Question for the masses

What type of performance gains would one see from upgrading from a super six setup to a offy 4bbl with a holley 8007 390 cfm. The engine is as follows

73 block decked 10 thou. 20 thou over on the cyl.
head shaved 75 for a compression of about 8.9 to 9.0 to 1
1.44 and 1.7 valves
isky cam 256 duration .425 lift
dutra front exhaust manifold with modified stock rear.
stock torque converter in a rebuilt 904 with the guts from a la 904.
msd 6al ignition and blaster coil

What do you think? worth upgrading to a 4bbl set up or not other than that wow factor of the offy are the performance gain really worth the $$$. I've got a line on a new intake for about 150 and already have a lokar kickdown cable so the only other expense would be a new or good rebuilt carb.

Thanks in advance

Brent...

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Arizona Duster in Canada

Brent,

By "performance" do you mean ET? or torque on a dyno? or...?

Many hundreds of lines are in threads here about generalities, however,

rock
'64d100

No just regular everyday can feel it in your but type performance. I've read lots of posts but haven't found a "clear" answer...maybe I am looking for too simple and answer.....since everyone has different experiences etc.. Just wondering if I would notice any difference between the 2bbl and the 4bbl all other things being equal?

FYI
my cr may be a little higher 9.0:1 was from memory but i found a few notes jotted down that make me think it may be a bit higher I know I cc'd my head and all the combustion chambers worked out to 47cc just can't find the rest of my calcs right now.

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Arizona Duster in Canada

The 4 barrel will get you a bit more 'umph', if you tune things in right it will also give you equal mileage to the 2 barrel (or better if you really pay attention to your timing curve, rear ratio, jetting and secondary opening event). The caveat to this would be to make sure you have a sufficient exhaust to go with it, if you are still running a stock 1 7/8" noodle pipe that all this is a no go.

Just as an FYI, going from the BBD to the Holley 390 allowed my duster to have better top end (the BBD went 'flat' on acceleration at about 80-90 mph...the Holley allowed me to get up to 127 before I ran out of road...but it was still pulling strong...)

-D.Idiot

I second what DI said. If you are going to drive this car on the street, you almost certainly would be happier with a two barrel, unless, as DI said, you are silling and able to spend ots of time fine tuning the carb and timing curve. DI is a tuning genius and always gets excellent results with his projects.

I would recommend you try something like a Holley 2300 with the "economaster" venturies to get a better vacuum signal. I think this would be the best compromise between street driveability, gas mileage, and performance.

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Casually looking for a Clifford hyperpak intake for cheap.

well for plain old street use the bbd is an ok carb, but as Duster Idiot said it does fall flat in the 80 to 90mph range. but your going to have quicker take off and accelration in the lower speeds with a bbd than any 1bbl.

as far as a carb goes, that really depends on how much money you want to spend. i ran a bbd just fine for months and put a ton of miles on it.

but there was a night and day difference when i got my holley 2300, i pull strong at any speed and i have burried the spedo on many occasions and watched the tach still rise. i am not a carb expert or a timing guru, but even i can change jets and set up a 2300 easly, i looked @ the bbd with a very confused look when it came to anything on it.

exhaust is a big thing when doing the super six upgrade, i'm running 2 1/4 all the way back to an insanely large glass pak with a 5 1/2 out. yes its over kill! but the bigger pipe lets it breathe and even a oem replacement muffler on the larger pipe sounds good.

reed has written a great super six page, i printed it out and read it almost every day for a month before my supersix swap, btw thanks to every one
for helping with that. i'm still running it! i would take this chance also to get really good gaskets, remflex or the aussie ones.

i will not be going the 4bbl route, i cannot aford it and i just don't have any room left under my hood. and since i really do not race my car i don't need it. and i do not know enough about tuning and timing to own one either. for most people the 2 bbl is enough.

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"Marilyn" 64 Dart GT & "Stella" 64 Valiant V100 Sedan - 63 Norton Project

Ok duster,,

now I got ya. I went straight from a 1 barrel Carter to a 500 cfm Eddy 1404 down to a 390 cfm Holley 8007. My engine is much like yours but the head was shaved 100 thousandths. Lots of porting, tuned exhaust, Dutras, etc. I use a 727 with a 2500 stall convertor. Note I didn't try the 2bbl but I have corresponded with Reed, DI and Ted sufficiently to think my results are much like theirs in a 2bbl. I did this corresponding early on as you are to see if I wanted 2 or 4bbls. Now, if they are relatively equal, why 4 bbls?

I wanted the sheer mechanical challenge of making up the linkage then learning Holley tuning and dizzy recurving. After a few years of working steadily I believe I have learned them. I am an endless recurver and tuner but have got about what I can out of my induction system, and confirmed it with a good wideband A/F gauge. I would kinda like to have the 500 cfm Eddy back, but not badly enough to make more linkage for it. I have toyed with trying the 2bbl "just to see" but heck, I gotta respect what Reed, DI and Ted report, particularly since it so close to what I have now. I came within hours of starting a turbo and/or a fuel injection setup, but heck my spouse would really get to griping if I started putting in the time I put in my current setup.

So, bottom line...I am like a drunk that quit drinking...what's next to do? Well, how about enjoy life and drive around? I have killed a number of local 318's and some 340's with my pool little slant truck. After all my 'sperimenting I don't think now it would make much difference in 2 bbl vs 4 bbl, but if you aren't into the tuning and recurve effort needed for the 4bbl (fun for me) then reluctantly I reckon the 2 bbl may be the way to go. Never thought I would conclude that, but three years of steady tuning and recurving lead me caution you about the time commitment for basically the same performance from the 2bbl when using the 4. If you really like mechanical minutae then yeh, start down the 4 road. But put in a wideband A/F gauge early on. It will save you many weekends of jet replacing.

rock
'64d100

Same experience here - I actually bought a RSA charger to test my manifolds on rather than stuff around with my 390 engine in the cuda - I had to do a brake ugrade dut to this - the 9 inch drums died on me after a top end run never had THAT problem with the BBD

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Regards,
Fanie Gerber
It's never junk, it's just a part you're not currently using

http://www.valiant50.co.za
Just say I own a few Mopars

Thanks for all the replies. Since the price of $150 sounds good for an offy I guess I will pick it up and hide it away until I get the itch to do more tuning on the car and can save up enough $$$ to buy a band new holley 8007 carb.

I really like tinkering on it..one of my only hobbies (other than hiding parts from my wife) so what the hay I guess I will be back with more questions when it comes time to re-curve etc.

HMMMM maybe I can find a hiding spot for one of those hurricane intakes somewhere too....lol

Thanks again

Cheers
Brent

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Arizona Duster in Canada

offy for 150 yeah grab it!

i think almost every married sl6 guy has a secret parts stash that he hides from his wife . i was so gonna get the 2 bbl hurricane intake but now that i have a dual pot power master cylinder the hurricane will not fit in my engine bay. as far as tinkering goes unless you really like it i would stay away from a huge 4 bbl carb a smaller 4bbl may be easyer to work with but again i have never had a 4bbl on my dart but i have seen other members struggle with them. your results may differ

i personally like to turn the key, pull my manual choke and back out of my driveway. by the end of the block my choke is off and i have clear windows and heat. and i can tear out minus some spent rubber and be on my way. but again my dart is my every day driver rain or shine.

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"Marilyn" 64 Dart GT & "Stella" 64 Valiant V100 Sedan - 63 Norton Project

I switched from a Super Six to an Offy/390 on my Duster. The car picked up 6 tenths and 8 MPH in the 1/4.

Yes, you can feel that in the seat of your pants.

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Official Cookie and Mater Tormentor.

The Offy intake is the best one I have seen for street use. It has a four barrel mounting pad but can accomodate any carb you want (I built an adapter plate to run a one barrel on an Offy, and I did!). Another benefit is that the runners actually have a smaller cross section than the factory intakes. This means better low RPM power.

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Casually looking for a Clifford hyperpak intake for cheap.

Reed,

How did that work out?
Did you get better mileage over the stock manifold?

Thanks,

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

Dont feel alone with the hiding bit - what works is to make a big show of the legal bits - the bits she knows about - and make certain that the garage is in a state of organized chaos - ergo a lot of props to keep her out....oil cans and such - in effect it will take you five minutes to sort out but for the missus it looks awful - the caper I am busy with includes new workshop / car shed - so the daily used cars - her Ford 1/2 tone truck and my TDi Jetta - does not get harmed - the story behind the story is that a local has given me a 60 r-series valiant wagon and I need storage space...........

But I know she knows whats up ...more or less

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Regards,
Fanie Gerber
It's never junk, it's just a part you're not currently using

http://www.valiant50.co.za
Just say I own a few Mopars

I totally disagree with the statement that the BBD will fall flat at 80-90mph. I could easily pull to 120 when I was using one. The 4bbl hasn't given me any real performance gain over the BBD, BUT, I never swapped cams, since you cammed yours I say go for it. without a good cam a 4bbl is over kill in my opinnion/experience.

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