1969cutlazz

Hello, I'm im process of rebuilding my 350 Rocket for my '69 Cutlass. It is a complete overhaul. Machined .040 over, Offenhauser intake, 4bbl carb. Nothing crazy. Automatic 350 turbo trans no stall. Manual Brakes(no booster). My question is What kind of cam should I buy? I would like to get the most radical cam I can for what I'm working with. Here is a copy below of what I found, I want something that will give me good low end torque and sound real nice. Would the below work? Any suggestions welcome. Thanks in advance. Eric


Melling (or Elgin) M Select street torque/RV camshaft and lifters for Oldsmobile V-8 1968-1980 350 400(1968-) 403 455 hydraulic NON-roller cam engines. P/N MTO-1 and (16)HL1951S. Cam specs are as follows:
Valve Lift (INT/EXH): .448/.472

• ADV Duration (INT/EXH): 280/290
• Duration @ .050" (INT/EXH): 204/214
• Centerline (degrees): 107/117
• Power Range (RPM): 1200-4700

J-(Chicago)

Sounds like you're on the right track, but you need to know the compression ratio.

f-85

Also what gear you running?

1969cutlazz

Compresion ratio I'm not sure. They are standard .040 over pistons. So I guess 9:1 or 9.5:1 ...The 12 bolt rear end is all stock and I think its like a 2.73 gear or something in that neighborhood.

captjim

Guessing won't work. Read this,
http://www.oldspower.com/vb/showthread.php?t=36717

Most "estimates" are way off, resulting in a poor camshaft selection. You have to measure and know for sure. If the pistons are el-cheapo cast with 1.595 C/H and 23 cc dish, Cr will be more like 7.6 to 1.

cutlassefi

If you really do have 9.5:1 and with a 2.73 gear then the cam you're looking at will work but if you want more low end torque and a little tone that same cam ground on a 108 would be better. A tighter (lower number) lobe seperation will give you more power sooner. I'd stay with a lower duration cam and have it ground on a 108, or find one already done that way. I think you'd like the performance of it.

Those generic cams aren't bad, but they're a bit lazy cuz of the lobe design and the fact that they're done on a wide lobe seperation, that's done for idle quality and for wide range of uses.

1969cutlazz

Thanks for the help.

1969cutlazz

According to Stock engine specification for a '69 Olds 350 its showing 9.00:1 for the 250hp engine, 10.25:1 for the 310 hp engine and 10.50:1 for the 325 hp engine. Thats why Im guessing around 9.5:1. I highly doubt its 7.6:1

bkeese

69,
You still have an incomplete picture. What is your intended driving purpose and RPM range? Do you just want to impress at the Dairy Queen or street/track or bracket racing? Exactly what pistons are in there, domed, flat top, dished, etc. What is the cc of the heads? from this you can determine the compression ratio. You desire a radical cam which equates to high RPM but you have gas milage gears, it doesn't compute.

So if you indeed want a radical cam then change the gears and change the stall, otherwise the RV cam is perfect, but it's not what you asked for.

cutlassefi

Any small duration cam ground on a tight lobe sep will still give you good torque and a little tone without affecting driveability too much, i.e. 208/214 on a 108, not the generic stuff.

Run to Rund

The cam you described, 204 deg at .050" will idle smooth and sound stock. Is that what you want? You said you want as radical as would be consistent with your setup. I'd go another 20 deg. at .050" and get a better differential ratio, mid 3s or more. As others noted, generic cams are just that. If you want to optimize, get something better.

1969cutlazz

I think this is what I'll be going with from CompCams:Part#42-228-4

260H High Energy™ is the perfect cam for vans, family sedans, pickups and tow vehicles.
This cam provides exceptional power and a gas mileage increase, especially on the highway. With its great torque and throttle response, the 260H cam can also be used for O.E.M. replacement in most big block applications. The 260H’s idle is smooth in large engines with stock exhaust systems. With headers, the 260H will produce a slight exhaust sound.

cutlassefi

That cam is very tame and a single pattern. On an Olds they respond to cams with more duration on the exhaust side than the intake. Jmo.

1969cutlazz

What would you suggest?

Run to Rund

Comp Cams Extreme Energy series are hydraulic and dual pattern as suggested above. In increasing power and roughness of idle, XE 250H (smooth) to XE268H (in the duration range I mentioned in a previous post) will work for you. They are ground on 110 degrees lobe separation, a good compromise for your application.

cutlassefi

Essentially an Erson RV15. Again you have stock heads, all the fast ramp stuff isn't necessarily the best for that. In a Lunati cams I'd look at the High Effieciency series. Your rear end gear is limiting your options.

70Wcars

I really like the Lunati VooDoo line of cams. I have used them in several engines I have built for folks, and the lobes are more recent designs than the older Generic stuff. I think they make a cam in the 213 dur. at .050 on the Intake side. That would sound healthy, run very well and not torture the rest of your Valve Train.

Just my .02

Danny S.

joesw31

I don't think your compression will be 9.1 or 9.5. It may be more like 8.1 or 8.5. I used the compcams high energy series with great luck no issues. it was like .212 at .050. it might have been the 260h.

captjim

You can guess all you want. You can doubt me all you want. Stock engines used either a 14cc dish or 6cc dish and a shim heads gasket. In reality, Cr was closer to 8.5 and 9.8 than the published numbers. Since the engine has been bored, new pistons are in there. Most engine rebuilds used replacement pistons with a 23cc dish. There are other choices, flat top or 6cc Speed Pros, 14cc old Badgers, etc. Point is, if you DO have the 23cc dish, Cr will be around 7.6 to 7.8 with no milling and a cheap head gasket. However, you can have as much as 10.4 to 1 with flat tops. Your reply of "standard .040 over pistons" does not help, you need to know what they are to choose the correct cam.

1969cutlazz

The only thing the box says that I got the pistons in is TC-1740 040 by Perfect Circle. They are dished. I'll be using a regular Fel-pro Head gasket and the heads are stock. This is all I know. Will this info get me any closer to figureing out my cr? Thanks for all the replies

captjim

http://www.fatherley.com/wp-content/...ton-Specs1.pdf
From this it looks like you have the destroked, big-dish pistons.

Using this calculator,
http://www.csgnetwork.com/compcalc.html
and the following values; 68cc chamber, pistons .040 down in hole (mine were .053), 4.250 x .045 cheapo head gasket, 23cc dish, Cr calculates out to 7.6 to 1. Now, chambers may be smaller, deck may have been milled, etc, but IMO at best you are at 8 to 1. This is a very common issue with 350s, usually resulting in an over-cammed dog of an engine.

1969cutlazz

So now that we have an idea of what the cr is what cam would you recommend?

cutlassefi

As usual I believe you're right on Jim. Even with the 14 cc you might be at 8.5:1. You really needed the 6cc.

1969Cutlazz you're back to square 1. Without exchanging the pistons imo the most "radical" cam you can get without making your car a total pig is the one I mentioned, 208/214 on a 108 in at 104. It's a little different than the one you listed. It has a tigher lobe sep and different profiles on the intake and exhaust. That'll give you a little tone and advanced install will help retain your much needed low end grunt. Again your gear and comp ratio are the most influential issues.

1969cutlazz

Great, thats what I'll go with. thanks for the help

cutlassefi

The one I mentioned is a custom grind, I don't think you'll be able to find one off the shelf. If you can find something real close go for it.

geckonz08

[quote=captjim;223621]http://www.fatherley.com/wp-content/...ton-Specs1.pdf
quote]

After looking at that site ,I had to have a beer and confirm inwardly I know "jack all" at this point