Thomas (Login broncosaurus) Member from IP address 24.181.100.14
Just bought a 750 3310 vac secondary holley for my 400. Getting a slight hesitation out of the hole at wot. Noticed it came stock with a dark green accelerator pump cam. Looks like the thottle moves a bit before and gas comes out of squirters and the pump arm is contacting the pump lever as it starts to move when touched. I thought all stock holleys came with a pink cam. It has .031" shooter in it stock. What are most of you using for pump cams? Thanks
the procedure calls for checking for clearance between the pump arm and adjuster at full throttle, you can actually be well into the pump at idle and still have a full fuel shot & recommended clearance at WOT
the point is to not be stretching the diaphragm at WOT, rupturing one will cause an external leak onto the intake manifold
there'll be phantoms, there'll be fires on the road... and the white man dancing
Yeah I always thought/seen the pink cams on performance carbs(new). The green cam is the most aggressive one (large initial shot, not total volume), it's what I use on the primary of my DP. Large cam and large intake plenum equals lots of fuel from the primary accelerator pump. I havent seen much benefit from changing squirters, but definitely the cams are the main tuning aid. Why not pull the cam out and verify the number on it, if it is a 290/green then you are probably too rich depending on cam/intake. Purchase an assortment pack and try some other cams.
There will always be a slight lag between throttle and pump discharge starting out from the closed position for the most part, but should not be excessive.
As previously mentioned, just make sure there is not free play on the arm and the cam.
It is the 290 green pump cam that came in it from the factory. I have another old junk 3310 that is about 3yrs old that came with a orange cam from the factory. There is no slack between the pump and arm. I have a pink and orange cam that i can try that was on the old carbs i have. From what i read the pink cam has the most shot volume, is that right? I thought i may try the pink one first. The intake is offenhauser dual port and cam is a lunati voodoo 262 with 219/227 dur at .05" lift.
going with more shot or bigger shooters can make the stumble worse. try the pink cam, it may shoot more volume, but it is stretched out over more throttle opening. If it still isn't right, try a smaller shooter. This goes against all other intake advice, because of the small plenum and runner volume of the Dual Port. This was about 12 years ago when I tuned a 351 4v.
Why they stuck a green cam in their IDK...
The pink and the orange are very close to each other(initial shot wise), the pink has more volume.. bad gas mileage(generally).. generally dont need a long shot, try the orange and if it works keep it!!
I have never seen one with a green cam stock. When i took it out of the box i thought what the heck thats not what nomally comes in them. Why would holley do that? Could that be a new revision on that model of carb? I ran a 600 holley with a pink cam before and had no problems and also ran a 670 holley with the orange cam and had no problems. So my logical thinking was to use one that worked on another carb on the same engine. I went out earlier and bolted in the pink cam to try first. It may be a day or so till i can may a test run though. Thanks for the help. I'll keep you all posted. Thanks again.
No one set-up is the same from one car to another, this is why we have to tune them!
Roo might be right the pink is the deal! My opinion is a carb is an imperfect device, never right in all circumstances. So figure out where you want the car to run the best and tune for that!
A side note: If the car is rich out of the hole, then lean(in your case my opinion).
If you then have a high rpm stumble, like a highway thing, then couid be it's to lean, not enough pump duration, so swap in the pink.
After messing around with all the pump cams i had (pink, orange, and green)i have found that the accelerator pump adjustment bolt and spring was set too tight from the factory. Boy do i feel like a dodo. It had too much tension on the pump lever and was starting out already in the stroke of the pump when the peddle was pressed. I think it was running out of shot before transferring to the primary circuit. I bolted the green stock cam back in and adjusted it out with no preload on the pump lever. Made a couple of wot bursts from dead stop and it didn't stall so its a starting point. Im still wondering which cam would be the best though. The orange is too aggressive i think because you have to almost tighten down the bolt to get the preload off of it. The green cam isn't as aggressive as the orange one but i wonder if the pink would be better for overall longer shot? I know Barry Grant puts the pink cam on all of his street carbs. I guess it doesn't matter as long as i comes out of the hole without hesitation. Thanks
Tuning by the seat of the pants will not be that accurate as an air fuel meter, and I can assure you the 290/green cam is the most aggressive initial shot of fuel. I think the Holley tuning book recommends going with the smallest pump shot/duration to overcome any hesitation(give it just enough fuel, not too much).
If you placed all the cams next to each other and look at the lobes, you might think wow that one cam has a huge lobe, but you have to take into account they are referenced to the screw hole, which places the pump arm at different points on the lobe, which means different shot durations as well as different initial shot (degrees of throttle opening), so size/shape means nothing when looking at them. Follow the chart as your tuning guide.
You said the orange is too aggressive? Is it the 466? The orange is too aggressive i think because you have to almost tighten down the bolt to get the preload off of it That really doesnt matter where the adjustment ends up (again size means nothing). Also you can slightly bend the arm if you run out of adjustment. Adjust the arm after every cam change, just to be sure. The orange is the second smallest cam in the bunch (degrees of throttle opening).
If your squirter is too small to take advantage of a large initial shot (290/green) then it will delay that discharge and act like it has a longer duration cam installed.
I would start out lean (orange) and richen as needed, just because gas is expensive, and if this is your daily driver, if not then give it the fuel lol.
I would tune for where you want the car to run best, from there I would fine tune all other driving situations.
Miller Mylan (Login 417strokers) Member 70.77.66.15
Holley slipping
January 25 2012, 12:14 PM
I ordered a new 1850 600 holley and the carb don't even have exturnaly adjustable floats, the carb was so poorly set up the engine would not run with out making adjustments to Idel and excelarator pump. it is no wonder they are losing so much buisnes to BG and Quick fuel. At one time a holley carb would work right out of the box.
BG must be using a different depression factor. Carter also used a close but different factor for their carbs, they flow a little less than a same CFM number Holley
all carbs can flow more than advertised if the motor can pull harder than they tested they tested the carbs, not unusual, but can the metering system keep up is the question
The old rule - Demon wet flows their carburetors so they measure lower than a Holley for the same size barburetor, add 100 cfm.
but the later carburetors that I've looked at don't seem to be much different than Holley.
The only way to be sure you're comparing apples to apples is to look at butterfly size & main jet size, but you also have to compare booster venturi types, because a straight leg booster requires larger jets than a down leg booster, and a down leg booster requires larger jets than a annular booster.
Back from the dead..........problem solved......shame on holley!!!
April 22 2012, 5:22 PM
After messing with the pump cams and adustments i decided to order a 35 and 37 pump discharge nozzle and try those. When i went to pull the stock nozzle out and when i got it out it was a 25. I just assumed it has a 31 nozzle in it when i got it cause thats what the spec sheet in the box says. Shame on holley. The spec sheets say the 3310 is suppose to come from the factory with a 31 nozzle not a 25. I just knew thats what the problem was so for grins i went ahead and put the 37 in to see what happened. It didnt hesitate out of the hole with the 37 but when the main jets opened up it acted like it was flooding it. I got a the 31 nozzle that was suppose to come in it and the hesitation is gone and it runs great now. I guess buying a holley carb is like a box of chocolates, never know what your going to get. Thanks for all the help guys.
Miller Mylan (Login 417strokers) Member 70.77.66.15
25 shooter
April 24 2012, 4:52 PM
Both of the holley 3310 carbs I have came with a 25 shooter, for most applications I have found the 31 does work best, holley just don't get it. The stock 3310 is far from well tuned out of the box!
Original Demons were wet-flowed while Holleys were dry-air flowed. Not sure how one relates the two figures. Also not sure of anything with the born-again Demons now on sale at Jegs, Summit and others.
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