Idle quality is important to most on a street driven car on a day in and day out basis. We also need to make enough vacuum to manage power brakes, and a good percentage of these vehicles have air conditioning.
I'll not argue with Ken or anyone else on cam selection, but there is no need for crappy idle quality in one of these engines, you can have good vacuum, and good street manners and still make plenty of power on the days you decide to go to the track.
We have at this point half a dozen cars that we race out of this shop, from high 9's over 135mph to high 11's at 115mph. The only one that has a tight LSA cam is the 9.90 car and it has 14 to 1 compression to manage it, and the timing locked out for decent idle quality.
All of the others, even the "little" 406 pump gas street engine that runs high 11's has a wide LSA cam, excellent idle quality and great street manners.
We've played around with tighter LSA on a number of our engines, and have found that you quickly get a lumpy idle, noticeable "reversion" just off idle, increased fuel consumption, and they just don't drive as well in the "normal" rpm range. Acceptable, yes, as good as the wider LSA stuff, no.
I'd also mention here that I've clearly showed with dyno charts that you can quickly get into BIG trouble with tight LSA cams in terms of being able to manage pump fuel and leave considerable power on the table with poor cam selection.
I'm wanting to go back to a flat cam in my own engine. First I want to get away from the solid roller lifter on the HR cam "hybrid" set-up, and want to see if we can make the power and run as well with a flat cam compared to the HR stuff. Since a cam swap is about 3 hours worth of my time, not a big deal to do some testing with a big flat hydraulic cam, then go back to the HR if/as needed.
I'm looking closely at the Ultradyne 239/247 cam, or the Crower 60245. Once I get my block checked out to see if it needs overbored, and select the pistons, compute the compression ratio, etc, I'll make a cam selection.......Cliff
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https://cliffshighperformance.com/
73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile),
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