The plan for my velle -66 is to make a weekend warrior with potential to get in the 11's at the 1/4 mile. My signature show how the car is know.

This is my coming combo:
454 block 2 bolt that had to go 070 over(makes 468 cui )
4,00 steel and crossdrilled crank.
7/16 6,135 rods with floating pins.
820 heads with 2,19/1,88 ss valves and no portwork yet( or 049 heads if I can buy them from a friend who has them on a shelf..)
Comp cams pro magnum roller rockers 1.7 ratio.
RPM intake.
UDlunati solid cam 288/296,.050 255/263 lift .612/.630,lob sep 110 deg.
Crane 99893-16 springs
KB pistons 207 and looking for 10,5 comp.
Carter 172 gph mech.fuel pump.
AN8 fuel line from tank to carb.
HEI ignition with Pertronix flamethrower upgrade kit.
TH 400 with ATI manual valve body.
ATI 10" Treemaster converter .
12 bolt rearend and a 3,90 gear with posi.
28" 275/60-15 rear tires.
Any advice about the combo would be nice, and I need help to pick a carb and headers for this combo.I was looking at Holleys hp950 or BG's 850 mighty demon for carb or is there a better one for me? I was searching for 1 7/8" headers which I think would be nice for my combo but haven't found any. So if I can't find any of those should I go 1 3/4" or 2" pipes ? If you have any suggestions, please chime in...

Kind regards Stefan B.

800cfm dp holley,2 inch primary tube headers--jmo,67rat

I don't think you'd be disappointed with an HP950 and Dynomax 1 3/4" headers with flowmaster scavenger collectors, 3" exhaust, Dr gas X pipe and Dynomax Ultraflows with dumps. Works very well on mine.

that 950 seem a little large for your combo dont it?maybe not!! dont over carb it.just my opinion-67rat

I use the HP950 and 1.75" dynomax headers and my cam is smaller than yours, alot less lift,and slightly more duration, ran 11.84 a month ago not too shabby after 5 yrs in the car,the last 3 racing full time. I'm going to try the same setup on the 505 and see what happens.

Thank's for the reply's!

I think 1 7/8" headers would have been a nice kompromise between 1.75" and 2" headers. There is now one that know about 1 7/8" primary pipe headers that fit a 66 chevelle with a healty bigblock ? I have looked at Summit, Hooker, Flowtech and some others but haven't found any.
If i can't find any of those I think I would stay with 1.75".
The exhaust is going to be 3" with crossover and some good mufflers.
Regarding carbs I like the HP950 but think it's "pricy". I also think that a dualplane intake , like the RPM, could handle a bigger carb then a single plane intake could, becuse the cylinder that are going to "inhale" only see half of the carb. Well, I have an old 750dp with a Proform house on it, I could try that one.. On the other hand I have never "tinkered" with BG's stuff, so I kind a curios of them.

Kind regards Stefan B

I think a HP Series 950 would be perfect for your combination. graemlins/thumbsup.gif

It sounds like alot of carb (950cfm advertised rating by Holley) but in reality it only wet flows about 820-830 cfm.

As far as headers go, another option is use a set of 2" primary headers and install a set of Flowmasters "Pulse-Tech" 4-2-1 collectors. This is what I did. In theroy, it should give the best of both worlds between the small and larger tube headers.

71454Chevelle.That's an interesting thought about the headers. I shall look up the Flowmasters collectors. And I agree on the HP950. In my book "super tuning and modifying Holley carburetors" by Dave Emanuell, the R80496 ( hp950 ) is listed with a throttle bore dia. of 1-11/16" ( same as the 700 to 800 DP's ) and a venturi dia of 1 1/2" ( sligthly smaller than the 850 DP which is 1 9/16" ).

Stefan B

so they flow 800cfm and some change? now that would work great,as I run an 850dp whats with holley advertising 950 cfm?--67rat

learn sometime new every visit!! graemlins/thumbsup.gif

Stefan,

On your combination we’d recommend using an 825 Mighty Demon. Being a little smaller than an 850 it will give you better air velocity, which should give you better torque, acceleration, and drivability on your combination, especially with the 3.90 gear. An 825 Mighty Demon will actually outflow the Holley® 950HP. A 950HP is essentially a 750 carburetor with an 850 baseplate. The rating was done to combat the carburetor modifiers of the time. The Mighty Demon has a Billet baseplate, and metering blocks, which will make it a more solid platform to work from.

Tech@BG. Thank's for the advice! That's leed to another question for you. For tuning and shifting jets, will my Holley jets fit the Mighty Demon or will I have to get another jet kit assortment?

Stefan B

Stefan,

Yes, all of your tuning parts (i.e. Jets, PV, Sqtrs, Bowl & Block Gaskets, etc.) will interchange between ours and most other brands such as Holley® or Moroso®, however to keep your Demon operating at it's peak level of performance we recommend using genuine Barry Grant components.

Tech@BG. Thank's for the info !
And to all of you that responded to my post:

graemlins/beers.gif

I should take a deeper look into the 825 Mighty Demon you recomended for my new combo, as listed in my first post. BTW how does the "idle eeze" thing work ?

Kind regards Stefan B

Stefan,

The Idle-Eze® system is an air bypass that allows you to set the butterflies in the proper orientation for the best idle quality, and throttle response. Once you set the butterflies, and install the carburetor you can then control the engines RPM by the Idle-Eze®, rather than the old method of having to drill holes in the butterflies. IT makes the setup a snap, and makes it real easy if you change a lot of parts to re-adjust.

Originally posted by 69shovel&90454SS:
I don't think you'd be disappointed with an HP950 and Dynomax 1 3/4" headers with flowmaster scavenger collectors, 3" exhaust, Dr gas X pipe and Dynomax Ultraflows with dumps. Works very well on mine. Is flowmaster still making the 1 3/4" scavenger collectors? Do you have a part number? TIA Wes

I bought mine about a year and a half ago and were made with a 3" out. It looks like they make them now with a 2 3/4" out. The part number is FLOPC134218234

69Shovel, thanks for the P/N. I was able to find the 1 3/4" scavenger collectors at summit for $109 under p/n FLO-C134218234. I'm pretty happy about this, because I thought they had been discontinued in that size.

i would go with the hp950 for sure, the headers would be a toss up. i would probably use the 2" Hooker S/C's just in case you want to nudge up the power some more later on, or if you try nitrous or something. power-wise, there's probably not going to be hardly any difference between the 1 3/4" or 2" on your motor, IMO. with the convertor and gear you have, i'd lean towards the 2" tubes.