stingry

Paging all Cam Gurus!

I have a Mellings Cam 22210 with the following specs:



I wanted the cam to be a 1970 L46 (350HP) cam but I am not sure if it is exactly what I am after.

Is this close to the L46 cam?

Here is what the engine/car is (pretty vanilla):

1970 4 Bolt 350CI bored 0.030" = 355CI
Stock 64CC heads port and polished (2.02/1.6 valves)
Stock manifold - ported and gasket matched
Rams Horn Manifolds - jet hotted
Stock QJET 750CFM
Exhaust 2&1/2" mandrel bent but 2" inlet (same as stock) and 2" tips

Here is the Dyno sheet (with a vaccum leak):



I would like the following out of the engine:

350 FTLBS Torque, 250-300HP at the rear wheels
Prefer a decent idle.

Which cam will do it for me with the engine combo I have?

I like the look of the Lunati Voodoo with a range from 1000-5000 RPM but unsure if it going to have more power/torque then what I have now.

Are these numbers attainable with this engine combo?

I don't want to change carbs or put on headers. Car has to look original.

Thanks forumites

Pete

GOSFAST

Not sure of about your option, but that is the OK specs for the L82 option, you'll have to do a little more research. I have that identical cam in inventory, but it was ground right at CMC (Camshaft Machine Company) for the OEM cam division for G.M. Way back when, G.M. had a contract to have "CMC" do all their cams. You can I.D. all factory cams by looking for the foundry stamping right in the forging. It will appear as a backwards "C", then a "W", then another backward "C". It's the foundrys ID and it's actually "CMC" forged in backwards. We used them to supply all the "OE" grinds to our local resto guys. I just sold 100+ cams up in N.Y. to a builder connected to a shop (resto) up here. The problem you encounter with ALL aftermarket grinds is they never sound (while running in the engine) the same as the OEM's. We think this was the reason we sold all the cams we did. I still have over 150+ left in stock. Thanks, Gary in N.Y.
PS: We also delivered the engine you're talking about, but we knocked the C.R. down to 9.2:1 (runs fine on 93) and tested it with ALL factory components, right down to his cast iron manifolds. We managed to achieve 355HP @ 5800 RPM and 384# torque @ 4100 RPM using the OEM factory cam. The customer was ecstatic when we handed him the dyno sheet. Also on the plus side, he's gettin' decent mileage, and doesn't need to "break the bank" to gas up. Drive in, fill it up with 93, and drive out. No detonation at all!

zwede

With the stock exhaust manifolds and intake that's about what you can get. Your air/fuel looks OK. Your torque is pretty good indicating good volumetric efficiency. Then the stock exahust manifolds and intake can't deliver the air it needs which is why you reach power peak at only 4500 rpm. Your same combo with headers and good dual plane intake will easily make 260-270 rwhp.

That said you should not use a single pattern cam with a restrictive exhaust. You should add about 10 dgr on the exhaust side. I would hesitate to go bigger on the intake as that will really hurt drivability and you can't take advantage of it anyway (more intake duration helps at high rpm where you're done anyway).

stingr69

Pete,
I can confirm that the Melling cam you have is the L-46/L-82 cam. Same cam that was used from '69 through '80 on HP Vettes. I am running the same basic combo in my Vette. With the thinnest steel shim gasket you will be right about 10.4 C/R with single trough flat top pistons. Mine runs great even on pump gas but has not been to the dyno. The vacuum is good, manners are fine it does get great mileage too.

You would get a little bit more power out of your setup with the LT-1 solid lifter cam. That is obviously the top step up for the factory grinds and was designed for use with cast iron exhaust manifolds. Considering that you are running a 4 speed it would be a great combo for a Vette. They were famous engines for a reason. Not a huge difference but it would be noticeable enough that you would probably not want to go back to the L-46/L-82 grind both you and I have now. I would have definately installed the LT-1 if I had a stick shift but I have the AT and A/C so I went with the hydraulic HP cam.

Has the dyno guy said anything to you about the A/F ratio?

-Mark.

joe73vette

Your cam is very close, but not exactly the same as the GM cam:
3896962; Hydraulic Flat Tappet – L46/L82
This hydraulic flat tappet is used on the 68-81 L-46 and L-82 Corvette. The duration at lash point in degrees (intake/exhaust) is 312/312; duration at .050" tappet lift (intake/exhaust) is 222/222 and maximum lift (intake/exhaust) is .450”/.460”. Lobe centerline is 114 degrees.
Joe

stingry

Marcus,

Thanks. If the intake and rams horn are the limitation I can ive with taht. Car runs great has about 17 of vaccum. I would like more torque but who doesn't!

Is there an available cam with the extra 10 degrees on the exhaust side off the shelf?

Pete

stingry

Joe,

I don't know it if is worth the hassle to pull the cam to get the extra if it is close to what it should be. I was hoping someone said Ihave the 300HP cam but it looks like mine is pretty close to the L46.

Pete

stingry

Mark,

My A/F ratio was a little rich. I had a vaccum leak through the headlight actuator relays so the RH side was actually leaner. (not sure if the one shown was LH or RH). He mentioned if I leaned out the carb a little I would get 10 more HP. I ended up getting some leaner secondary rods and it made a noticeable difference. I haven't been back to the dyno since though.

Can the LT-1 Solid lifter cam use the same pushrods I have now?

I don't know a lot about solid lifters so what is involved with putting one in and regular maintenance?

Thanks,

Pete

toddalin

Wake that engine up with some good headers! Your combination isn't very different than mine and in many ways is more radical (with a bigger cam).

My combination:
331 CI, pump-friendly 9.5:1 CR
K&N 14"x4" air filter, Corvette drop base and lid
Holley 600 dp, choke horn milled, polished
1/2" Aluminum open spacer port matched to manifold, exterior polished
Edelbrock Performer RPM, port matched, exterior polished with all extraneous castings and lettering removed
Homemade lifter valley splash shield to keep hot oil off manifold bottom
Camel hump 1.94/1.50 heads hogged out to 2.02/1.60, pocket ported, port matched, pump-friendly hardened seats, 3-angle valve job
Comp Cams 1.52:1 roller-tip rockers
Crane Cam Vintage Muscle 327/350 hp cam, 222 degrees @ 0.05, 0.447" lift (with 1.50 rockers)
Doug Thorley headers, dechromed and ceramic-coated
2.5" mandral-bent exhaust (including tips), 2" cross-over just before rear axle
DynoMax stainless Ultra Flow mufflers
Mallory Hyfire IV CD ignition box triggered off Accel points
Mallory high voltage chrome coil
Mallory spiral-wound coil wire
Mallory solid copper plug wires, ends soldered to wires
Champion plugs
37 degrees total ignition advance
Carter high-volume fuel pump
Melling high volume oil pump
Open breathers
Polished aluminum high flow water pump
Flex fan with polished aluminum spacer
Polished aluminum one-wire 100 amp alternator
Muncie M-20 CR 4-speed
Hurst shifter
3.70:1 positraction
225/60/15 Firestone Firehawk SZ50s on 7”-wide Western 30-spoke Turbine Wheels

Engine had never been professionally tuned up at time of dyno pulls. Car did 293 ft-lb and 293 hp @ 5,500 rpm on the chassis dyno. Engine pulls to 6,200 rpm and does over 200 ft-lb from 1,900 rpm. This was prior to some clean-up work around the junction of the carburetor and base of the air cleaner that smooths the flow through this area AND a LARS tune-up that should be good for a few ponies.

Car has run 107 mph in the high 13's (old, bad tires) at the quarter. Car is extremely streetable and could probably even run 87 octane if it had to. (I can't get the engine to ping no matter how far I advance the ignition.)

My chassis dyno sheet:

zwede

Sure. All the cam companies have cams with about 220-225 intake duration and more exhaust. Personally I wouldn't consider the gains worth the effort though as you're only likely to gain 10-15 hp.

stingry

Toddalin,

I would like to do headers but I need to keep the engine bay looking stock. (also just had the originals Jet-Hot'd)

I am going to do the following and see if it helps on top of what I have:

MSD
X-pipe 2&1/2 inch Magnaflow
Comp Cams Magnum 1.62 Roller Tip Rockers

You have done well with your setup. Congratulations.

Pete

stingry

Marcus,

Well for 10HP I will leave the cam alone.

Is the peak at 4500 normal though?

Is it exhaust/intake or ignition causing it to drop off at this point.

I would easily get another 20HP if it just kept climbing like in Toddalins graph.

zwede

I think it's exhaust mostly but the intake isn't helping any. Doesn't look like ignition. When the ignition craps out you'll see ringing in the curve. Like what you have 4400-4800 rpm just much, much worse.The minor ringing you show looks like slight pinging but nothing to worry about.

stingr69

Pete,
Solid cams install the same as hydraulic except the valve adjustment procedure is a little bit more involved. The pushrods can be the same either way but would advise having pushrod guideplates, screw in studs and hardened pushrods if you install the LT-1 cam. The RPM redline is 6500 RPM for that LT-1 cam so you will find it more exciting to drive as compared to the L-46 350/350 grind you have in there now. Extra HP and extra RPM make it worth the effort to do the swap. The only real downside is that you will need to check the valve lash once a year or so depending on how much you drive it. I have solid lifters in my Camaro and they have never "needed" adjustment but I do check it once in a while and they are usualy fine. I think the 1.52 Comp roller tip rockers help hold the adjustment longer. They fit under the stock valve covers no problem, and reduce wear so consider them if the ones you have now show any excessive wear. They seem to quiet the solid lifter noise a little. I put them on everything I build.

Hope this helps.

-Mark.

stingry

Mark,

I have pushrod guideplates and screw in studs. I had them put in last year with the engine rebuild. I am about to buy the Com Cams Magnum Roller Tip rockers regardless of what Cam I get or even if I leave the L46 cam (wannabe) in there.

I also have Magnum Push Rods.

Are they rigid enough Push Rods?

How rough is the LT1 Cam idle?

I can live with checking valve lash if I have too. I don't intend to put on more then 2000 miles a year.

Pete

stingr69

Pete,
The pushrods need to be hardened so they do not wear on the guideplates is the only real concern. It is not about rigidity so the ones you are running now should be adequate. The LT-1 should not give you any problems with the idle as it was stock in Vettes from the factory so all the vacuum accessories will work fine. You might notice a little difference in the idle as compared to the L-46 cam if you have a good ear for that type thing but it will not be a lot. One thing you will hear is the subtle sound of the solid lifters which is "music" to any true gear heads heart. People will notice that and comment.

I would definately put the LT-1 cam it in there If it were mine.

-Mark.

thevetterisbetter

This dude has a list of cam specs for certain years and engines...
http://www.geocities.com/MotorCity/D...000/vette.html

stingry

Thanks