Down to 2 cams

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tony20110

tony20110

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Another cam decision:

I have a 1973 360LA bored .30, zero decked 9.5-1 comp. KB 107 pistons, stock crank, J heads (2.02-1.60) ported, comp 901-16 springs, 273 adjustable rockers. RPM Air Gap, Holley 750. Converter 2500-2800 stall. Currently stock 360 manifolds but Dougs headers in future. Rear end 3.55

The choice comes down to 2 cams.

1. Comp xtreme energy 268.

http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=627&sb=2

2. Comp xtreme lift 275.

http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=631&sb=2

I am leaning 275 but I worry about going too big with the cam. This is going to be a weekly driver. Maybe a few trips to the track in her life but almost exclusively a street car.

Any thoughts are appreciated. I need all the help I can get!
 
With that stall and compression on a street driver, I would pick the 268.
 
I oppose and would run the 275. Though some would say you would be a little light on gear with it. What size tire are you running?

You have the compression and stall for the bigger cam, which will make for a nice street machine.
 
The 275 is an awesome grind. Essentially the same as the Dual Energy for the big block. I have a friend who runs one in a 383 in a rat rod truck. He is very happy with performance and sound. It has highway gears and he drives it all the time, yes it will fry the huge back tires. I think they are like 315s. They are huge. That cam is similar in design to the Thumpr or Hughes Whiplash in that it has a big duration split with a much longer exhaust duration. Just something to think about.
 
The 901-16 springs you have are perfect for the 268 cam. The 275 cam is a good cam. But, to run this cam you will need the recommended valve springs. The 995-16 are a dual spring and will require that you take the heads to the machine shop and have the head casting around the guides milled down so Viton seals can be installed, the rubber stock type seals will not fit inside the dual springs.
 
The 901-16 springs I have were recommended to me for the 275 cam by someone very respected on fabo. I was told no machine work needed.
 
The 901 spring is plenty adequate.
 
comp's catalog shows a 995 spring for the 275 cam....

275 cam has 231/237 at .050....not a big split
 
My 2 cents is that the 901 spring isn't gonna cut it for a XE275HL. It has around 100 # of seat pressure at 1.65 nominal installed height, and at 1.15 open (.500 lift) it will have around 275 #. Turn the RPM up and you'll have valve bounce and maybe lifter toss. If you want to run a single spring look into the 926 instead. I would run the XE268 anyway, IMO its a better fit to what you're doing.
 
Someone edgemecate me hear....
Adjustable rockers on a hydraulic cam ?
Wouldn't a solid cam be better ?















.
 
tony20110 said:
...I am leaning 275 but I worry about going too big with the cam. This is going to be a weekly driver. Maybe a few trips to the track in her life but almost exclusively a street car.
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Click to expand...

Do you plan to commute daily back and forth to work in it every day???

Is it a car to have fun on weekends running errands, cruise-in's, car shows, etc. And maybe having fun going to store on weeknights after work???

The 273 rockers are about 1.46 ratio. Not 1.50 ratio. So that will reduce your lift slightly and take a slight edge off. Factoring the 1.46 ratio that might change your valve spring requirements.

I run a 275-Solid with 1.5 ratio rockers in a 416 stroker. The stroker sucks up cam. I have a single plane M-1 intake that takes away some streetability too... Pluses and minuses...

Run the 275HL with 273 rockers, full 2 1/2" exhausts all the way out back with Dynomax or other quiet muffler.
 
Johnny Dart said:
Someone edgemecate me hear....
Adjustable rockers on a hydraulic cam ?
Wouldn't a solid cam be better ?

.
Click to expand...

Nothing wrong at all running adjustable rockers on a hydraulic cam-allows you to properly set the preload without shims, and changing the preload up or down can offer some flexibility with engine performance.

Just my .02
 
Thanks for all the input so far. To be more specific. I mainly plan on driving it around town. I'd guess a few days a week.
 
run the xe268h
or get a lunati voodoo 268 cam, old 60403 # as mentioned.
 
If you really only have those 2 cams to choose from the 268he is fine.
 
tony20110 said:
If I went with the Voodoo 268. Would the 901-16 springs do the job? Also would the correct lifters be lunati 71977PR-16?

http://www.lunatipower.com/Product.aspx?id=780&gid=209
Click to expand...

No on the springs and yes on the lifters. 901 springs just don't have adequate pressure for modern aggressive .904 lobe cams. You need around 120#-135# seat pressure and 300#-340# open for cams such as the Voodoo, Hughes, Extreme Energy HiLift. If you are set on using the 901 springs go with the XE 268.
 
Your total combination is really close to what I use to run in my Cuda. The only major differences were I started with a Comp XE274 cam and always had headers on it. The Comp had lifter problems twice (internal tolerances were sloppy so they bled down bad after just setting for 1/2 hr.) in less than 1000 miles which comp warrantied, but I got tired of screwing with it and pulled it out and put in a Lunati 60404. IMO it turned out a little too big for the stall and gears I had because takeoff was a little soft it but ran real good on the top end. I think the Lunati 60403 would have been a better match but what is, is. IMO since you said yours is more of a driver/cruiser than racer and the stall converter isn't real loose and your running 3.55's I'd go with the smaller XE268, or even better the Lunati 60403. If you decide on tires taller than 27" I'd definitely go with the smaller cam. If your gonna run a short tire the larger cam should work ok
 
I have ran the XE268 cam before on a similar combo. You won't be disappointed. Outstanding cam, IMO.
 
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