Technical 283 camshaft in light car for 6500-7000 rpm?

Hey all. Long time lurker, first time poster.

Two questions:

1) I am working on a light weight Track-T project that will be about 2000 lbs. It will have a stick with 3.90-4:10 rear gear and 24" tall tires. I have a 283 and want it to spin to 7000 (6500 redline with 7000 ignition cut). Will likely have 58cc heads. It doesn't need a ton of torque below 2000 rpm but would like a 4500'ish rpm sweet spot and then build to 6500. What hydraulic cam do you suggest? Was kneejerk thinking L46/L82-like specs but surely there is something better.

2) Due to the clutch arrangement I am thinking of using I will likely need to space the trams out about 1/2". I've Googled but come up short. Is there a full plate spacer available for the SBC holes/dowels that I could just get machined for the flywheel hole size I need? I know I could just buy a plate of aluminum and start cutting but thinking there might be something OTC.

Randy

 

30-30

 

He said hydraulic, L79 seems to be the standard. Designed for a light car, and still deliver some rip-ums.

 

What else have you done to the motor? Bone stock?

I have a fetish for the 265 and 283’s. This is the best all around cam for the small cubic inch motors. Don’t get caught up in all the hype about turning high rpms. Buy this cam and I you will be happy.
https://www.jegs.com/i/COMP-Cams/249/12-210-2/10002/-1

 

My first thought is, "you're going to need taller tires"! Or just more of what you have. Should be a Fun ride either way.

 

There is a dizzying variety of hydraulic "street" cams out there but the L79 (327/350 hp) factory cam was a pretty respectable grind. They are available from some of the aftermarket cam companies and they are reasonably priced, I'd recommend a cam/lifter kit if available.

 

don't forget the Kevlar socks.

 

...yeah...a SFI approved clutch in a SFI approved bellhousing would be a great idea if you're spinning the motor over 6K.

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http://schneidercams.com/LSP-2Hsbchyd.aspx

This is in my 327, it’s one step above the L79 cam and revs good

 

I bought the comp L79 kit and the lifters came apart , the next time I used Isky super lifters they have a heavy duty C clip not the little paper clip style retainer on the lifter top .

 

Remember the cams will be exaggerated in a 283.

 

“Exaggerated camshafts” sounds like the name of a hard rock band

I do like Schneider, I bet if the original poster called they could hook him up with a good one .

 

I know you listed that you wanted a hydraulic "girlie man" cam,... but that is somewhat contrary to your other desired quality, the 4500 rpm wide powerband.
Despite what ad copy the marketing department might attach to a cam design, it is impossible to design any cam with a powerband wider than about 3500 rpm max, that's just a fact of physical limits.

I'd say "What's so tough about checking the settings on a solid lifter cam once or twice a year?" With modern pushrods, roller rocker arms, poly lock adjuster nuts, and aftermarket rocker studs everything stays stable and doesn't need adjusting all the time like they did in the old days....I've run some pretty stout 500+ HP SBC .600" lift solid flat tappet stuff to 7500+ rpm every weekend in a street/strip cars and only touch the vaveltrain once in the beginning spring of the year and once mid August....and rarely find the adjustment out more than .002" on more than 1 or 2 valves.
I'd look at the "Duntov" GM #3736097 283/290HP cam, and run it with a split set of rocker arms, 1.6 or 1.65 ratio on the intakes to get the lift up, and 1.5 on the exhaust(exhaust is relatively lift insensitive but higher ratio on the exhaust hurts torque).
The split rocker ratio and use of a solid cam helps to push the width on the cam rpm range a slight bit wider, to get you closer to a 3800 rpm wide powerband...but you're not going to get a 4500 rpm wide true powerband, no matter what some cam company "tech idiot" tells you.

If you wanted a custom solid, Bullet cams has all of the UltraDyne masters developed by "UD Harold" Harold Brookshire (RIP). Same guy designed Comp Cams XE line and Lunati's VooDoo line. The guys at Bullet could whip up something nice in a tight lash design. (The "097" is also a tight lash).

 

Ain't that the truth!

Thanks all for the cam insight. I think I may have it narrowed down to 4-5 choices. It's still all a guess for me though as all the published cam characteristics are based on a 350 so knowing how it will act in a 283 will be somewhat of a chance.

Does anyone have knowledge of a 1/2" spacer plate for the SBC (question #2)?

Thanks again?

R

 

I agree with Ericnova72. Have built a few 283's and 327's with solid cams and drove them a lot. Had to maybe adjust a few flyers now and then-no big deal. Had very good luck with the 097 on the street in 283's

 

We'll need more info on that issue. I'm a little lost as to why you need to push bellhousing back 1/2". What all is being used behind the 283?

 

I used the Duntov 097 in a 283 and a 327, the 283 would rock 7,500 to 8,000 very easily. Adjusted only once in a while.

 

I am thinking about adapting a very vintage road racing transmission that uses an oddball 11.75" OD flywheel (smaller than the 14" or 12.75" chevy standard flywheels). The bellhousing is MIA so need to make my own. Tape measure says I can adapt a standard SBC bellhousing if I can space it out 1/2" to make the input shaft compatible. Starter will likely need to be reverse rotation mounted in the rear to reach the smaller flywheel

 

Pick a favorite cam Co. or two. Call them and lay your engine/vehicle specs and RPM desires. They'll match you with a cam.
There's plenty of cams out there in your RPM range. I'm more concerned about your engine holding up North of 6000 RPM. Good bottom end? Valve train? Clutch? Safety bell housing? Etc.

My friend ran a 283 with a Sig Erson hyd cam that kicked in at 3000-about 6500. Steel crank, 2.02 heads with good springs, screw in studs, street/strip clutch, safety bellhousing, etc.

 

You are loosing me on the trans deal. Just shorten the trans input shaft and use standard flywheel. Redrill flywheel if you really need a smaller pressure plate. I would use a 10.5" clutch with a custom disk if the trans has some odd spline.

 

If you use a smaller than stock flywheel would you going to use for starter

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As to a cam, it would help to know what compression ratio you are looking at running. Many cams for the 283/292/301 are very compression ratio sensitive. Also when intake valve diameter.

 

Relocated to the back, at the proper distance, just like a NASCAR starter (which they use a 110-tooth, 9.16" flywheel for a 7" twin disk) . Google shows the Mazda RX-7 flywheel is also 11.75 diameter so likely look into using its 2 amp reverse rotation unit.

If I shorten the input shaft then I loose the pilot bearing tip. If I use a bellhousing spacer then I have enough left to support the input shaft. Thank you for the alternate design ideas but after measuring and head scratching, using a spacer is the best way to go. After more Google looks like I will just use an inexpensive Chevy to BOP adapter and drill the holes I need.

Thanks all

Randy

 

eyebrow flattops (-6cc) with 58cc. As close to the top of the deck as I dare get them. .028 MLS head gasket

 

Watch the aftermarket screw-in studs! The rolled threads they have leave the ends of the studs concave.
A quick swinging 90* fixture on the end of your bench grinder lets you square up the ends of these studs, (one by one) so the locks can grab them, not affecting your valve adjustment.

 

Well there are many ways to skin a cat. I have shortened a number of input shafts. You machine back the pilot diameter by the amount you will shorten the shaft. Most of the time with only shortening 1/2" you will have enough spline left. Occasionally you will have to deepen the spline and perhaps shorten the trans snout or the disk hub a bit. But if you do not want to modify the trans, a 1/2" spacer between the trans and bell works. As to the small 9", 7", and 5" race clutches, they are pretty much all an on/ off switch and won't live much on the street. They don't like any slipping. The heat will kill them.

 

I ran one of these in a self starting to 2 Barrel Sprint car if you have a lot of compression sometimes they're a little tricky to get started cuz those smaller flywheel you can get the bellhousing from Circle track racers they ran them in stock cars and stuff but yes the starters on the other side of the bellhousing

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Still not sure of your CR goal. To many pieces of missing info- compression height, deck height, etc. If your 58cc heads are Vortec, you have cam lift limitations without some work. That's actually true with the early heads as well. The old GM 140 cam for the DZ302 needs 11 or 11.5 CR and has 0.512 ex lift with 1.5 rockers. So with today's gas not practical. Hell it was not that smart in the early 70s, but we could fill up with Sonoco 260 and get away with it being young and dumb. And it's old tech. So I'd stay in the 9.5 to 10.0 CR and get a cam that will work. As to your head gasket choice, I would stay with a 0.035" to 0.049" quality gasket and play with compression height and deck height to get CR and quench with the chosen gasket. Thin gaskets typically don't last as long as you want on the street.

 

Wouldn't you get the same "reaction" from an Alum. flywheel as you would the one-off wheel you are trying to adapt?
Put-me-down for the 'numbers' off the Scheafer Camshaft. 230-ish duration on an LSA of 110*.
108* (that most Isky grinds use) would let the engine 'wrap-up' quicker but by 7 grand-ish they would probably be done. But the 110* would give you some "adjustability" by advancing/retarding the cam timing.
You should degree any cam and can tweak the performance by adjusting the cam timing up or down a few degrees. MOST custom ground camshafts are ground straight up with NO advance.
"So-I-been-told!"
6sally6

 

I see. I'd be spacing the gear box from bellhousing then work on what pressure plate will work or re-drill a flywheel that would have the surface required for pressure plate needed. Research is easier I think.