Cam choice for 350 with Vortec heads - Chevelle Tech
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post #1 of 46 (permalink) Old Jan 15th, 12, 1:44 PM Thread Starter
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Keith
 
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Question Cam choice for 350 with Vortec heads

Does this look like it would be a decent performing cam for a 350 with stock Vortec heads ?

http://www.summitracing.com/parts/LUN-00016LK/

The engine is a 1971 350, has headers, Holley 600, 2100 stall, 3:31 posi gears.

Any suggetions or comments would be appreciated.
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post #2 of 46 (permalink) Old Jan 15th, 12, 2:05 PM
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Bill
 
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Re: Cam choice for 350 with Vortec heads

If your goal is not to have the heads machined for the 470 lift capacity and a good low end torque motor then yes that is a good choice.

Bill
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post #3 of 46 (permalink) Old Jan 15th, 12, 2:13 PM Thread Starter
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Keith
 
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Re: Cam choice for 350 with Vortec heads

Thanks Bill. I really don't want to have anything done to the heads. Just looking for something that matches up good with what I have. This car is just a cruiser, but low end torque is what I'm looking for.
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post #4 of 46 (permalink) Old Jan 15th, 12, 2:52 PM
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Re: Cam choice for 350 with Vortec heads

That Lunati cam is about the same specs as the old comp 268HE cam and will work fine. Isky 264 Mega cam is similar with 216-216 dur. at .050, .450 lift on a 108 lsa which would give you a little better low and mid range in my opinion. If you want a similar cam with a rump rump idle you could use the old crane 274H06-218-218 .450 lift on a tight 106 lsa. I have this cam in my 84 Vette and it has tons of low and mid range and the nasty idle at about 700-800 rpm. It works with stock springs too. There are quite a few people using this cam. Elgin makes a copy of this cam under part# E1785PM and is around $100 including lifters from competitionproducts.com My 350 has the stock small valve heads, 8.5 c.r., edel. 600 carb on a zz4 intake, factory tube headers and true dual exhaust with no cats, AT, and a 3.07 rear gear. The Lunati cam will have a slight lope to it, the Isky a little more lope and the 274H06 quite a bit more. It is an old circle track lift rules cam Crane used to call the "saturday night special".
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post #5 of 46 (permalink) Old Jan 15th, 12, 2:56 PM
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Tim
 
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Re: Cam choice for 350 with Vortec heads

i had that cam installed in a 305 ho. i wasn't impressed.
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post #6 of 46 (permalink) Old Jan 15th, 12, 3:04 PM Thread Starter
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Keith
 
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Re: Cam choice for 350 with Vortec heads

Thanks Greg. I'll check into the cams you mentioned. What heads do you have on your Vette ? The ones I'm swapping out for the Vortecs were the stock 882's.
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post #7 of 46 (permalink) Old Jan 15th, 12, 3:34 PM
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Re: Cam choice for 350 with Vortec heads

Wrong cam for those heads.

The thing that makes those specific heads different from any other SBC head, is the INTAKE ports. They moved them so they have all this wonderful FLOW. So think about that: lots and lots of FLOW, all this stuff going INTO the cylinder.

But.... (there's always a "but", eh??) they didn't do ANYTHING about the exhaust ports. They have the same sucky restrictive exh ports as any other SBC heads. Therefore, NO FLOW going out.

Therefore, it isn't hard to see, they can use all the help they can get on the exh side so that the flow IN and the flow OUT are more nearly balanced. They'll respond HUGELY to a cam with a bigger exh lobe than int lobe; something that will "crutch" the exh side, so to speak.

Look at the modern asymmetrical cams like the Comp XE and Lunati Voodoo series. Both of them have cams with about that same size intake lobe (which is a good choice for the rest of the combo), but a MUCH larger exh lobe, which makes a DRAMATIC difference to the overall results you will get.
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post #8 of 46 (permalink) Old Jan 15th, 12, 4:12 PM Thread Starter
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Keith
 
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Re: Cam choice for 350 with Vortec heads

Quote:
Originally Posted by RB69SS396Conv View Post
Look at the modern asymmetrical cams like the Comp XE and Lunati Voodoo series. Both of them have cams with about that same size intake lobe (which is a good choice for the rest of the combo), but a MUCH larger exh lobe, which makes a DRAMATIC difference to the overall results you will get.
I dont think any cams in either of those two series will support the max lift of stock Vortec heads which I think is about .470 lift. I really didn't want to have to do any modifications to the heads.
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post #9 of 46 (permalink) Old Jan 15th, 12, 6:45 PM
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Re: Cam choice for 350 with Vortec heads

Comp Cams XE268.

Bill
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post #10 of 46 (permalink) Old Jan 15th, 12, 7:31 PM Thread Starter
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Keith
 
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Re: Cam choice for 350 with Vortec heads

Quote:
Originally Posted by 65 Skylark View Post
Comp Cams XE268.

Lift .477" / .480"

Pretty sure that is out of range for stock Vortec heads
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post #11 of 46 (permalink) Old Jan 16th, 12, 6:19 AM
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Re: Cam choice for 350 with Vortec heads

Quote:
Originally Posted by midnight1961 View Post
Lift .477" / .480"

Pretty sure that is out of range for stock Vortec heads
You're right, I actually meant to put XE262. Sometimes my fingers don't do what my mind is telling them to do I had an XE262 in mine for a few years and it is an incredible street cam, great torque, wide power band and good manners. I've actually thought about putting it back in.

Bill
_____________________________________________
'65 Buick Skylark,
355 sbc, 10.2 comp, Trick Flow 195 heads, RPM Air gap, Holley 3310, Bullet 224/230 .483/.485, Hedmans, 200-4R, 10" 2,800, 4.10 12 bolt.....and factory a/c
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post #12 of 46 (permalink) Old Jan 16th, 12, 6:53 AM
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Re: Cam choice for 350 with Vortec heads

I am very happy with the Elgin E-923-P in my DD Blazer with a 350, which sees some towing and is about 1000lbs heavier than a Chevelle and has a stock converter. That cam is 270/280 advertised, 204/214 @ .050, 107/117 lc, 420/443 lift.

For the OP, with a lighter car and a bit of converter, I think the next "bigger" cam would work well: the E-922-P, which has 288/298 advertised, 214/224 @ .050, 443/465 lift, 112 lc (probably the same 107/117 split - don't see it on the website I'm looking at)

_____________________________________
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post #13 of 46 (permalink) Old Jan 16th, 12, 7:43 AM
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Re: Cam choice for 350 with Vortec heads

Those are both completely generic, "universal" cams. Can be had most anywhere for DIRT cheeeep. Been around for 35 years or more that I know of. Very "low tech" but easy on parts since they were designed way back before you could really buy valve springs in the variety you can now. Won't win any races but as said might be satisfactory in some situations.

http://www.summitracing.com/parts/SUM-1102/
http://www.summitracing.com/parts/SUM-1103/

The first one is what people often mean when they say "the RV" cam, the 2nd when they say "the mild" cam.
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post #14 of 46 (permalink) Old Jan 16th, 12, 7:55 AM
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Re: Cam choice for 350 with Vortec heads

Quote:
Originally Posted by midnight1961 View Post
Thanks Bill. I really don't want to have anything done to the heads. Just looking for something that matches up good with what I have. This car is just a cruiser, but low end torque is what I'm looking for.
This is what I had in mind when I posted. A stretch to call either of the cams I mentioned "performance" cams, but I suppose both of those mild or RV cams are higher performance than the stock cam likely is/was.
The 350 in the Blazer was a 92 TBI engine, and the E923P is "larger" than what it came with. It has a smooth idle, plenty of low end torque, and gets 16mpg on the highway with a 600 vac sec, 3.08 gears and a 700R4. From what I hear, that's not too shabby for a C10 Blazer.

_____________________________________
68 Chevelle
flat top 406, AFR 195's, XR286R, RPM AirGap
750 Holley DP,TH400 w/brake, 4000 stall FTI
3.31 gear, 12 bolt
... for now.
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post #15 of 46 (permalink) Old Jan 16th, 12, 8:55 AM
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Re: Cam choice for 350 with Vortec heads

I will add some for you...Stock used springs suck..stay with a "lazy"
cam unless you change springs the upper R's of some of those cams will not be there.
If you are happy with 5000-5500rpm then I would look at what you originally posted.
I have ran the 268HE many times, even with stock springs,,great mileage and performance,,you get the isky or others in that same size ground on a 108 or 106 they will pull a bit harder but the mileage will suffer by a few MPG.

I have got 20.5 mpg with the 268HE in a 78 nova with 308's and a th350
grind it on a 106 and i get 14mpg and this is with more compression to boot. 210psi cranking pressure

But the later runs 13.51...with a lot of gear in it and good springs shifting at 6000-6500.
Are you installing the heads yourself?
Are these already installed?
Sometimes a spring and retainer change is all that is needed to run higher lifts.
This is something easily accomplished in the garage or kitchen.
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