Roller cam swap in 1991 360

[CMX360]

I have what I guess you could call a nos 1991 360. It's got zero miles and its never even been started. Now here is the problem I have. I wanted to put a comp cam in it to butch it up a bit. Stock hp is only 190. However, comp cams says I can not use the factory vavle springs. These engines have different springs for exhaust and intake as well as different lock groove locations on the valves. Plus two different types of retainers. It sounds like I'm going to have to do the whole damn engine over just to put a cam in. Is this really the case or is comp cams just trying to hose me? I figure someone on here has to have gone through the same bs with one of these pre-magnums. The engine needs to go in a car soon so any and all advice is welcome.

 

[70aarcuda]

exhaust valve have rotators on them...you need to replace them with regular retainers like the intake ...

how big of a butch cam do you want to use?

 

[Prine]

They are right. The retainer to valve guide clearance is engineered into the cylinder head. Coil bind on stock springs happens at....I dunno somebody throw out a number...... .480, which will run into valve "float" cause the spring is bound up....so lets say you just throw on some "different" springs.....still a No-Go....cause the Retainer will smash the valve seal and hit the guide at .500".

The answer is to buy some RHS heads, or....have the smog ports welded up, gasket match them Intake/Exhaust...have the guides cut down for a Chevy Style valve seal, and get a Correctly Matched set of springs for your cam (Make sure they are rated for .050" more than your max lift.) and have the seats cut/shimmed to reach the recommended installed height....and go from there.

:cheers:

I also want to note that 190hp is the factory rating for a 1988-91 LA 360, with a Holley Projection 2 squirter Fuel Injection.., through a choked down 2-1 exhaust system...The Entire Longblock should be Black..and..you should see a block off plate on the fuel pump flange......I think with a 4bbl intake, carb, headers,....a Roller 360 could realize 350 hp at the crank pretty easy....stock cam.

 

[67Baccaruda]

Prine,

Is that stock long block and cam really capable of that kind of hp, with a good intake and exhaust? A have one of these on the shelf. Your making me think about sticking it in the car.

 

[CMX360]

exhaust valve have rotators on them...you need to replace them with regular retainers like the intake ...

how big of a butch cam do you want to use?

Comp cam part # 20-612-9. They have 3 to choose from for my engine type and all need the same great deal of work done to be used it seems. Oh well. I'll just leave the stock cam and put the money into one of my earlier engines.

 

[4woody]

Prine,

Is that stock long block and cam really capable of that kind of hp, with a good intake and exhaust? A have one of these on the shelf. Your making me think about sticking it in the car.

I'm interested in the answer to this too. The stock output numbers on the Plain Jane Magnum seem so wimpy...

 

[67Baccaruda]

I was looking through some of my books. I found some specs on the 89-91 roller 360 cams. Their specs seem identical to the earlier 318 roller cams. I have listed some 1992 and up Magnum Cams for comparison

Lift Duration Installed CL
89-91 360-R .391/.391 240/240
5.2 Magnum .432/432 251/264 115
5.9 Magnum .410/.417 249/269 117
R/T .458/.467 260/264 117
R/T Plus .467/.482 272/278 119

I'm in the learning phase. Would one of these stock cams or the R/T cam, with correct springs (hughes has one similar) Wake these motors up, with out causing a coil bind problem?

The Magnums seem to have quite a bit more cam stock, and only made 230 hp.

Brian

 

[67Baccaruda]

Lunati Also has 4 hyd/roller cams

http://www.lunatipower.com/Performance-Cams.aspx

1.
Hydraulic retro fit roller, good idle. Excellent towing cam for 340-360 cubic inch engines. Good all around performance cam in 273-318 cubic inch engines throughout the RPM range. May require computer modifications for later model 5.2-5.9 liter EFI type engines.

• Advertised Duration (Int/Exh): 258/264
• Duration @ .050 (Int/Exh): 207/213
• Gross Valve Lift (Int/Exh): .485/.485
• LSA/ICL: 112/106
• Valve Lash (Int/Exh): Hyd/Hyd
• RPM Range: 1000-5000
• Includes: Cam Only

Part Number: 60710


2.
Hydraulic retro fit roller

• fair idle. Great performance cam for 340-360 cubic inch engines. Will need upgraded induction, exhaust and 3.42 or better rear gears. Will need computer modifications in later model 5.9 liter EFI type engines.
• Advertised Duration (Int/Exh): 264/270
• Duration @ .050 (Int/Exh): 213/219
• Gross Valve Lift (Int/Exh): .485/.485
• LSA/ICL: 112/106
• Valve Lash (Int/Exh): Hyd/Hyd
• RPM Range: 1200-5500
• Includes: Cam Only

Part Number: 60711


3.
Hydraulic, good idle. Excellent stock replacement cam with good economy and excellent torque and horsepower.

• Advertised Duration (Int/Exh): 272/272
• Duration @ .050 (Int/Exh): 206/206
• Gross Valve Lift (Int/Exh): .447/.447
• LSA/ICL: 114/108
• Valve Lash (Int/Exh): Hyd/Hyd
• RPM Range: idle-4800
• Includes: Cam Only

Part Number: 504A1LUN


4.
Hydraulic, fair idle. Good high performance street cam with slight lope. Works with all power accessories.

• Advertised Duration (Int/Exh): 276/284
• Duration @ .050 (Int/Exh): 210/218
• Gross Valve Lift (Int/Exh): .492/.492
• LSA/ICL: 112/106
• Valve Lash (Int/Exh): Hyd/Hyd
• RPM Range: 1200-5200
• Includes: Cam Only

Part Number: 504A2LUN

Maybe some of the more experienced guys can jump in. Without machining, would one of these cams with correct springs work, and provide a decent upgrade in performance. Might be worth a call to Lunati.