Holley discharge nozzle 202

Quick, its on special!!!

http://www.summitrac...6-184/overview/

Thats what i have. Makes it easy if your a retard, just keep changing stuff till it works

Cheers.

When you take a carb meant for a bigger engine and stick it on a smaller one you'll generally lose some signal and need to use bigger jets and so on, not smaller. Having said that, I don't think you'd want to run a very big nozzle (a 0.031" is usually close), but you will want a biggish cam so that the pump shot lasts long enough to allow the main system to get its act together. A longish pump duration might also allow you to run a slightly lighter secondary spring without bogging.

Definitely grab the kit Bomber mentioned but what really helps is a wideband O₂ meter. With these you can get the pump setup properly in half an hour instead of half a day using trial and error.

I also find this usefull

And a version showing just the first screw hole, easyer to read quickly

Cheers.

Edited by Bomber Watson, 17 March 2013 - 06:25 PM.

Do the colours on those charts agree with the cams you have Bomber? I think they may have changed the colour code somewhere along the line because they don't seem to match the cams I've been using. Not even sure that those two charts agree with each other for that matter.. and I don't remember ever seeing a yellow cam.

For a small engine / biggish carb combo the brown cam is usually pretty close, but remember for any of the bigger cams you need the 5cc pump if it's not fitted already.

I have a yellow pump, its impressive.

Your right, i looked again and those two graphs dont agree do they, thats what i get for quickly googling, one i have on my puter with all the positions must be different. The lower one is the one i have been using, and seems to agree with the pumps from what i can see, mind i didnt take your wise adivise of putting them into a carb on the bench and checking, just look at the graph and go "i need more fuel here"....

From what I've read, making the nozzle smaller increases the duration. It is a 0.031 now

it can..but it can also mean the nozzle is too small for the cam and you will get fuel discharge after the throttle has returned to idle or cruise

is there a hesistation or bog(black smoke) after you hit the go pedal?

an Bomber the first graph is very similar to the Holley one..the second one doesnt make sense

ok..try a smaller cam if you can get one..like a "white" one ..do you know what is on there now?

dont change the nozzle..the nozzle is located just above the primaries..front and center with a large phillips head screw in it youll see it if you crack the choke open an have a peek down there..but dont change it yet..one thing at a time

oh and be sure to readjust the accelerater pump screw n nut after you change cam

Edited by S.S., 17 March 2013 - 08:11 PM.

Where does your water inject in?

On my boat the water from the engine enters the S pipes about 2" from the flange that attatches to the water heated manifolds, I just put the bung between that and the flange. Doesnt seem to affect it.

Cheers.

I can't see any smoke as I run water through the exhaust pipes, the boat just feels boggy when when I hit the throttle, it feels like it needs to chew the fuel down before it cleans up and gets going.

Edited by oldjohnno, 17 March 2013 - 09:11 PM.

Thinking a bit further on this.... if it still bogs with the 31 and brown cam (and you'll need the 5cc pump for this), I'd be trying a bit more secondary spring.

It'll be worth getting the carb setup right; any perceptible hesitation or stumble at all indicates a grossly mis-tuned engine, so there's still a fair bit of performance to be had from tuning.

Thinking a bit further on this.... if it still bogs with the 31 and brown cam (and you'll need the 5cc pump for this), I'd be trying a bit more secondary spring.
Ok, I've got all the different cams so I'll try the white and the brown I think that's one bigger and smaller than the orange that I'm using and should hopefully show which way I need to go. It's not terrible at the moment, but I can feel its not quite got the berries off the line like it has had before and I accept that the big cam isn't helping that.. How do I know what pump I've got? Is it a big deal to change?

It'll be worth getting the carb setup right; any perceptible hesitation or stumble at all indicates a grossly mis-tuned engine, so there's still a fair bit of performance to be had from tuning.

Edited by Bluejinx202, 18 March 2013 - 08:03 AM.

The easiest way to ID them is to check the actuating arm, the little pump uses a small arm with a fully exposed spring, while the big pump has a much heavier arm with the spring partly enclosed. The pump itself is slightly deeper and is very easy to change, maybe you could borrow one for testing. Pic is of big pump kit.