[drmdlucas]

On a 350 HP 396 with stock heads, is there much benefit to be had to replacing the cam without also replacing the heads? The application is primarily street, but with increased horsepower.
Doc

 

[One Feather]

I don't have my book in front of me but I think that cam is fairly mild.

 

[cyberray]

hey Doc, which year would that be? and depending on what the lift is, would it be easier/feasible to just swap different rocker arm ratios in there? (1.6 vs 1.5, for example)

 

[drmdlucas]

hey Doc, which year would that be? and depending on what the lift is, would it be easier/feasible to just swap different rocker arm ratios in there? (1.6 vs 1.5, for example)

The year is 1968. I need to get a reference for this motor to know anything about the rocker arm ratio, but I also want to go to a roller tappet system. What I really should do is save up for an Edlebrock top end kit. Your idea has merit as an interim solution. I'll look into it, I need a Chevy big block book anyway. Thanks, great suggestion!

Doc

 

[pbr400]

A 396 powered Camino in good tune should have more power than the tires can handle in stock trim. Once you’re moving it should have more power than you’ll need on the road. More than the brakes and suspension can use, too. That said, there’s two reasons to upgrade. (1) If you want more power for a faster quarter mile, you’ll need to match the cam to your compression, transmission and rear gears. Heads will also affect cam choice. If you have an ET goal, it will determine the need for heads. You’ll also need slicks and some rear suspension help to get it off the line. All these things will make it quick and a byproduct of that may be a lumpy idle and ‘mean’ sound. (2) If you don’t have any interest in actually racing or doing the mods for racing, you can pick a mild cam that will sound close to stock and put out more power for more driving pleasure, or you can go big, sound lumpy and actually worsen performance. Swapping in shorter rear gears (depending upon what’s there now) is one of the best ways to wake it up without touching the engine. The heads are not really going to help on the street except, as part of a whole build, they’ll allow more conpression on pump gas.
With either choice it’s critical to match the cam to your conpression and rear gear (unless all you care about is sound).
I’d do a mild cam swap, maybe gears and see what you think. If that leaves you wanting more, then I’d consider heads carefully, maybe as part of a fresh build.
Patrick

 

[drmdlucas]

A 396 powered Camino in good tune should have more power than the tires can handle in stock trim. Once you’re moving it should have more power than you’ll need on the road. More than the brakes and suspension can use, too. That said, there’s two reasons to upgrade. (1) If you want more power for a faster quarter mile, you’ll need to match the cam to your compression, transmission and rear gears. Heads will also affect cam choice. If you have an ET goal, it will determine the need for heads. You’ll also need slicks and some rear suspension help to get it off the line. All these things will make it quick and a byproduct of that may be a lumpy idle and ‘mean’ sound. (2) If you don’t have any interest in actually racing or doing the mods for racing, you can pick a mild cam that will sound close to stock and put out more power for more driving pleasure, or you can go big, sound lumpy and actually worsen performance. Swapping in shorter rear gears (depending upon what’s there now) is one of the best ways to wake it up without touching the engine. The heads are not really going to help on the street except, as part of a whole build, they’ll allow more conpression on pump gas.
With either choice it’s critical to match the cam to your conpression and rear gear (unless all you care about is sound).
I’d do a mild cam swap, maybe gears and see what you think. If that leaves you wanting more, then I’d consider heads carefully, maybe as part of a fresh build.
Patrick

Thoughts to carefully consider. Thanks, Patrick, I appreciate your analysis. Doc

 

[C.NORMAN65]

I think the last response is spot on, swap the cam in the car you can do this in a short day, run around and see what you got. Cam and Ignition upgrades will give you a nice seat of the pants upgrade. If you are looking to dump money and you don't care about the originality of a 396 bump up to 496. I am in the process of changing out a 396 in a friends boat to a 496, all said and done we will be into the 496 for $4200 to $4500. (4 bolt block / 781 with big valves / forged rotating assembly)

 

[69 SS396]

In a 350 hp 396 (10.25:1) just good tuning and hei will give you tire smoking fun. My 69 would roast the tires with 3.08 gears. Basically stock just headers, hei and pypes exhaust.

 

[pitts64]

You either want a cam for drag racing or street performance, one or the other, you can't have both..

 

[drmdlucas]

You know guys, I can't explain why I want a little more power. Engine upgrades are last on my priority list. I'm working down my list bit by bit as money comes available. I've swapped out the transmission for a 700r4, built by a local company specializing in performance transmissions, to get overdrive. Eight MPG just is too much. I need to pop 10. It's my own doing; I swapped the 3.08 for a 3.73 and limit-slip awhile back and that's why. I can't say how much my motor has been modified as the guy I bought the car from did nothing to the engine and failed to get records when he bought the car at auction. I've had the car for barely a year. I've got headers, 3" X-pipe exhaust (I installed the 3", up from just under 2" when I got it). There's a Moroso oil pan and a serpentine setup with nice dual electric fans. It's got a Street Performer intake with a Holley 670cfm carb. I installed a Dakota Digital dash, cruise control and a couple of other modules, like tire pressure and so on. I put Hydro-Boost on the PB system. It's got front discs already. Right now I'm focused on the interior comfort. I replaced the AC with a Vintage Air because the vacuum switch in the control unit failed and that is the only part on the system unique to 1968 only, and no one makes a replacement. We tried adapting another year's switch, but that didn't work so well, so I bit the bullet since my only choice was a 52 year old part from a yard no matter what I did. I've replaced the front seat (sagging springs) and now I'm working on the stereo and other interior improvements. That's not all I've done, but this is already a long post. After the interior, I'll install an EFI, then a major suspension upgrade followed by 4-wheel discs. When everything is done, I'll tinker with the motor. I'd like to see around 500 HP or so, but I'm not upset with what I have now. So you see, I don't need anything much on the motor, I just want more power tuned for the street. I'll never take the car to the strip...well, probably I won't, but it could happen, just for fun. This is long enough. Sorry for taking up so much space.

Doc

 

[roccodart446]

my big block makes 500hp on the crank dyno. You'll need heads to make that number, not just a cam. And you'll need the right supporting items too. I.e. headers, carb, intake, ignition.

With your stock heads, You can esily make 50 more HP and still have a very mild cam that is street friendly.

Look to a camshaft, ideally a roller cam, that is [email protected] At least .550 lift. The LSA will depend on your compression ratio and cranking compression, but for the street, error on the higher end of the LSA's.