[78 monte]

I'm thinkin bout experamenting w/ eccelerator pump cams.I have a 600 vac sec 1850s holley.I rebuilt it w/ a better pump dia.(I believe 50cc).The car ocasionaly has a slight bog from off idle.I'm all so looking for a snapier rev.
My question is:is there a starting point to these or do I just expeirament???
Also I don't remember what power valve I've got in.Should I start by matching my power valve to my vac. signel befor I play w/ pump cams???

[4 Jaw Chuck]

Whoaaaaa there big guy, change one thing at a time. The brown cam is pretty well what I use on every engine I have built, I just wish they sold it seperately. I have to buy the whole darn kit just to get it, I must have 5 each of all the other colors. You can experiment but I always come back to brown. Black is standard.

If you have a bog check for zero clearance at the accelerator pump lever, the cam should start shooting gas as soon as the throttle moves...even a little bit. There will only be one hole position which will work well, can't remember which hole it is #1 or #2. Experiment and you will know immediately. Make sure there is 0.015-0.020" clearance at the override spring at WOT, you don't want to bottom the pump.

Once you have that sorted out you can play with power valves, I always use a valve that opens at 1 inch of mercury below what I see on a vacuum gauge at light part throttle (cruise), on mild cammed engines this is almost invariably a 65 valve. If you have a wicked 300 degree duration cam and open plane manifold with a big carb and big heads you might need to drop down to a 30. Factory stock engines usually use an 85 or 75.

If you can't get rid of the bog using these mods you might need a bigger shooter. The list of changes you can make is endless, just make sure you do one thing at a time. <img src="graemlins/nono.gif" border="0" alt="[nono]" />

[dmorris1200]

There's some good info at holleys tech support website about this stuff.
<a href="http://www.holley.com/HiOctn/TechServ/TechInfo/Trblsht.html" target="_blank">www.holley.com/HiOctn/TechServ/TechInfo/Trblsht.html</a>

You can go to <a href="http://www.holley.com" target="_blank">www.holley.com</a> and navagate through their tech support, there's some neat info. there.

Keep in mind even ignition timing being off could cause a hesitation off idle, it is a shame, like chuck said, that you have to spend $100.00 for a whole kit when you only need one pump cam.

[ August 11, 2002: Message edited by: dmorris1200 ]</p>

[willys36@aol.com]

In my experience, 4-jaws advice about setting the cam to squirt immediately is the key. there should be 0-clearance (set it with 1 or 2 1000's of initial stroke at rest).