Question for ya JimV...
 

Jim, I have a set of Holly Dial-a-jets on my 850dp. Bruce was saying that you had recently tried a set of these and had some problems with them. Because I already have them, we were going to give them a couple of pulls on the dyno, but we would like to know what your experiences were.

Cord - are those the electronic fuel bowls with solenoids controlling the metering area that Holley tried years ago, or the ring that goes on the air horn and drips extra fuel into the venturi?

Tomcat, they are neither. These are a replacement metering block with a long needle and seat arrangement that is accessable from the top of the block, outside the carburetor. The concept is to allow manual changing of the main jet circuit from outside the carburetor. My concern is with their accuracy and consistency.

Cord

Sorry I havn't posted. B.J. went to the dyno so I cant answer your question. I will try to get him to answer you.

ttt

Cord

I've got a 4-pack of Dial-A-Jets waiting for me to do the blowers on my 311. Planning to put them on a pair of 950cfm 4150HP's on blowthru (prochargers).

Can't imagine big problems with them. I am as interested as you in getting the lowdown here. I figured they would pay for themselves many times over in dialing in the blowthru setup(especially on a boat with not having to take the bowls off 250 times and spilling gas all over on a hot day thus filling the bilge up with explosive fumes..).

M

Dail-a-Jet
 

Cord, This is B.J. @ Valako Race Heads. I dyno'd the Dial-a-jets on Kaama's 540 about 3 or 4 weeks ago. They seem to work OK at WOT but were fat on the bottom and lean in the middle. I think that the theory is good but intended more for drag racing where part throttle is not a concern. Also in drag racing jet changes are made daily due to weather and other factors. In marine once the motor is dialed in, it stays there until a change is made to the motor.

I think we could have got them to work better if we would have spent more time tunning, but we never saw the light at the end of the tunnel so we went back to the tried and true 950HP Holley with 78's. The BS number with out the dial-a-jet didn't change more than .01 from 3000 on up. I guess what I'm tring to say is with a Carb that "follows" so well it was discouraging to see the fuel curve go all over the place when the dail-a-jet was installed.

Mind you that I really don't have a good understanding of the Holly, but would there be something to gain by juggling the power valves? The numbers refer to the point that they open, but is there a way to control their flow? Or, can the idle circuit some how be leaned out? I know that it's easy to richen it (by drilling right?), but how do you lean it?

I'll give Holly a jingle on monday and get their take on the problems with the dial-a-jets.

In the holley 950 were you using 78's all the way around and did it have a secondary power valve? Thanks, Ironman.

Yeh, we had 78's in all 4 corners. I don't remember if we had a power valve in the rear or not. I never took one out or put one in it so If it comes stock from holly, then it was in there. B.J.

I am planning on switching from an 800 to the 950hp and was wondering if I can jet the same with the 950 as with the 800? Any advice would be appreciated. Thanks, ironman.

Ironman

Usually when changing to a larger carb you have to richen the jets. Due to the increased size in the venturi the carb looses signal and will generally run leaner. I'v seen it where guys change to a bigger carb thinking they made more power, in reality they made more power by making the engine leaner.

Jim, Cord & everyone....
I had purchased a dial-a-jet for my Procharged HP454 due to fuel tuning problems (running rich). I found out about Dean Nickerson Performance & called him. I decided to use his services as he flow matched all the venturi, & remachined every required air-fuel passage/port. On reciept, the carb was so close I only had to adjust the idle speed 100 rpm up. He runs his carbs on a dyno in his shop also before return to you. I have been very impressed with the result. You all may wish to speak to Dean. 215-781-1370
I have no black transom & balanced power thru out the rpm range. Great stuff. :D