I have been trying to get my car dialed in and have been having problems getting it right.I put a Holley 390 CFM on it and have changed the power valve ,jets,acc. pump.Checked it with a vaccum gauge ,timing,valve adjustment ect...The motor is 105 overbore,Clifford 4 barrel intake,10.68 compression,headers,custom ground cam (for nitrous) with 230 gegrees duration @.50,complete MalloryHy-Fire iignition 177/144 valves with lots of port work and cc'c combustion chambers,2600 stall speed convertor.I just can't seem to get a good balance of power out of the hole to the top end.It reads 0 vaccum at wide open throttle (5850 rpms).I have done plug reading and it seems always rich no matter how small of a jet.I'm thinking that the 390 cfm is to small.Should i be looking at something more in the 5-600 range.It's a weekend driver and I could care less about fuel mileage.I built it to drag race and the street drags are this weekend.I have spend a lot of time trying to get this thing perfect but I'm stumped.
What are you guys using on a modifed slant?Thanks for any input.

_________________
SOOOOO much money spent and I keep gettin' told that I could have had a V-8

Given what I see and what you have listed... you might look at a 500-600 cfm carb (500 AVS or maybe a 600cfm Holley...600cfm Holley's are about $75 tops on Craigslist....). I think it will dial in better, with vacc. secondaries you can restrict the back two with a spring change on the Holley if 600 is too much...

-D.Idiot

Where's that eating popcorn emoticon.

_________________
62 Valiant, 225cid Slant 6/PB 904 with lots of good bits

http://www.moparmarket.com/readersrides ... user=SV162

Well I talked to Holley and they said that the 390 should be what I need.They base it on the Slant needing about 410 cfm give or take 20-30 percent error?I explained this wasn't stock and I didn't have any flow numbers but told them what was done the the vehicle.Lost hope there.I called B/G and they took all my information and seemed like they wanted me to select the proper one for my application.They came up with the motor needing closer to 550 cfm and reccommended a 575 Speed Demon with the vaccum secondaries.Is anyone using one of these on a slant that was built for more of a strip car then a cruiser?I know the car needs to go on a diet but still the thing should run better then it does.I just want good spark plug coloration and crisper throttle response without falling over on the top end.It all seems to lead towards carburation.Maby I'm looking in the wrong spot but not to many people in my area seem to know much about Slant Sixes and performance.If nothing else I have been very patient with this car and I would really like to participate in the street drags this weekend instead of just the car show,but I want it to run right because I plan on spraying it to make up for the 3.21 gears in the rearend (I put a 100 shot in it,not to much but should be enough
to help).I plan on driving it to and from (hopefully) , it's a couple of hundred miles>I goota go and see a shrink!This thing is driving me NUTS!

_________________
SOOOOO much money spent and I keep gettin' told that I could have had a V-8

Here's a start...
http://www.csgnetwork.com/cfmcalc.html

I'd go back to where you started on that carb.... what's your intial timing? total advance in at how many rpm's? Try a two barrel Holley and see if that will make it run better...

Maybe some dyno time would help you sort it out...

_________________
Check it out... www.symcoshakedown.com

I have never used one but a 390 Holley should be the right carb to use. Did you buy yours new? I have always found that the way carburetors come out of the box is a good starting point. If you have made several modifications why don't you try to put it back like Holley built it. Carburetor jetting is related more to the size of the carburetor than what kind of an engine it is installed on.

I have had very good luck with an out of the box Holley 500 2BBL. Also the BG 525 Road Demon with vacuum secondaries--after I sent it back twice to fix manufacturing defects. Do you have access to other carbs that have worked good in other applications? It is pretty easy to bolt them on an give them a try. As long as they have vacuum secondaries you use something up to the 650 or 700CFM area but don't expect it to go faster than a properly set up 390. A 390 should give you better gas mileage and throttle response too. Good luck.

_________________
If you didn't drive it there, it's not a street car.

How fast are you running?

Lots of people have run in the 14s and faster with 390s and 500 2bbls. For simplicity and power, it is hard to beat the 500 2bbl as Exner Geek said.

I hope to try a 500 AVS Edel soon. I liked my Edel Performer 500 4bbl.

Lou

_________________
Home of Slant6-powered fun machines since 1988

I really like the Eddy 14XX series. They are great right out of the box. PM me and I might just make a deal for you to use one.
Frank

_________________
Scrapple: Because a mind is a terrible thing to waste.
73 Duster - Race Car
66 Dart Wagon - DD
178" FED
82 D150
All Slant powered

My initial timing is 10 degrees and total is 36 @ 2600 RPM.I have put the carb back to as I reciceved it new in the box and have tried diffrent combinations and timing.The motor seems to like more advance .I fires up better but losses preformance.I have redegreed in the cam just to make sure that wasn't the problem swapped the dual point for a Pertronix unit,tried diffrent valve lash setting ect...It really never seemed right.Always seem to be fighting bugs.I would like to put it on a dyno but lack of funds make it impossible at this point.I have a 650 on my shop truck that work?I got a line (good deal) on a new in the box Demon 575 carb and am going to give that a try tomorrow.Hopefully it'll help.I'm wondering if I got a Friday card from Holley when I bought this one new.I post back .

_________________
SOOOOO much money spent and I keep gettin' told that I could have had a V-8

A good wideband air-fuel gauge would help you with you tuning.A 390 cfm carb should work well,I agree with E.G.,the carb should be very close right out of the box.The AF gauge will show you if your rich or lean throughout the entire RPM range,it could be lean in one spot,and rich in other spots,darkening the plugs. I'm using an AEM brand gauge that costs about $350,cheaper narrow band AFGs are not as accurate,and a waste of money.

_________________
V8?? We don't need no stink'n V8!!