Has anyone dialed in one of these for their slant combo? Funds are scarce so I need to use what I have whenever possible. I will be using and H-pak and Clifford shorties with Y pipe. Thinking a first step will be remove the head and bowl porting, good valve job and more compression. What should I shoot for on my stock 63 engine with stock cam and 3.23 gears? |
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| Author: | DusterIdiot [ Wed Feb 23, 2011 7:12 pm ] |
| Post subject: | Worst of both worlds.... |
I ran the Holley 0-1848 brand new out of the box, converted to secondary metering block, quick swap secondary spring pod...on my Erson 280/270 10.3 compression mill with dutra duals...(A-833OD/3.55 rear at that time 3200 lbs Feather Duster-3400 lb in street trim/add tools and other "crap") Initial tests using the 8007-390 cfm showed that the carb was great for the street and turned out best mileage, but even with the short yellow spring it would leave me about 5-8" of vacc at WOT...typical mileage was 22-24 mpg 100% freeway depending on timing and fuel used. I had a holley 600cfm squarebore converted to all 4 bores with annual venturies. This has the same acceleration and reaction the 8007 had, but the gas mileage just went down (18mpg highway at best...11 in the city on stoplight to stoplight). At the track this carb would drop my time .5 second from the 390...(Brown spring in secondary pod, slants don't need all 600 cfm). Like you I had surmised that the mill might actually want about 450-500 cfm. Holley doesn't have a 500 in a 4 barrel, but did have the 450... I got it and swapped all the good mods onto it, using my jet orifice chart based on the jetting for the 390 and 600...I dialed it in a few numbers up on the primary side and kept the same jet size on the secondaries...I tuned it in using the O2 sensor method and a vacc. gauge... Mileage and power were not much different than the 600, vacc gauge did go to 0" at WOT so I was correct there...throttle wasn't crisp on the low end,played around with jetting and stiffer secondary springs never gave back the mileage either. So...I took it over to the guy in town that put annulars in my 600...Holley doesn't make a true annular for the 390/450 carb, and you'd have to scav a set of economizer 'wagon wheel' boosters from a 350-2barrel to make one up. He did find a set of downleg annular boosters for the carb and modded it for me...Played around with this configuration for a while and it still didn't make a lick of difference, still no immediate tromp on the pedal and go...gas mileage still the same as the 600... Maybe you'll have better luck at it, this is probably one of the reasons why the Edlebrock AFB/AVS are popular in the 500 cfm range for slants (I'll be trying an AVS out soon in another build/car...)... Good Luck, -D.Idiot |
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| Author: | drgonzo [ Thu Feb 24, 2011 5:23 am ] |
| Post subject: | |
Thanks for all that great info. I am going to try the carb since I already have it and we shall see. Again thanks. Brad |
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