CheezMoe

Greetings,

I have a 73 Coupe with NOM crate motor per this spec.

http://www.paceperformance.com/index...&ProdID=154046

I have an Edelbrock 2101 and ramhorns w/ 2 1/2 X-Pipe and Flowmaster Delta 50's.

An old racer at work who seems to know what he is talking about tells me to install a GM spec CAM for L-46 350/350 in it and it will run like mad. (Stated 300-325HP)

So I research for the CAM and find this..

GM PART # 3896962
CATEGORY: Engine Camshaft
PACK QTY: 1 CORE CHARGE: $0.00
GM LIST: $182.68
OUR PRICE: $132.98
DESCRIPTION: CAMS- 350
Hydraulic Flat Tappet

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 with 1.5:1 rocker ratio (intake/exhaust) is 450/460.

Can this be true? The L-82's were rated at highest 250 horse, and down to what 210hp? Is it possible that all the L-82's had this CAM and were just choked down that much?

If you look at the engine spec on the crate, it's is a significantly milder CAM and still rated at 250hp.

Something don't add up. I'm confused.

I'm ready to pull the trigger on the CAM... seems like a good spec for low-mid range power..but I wold like a little more confidence by hearing a 'hrrmphh' from the "all knowing one's" on the forum.

big_G

That is a good cam, originally used on 11:1 compression engines. The L-82's had reduced compression, and were rated at SAE NET horsepower, whereas the late '60's 350-350 was rated at GROSS horsepower. The L-82 in a light 'Vette, (like a '73 without A/C) could rip off high 14 second passes, only slightly slower that it's earlier counter-part. Emmissions equipment and lower compression were the two main reasons for lower performance. Keep in mind this cam likes a little gearing, as the torque peak is a little high.

63mako

Looks like a good cam for your engine specs to me. Should be much stronger than that crappy cam in it now.

big_G

The real crippler on the engine you have are the heads. Compression is a little low (8.5) for that cam, IMO.

hwcoop

Thats the same cam I have in my 73 L82, 4Spd, 3.70 rear end.
The P.O. put it in when he did the rebuild, motor has ram horns, stock intake and rochester.
Has nice idle and seems pretty responsive, good pull through the rpm range. I'm going to put headers on this winter to help it breath a little

stingr69

I run that "962" cam and it would not be an improvement if you do not have some compression to run with it. 10.0-10.4 would be good. Even with that, the bottom end torque is a little lacking as compared to a lowly stock "929" cam. Lots of mid range and RPM potential if you fix the compression and exhaust issues.

The L-82 was 9:0 compression and had a very restrictive catalytic converter. The exhaust combined with the crappy heads made the car slow. Emissions calibration did not help either. That is why they do not perform like a '69 L-46 350/350. That CAN be fixed.

-Mark.

MYBAD79

The cam that's in the engine is similar to the Edelbrock Performer cam that I currently run. It's a truck-cam, you get a lot of low end TQ and nothing above 4500rpm...
The 8.5:1 CR is a little low, not sure how well the 222/222 cam would work.

mvftw

Have you looked at Lunati's Voodoo 60101?

CheezMoe

Apparently the difference in the current 260hp and 290hp crates is this CAM.....so I think I am going to give it a try....I am hesitant to raise compression on the bottom end without rebuilding the whole thing...good way to create a blow-by ring problem..

From what I can determine, the 72 Vette engine labeled LT1 was 8.5:1 compression and had this 962 CAM, but rated at 270HP.

I certainly don't think it will hurt anything...I hope

ps; Thanks for all the input....much appreciated...

ajrothm

Why not just buy a modern cam and leave those old school cams back in the 70's?

Crane 272h or Comp XE series make some good ones. If you are at 8.5-1 comp and running stock manifolds(ram horns) definetly stick with something under 220*@.050 and .450 lift.

All that being said, I have a blue print 327/350hp cam in my 8.5-1 stock 71' 350. That cam is similar to what you are talking about 222@.050 and .442 lift... Its a dog. No real tq on the bottom and nothing above 4500rpms. This is with a performer intake. The cam was in when I bought the car but... I would recommend getting a more modern design cam for more power and sound.

big_G

'72 LT1 is 9.0:1

CheezMoe

So I'm still a little confused on these opinions. The current 250-290HP crate is spec'd with 8.5:1 CR, 76CC, and .450/.460 222/222 CAM making 290HP@5100rpm. The GM 962 CAM that is the topic of discussion is .440/.450 - 222/222. So So the L-46 CAM is actually .010 less lift on both intake and exhaust than the CAM in the 290hp crate with the same duration.

What am I missing? I will look at the Lunati and Crane parts that were mentioned, but it appears that old school thinking or not even GM is still the same space .......TBC...

big_G

I'm thinking the LDA (lobe displacement angle) may be closer on the old school cam.....

CheezMoe

Ok...you got me on that one...I had to go read up..
so big_G your suggesting the old school cams have less lobe seperation than the new ones? So the thinking would be that a new cam with same lift and duration but with a wider lobe angle would be better for low-mid rpm power in low CR engine?

Thanks again. Everytime I post a new question on this board I learn new stuff.

Scott Marzahl

If you run the '929 cam aka the "300HP cam", just retard it 4 degrees to increase your rev range. It too would like more than the 8.5:1compression you have. If the motor has composition head gaskets I would investigate using thinner ones to gain some compression. It is a very good low end torque cam and will rev very well up to 5,000 if retarded 4 degrees. It is an excellent cam for an automatic car with a 3.08 or so rear end. With some mild pocket porting, it will rev to 5,500 very nicely.

The L-46/L-82 cam needs to have at least 9.75-10:1 to work well since it has a late closing inlet and it will reduce your DCR too much ending up with a dog of an engine.

CheezMoe

Scott, according to GMPP the "962" Cam IS the L-46/L-82 cam, so I am not aware of another choice here from GM. The guy at work did in fact mention that I should degree the cam when I install it.

Both the cams I looked at (the L-46 and the 290 Crate) have lobe seperation of 114.

I thnk I have concluded that minor variations of this basic cam are used in several very popular GM motors and is worth the risk of $131.00 and a few hours work. If GM can claim 40hp from adding the same basic cam to the exact same motor I have, I would hope I could count on 25-30hp and a few lbft, which would make it worth it.

Still checking other cams...probably won't make a final decision for a week or so.

thanks again for all the input.

fauxrs2

Keep in mind your 290 hp crate is also gross HP rated along with the motor that that cam became well known in.. in other words you really arent looking at much of a change...

That said the L-46/L-82 cam is just fine, but it really does want higher CR than you are offering. I would keep looking for a cam.. replacing the cam you have with the one you suggested would most likely not feel any different.

What I can tell you was for a short time I ran the L-82 cam in a 10.5:1 engine - edelbrock heads and intake and it ran great in comparison to the original L-82

frostbitten09

I bought the Vodoo 60102 469 lift... Waiting to install though parents bought it for christmas for me, but had me pick it out.

I talked with lunatis tech they said the 60102 would work well and cr boost would be recomended, it also was the max cam i could go and run all my vaccum eq efficiently..

Scott Marzahl

Sorry about that, that is what happens when I'm on the phone with a customer and typing . I meant to say the '929 300 HP cam.

The current replacement for this cam is GM 14088839. The basic timing numbers are the same, but there is a very slight change in dynamics.

Here is some history on the 300 HP cam:
The early cam used the same lobe on both sides with duration at .050" lifter rise of 196 degrees and points of maximum lift indexed at 109.5/112.5 and was designed for the medium port small valve heads circa 1957. The second design (ID 6930) has durations of 194/202 with POMLs of 108/116. The increased exhaust duration and earlier POML yields an earlier opening exhaust valve as the most significant timing change. This compensates for the relatively restrictive exhaust port of the large port heads as OE machined, so the design is more closely "tuned" to 461 and later big port heads.

jackson

Dosoctaves:
I think there're better cam choices than the 3896962 / L82 cam for your AUTOMATIC trans vette w/ universal 350 ... but if you insist, you don't need to pay GM double for a cam that someone else makes for them and elsewhere sells for half. Here are direct equivalents to 962 cam:

Clevite-Dana P/N 229-1990
Elgin P/N E-921-P
Melling P/N C410P (and) 22210
Sealedpower-speedpro-TRW P/N CS1095R
Wolverine P/N WG973

Those thin shim steel head gaskets (felpro P/N 1094) and a cam&lifter kit with profile like .443"/.465", 214*/224*, LSA 112* (such as summit's P/N SUM-K1103 or SealedPower's P/N KC1013R or Clevite's 229-2205) will have good street manners with your trans & universal 350 and probably make about 290-300fwhp w/ nice flat & fat tq curve.

For comparison, the 962 cam has wider LSA ... close to 114.5*.