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Old 05-17-2006, 04:45 PM
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350 L79 cam & vortecs?

okey so my engine is in engine heaven.

Can someone please criticize this new combo.

I'm focusing on longevity and reliability for street driving.

60 over 350
moly rings
vortec heads - stock sdpc2000.com ones
corvette cam
Performer intake
600 holley single

corvette cam specs:
This hydraulic flat tappet is used on the 65-67 Corvette and Chevy II L-79. It has excellent power and torque (ID# 3863152). The duration at lash point in degrees (intake/exhaust) is 320/320; duration at .050" tappet lift (intake/exhaust) is 221/221 and maximum lift with 1.5:1 rocker ratio (intake/exhaust) is 447/447. Valve lash is zero/zero and lobe centerline is 114 degrees.

I believe this cam is made for 300hp
With the heads and performance parts Im aiming for 350.

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Old 05-17-2006, 04:59 PM
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That cam is real old school and has very slow ramps. I'm not a big fan of flat tappet cams with extreme lift rates because for noise and durability, but the cam you want to use has very slow ramps.

Plus vortec heads need more exhaust duration due to a poor intake to exhaust ratio.

You are aware that vortex heads require and vortec intake, vortec valve covers, and vortec rocker arms.

The cam you choose should depend on the compression ratio, gears, transmission type, stall speed, exhaust system, car weight, and preferred idle quality.

Is this engine in a Vega?
Flat top or dished pistons?
Headers or exhaust manifolds?
auto or manual and if auto what stall?
Gear ratio?
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Old 05-17-2006, 05:08 PM
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yup for my vega

flattop pistons - so I can use pump gas

Headers

3.42 posi rear

Th350

-----------------


I am trying to keep the heads stock. Their maximum lift is not that high so I thought that cam would work okey. Is there a smooth idle cam that you know of that might be a better choice?
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Old 05-17-2006, 08:21 PM
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Quote:
Originally Posted by 454C10
That cam is real old school and has very slow ramps. I'm not a big fan of flat tappet cams with extreme lift rates because for noise and durability, but the cam you want to use has very slow ramps.

Plus vortec heads need more exhaust duration due to a poor intake to exhaust ratio.

You are aware that vortex heads require and vortec intake, vortec valve covers, and vortec rocker arms.

The cam you choose should depend on the compression ratio, gears, transmission type, stall speed, exhaust system, car weight, and preferred idle quality.
I agree BUT I know of a guy running a 9.0 to 1 Vortec head 383 with the L-79 cam in a 1/2 Ton PU with a 700R4 and 2.56 gears and he's very happy with it and claims to get 20+ MPG on the Interstate. I would never try it but it seems to work for him.
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Old 05-17-2006, 08:51 PM
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350hp should be easy, since the 350hp 327 from 1966 used that same cam, and you have better heads. Might do even better if you could get the exhaust ports to flow a little better.
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Old 05-18-2006, 08:22 AM
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Ok, so you have a fairly light car, with headers, 3.42 gears, automatic, and I assume a stock converter.

If that was my car and I wanted good mpg, good idle, and decent performance then I would use one of two cams. Crane CRN-114132 or CRN-113931

CRN-114132
270/276 advertised
210/216 at 0.050"
0.440/0.454 lift
114 lobe separation

CRN-113931
262/268 advertised
212/218 at 0.050"
0.446/0.459 lift
114 lobe separation

Notice the advertised duration is much shorter on the crane cams compared to the L79 while the duration at 0.050" is just little less. The crane cam will build more cylinder pressure which will improve torque throughout the rpm range. Plus a little more duration on the exhaust side is needed for the Vortec heads. The 114 lobe separation is not ideal for a carburetor but it really improves idle quality by reducing overlap. FYI, a street drive carb'd engine does better with 110 to 112 lobe separation but the idle with suffer.

The CRN-114132 with give a little more top end power as compared to the CRN-113931 and will do a little better driving down the freeway with those 3.42 gears. The CRN-113931 will have more tire spinning torque and do better around town.

Use only diesel engine oil with your flat tappet cams! Check out CompCams website tech section and it will explain how the oil formulation has recently changed in regular engine oil and that it is real bad for flat tappet cams.

With flat tops, 355cid and 64cc heads, you are looking at a 10:1 cr engine. Fairly high for pump gas and a mild cam. However, Vortec heads require less timing due to the fast burn combustion chambers. Plus you have a light car and a 3.42 gear which makes it less prone to detonate. You may need to get your distributor re-curved to allow 15 degree initial timing and 34 degree total. The re-curve will include welding up some the the advance slot to reduce the total mechanical timing.
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Old 05-18-2006, 10:12 AM
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great info ...thanks alot
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Old 05-19-2006, 12:22 PM
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check this out.

http://chevyhiperformance.com/techarticles/94138/
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Old 05-21-2006, 04:37 PM
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I'd stay away from a old grind like that there are SO much better grinds out today ie comp cams extreme energy and a lot of others, give com a call on their cam help line they should Set you straight.
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Old 05-22-2006, 08:55 AM
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thanks for the info guys. It looks like I was going to make a big mistake.

It is worth getting the springs changed on the heads so I can use a better cam.

thanks
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Old 05-22-2006, 03:27 PM
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I believe that you may have to have some machine work to the valve guides, not just the spring, BUT the vortec heads are good for .480 Lift, not to shabby from the factory.
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Old 05-22-2006, 07:11 PM
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Vega,
I'm running a .060 over with updated vortecs from SD and a cam real close to what 454C10 suggests above CRN-113931 in a '71 Nova 373 gears/2004R/625 demon "except" I had it ground on a 112 LS as he also suggests. Just a snappy idle, and it can be run with a stock convertor. Currently getting 23 MPG, I'm very pleased. I also ran it in front of a TH350/stock convertor, good street manners but not too good a gas mileage. If you want to let it breathe a little better throw on some 1.6 rockers. I've measured literally dozens of these heads 062's and 906's, .470 is the norm between the valve seal and retainer (subtract .050 and you see updates are necessary). Comp makes a behive drop in spring/retainer that'll let you run the extra lift without machining if you wish (don't quote me but I think it's 10309).
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