Re: Told you so! 850DP too much (norvalwilhelm)
 

:iagree:

I'm with Norval. I have .125 holes drilled in the primary throttle blades and the idle curcuit is leaner.

I don't use square jetting but mine are within 4 sizes 76/80's but this is on a 750 speed demon so you really can't use them as a comparison to a H-850

Re: Told you so! 850DP too much (norvalwilhelm)
 

:iagree:


I say you are too rich. My 427 runs with a 950 Holley dp. I use 72's in front, 73's in back. On the chassis dyno I was at 13:1 a/f ratio and made 483rwhp. I also get 15mpg at steady 75mph cruise. If you only drive below 5000 rpm, the 850 is overkill, a 650 would probably be more to your liking. But if you run up to or over 6000rpm, the 850 is just fine. I don't think there are even 5 guys on this forum who could feel the difference between a 750 and an 850 with their butt meter, I know I couldn't.

I have also been told that the correct power valve number will be a little larger than one half of the idle vacuum. i.e. 12" hg @ idle = 6.5pv; 10" hg @ idle = 5.5pv. I have 7" hg at idle and use a 3.5pv.

Chuck

Re: Told you so! 850DP too much (Fevre)
 

You could, but then the front cylinders will run leaner than the rears at WOT. You'd also be lean at 3/4 throttle where the primaries are almost open and the secs almost closed (progressive linkage).

Re: Told you so! 850DP too much (zwede)
 

I have got plenty of room under the hood, with my L-88 style. I guess that I will leave the 850 on the car until winter, then explore new or different carbs. Its hard not to like it a WOT!!!! The around town driving is not to bad, although it attracts a lot of attention, sounding like a drag car!!! :chevy

Re: Told you so! 850DP too much (467-Ratman)
 

Problem solved today, we changed the power valve to a lower one 3.5 from the 5.5 and its running way better. He tested the old power valve though and it was leaking, so that was the problem on running rich. Still has great power with no hesatating at low rpms.

Re: Told you so! 850DP too much (467-Ratman)
 

ANyone got pics of the holes in the throttle plates. Im kinda new to holley and I am working on my idle being to rich. I am dropping the powervalve from a 6.5 to a 4.5 since my idle vacum is only 8-9 inches. If that does not work, I want to try the drilling holes thing.

--marc

Re: Told you so! 850DP too much (BigBadOrange)
 

Holes in the throttle plates are more for idle charateristics, allows more air into the carb with the plates closed. Once you crack the throttle the finds the path a least resistance which will be around the plates not through the holes. Lower the pv should help. Also try staggering your pv if you have a dp so they don't open at the same time.

Re: Told you so! 850DP too much (BigBadOrange)
 

Chlem Z. helped me with this problem and correctly suggested inserting 0.015" (I think that was the diameter) wire into each of the idle restriction holes in the primary metering plate.

I had also drilled out the power valve restrictions adding the same area as would be equal to 4 jet sizes. This has allowed me to run even samller jets sizes than would otherwise be possible. At WOT, I have the same amount of fuel going to the engine with 73 jets as I would have had with the original pv restrictions and 77 jets. The carb came from Holley with 78's.

Chuck

Re: Told you so! 850DP too much (Chuck Harmon)
 

you dont buy a 454 for the Fuel economy :lol:

Re: Told you so! 850DP too much (QuickVet)
 

That's why I bought a small economical 427! :thumbs:

Chuck

Re: Told you so! 850DP too much (QuickVet)
 

Ok, no more complaining about gas mileage from me! It just hurts a little when I fill up with Sunoco 94 at $2.05 a gallon. But then I drive the car and the smiles per gallon come back to me!!!! Great therapy this BB is!!!