Slant Six Forum :: blow through or efi

I appreciate all the great responses to my question. I am a not-too-smart-guy, who is not comfortable with a jump to EFI at this point, so while it may seem the right choice for some, I am electing to stay with the blow-thru carb setup I have right now. This "tip-in" lean condition is the ONLY driveability issue I have. The engine is an almost stock, 360 Magnum, with only a cam and intake manifold change from BONE stock (a 214/218-degree @ .050"-lift, .525"-gross lift. grind, on 116-degree lobe center separation Hughes engines, hydraulic roller regrind, and a Professional Products "Crosswind" intake manifold.

That's it.

It made 445 rear wheel HP (I run 10 pounds of boost from a Vortech V-1, S-trim blower) on a chassis dyno a while back, and I am happy with that number (runs about 118mph in the quarter in a 3,500-pound car; mid-elevens.)

It's in a '72 Valiant 4-door sedan, and is a fun street car, but that stumble on mild accelleration at roll-on, part throttle, has me baffled.

I still need Brent's contact information, if anyone has it. He can probably fix this...

The "slant-six" part of all this is, I am also half-partner in a turbo /6, '64 Valiant (also a 4-door) that SHOULD make my V8 car look like a slug, by comparison if it runs anything klike the way it's supposed to. That /6 car is nearing completion and will be operational in the spring, and looks to be a ton of fun!

Thanks again for all the good advice!!!

Bill

Author:	Stoopid john [ Sat Jan 21, 2012 9:30 am ]
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Quote: Can you post contact information for Brent Davis, please? I have a blow-thru Holley 750 DP 4150 on my Vortech blown 360 Magnum and the Carb Shop didn't get it right (for $900.00!) Part-throttle tip-in, it exhibits a lean condition that I haven't been able to fix with higher float levels accelerator pump mechanations, (accelerator pump plastic cam changes, and pump-stroke changes, plus bigger squirters,) richer jets (A LOT) and smaller air bleeds. It's lean enough that part-throttle tip-in, it backfires through the intake. I'm sick of it... Maybe Brent can fix this???? That's the exact problem we had, tip in, just as the boost came in. Brent fixed it all. Our carb had 75 jets in the front and 88 in the rear. With Brents set-up we had 70's front and rear. It's the way to go. http://www.theturboforums.com/smf/the-' ... h-section/

Author:	turboram [ Sun Jan 22, 2012 4:46 am ]
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My opinion is use efi, I spent only a 1,000 on my setup and it started hot or cold idled smooth had awsome throttle response ,great fuel mileage. When I finaly dialed it in it ran like it came from the factory with efi. The computer would adjust the afr itself, and every setting could be changed in seconds with a laptop. Try changing your main jets and accelerator cam at a stop sign data logging is also a big plus,and you can possibly get tunes from other people running a similar setup to start you off.you can even have launch,boost,and nos control and change from a driving to a race tune in a minute

Author:	Dart270 [ Sun Jan 22, 2012 6:23 am ]
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And that's the game... Couldn't have said it better myself. Lou

Author:	Stoopid john [ Sun Jan 22, 2012 6:50 am ]
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But if you go with a carb, Brent's set-up is the best way to go. Any way go, the fuel system is key. Don't cheap out on the fuel feed or return. It will only cost you more in the end. john

Author:	Dart270 [ Sun Jan 22, 2012 9:58 am ]
Post subject:
Agreed! Lou

Slant Six Forum https://slantsix.org/forum/

blow through or efi https://slantsix.org/forum/viewtopic.php?t=47602	Page 2 of 2

Author:	Turbo Toad [ Sun Jan 22, 2012 11:15 am ]
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I agree also on the fuel delivery system I did a bunch of research before I decided on my setup but when all was said and done I copied a couple members that have set the bar high Here's what I did Walbro 392 external fuel pump 8 an fuel line Mallory 4309 fuel pressure reg with return 10 an return fuel line 6 an fuel line to the carb

Author:	billdedman [ Sun Jan 22, 2012 3:56 pm ]
Post subject:
I appreciate all the great responses to my question. I am a not-too-smart-guy, who is not comfortable with a jump to EFI at this point, so while it may seem the right choice for some, I am electing to stay with the blow-thru carb setup I have right now. This "tip-in" lean condition is the ONLY driveability issue I have. The engine is an almost stock, 360 Magnum, with only a cam and intake manifold change from BONE stock (a 214/218-degree @ .050"-lift, .525"-gross lift. grind, on 116-degree lobe center separation Hughes engines, hydraulic roller regrind, and a Professional Products "Crosswind" intake manifold. That's it. It made 445 rear wheel HP (I run 10 pounds of boost from a Vortech V-1, S-trim blower) on a chassis dyno a while back, and I am happy with that number (runs about 118mph in the quarter in a 3,500-pound car; mid-elevens.) It's in a '72 Valiant 4-door sedan, and is a fun street car, but that stumble on mild accelleration at roll-on, part throttle, has me baffled. I still need Brent's contact information, if anyone has it. He can probably fix this... The "slant-six" part of all this is, I am also half-partner in a turbo /6, '64 Valiant (also a 4-door) that SHOULD make my V8 car look like a slug, by comparison if it runs anything klike the way it's supposed to. That /6 car is nearing completion and will be operational in the spring, and looks to be a ton of fun! Thanks again for all the good advice!!! Bill

Author:	Turbo Toad [ Sun Jan 22, 2012 5:06 pm ]
Post subject:
Bill ill try and fund you Brents info I looked for for about a hour ago the other day but I couldn't fund it ill pm him and shoot u over the info if I can Aaron

Author:	Stoopid john [ Sun Jan 22, 2012 5:53 pm ]
Post subject:
Quote: I appreciate all the great responses to my question. I am a not-too-smart-guy, who is not comfortable with a jump to EFI at this point, so while it may seem the right choice for some, I am electing to stay with the blow-thru carb setup I have right now. This "tip-in" lean condition is the ONLY driveability issue I have. The engine is an almost stock, 360 Magnum, with only a cam and intake manifold change from BONE stock (a 214/218-degree @ .050"-lift, .525"-gross lift. grind, on 116-degree lobe center separation Hughes engines, hydraulic roller regrind, and a Professional Products "Crosswind" intake manifold. That's it. It made 445 rear wheel HP (I run 10 pounds of boost from a Vortech V-1, S-trim blower) on a chassis dyno a while back, and I am happy with that number (runs about 118mph in the quarter in a 3,500-pound car; mid-elevens.) It's in a '72 Valiant 4-door sedan, and is a fun street car, but that stumble on mild accelleration at roll-on, part throttle, has me baffled. I still need Brent's contact information, if anyone has it. He can probably fix this... The "slant-six" part of all this is, I am also half-partner in a turbo /6, '64 Valiant (also a 4-door) that SHOULD make my V8 car look like a slug, by comparison if it runs anything klike the way it's supposed to. That /6 car is nearing completion and will be operational in the spring, and looks to be a ton of fun! Thanks again for all the good advice!!! Bill I sent you his list and number. john

Author:	Stoopid john [ Sun Jan 22, 2012 5:58 pm ]
Post subject:
Same problem, if it was a "track" car you would never know you had an issue. Idle and wide open was great.

Author:	billdedman [ Sun Jan 22, 2012 9:42 pm ]
Post subject:
Quote: Bill ill try and fund you Brents info I looked for for about a hour ago the other day but I couldn't fund it ill pm him and shoot u over the info if I can Aaron Thanks, Aaron; John sent me a p-m with Brent's info. I appreciate your interest! Bill

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