Dreaded.... which cam should I get question!

[bft305]

Hi I just joined i am still trying to research and learn about cams, so bear with me. I know this question is probably asked all the time, but here it goes....

I have a 1976 K20 with 6" lift 37" swamper Iroks. It has a 350/ th350/ np203 and 4.10 gears. The head gasket in my current motor is about to go and I picked up a clean stock 350 w/ tbi heads but has been converted to a carb, for not much $. I just want to bump the performance up a bit over stock with a new camshaft. It is basically open and on the stand at the moment so I thought it would be a good time to swap the cam. I am looking at the

lunati voodoo flat tappet- 10120700:

• Advertised Duration (Int/Exh): 250/256
• Duration @ .050 (Int/Exh): 207/213
• Gross Valve Lift (Int/Exh): .437/.454
• LSA/ICL: 112/108
• Valve Lash (Int/Exh): Hyd/Hyd
• RPM Range: idle-5000

Or lunati 10120701:

• Advertised Duration (Int/Exh): 256/262
• Duration @ .050 (Int/Exh): 213/219
• Gross Valve Lift (Int/Exh): .454/.468
• LSA/ICL: 112/108
• Valve Lash (Int/Exh): Hyd/Hyd
• RPM Range: 1000-5500

Which would be a good choice? I know the tbi heads the weak part here, but I am more after torque. Is the 10120701 too much lift for stock tbi heads? I would be happy if I ended up with around 250 hp/ 300 ft/lbs, but maybe that is too optimistic? I am not stuck on getting a lunati cam if someone knows one that would be better. I just read good things and it seemed to be a good match with the tbi heads. Thanks guys!

 

[Honky Kong jr]

Me personally I wouldn't use the TBI heads. Remember compression is hp. Old school double hump heads with 64cc chambers would be a good choice even if you can find a good set of CPI "Vortec" heads would bump your compression up a bit. With out decent compression a given cam would live up to it's potential. It all just has to work together. If one component isn't right it just won't work properly. It will work just not in harmony with everything else.

 

[bft305]

Ya I know the heads suck, I could swap over my other heads which are 882's I believe, but probably not worth it. Trying not to spend a lot of money on the truck at the moment. I know I should probably just do it right the first time..... any thoughts on a cam though?

 

[Honky Kong jr]

Ya I know the heads suck, I could swap over my other heads which are 882's I believe, but probably not worth it. Trying not to spend a lot of money on the truck at the moment. I know I should probably just do it right the first time..... any thoughts on a cam though?

Look at the comp. 268/454 I think it's in the magnum series. Knew a few guy who ran that cam good all around street/towing cam.

 

[bft305]

Thanks! I will take a look

 

[rich weyand]

You don't need more compression for torque. That's for horsepower.

Use the Comp Cams 12-235-2.

If you want the most torque, use the 12-300-4. That's what I use. 275 hp and 420 ftlb.

Google my last name and those cam numbers for much discussion on the forums.

 

[bft305]

Hi Rich thanks for the info!

 

[MikeB]

In what RPM range do you want to make power? And how many RPMs is the engine turning at highway speeds?

Also, have you done a compression check? How about vacuum at idle? I'd guess you should see around 20" and a fairly steady needle.

Adding a bigger cam to an otherwise stock engine MIGHT add a little performance, but it's guaranteed to do nothing unless the engine is in good shape.

 

[bft305]

My RPM range i am looking for is 800-3500. I really don't go on the highway since it is my off-road truck. The engine in it now will be pulled out. The "new" engine has about 65k on it and had no issues when pulled supposedly. It was open and I looked it over and it looked really clean. I have not done a compression test or started it yet. This is why I thought it would be the best time to add a cam.

 

[rich weyand]

My RPM range i am looking for is 800-3500....

Comp Cams 12-300-4.

 

[bft305]

Thanks for the input everyone! Looks like I am leaning towards the comp cams 12-300-4

 

[bft305]

Thanks everyone for the replys!

 

[4WDKC]

My RPM range i am looking for is 800-3500. I really don't go on the highway since it is my off-road truck. The engine in it now will be pulled out. The "new" engine has about 65k on it and had no issues when pulled supposedly. It was open and I looked it over and it looked really clean. I have not done a compression test or started it yet. This is why I thought it would be the best time to add a cam.

What are you doing with this truck? The 8-3500 RPM sounds appealing till you realise you have a 1500+ RPM converter in the truck. This gives you a 2k RPM band. My 87 is like this and its disappointing to try and do anything other than cruise at a steady speed. I know you said you dont drive the interstate but anytime you have to down shift, the truck will just get loud and go nowhere. If it were me I would opt for the first cam and use your 882s or find some TPI heads, vortec heads make good power but can run the budget high getting them ready (I have $600 in mine and the intake)TPI will reuse your intake and arent near as common to crack.

 

[bft305]

Hi 4wdkc, when you say first cam do you mean the lunati? I have not fully decided yet, thanks for the input!

 

[rich weyand]

I'm running the CC 12-300-4 with the stock 1400 RPM torque converter. The 12-300-4 runs out of breath at about 4600 rpm, so I did move the WOT shift points down about 500 rpm by going one size larger on one of the weights on the governor, which takes maybe an hour to do. That keeps it from downshifting into a higher rpm than it can deliver at. But it pulls like crazy out of the hole. The behavior of downshifting and then just making a lot of noise is due to improper shift points. Like anything else, the parts have to be set up to work together to get what you want.