Cole Neadow

Thanks to the excellent information from Joe ( Flareside) I will be using my LS6 intake on my oval port 454 ( see you can put a square peg in a round hole ) now I am looking for carb imput, this is what I have available. 650 Holly DP,(new) 750 Holly vac sec, (used) 850 Demon ( almost new ) my 454 is an early 70,s vintage non vette stock with headers and 4spd, as always I am looking for lots of power with low rpms
Thanks Cole

1980 Convertible 454 BB 4spd

rainman69

Demon...Lars and BlkBlt will tell you why. I think it had to do with a quality carb that takes Holley parts and added 28 RWHP to BlkBlt's BB 66...

I wish I had a BB for a Demon to go on... but that's later in life when I buy my 2nd. :D

gkull

No Brainer - Demon

norvalwilhelm

Sure you can put a square beg up to a round hole but if the beg is too large it will not fit. The rectangular ports are way bigger then the round hole so I think you will have alot of port missmatch and turbulance.
I also vote for the Demon

Flareside

Guys, I just pointed Cole to all the helpful people over at http://www.Chevelles.com. These guys have done some very impressive testing with many different big block manifolds and heads, and they really know what works. (Some of them race at a track near my house, Englishtown) They have been very helpful with my big block build-up questions. These guys are running in the 10's without nitrous or blowers in 4000 pound cars, and they're not doing it with huge 500+ displacement engines or $2500 aluminum heads. Great stuff if you ask me...

Big block owners that want to keep the stock hood line and external appearance have very few manifold choices, and the square port low-rise aluminum manifold on oval heads sounds like a great street combo to me. What's the other option? A Torker II! Maybe the oval port 454 big block can use a little extra plenum volume and turbulence at street rpms? Plausable?

-Joe

RatRacer

Do not use the LS-6 manifold on oval port heads. It will work very poorly. I reccommend selling it. If you want to maintain a stock hood the the way to go is to port the original low rise manifold. What you need to do is grind the area between the front primary ports and rear secondary ports completely out. With an iron manifold this requires some aggressive carbide cutters. I had a guy from Reher/Morrison do mine for $75. The modified manifold will now flow like hi-rise. The mod is good for 35-40hp on a healthy BB.


[Modified by Cam Potter, 8:34 AM 10/25/2001]

Marks69BB

If it is a DP use the Demon if it's in good working condition. I'm using the same 454/850cfm combination and the car has lots of torque and the previous owner claimed it outperformed the Holley 850 that was on there before. Although I haven't had to change mine, I was shown that compared to the Holley, the nice thing about the Demon is that the jets are much easier to change. Plus, the look of the billet aluminum finish has to be worth an extra 10 hp! :jester

Not sure about the oval port heads with the LS6 intake since I'm running an L88 hood so my heads and hi-rise intake both have rectangular ports. :D

Hope this helps. :cheers:


[Modified by Marks69BB, 8:36 AM 10/25/2001]

Cole Neadow

Thanks for the feedback guys I am going to try the Demon. The Chevelle people tell me they have used this manifold for years with as good as and sometimes better performance then oval to oval ??? I will let you know how I make out. I have looked into these Demon carbs, and found that people are pretty impressed by them. Hope I'm not on here next week looking for tranny or rear end parts.
Thanks again Cole


[Modified by Cole Neadow, 11:02 PM 10/25/2001]

oger

We just had another round on the big port manifold on oval heads. Von just put a big port on his ovals to make it look like an L78. His comment was it killed alot of low end torque. Stick with the sunken Corvette manifold or an iron Chevelle one.

Cole Neadow

oger
I do not want to loose low end torque thats why I went to the BB. I can't use the intake on my car now as it will not accept my Holly or Demon, I don't have room for adapters. Any other intake I have seen is to high, the Torker that Joe mentioned might work but its stated that its range is 1500 on. I would like power from idle on
Thanks for your help all
Cole

lars

Cole -
Check out our Demon installation and results on the C1/C2 Forum:
http://forums.corvetteforum.com/zerothread?id=170591

RatRacer

Cole, blow off the square flange carb idea and get a quadrajet that is set up for your car. Lars can help you out here. Do the mods to the stock intake that I mentioned above and you will have all the low end torque you need as well as a lot more HP on top. The total cost for Quad and the modification to your manifold will be less than $300. The best part is that it will look stock but perform much better.