ksmitty

I have a 1970 350 with#6 heads on Motor. It has been rebuilt in the past and heads re worked of some sort. Has a eddlebrock performer rpm intake, headers and 750 cfm carb. It was dynoed at 230 HP at the rear axle with an automatic transmission. If I put a more radical cam in it can and how much HP can I gain without changing the heads? If thats an option does anyone know what cam I should go with to get the most out of this motor.

71 Cutlass

What cam is in there now? What's the comp. Ratio? What rear gears are you running? What's the stall? All important info, in order for cam and other components to work together as a unit.

ksmitty

I dont know what the cam is. from the HP readings I would guess close to stock.Its not a lopey or a choppy Idle. 373 gear in the rear end. 10.25:1 compression ratio. It does have a stall torque converter with a street strip 200 4r transmission. The receipt I have for the torque converter says 12" Hi stall lock up converter brazed. It came with the car a 1987 cutlass 442

71 Cutlass

Since you are not sure what cam is in there now, I could suggest an array of cam possibilities, as could a cam company, but you may have the cam in your engine now that someone suggests, so obviously you would not gain any HP. Knowing what's in there now is going to be an important part of knowing what cam to get and how much HP you might gain from the new cam. As an example, and this is just totally hypothetical, let's just say you have the 204/214 generic grind cam in there now. Based on the info you've given (rear gears and CR), you could easily move up to something in the 224/234 range...but maybe that's the cam you already have, so you would just be buying the same cam again and going in circles.

ksmitty

I hear you, that makes sense and I didn't look at it that way. I really feel it is close to stock or slightly a mild cam from the test and comparison from stock documentation I found on the 1970 350. OK we are gonna pull the cam and see whats in there and I will get you the info I find out. Just for curiosity sake what if its a stock cam. How much HP can I gain by switching it to an aggressive lopey idle type cam?

Aceshigh

Horsepower ratings for Oldsmobile 350's
I know for a fact it's putting down 334ft lbs but it wasn't tested to the limits. Nor was the carb finely dialed in perfectly either. Ran great!!! But not 100% dialed in. So to come to that with a perfectly tight Automatic and torque converter , and rear end (assuming a perfect world) you deduct 20% drivetrain loss. I forget how to do it reverse from 334 upwards. But if you take 420 and multiply it by .8 for 80% you get 336ft lbs. So roughly 420ft lbs @ the crank.

I'd strongly suggest getting the Wideband o2 setup and the tune the carb perfectly and redyno it before you just start changing things. You might be surprised.

What is your goal for the car ?? Drag racing or Cruising bruiser ??
Torque is king in a street car going stop light to stoplight.

Here's a thread that might help you with inspection questions.
I don't know how far you want to rip the motor apart to see what's in it.
http://www.hotrodders.com/forum/1970...ce-189624.html

ksmitty

I read somewhere the only difference between the 310 hp motor and 325 hp motor was the cam it came with. In 1970 they all had the same #6 heads is what I read. Maybe I will just drop it in and see what she will do!

firefrost gold

that was a good read ace . Even had a little joe in it.

cutlassefi

That cam is slow and lazy, you can do better than that. I'll either grind one for you or help point you in the right direction when you have all your info.

ksmitty

well I cleaned up the motor tonight and removed the valve covers to find competition cams roller rockers, and pushrod guide plates. If I pull the intake off will I be able to see any numbers on the cam that would tell me what it is? Or do I have to pull the cam itself?

Aceshigh

Did you smile ?? I posted this before.

OldsEngineRockers.jpg

442much

Remember, that HP rating is apples and oranges. The 1970 and previous is gross HP and 1971 and later is net HP. Is this is going to be a street machine or a race car? I see so many cars at cruise nights that are built up so much they look like they would be unpleasant to drive anywhere with distance. Also, I've heard that at the track HP rules, but on the street it's torque.

Aceshigh

He's right, I forgot about that. http://en.wikipedia.org/wiki/Horsepower#SAE_gross_power
1970 HP ratings were with a stripped down motor, no accessories in perfect conditions.

1972 to the present is rated by a fully accessorized engine's output.
So those Dyno #'s I gave you were SAE Net HP and TQ.

MDchanic

Including, importantly, an exhaust system that was essentially headers and straight pipes, even in engines destined to be equipped only with restrictive exhaust manifolds and single exhaust systems, so those power peaks are right out the window.

- Eric

455man

There's another question. What exhaust is on the car? Olds motors like free flowing exhaust.

Aceshigh

The engine had aftermarket headers on it.....
I don't remember if they were Hedman or Hooker

You're saying a 1970 car came with headers from the factory??
Never heard that claim before.

MDchanic

Nope. I'm saying that the SAE-specified equipment for testing gross HP is the equivalent of a set of headers. Since, as you point out, they never actually equipped any production car with headers, this alone guarantees that the pre-'72 HP ratings will be very optimistic, and will reach their peaks higher in the rev band than they will in practice when actually installed in the car.

- Eric

Aceshigh

Thanks for the clarification. Understood now.

ksmitty

what does it mean when the recommended rpm range for a cam is 2000 to 6000. I sent comp cams all the info I knew and they recommended a cam to me. They told me I needed to use a 2500 stahl also. Not gonna do it as were gonna run it 1st and see how it works in this car before adjusting anything. But I was curious about this specification and what it would mean to the way it ran and idled.

Aceshigh

It means the cam makes the power in the 2000-6000 rpm range if I'm understanding you correctly.
Since that is an Edelbrock RPM intake, it's targeted RPM band is 1500-6500

I had that 27 spline new 2200-2600 converter I could have sold you too for $150.
http://www.roadrunnerconverters.com/gm.htm
I just sent it back and it was $38 shipping. Sucks......

ksmitty

I already have a stall converter. When we pull the motor I will find out exactly what it is

cutlassefi

Here's a little fyi about the postings the cam companies do. When they post an rpm range for any given cam, that is for the whole group of engines listed. For instance, do you think the same cam will have the exact same power band in a 455 that it would in a 330? The answer is no. It'll run out of steam faster in the 455 and start later in the 330, See? It's an average and also has to compensate for a bunch of variables, manifolds, headers, carb, and so on.

And by the way, 455man, all internal combustion engines benefit from controlled back pressure in the form of free flowing exhaust, not just Olds'.

When you're ready for a cam, give me a shout, I'll help.

ksmitty

well 2 long nights 2 short nights and she lives. Got the motor running tonight but had to shut her down after a few minutes. Very loud with open headers in a subdivision at 10:30 at night. waiting for the new crossmember to show up then it goes to the exhaust shop.