67mustang302

I've noticed some of the cam manufacturers say not to use high pressure/volume pumps with their cams as it can lead to dizzy/cam gear failure. Yet the pump manufacturers, such as Melling, say that high volume/pressure pumps are not the cause of cam/dizzy gear failure. There also seem to be quite a few people who have used either high volume or high pressure pumps on both roller and non roller street engines with no issue. I'm just curious how many people here have used/are using HV/HP pumps without trouble. And has anyone had trouble? It would seem to me that the gear failures are more the result of improper endplay on the cam/dizzy or putting worn gears on new gears etc. Also, has anyone ever used a new cam with a used(but still in good shape) dizzy gear?

JZTRK

The pump I put in is an HV pump rated at 25% more flow and its on a stock motor and I have had no problems with it the instructions said to be careful b/c at sustaind high rpm it would starve the lower end and flood the heads

91hatchgt

My 91 had a HV pump in it when I dropped in the new engine, also used a brand new cam with the stock dizzy gear with no problems whatsoever.

67mustang302

So you already had miles on the dizzy gear with proper wear, and notta thing happened? How many miles since?

91hatchgt

Well it was stock, so it had 125k miles on it... I don't own the car, I sold it to a friend, it has about 10k on the new engine.

my77stang

most dizz gear failures are because people will use one type of gear with another type of cam. like, if a roller cam has a hard gear and the older style dizzy doesnt it will chew up the gear with a quickness. a high pressure pump can increase your chances of twising an oil pump driveshaft, but they are less than 20.00 for an arp hardened unit and should be upgraded upon rebuild anyways as cheap insurance. also, a high pressure pump will not starve the bottom end of oil at sustained high rpm use like a HV will, and keeps that pressure up on your bearings where it can really use that extra cushion of oil.

this is why i always say HP > HV

but what do i know, i questioned the gains from a custom cam grind vs. a good off the shelf choice - so apparantly i know nothing about motors [&:]

91ford302

im using a HV pump on my engine with a new cam and old dizzy gear and i have almost 2k on the new engine with no problems.

67mustang302

I see occasionaly some people have gear failures even with the right material, but it makes me wonder whether or not the gear on the dizzy was excessively worn, or if cam/dizzy end thrust was bad and it had improper gear mesh.

15austin

Ive had a HV pump in my motor every since I built it for 8yrs now, no problems with anything.