FE Power Forums
FE Power Forums => FE Technical Forum => Topic started by: drdano on June 20, 2012, 12:21:44 PM
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I've come to a bit of a crossroads with the carb on my new 428 and need some advice from the seasoned FE folks on what to consider. I don't have any experience at all with Holleys outside of the stock 4100 that came on my now dead 390 when I bought my Galaxie. When the stock 390 was still alive I was running a quadrajet with great results, but it is looking like I will need a fairly custom quadrajet to get this new motor to idle and run happy. For the same money to modify what I have, I may be able to get into something else new, but am not sure what to consider.
Here is the breakdown of the motor
428 + .030
10:1 CR
C4AE-G heads, CJ valves, bowl porting, intake gasket matched, mild runner port cleanup
Performer RPM intake, gasket matched on sides and roof
Comp custom hyd roller, 242@50, .633" lift at valve, 110LSA, installed at 104 ICL
Sanderson shorty headers, 2.5" dual exhaust, 3" x-pipe, 24" steel packs
4200lb car, 5-speed trans, 4.11 gear, 26" tall tire
Looking for something semi-bonehead friendly, as I have zero experience outside the rochesters. Thanks all.
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I like Patrick James of Pro systems.
It cost you nothing to fill out a form and see what he suggests. I am betting on a 750 HP.
http://www.prosystemsracing.com/proseries4150.html
http://fs16.formsite.com/prosys12/form1/index.html
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I am an AED lover, call them directly out of Richmond for a recommendation. I have had incredible success with their builds
My choice would be an 850 double pumper, but a 750 would probably work just as well.
434 cubes, short gear, deep 1st gear, healthy cam, no reason to go gentle
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750 double pumper. Bolt it on and go:
http://www.summitracing.com/parts/HLY-0-4779C/
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I found a new 750DP mechanical secondary new in the box locally for $300 that I'm eyeing up. It appears that Holley has a whole pile of videos on youtube as well on tuning, so I'm not feeling quite so lost now.
Given the heavy weight of the car, would a vacuum secondary model be worth considering?
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I found a new 750DP mechanical secondary new in the box locally for $300 that I'm eyeing up. It appears that Holley has a whole pile of videos on youtube as well on tuning, so I'm not feeling quite so lost now.
Given the heavy weight of the car, would a vacuum secondary model be worth considering?
Worth considering, yes, but it looks like you have found quite a good deal on the 750DP for $300.
Is the car mostly race or mostly street?
Here's an online carb calculator from Holley that's kind of fun:
http://www.holley.com/applications/CarburetorSelector/CarbSelection.asp
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95% street. May make an occasional trip to the drag strip to see how fast the old barge will go.
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Still say DP ;D
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3X on the 750 double pumper with 4 corner idle. It's a fine carb especially for a stick car and when tuned well (given good final drive gearing and a moderate right foot!) can equal a vacuum unit in MPG, yet give that instant oomph when needed.
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What's the 1st gear ratio on that 5-speed?
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What's the 1st gear ratio on that 5-speed?
2.87 in the TKO600 I have. The smaller TKO500 has the useless 3.27 first gear.
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2.87 1st gear, 4.11 rear gear, 26" tires, sounds like tire burning fun to me. ;) 8)
The car may very well handle an 850. ;D
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You are going to dig a double pumper in that car, especially after a Q-jet.
The float bowls will actually stay full in a Holley :)
I personally think that its a perfect match for an 850, but either will be within single digits of each other.
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An interesting read and new formula for sizing carbs now a days.
http://www.pro-system.com/pjames011900.html
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One thing that hasn't been mentioned is the intake manifold. You can run a larger cfm carb on a dual plane intake than you could on a single plane intake, everything else equal. That combined with the fairly big cubes, and the low overall gearing, point towards more cfm, and a double pumper.
A 750 double pumper would run great, but an 800 or 850 double pumper would be even better, IMO. One thing that has been said about the Holley 850 is that the relationship between the boosters and the venturis is not optimal. I can say I changed my Holley 850 double pumper's main body out for a Proform main body (Holley woudn't sell me an HP main body) and it made a big difference in responsiveness and power.
paulie
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I've got an 850DP on my fairly stock 428 with some cam not sure how much though as I didn't build it. Runs great at the track but would like to have a 750DP to compare it to. I know the 428 loves gas pretty much any amount I try to throw at it and it still barly reaches 12.5-1 Air/Fuel ratio. Hard to get good gas mileage though. Its either rich or lean. I've tried pretty much everything to get it in between when i'm not at the track. Right now i've got 82/80jets which runs good on the street. I also took the air horn off to open up air flow and a few other things to the distribution block.
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Small update on the carb. I found a brand-new never been mounted 750 double pumper on craigslist for $300.
(http://farm9.staticflickr.com/8144/7476082406_e656298bfe.jpg)
Nice price for a new carb. Got it home, gave it a quick inspection and mounted it up on the motor. I had to mount a new canister style fuel filter on the motor since I couldn't find anywhere on the fender well to mount it that didnt look as awful as a hipster chicks black glasses. Drilled and tapped the fuel line for a fuel pressure gauge while I was at it.
(http://farm9.staticflickr.com/8161/7476071540_1d45282db9.jpg)
Got it all mounted up, pulled the float inspection plugs and filled each bowl with a syringe. Turned each idle mix screw out to to 1.5 turns and hit the key. Nothing...hmm..ok. Pump pump squirt squirt. Hit the key, no fire. More pumping. Dah, CRAP. Flooded. Doh! Few minutes later did get it to fire, set the idle speed to 750rpm and let the motor warm up. Turned on the Innovate LM-2 AFR computer and started in on the idle mix screws. I was told the mix screws would make a big difference in just a half a turn, and that is no joke. Turned out to be super rich at 1.5 turns out, just 9:1 AFR. Moving them into 3/4 turn on all four corners has me in the 13:1 ballpark. The motor is idling smooth and pulling 10 inches of vacuum. I'm impressed so far out of the box I've not had to drill or mess with anything, which is nice.
A tick has developed on the right bank that I need to go investigate before I want to proceed any further. It sounds an awful lot like an exhaust leak, but I spent most of yesterday putting Nord-Lock washers on the collectors and tightening them down, so I'm reasonably confident it isn't that. It sounds like a pop each time a single cylinder fires, so I'm betting the high-temp silicone on one exhaust port let go. Bad part is this is probably introducing a small air leak into that side which is where my wideband O2 sensor is, so it's got to be fixed.
So, I'm happy thusfar with the 750, thanks for the recommendation.
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That is a really good deal on a 750 double pumper. I'll bet you will like that carb, especially at higher engine speeds...