PERFORMANCE CAMS FOR STOCK FI MOTORS

[So Cal Mark]

I now have a grind available for motors using the stock Bosch FI system. This is a mid-range torque producer that will make power up to 6000 rpm with the following specs; 28/66 opening and closing, 274 duration with a .380 lift. This is based on a 109 degree centerline.
These are regrinds and sell for $250 for the pair, exchange

[rlux4]

I need educated on this Mark. I'm not a racer, so I don't follow the technical specs on these. If the mid range torque increases, does this mean the horsepower is increased also? (Can torque be increased without increasing HP?) In layman's terms, what are the performance advantages?
Thanks,
Ron

[So Cal Mark]

hp is a fictional number calculated from torque readings. Both hp and torque will be increased over the stock figures. These cams will increase power from 2500-6000rpm, which is the point the stock FI system maxes out. The reason these cams will work with the stock FI system is reduced overlap.

[rlux4]

Thank you Mark. It sounds really good, and all makes sense. It sounds like an easy, inexpensive mod for better performance. Any idea what percentage the increase in torque would be?
Ron

[So Cal Mark]

we ran some similar cams on a dual carbed motor and got a very flat torque curve that peaked at 119 ft lbs. I'm building a head now with these cams for Bob Kuhn (kuhndog) and he'll be installng one of my header systems too.

[STP]

Mark,

What would be the cost for the pair without exchange?

Steve

[So Cal Mark]

the pair of cams is 250, an extra 50 without cores for a total of 300

[lanciahf]

Mark,

Not sure how to phrase this but I heard when cams are reground its tough to get the valve adjust correct due to reduced cam base circle. Sometimes you need valve caps or extra thick shims. Is any of that required with these cams?

Also are adjustable pulleys required or can one use their stock pulleys.

Thanks,
Ralph

[So Cal Mark]

reground cams do have a smaller base circle, so the gap has to be taken up with either thicker shims or valve caps. The problem worsens with higher lifts. These cams don't have that much lift so the clearances can still be set with shims, although it does take shims in the upper ranges.
Even new cams are no guarantee of a stock size base circle though. IAP claims their cams are new, but have a reduced base circle and require spacers or valve caps.
Valve caps are readily available from Manley
As for adjustable pulleys, they are not required but certainly have some benefits, even with a motor using stock cams. If you're not going to degree your cams, the adjustable pulleys offer the ability to properly time the cams after the head has been resurfaced.

[Tappy]

is there somewhere i can find specs or a detailed drawing of different cams ? i know a place where you can let make cams from scratch. But i'm not familliar @ with the requested specifics. This way you would be able to let them make like you want , i was thinking of higher lift duration etc . Is there a site where i can do some reading up ?

[karhawk]

Any idea how the cams will do at passing Ca. emissions testing?

Chris

[So Cal Mark]

we have several cars using our street perf cams that pass the smog checks without a problem, so these cams should easily pass. They have less overlap than the street perf cams

[BrianAz]

Mark,
Do you know how your new 28 / 66 cams compare against the 34 / 72 with 286 duration cams that I got from you some time ago ?

Brian.

[So Cal Mark]

they will provide a bit better idle quality and low end power. It will make tuning a little easier in regards to fuel mixture

[henry]

What about the idle, will it be lumpy or normal as factory?