This Speed Pro cam is being offered on our Ebay and I was wondering what comments anyone may have on it for my upcoming 383 rebuild.
Btw, I have fitted a Hydroboost so vacuum is not a great concern with my car.
Thanks
This is a great cam for your small block chev, it's a Brand New USA MADE Speed Pro hydraulic cam that suits all small block chev engines & will provide good mid range torque and horsepower between 2500-6000 RPM & is the half price of a CRANE cam with similar specs and lets face it cams that are similar are going to give similar performance. It would be suited to a basic compression ratio of 9.5 - 10.5:1 The specs for this cam are:
Adv duration 288deg

Duration @ .050" 232deg

Valve lift .480"

Lobe separation 108deg

This cam would have a fair to rough idle and would make a great cam for every day performance and occaisional strip duty. The Cam spec card is not pictured but is included with the cam.

 

I did not go to your homepage to see other mods but did see you have a automatic trans...you might want a higher lobe separation for a more broad power range and a little less duration, just depends on you mods , torque converter ect.

Recently there was a shortage of Chevy lifters in the USA and they have gone up in price now. This makes the Crane cam and lifter packages more appealing

 

Thanks for your input MM. I realise you have a great depth of knowledge on these things and I appreciate your input. The XE262 Cam I had originally bought for what began as a 355 rebuild has a 110 LSA and with considerably less duration @ 50thou. so I was just curious as to whether this other cam would be too much for what is basically a street driver albiet not a frequent one.
Thanks again.

 

What you could do with the emphasis on good heads/intake and exhaust is to continue the build and run the Comp cam you already own for a year or so. With all else equal some of these cams can only mean a 10-15 hp gain when stepping up to the next size in the manufacturers line but it just depends.

What is your rear gear ratio and the gasoline octane availabilty in Australia ?

I hear it gets plenty hot in some areas there , sure don't want it detonating .

 

I'm running Richmond 3.7s in the rear so that end's pretty well covered and there's no problem with octane over here. I should have a fair idea I suppose as I work for a major oil company. :rolleyes:
I've just latched onto a 383 stroker here in our Ebay that's for sale and from what I've gathered from writing to the seller, it's a pretty reasonable buy. It's running Avgas with 12:1 compression at the moment which of course doesn't suit me, but I'd be dropping my AFR heads onto it if I decide to bid for it which would correct that aspect fairly well I should imagine.
The other thing I'd like to know more about is that I've heard that stroker motors require small base circle cams for clearance concerns. Is that a correct statement?
Thanks.

 

From what I've read, it can depend on the rods (how the big end is sized and shaped). some of the aftermarket rods like Scat I beam with capscrews advertise that they will clear a standard cam.

I'd prefer that, esp w/any elevated spring pressure causing more resistance to
the cam rotating.

As far as the cam itself - even cams with the same 050 specs and lifts can be vastly different because of the lobe profile and resultant "area under the curve"
http://www.davidvizard.com/camshaft.html

Check this out - makes sense and is the only one I've seen like it.
Also, read an article on an outfit that builds NASCAR engines that uses
it and swears by it, also builds hi end crate motors and uses it for that.


Also, check out the AFR website, their dyno articles. Lots of very impressive
results using (of course their heads, like 190) Comp Cams hydr roller cams
in the 2-hi teens to 236 duration and 500+ a little lift - with a 750 demon,
9.5ish cr and an RPM Air Gap, lots of them getting 400 to 440 torque at 2500 with peak torque near 500 and peak power near 500 at just a little over 5000.

Also check out Lingenfelter Racing website for more dyno tests.
But, I'm going to try this guy anyway and see how close he comes to
one of those Comp setups. A cam is so critical, it's a real crap shoot
even using 050 and lift and lda info, so would think all the informed tech
help you can get (and not just some guy answering phones at a cam company), the more you'll get out of the money you spend. Good luck!!

 

By the way - anybody that tells me any particular cam suits all Chevy engines from short stroke small bore small or big valve small inches with short or long rods to long stroke, big bore, short rod, big inches - never mind what cr or type of heads, well, I have a hard time choking that down!

 

Macx...Good info and thanks for your input. Much appreciated.

 

The base circle of the cam really comes down to the size of the big end of the rods. All the modern stroker rotating kits can tell you if you need to get a cam with a base circle near .900 inches

My last billet Crane roller was considered a small base circle at .930 inches.

My present sollid roller is 1.030 inches. The problem is as duration and lift goes way up the base circle has to increase because the ramp speeds become so radicle.

I would not buy a 12:1 race motor and detune it. At some point you should at least get a solid cam. 383's don't have the vacuum problems that 355 ci does.

 

I’ll warn you now that I’m no cam/dyno expert but I did study before choosing my camshaft. Following David Vizard (the Wizard’s) advice for an optimum Lobe Separation Angle (LSA) the 350” LSA would be only 108 degrees. But for your 383”, 106 degree LSA is best and a 400” motor only 104 degrees separation is optimum. Yes this produces more overlap but it will close the intake valve sooner (ABDC) trapping more charge – to make up for the relative smaller valve area to cylinder volume ratio of a 383”. Vizard also recommends 55 degrees overlap max for a reasonable street machine. That limits your duration to 267 degrees for a single pattern cam – for a dual pattern you need to do the math. The major problem is it’s hard to find off the shelf short cams with 106 (and 104) LSAs.
Now with flat tappet cams I don’t see how their fairly low cost would justify a no name brand to gamble on quality. When even saving $100, it’s too much work for me to swap camshafts again if needed. Though I haven’t heard anything bad about Speed Pro I have heard a lot of good things for Crane Cams. And I liked how mine was dead on when I installed just by the sprocket marks and verified it with a degree wheel. I did use a 110 LSA only because of the need to meet California smog requirements.
The closest quality off the shelf camshafts I can find are the Iskyderian (Isky) Mega cams with a 108 LSA but in various durations.
Good luck, cardo0
:seeya

 

Interesting thoughts and good information guys...... thanks muchly.
Here's a cam from one of our own local race engineering shops. Any thoughts on this one?

Grind #CSBH 222
Advertised Duration: Intake 273 Exhaust 273
.050" Duration: Intake 222 Exhaust 222
Cam Lobe Lift: Intake .313 Exhaust .312

1.5:1 rocker Valve Lift: Intake .470 Exhaust .468
1.6:1 rocker Valve Lift: Intake .501 Exhaust .499
1.7:1 rocker Valve Lift: Intake .532 Exhaust .530
Lobe Centre Separation: 110

HYDRAULIC: Moderate lopey idle. Hi velocity profile, which makes more power and torque than traditional grinds with up to 8 deg more duration at .050". Very powerful profile where full street equipment is used, mid range and top end acceleration are very potent. 9.5:1 compression and Streetmaster heads recommended. Small 1800-2000 RPM Converter an advantage. Excellent Holden EFI grind in all size engines with the right engine combo. RPM Range 2000 - 5700 plus.







[Modified by Brutus, 10:12 PM 8/15/2003]

 

I think your automatic trans car would be happier with the XE262. It will idle much better in gear. You could add some 1.6 rockers to get better lift for more TQ and not have to sacrifice idle quality and bottom end TQ.

 

Now with 12:1 c.r. and running Hydroboost that Speed Pro cam with the longer duration would be a better match (than the CSBH 222). Just forget about idling across the parking lots. Using 1.6 rockers (intake only) will make up for some of the 108 LSA rather than optimum 106. Its my mind set that over 280 degrees duration is roller cam/lifter territory. But your the customer here. Good luck and please post the result.

 

Bob,one thing you haven't mentioned is the inlet velocity,you have to be aware that the volume through the inlet manifold and heads isn't the end of the issue,you need to ensure optimum velocity in.....and obviously ensure that it is getting out afterwards.....this is where the cam science starts turning into magic or art rather than science......the cam timing and combustion chamber efficiency have a huge effect on the velocity of the charge entering and leaving....Chevy Hiperformance have a long head comparo article that goes through these issues and seemed to me to make sense...john :chevy