Out with the old and into the new. I can not believe I am looking at this Demon Carburetion 1904 750cfm for my DX build. It did OK on Engine Masters.

Replacing my beloved 750cfm Rochester Carburetor. Hoping it will fit under my G body 2'' cowl hood and a Victor intake for small block. Rpm on now, will need to rework my cowl tray and 86 the resin spacer. 434cu in and 7000 rpm. 750 cfm should be about right? Or I need a little bigger? My goal is around 600- 650 HP.

The 750cfm Rochester i have now was nos still in plastic wrap in 2010. Was for a 1970 Old's motorhome engine. I change out the needles and seats to AU or AX. Would have to look at my paperwork. Feels like more bottom end with this carb compared to the old rebuilt 1972 carb. I have not seen a nos 800 Rochester or higher in the last few months of looking.

 

I'd go bigger if you want to pull 7k. 850 minimum, and I'd go 4150 or 4500 style. Just another stinky hole opinion....

 

x2

 

Not much room. I would need an adaptor to fit on Victor intake? That why I wanted the Demon. Rochester Carburetor 850 - 900 rebuilt? Never had a Holly, know little about them. Not looking to change to a 4'' cowl.

 

I really like the Street Demon design, except one important item. Holley improved the Thermoquad nearly everywhere except one spot. One member had the issue on their hot 403, not enough fuel flow, even with huge Holley jets. He could only pull 13.3 AFR at full throttle. You don't need a NOS 800 cfm carb. Just get a rebuildable 76 to 80 Qjet and bush the primary throttle plates and totally recalibrate it. Get quality parts from Cliff Ruggles, he will suggest the idle down tubes, jets, primary piston spring, get his fast choke pull off and everything to get it like new. It will be a good starting point and get it bang on with a wideband.

 

Don't pick a carburetor by advertised CFM. You need to pick it by application. I wouldn't even suggest anything with the limited amount of information given. My advice is, if your looking at a street carburator you probably don't need a victor. Stick with the RPM and use the money to get the right carburetor, not a cheap one, you won't be sorry.

 

For the kind of cash you're going to drop on a good carb, I'd be looking towards one of the TBI deals. I did and it's been a pain, but changing stuff is a breeze and you have an AFR to work with. There's no pulling bowls to rejet or float levels to set. So, throw a wideband on top of your carb cost, and it makes sense (to me anyway). Just bear in mind that the sensors they come with are junk, but easily replaced with better parts store or AC Delco TBI stuff.

 

Agree however like he says if going the victor intake route thats the wrong demon carb to use. Get a 4150 based version in 850 cfm.

 

Victor is for Square-Bore Carburetor. My bad, I should of checked. How about a SNIPER EFI 4150 SUPER SNIPER 650. I will have to pull down the gas tank again and change out the fuel pump. To one that is higher pressure. More wires! There a lot now in the engine bay. Need the Victor, i believe to get the most out of the combo. I am putting together.

No rush, moving back to south Texas in February. New BBO Edelbrock, well maybe by summer. Who knows, Holly may build a bigger cfm demon carb, I will call them. I like the simplicity of the Demon.

My Lighting Rods like high rpm and I like it even better. Lonnie at Extreme Automatics builds one hell of a 2004r. There is something about moving the shifters a 1/2'' at 6,500 or higher. The instant upshift, better than I could shift with a 4 speed manual, Even downshifting with big bear brakes. I just love it! Bought my 1984 Hurst/Olds new from the dealer. After 37 years, I never get tired of them. Almost as good as sex! Sorry I keep showing pictures of her. She just F**king beautiful!



8e2e 3

 

Gorgeous car, one of the nicest G bodies on any site, we will tolerate it😎. Too bad Holley doesn't add a 800 or 850 cfm version like the old Thermoquad. The Super Sniper 650 sounds like your best bet. Glad to hear the EA 2004R has held up. One member had two Stage 2 models fail and he went to TH400. It was drag raced and 500 ft/lbs. I need to start building mine as soon as I can spare $1000 US for all the parts. For now the CK pump, Servo and shift will hopefully be enough behind the iron head 357.

 

The EFIs are only 4 wires= very easy. Be prepared for "the list" if you ever have to call Holley's tech line. "Is it powered directly off the battery" "Are any wires near the ignition?" Blah, blah, blah, worthless.

 

Some more usable info here;
I did a 434 Stroker, out of the box Gen II Edelbrocks, Victor, QF SS830, 238/244@.050 Hyd roller. Made 533@5700. Peaked way lower than I thought it would. Use an 850 and open up the intake as well.
Holley now makes an X flow Sniper, 900cfm. But buyer beware, I’m a Holley dealer and have had all kinds of issues with Snipers lately.
As mentioned buy a good carb, maybe even from Dale Cubic or similar, or even a 4150 style 950 if you plan on spinning it to 7000. Then buy a wideband.

 

olds 307 Thanks! There are some cutlass's on Facebook G Body groups. That are nicer. I am happy with mine.

fleming Like your engine bay. Brakes and hydraulic clutch setup is interesting. Intake manifold? Mine is so busy with wires Poor planning on my part. I keep adding thing to remove parasitic drag on engine.
Your electrical fuse- relay box, looks like just what I am looking for! Where did you get that one from??

cutlassefi Not a pro at porting. But the few I did, made a huge different. New BBO Edelbrocks heads and SB Victor max porting by me, right cam(had a lopey cam that sounded like 4 Harley-Davidsons going down the road. a little over 2,000 rpm. I would break the tilt steering wheel lock, if my hands are top of the steering wheel), high compression, I can live with 10.5 -11 to 1. Vacuum does not matter with my brake setup. Hopefully close to the 600+ HP.

As you are Holley dealer. Maybe talk to them about bigger 800, 850 or 900 cfm version of Demon like the old Thermoquad . Simplicity of theDemon and almost everyone who has one loves it. I love the sound of the secondary air doors opening on the Rochester Quadrajet. For you only Holly guys, this is what you are missing. I was raised on that sound from my parents 70 Buick 350 GS at 16 years old.


God knows that other little goodies, you are working on. You don't tell me!

 

I have time, but i am looking at a Holly 950CFM XP CARBURETOR? Or bigger?

 

I think Holley did something screwy with the HP series. According to a friend of mine, they are 100cfm less than their model number? Someone else can verify.
The master cylinders are Wildwood on a 2 unit fab plate from Stock Car Products. I made a filler to bridge the gap back to the firewall, then blended it in.
The intake is a Holley Street Dominator. I was originally going to use a pre-EGR Torker, but it was crunch time and the Torker needed cut to fit.
The fuse and relay center is a cheap Bezos piece.
12V Auto Waterproof Fuse Relay Box Block The little one is just a distribution point. You need a set of Delphi crimpers and the fuses and relays to fill it. They're really nice for the price with silicone weather seals on everything. Thank you Ding How.
I made the bracket for the fenderwell. I had to lose the washer bottle, but I may put that back if I W-30 clone it and the battery goes in the trunk.

 

Yup, that was my 403 that just couldn't get enough fuel through the secondaries on the street demon. Otherwise it was a nice carb. That engine was ~450HP, so at closer to 600HP it would definitely be struggling.

A quadrajet can probably be made to work, just need to do normal tuning. The single fuel inlet is a concern though. It's really unpleasant to run out of fuel flow and spike lean when you're really getting into it. Thankfully we're not talking a boosted application so it probably won't break stuff... Just noses off.

The Motortrend guys really really love the HP series, and that's good enough for me. An 850 or 950 should be good for this.

I also ran a 4150 style 850 carb (Brawler). It ran really great, but I simply could not stop fuel from boiling in the front bowl. That caused the front squirter to dribble and run dry, which then caused a major stumble at every green light once the engine was hot. Tried spacers, isolators, heat shields, different bypasses.... no dice. That appears to be a somewhat uncommon problem, so probably just because of how I have my junk set up and the electric fan blows straight onto the engine, whereas a clutch fan tends to blow air out towards the driver fender.

Just note - all the different variants and brands and labels and series and stickers for 4150 carbs do not necessarily mean all that much. The basic carb design has been the same for many, many years. There are very minor differences, mostly how many tuning tools they give you (how many bleeds and whatnot) out of the box. But you can build a 4150 from parts to exactly the setup you want.

 

Edelbrock AVS2 800 cfm .
I have had a nice boost using this new AVS2 carb over the old 750 edelbrock. Noticeable gain driving it on a 550 ho 455

 

My opinion, look for 800 cfm or higher. Attached is a dyno test with my 482 stroker and dual plane manifold. The Qjet Is a 800 cfm Level 2 unit from Ken at Everyday Performance, no big mods other than the secondary air door fully open at 1.250" ish. Primary throttle shaft thinned slightly. No choke blade.. 586 hp.

The TQuad started out life as a production 850 cfm unit, 6322 but modified by Steve Stills. The primary booster outer ring has been removed and the primary venturi bump in the bowl was removed. The secondary air door is set to .800" and sec blades set to 86 deg. No choke hardware. So prob 900 cfm. 590 hp.

The Holley is a 950 Ultra HP. It's a second gen unit which flow more than the initial 950 HP when they came out. Venturis measure 1.6" with 1.75" throttle blades, so its not simply a 750 body on an 850 base (which some are). Box stock except for jets. 595 hp but killed the others on torque.

Care was taken on the spreadbores to ensure adequate fuel flow (large needle and seats, enlarged fuel fittings etc)

 

Very good info. Usually the Holley beat the spreadbores by a bigger amount but those have some interesting mods. The Qjet is better down low than the TQ and pretty close for torque till 4000 rpm, then the Holley pulls away. Thanks for sharing the info.

 

I want to thank everyone again. Things have turned for the better. Maybe Great is a better word for it. I with have realty good news on the DX build in a few days. For the first time in my 65 years, I am going with a big Holley. Maybe this old dog can learn something new to me.

 

Please share your impressions on how it compares to a Qjet, drivability etc.

 

If you’re spending decent money on a DX build, I’d look at having a carb built to your engine specs.

 

Having Bill at BTR do the thinking for this one. Have him do a complete engine. Dyno the whole deal. Thinking, if the Battens AL 2 and intake do not sell soon. I will have them put on the engine. He wants me to send them. They have some porting done,push rods moved to open intake ports. Needs all new valve guides and 2.180 valve plus exhaust ones. Oldsmobile is one of my hobbies. The Nascar DX is not meant for a hobbiest to build..

 

Yes I know a bit about them.

 

Sounds like Dominator territory

 

Batten heads going on the HP DX. Holley Terminator X Stealth 4150 EFI Fuel Injection Systems

.
Gives me more control.

 

This is what you need. Model 7320. Simple and will handle that animal build by Bill. Replace tank with EFI tank and in tank pump from tanks inc for future EFI unit. Add low pressure fuel regulator for carb and remove it when switching over to EFI. Increase fuel line diameter for both feed and return.

 

The EFI pump in tank works, but you have to return a bunch of fuel. Been there; done that. I ended up putting a tee at the sender (5/16" port), and using a vent port as an additional return. The single return in the sender wouldn't allow pressure below 9psi at the regulator.

 

Hi Rick! Have an low pressure elect fuel pump in tank now. For the ProComp on a SBO. And new pressure regulator in engine bay, with return line to tank

Looks like the holly needs a higher pressure pump? Guess I will get to cut a hole in the trunk, over the fuel pump. And install a cover. Not looking to pull down the tank again.

Holley Terminator X Stealth Max is the way to go. Starts right up, learns on its own. Self contain. Injectors in the carb itself. Bill recommended. After looking it up in YouTube and groups in Facebook.
I like what it does.

 

Hey John ! Hope all is well.and things are calming down from the move.
That Holley system looks awesome. Your still going to need an EFI tank if you don't have one. Seems like most people I talk to love the Holley system. Those who are having trouble with them all seem to be self inflicted with sloppy wiring install. Have to be careful with interference.
Looking forward to the completion of your build.
It's gonna be a wild Ride !

 

Getting settled. Weather getting warm this week.

Not sure I need a EFI tank. I drop my existing tank years ago and add Delco Elect pump with pick-up mat to the fuel line. Along side the sending unit. Pump is a low pressure and the same one that's in my Cadillacs..

I think I just have to replace that pump with 60+ higher pressure one. Put the high pressure spring into Aeromotive 13301 Regulator.

Cutting the trunk floor and adding a door over the sending unit. For ease of install and replace if it goes bad. Nothing much original left on my cutlass.

 

"Self learning" is a fairly narrow window. Save changes as you go. It's a pretty steep learning curve if you're not real good with computers
Tanks Inc is nice- 24 gallon, comes with straps, 2 vents. Upgrade the sender to the tube type.

 

Holley Terminator X Stealth Maxv $1900 . Tanks Inc another $500 or so for the tank, pump, etc. Or $200 for a Delco elect in tank pump from Germany with two filters.

I need to pick my battles on cost. Or it can get out of hand. Bill is not cheap. Nascar block and Batten heads was not cheap. Putting in the best parts engine parts is not cheap. Batten headers, S60 Rear end, drive shaft, Safety loop, transmission shield, beefing up the frame. Not cheap.

But I know it will one of the best engines and car. No matter what anyone says! Not that I think bill is god.

His lifetime of experience. Even him add extra clearance on the bearings. And the other clearances that must go along with it. To help trap the oil somewhat in the bearing That many here Knock. I see the wisdom in it. Smoother cooler running engine that lasts! Higher pressure on the gauge is not better than the crank floating in the oil.

 

I get it, man. I'm living it, too. My Tanks setup was closer to 700, all said and done. It's also the 2nd go 'round. The 1st was a Spectra. Not enough venting ballooned the tank and buckled the trunk floor. I could have been rocket powered, literally. It's not just about cost, but safety, too.
These tbi efi systems are all pretty much the same. I went fitech, and it was still 1100. They come with junk Ding How sensors; be prepared.
One thing I wish I had done was an external regulator (another 300 plus fittings).

 

I have two gas caps. One vented the other not. Only use the non vented for full gas tank. Vented one for all other time. Super important in hot weather to use vented one. Is that way yours ballooned?

Also have a one way check valve to let air into the tank. That was connected to canister. Maybe need to add one of Tanks Inc remote mount rollover vent.

Your car looks like the 67 my brother had. Is there not a vent behind the tank. A little plastic doohickey with something that looks like cotton inside?

 

On the Spectra tank, it was a 1/2" line ran up the filler neck. That's what surprised me. The only thing I can think is it hydrolocked parked up hill. Ellifino.
Tanks has 2 1/4"- 1 on the sender, 1 at the top of the tank. Came with the y, and I can't remember if I had to supply the rollover. Also, got their capless filler (couldn't get the OE style 1/4 turn to work). I dig it. Plus, the added capacity helps on trips.

 

"I know it will one of the best engines and car. No matter what anyone says! Not that I think bill is god."

Maybe consult Bill on complete fuel setup.
​​​​​​He may not be God, but maybe the Son of God. He is human like the rest of us. A lot of awesome Olds engine builders out there. But let's face it, he has experience. Lots of it. On and off the track. I know when I was deciding on a BTR build I contacted over a dozen people with engines from Bill. Not a one had been disappointed. They all said he build's a cool running killer engine and it was everything he said it would be and more.
You are fortunate to be able to afford a specialty build from Bill.
​​​​​​​In the hands of Bill that Nascar motor is gonna be insane. You just have to feed it correctly.

 

I am not a engine builder. I readied enough to know what I want! A high 8,000+ rpm screaming animal. Lightweight, strong internals with Batten heads in a bulletproof HP DX block. That will spin up fast off the line. HP climbing fast. Nearing peak horse power around 7,000+ rpm and maintaining peak HP(Almost flat horsepower line all the way to 8,000+) Blow away the Ford and Chevy guys. Maybe surprise a rice burner or two, along the way.

Bill is doing what I ask for. No problem. It will be above and beyond what I wanted. Will last for years and years.. Just ask anyone who Bill built an engine for!