Holley 850 double pumper HP street

[RECHRGD]

I've been having ongoing issues with my old 750 Holley DP with a Proform main body.  I'm thinking of trying the "new" Holley 850 DP HP street all aluminum carb.  Is anybody using this?  Are you Happy with it?  My combo has always loved what I have, but I think it could go to the 850 without issues.  It's a 446 with a cam that's very close to the Comp Cams 275 EXtreme energy high lift.  Mopar aluminum heads (452), RPM intake, 10.? Compression, 1 7/8 hooker competition headers, 2 1/2" exhaust, 3.55 gears with GV overdrive.

[c00nhunterjoe]

Refresh my memory with the current issues? The hp series are nice, i run a 950 on a 440.

[RECHRGD]

Refresh my memory with the current issues? The hp series are nice, i run a 950 on a 440.

I haven't really posted about them.  It had been running really rough on start up.  When punching it, would flood out.  Seemed that the needles and seats were an issue.  Replaced them and things seemed fine.  Went to start it up today and had to pump the heck out of it to start.  Babied it until warm, but still wanted to die when put in gear.

[PRH]

Nowadays you really need to look at the specs for Venturi and throttle bore diameter to know what you're buying.
"750", "850", "950"........ It's just marketing blather and often doesn't reflect how big the carb really is, compared to other "750", "850", etc carbs........ Even within the same brand.

The Holley Street HP 850 is a 1.563 Venturi, 1.688 throttle bore.
Big Venturi, small bore........  Not what I'd be looking for.

The "if it were me" answer is, I'd call AED and talk to them about building you one of their HO series carbs, or advise you on which one would be best for your combo, and you can get it from Summit.

[RECHRGD]

Nowadays you really need to look at the specs for Venturi and throttle bore diameter to know what you're buying.
"750", "850", "950"........ It's just marketing blather and often doesn't reflect how big the carb really is, compared to other "750", "850", etc carbs........ Even within the same brand.

The Holley Street HP 850 is a 1.563 Venturi, 1.688 throttle bore.
Big Venturi, small bore........  Not what I'd be looking for.

The "if it were me" answer is, I'd call AED and talk to them about building you one of their HO series carbs, or advise you on which one would be best for your combo, and you can get it from Summit.

Thank you Mr. Porter. 

[PRH]

Actually....... I lied.

About the "if it were me" part........ I really meant "if I were you".

I'm pretty handy with carbs, so I'd probably just tweak on your current carb until I had it sorted out.

For the cost of a new carb you can buy a lot of parts, and you already have the main body.

For around $400 you should be able to buy a pair of billet metering blocks, billet base plate, and some aluminum bowls. Of course then you have to tune it....... And in theory a new one would come with decent calibration ootb.

I have built a few complete carbs out of the Proform hp 750 bodies.
I kept it pretty simple....... I used normal 750dp metering blocks, a std throttle body, and the quick-change bowls from Holley. They worked well and didn't take much work at all to get them running to my satisfaction.

I built another carb with the Holley HP750 replacement main body, only this time I used QFT billet metering blocks, billet base plate, and aluminum bowls.
I haven't had a chance to run it on anything yet, but it'll be interesting to see how it runs compared to my built-from-parts-dyno-carb Holley 4779.

[firefighter3931]

 
My combo has always loved what I have

Bob, the motor liked the 750 PF carb before and ran very well so something has changed. I'll bet the air bleeds are gummed up. Try hitting the idle & high speed bleeds with some carb cleaner. The carb probably just needs a quick rebuild...

If you were looking at a new carb the PF 850 is something to consider. Eldon has a similar build to your's and he had great results with a PF 850 dp'er 

http://www.dodgecharger.com/forum/index.php/topic,128336.0.html

I'm pretty handy with carbs

That's an understatement....more like a "Wizard" would be a better description ! 



Ron

[RECHRGD]

I pulled the carb and went through it yesterday.  Everything checked out fine, except the primary float seemed to be adjusted too low.  I raised it a bit and will put it back on today and check the fuel levels.  I'm starting to lean towards a vacumn leak again, although I Couldn't find one earlier. 

[RECHRGD]

I put on the carb and raised the primary float level.  It now purrs like a kitten.    here's the history:  the last few drives of the season last year, the car started running rougher than normal, especially when cold.  With the rough idle it felt like a header pipe was hitting part of the steering, but was never able to locate any area of contact.  I decided to go after the rough idle problem first.  I replaced the plugs, as they were a few years old.  The plug wires looked fine so I did nothing there.  The rough idle remained, but seemed to get better as the car warmed up.  I suspected a vacumn leak.  I don't enjoy wrenching as much anymore, so decided to take it to a local shop that is a favorite with the hot rod/classic car crowd.  On the way there I punched it up to about 80 to see if I could clear it out some.  After I let up on it, it flooded out and died.  It would not restart so it made the rest of the trip on the back of a flatbed.  Of course, it started right up when off of the flatbed.  The owner of the shop took it for a drive and the same thing happened to him, but he was able to baby it back to the shop using the two foot driving method.  They replaced the needing valves and the flooding problem was gone.  But, it still was running rough.  They put a scope on it and discovered that three of the plug wires were toasted.  Although they looked fine, the heat from the headers had compromised them.  So, with new wires installed the car ran smoothly and I drove it back to where I store it in the summer.  It didn't feel quite right on the drive back, in terms of throttle response, but I just parked it.  A few days later I went to start take it for a drive and i could barely keep it running, so I pulled off the carb and brought it home, only to find that the primary float was adjusted too low.  Anyway, the car runs great again.  I never did find where the header banging was coming from, but with a smooth running engine I can just barely feel it upon initial start up..........

[firefighter3931]

Good work. A misadjusted float will cause huge drivability issues. 

Glad it's fixed Bob 


Ron

[RECHRGD]

Good work. A misadjusted float will cause huge drivability issues. 

Glad it's fixed Bob 


Ron

Thanks Ron.  Pretty obvious that the "shop" neglected to set the float level after replacing the needle valves.  I'll still keep trying to do all the wrenching on the car as long as I can....

[PRH]

Sounds like you saved yourself about $600.

Today's ethanol blend fuel is pretty rough on the needle and seat o-rings.
The brown Viton ones seem to hold up a little better.
That sized o-ring is usually pretty easy to get at a parts store or hardware store.

IMO, the o-rings should be replaced at the beginning of the season as part of the normal pre-season prep(if you're running ethanol blended gas).
It only takes a couple of minutes, is super cheap to do, and can save a lot of headaches.
You'll also want to have the needle and seat adjustment gaskets handy for that job.

[8WHEELER]

Hey Bob, long time since I have been on, hope all is well.

This is a subject I have been working with recently, and I started reading your issues and I was going to suggest you stay with your smaller carb because
it was working well with you setup. I went from an 800 Holley in 81 to an 850 in 91, yes its old technology, but they work well. But I no longer race my red
Charger nor can I give it much more than 1/4 throttle with my hand controls. So I have gone through my 780 Demon and plan on running that, and will get
better mileage and throttle response. Bigger is not always better, especially talking a street car.

Dan

[RECHRGD]

Hey Bob, long time since I have been on, hope all is well.

This is a subject I have been working with recently, and I started reading your issues and I was going to suggest you stay with your smaller carb because
it was working well with you setup. I went from an 800 Holley in 81 to an 850 in 91, yes its old technology, but they work well. But I no longer race my red
Charger nor can I give it much more than 1/4 throttle with my hand controls. So I have gone through my 780 Demon and plan on running that, and will get
better mileage and throttle response. Bigger is not always better, especially talking a street car.

Dan

Good to hear from you Dan!  Things are fine with me, just getting older and grumpier.  Hope all is well with you and yours.  I need to get the car back over to your side of the State one of these days......