TripleBlack

Got a little question for you all and I would like to see some input on my cam shaft choice. I'm rebuilding my 350 thats going into a 6000 pound 1978 K-5 Blazer (all time 4 wheel drive).

Here it is, very simple nothing crazy:
-1978 350 SBC block
-4.030 bore (piston will be hyper.)
-3.75 stroke (cast crank...not spinning past 5500rpm)
-6" rods (cast and clearanced)
-Vortec Heads (1.94i,1.50e)
-RPM air gap
-750 cfm carb (might go to a 650, not sure yet)
-10.0:1 Compression (still working on the number but it will NOT exceed 10.5)
-The final gear might be 3.42...it hasnt broke yet so I dont know whats in the front or rear.
-Tire size are 35s

The cam i have been looking at is the following:
Basic Operating RPM Range: 2,000-6,000
Intake Duration at 050 inch Lift: 230
Exhaust Duration at 050 inch Lift: 236
Advertised Intake Duration: 268
Advertised Exhaust Duration: 274
Advertised Duration: 268 int./274 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.552 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.564 in.
Valve Lift with Factory Rocker Arm Ratio: 0.552 int./0.564 exh. lift
Lobe Separation (degrees): 110

It is in fact a solid roller....you might be able to talk me out of it. I do have one more choice that I think would be a good bump stick, but I want to see what you all think about this.

Thank you a bunch, this is the last thing I need to work out and I can start ordering parts and ripping the motor out.

TripleBlack

HERE IS THE SECOND CHOICE AND I THINK THE MAJORITY OF YOU ON HERE WILL SAY THIS IS A GOOD MATCH FOR THE HEADS. I REALLY WANT TO GET SOMETHING THAT WORKS WITH THE HEADS BUT I ALSO WANT THAT SOUND...YOU ALL KNOW WHAT I'M TALKING ABOUT. THE CAM BELOW IS A MECHANICAL FLAT TAPPET CAMSHAFT (I KNOW THERE TWO DIFFERENT BEASTS)

Basic Operating RPM Range: 1,300-5,600
Intake Duration at 050 inch Lift: 218
Exhaust Duration at 050 inch Lift: 226
Duration at 050 inch Lift: 218 int./226 exh.
Advertised Intake Duration: 262
Advertised Exhaust Duration: 270
Advertised Duration: 262 int./270 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.462 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.480 in.
Valve Lift with Factory Rocker Arm Ratio: 0.462 int./0.480 exh. lift
Lobe Separation (degrees): 111

ZONES89RS

iTrader: (25)

Of those two, i say if you are running a 2500 stall or better the first is a great choice, but if you are not the second would be better, what is the use of the vehicle???

TripleBlack

I also agree with you.

Its a 1978 Chevy k-5 Blazer (6000 #s) and I'm mostly going to be driving it to work. It's 6 miles to work form the house, 12 miles round trip. I also will be using it for towing. Majority of the time I tow 3 four wheelers on a trailer, and eventually I'll be towing the race car next year (about 2200 #s).

Thats why I think I should go with my second cam. I don't have to change the springs in those 906 heads (I'm going to stay with a 1.5 ratio rocker arm, 3/8" stud) and the vehicle is also all time 4 wheel drive (that cam is the comp cams 4X4 truck specific series).

I also like my second choice because its also cheaper. It is a flat tappet which I hope the lopes don't get ate up too much on the cam shaft for the next 3 years.

I could get a new Thumpr cam ! The overlap on them ones is unreal...but that requires all kinds of new stuff. Puts me in the 1100 dollar range just for a bad *** sounding cam shaft with the same performance.

Thank you for the input!!!

WickEdSix98

iTrader: (4)

Run Rotella T and you won't have any problems with cam lobes. Just be sure to follow the proper break-in procedures.

ZONES89RS

iTrader: (25)

Honestly, it is worth the time and money to go roller now days, it is headache free, no break in worrys and run whatever the hell oil you want. Just my 2c.

smokin2002

iTrader: (10)

If money is no issue id go for the roller. I have a cam near idntical to your 2nd choice in my 65 c10 but its a 110 Lsa {rougher than your choice of a 111} and i have to really bring the idle down to get a good lope.. to low.. 600rpm in park making **** for oil pressure.... at 850rpm its has a wee lil chop but a consistant one. it does cam cruising low speed at part throttle.. but Im a fan of crazy speratic idles lol i cant tell ya exactly how much smoother it will be 111 over 110.. but it will be smoother than my 110.

i put mine together for same reason i wanted something with some atitude pulling my race car hahaha but im reconsidering now the more money i have in my race car the more im not likeing the manua brakes the truck has!!!!

capn smokey

iTrader: (1)

Go with a roller and you will notice much better mileage and power, something along the lines of your second choice but in a hydraulic roller. A roller with a lsa of 108-110 and 230ish duration will do the job quite nicely and give a choppy idle that turns heads, good luck.