Author Topic: ‘80 K10 Cam Help.  (Read 2115 times)

Offline ArtO89

  • Newbie
  • Posts: 5
  • Newbie
‘80 K10 Cam Help.
« on: May 27, 2018, 09:41:38 PM »
Hello everyone I am new to the site and to the project world, I just bought a 1980 Chevy K10 long bed and have a few things in mind that I would like to do, I pulled the engine last week and turned out to be vin matching 350 4 bolt main. When I bought the truck the engine was missing intake/ valve covers and when I drained the pan it was fool of coolant so decided to take it to the machine shop to start fresh, I am currently stuck on which cam to go with for my build I’ve done plenty of research and it’s still a bit confusing or I may be over thinking it, I plan to do a 4” lift with 33s or possibly 35s it currently has a TH350 transmission and have not identified the transfer case, this will be a weekend driver and would like the truck to be able to spin the 33s or 35s easily. I plan to go with a set of vortec heads from Scoggin-Dickey because I hear the vortec heads will add good horse power/ torque for the price. I’ve read I may have to upgrade the gears in the rear as well so I’m trying to do my research on that as well. What cam do you all recommend for this set up? I greatly appreciate any input, will post pics once I figure out how to.

Offline ArtO89

  • Newbie
  • Posts: 5
  • Newbie
Re: ‘80 K10 Cam Help.
« Reply #1 on: May 27, 2018, 09:51:20 PM »

Offline ArtO89

  • Newbie
  • Posts: 5
  • Newbie
Re: ‘80 K10 Cam Help.
« Reply #2 on: May 27, 2018, 10:12:44 PM »
This is what the engine looked like when I bought the truck.

Offline 75gmck25

  • Frequent Member
  • **
  • Posts: 439
  • 1975 GMC K25 Camper Special, 350/TH350/NP203
Re: ‘80 K10 Cam Help.
« Reply #3 on: May 28, 2018, 07:04:06 AM »
The Vortec head swap is a great idea, since the stock heads really suck.  It will give you better flowing heads, and about one more point of compression.  More folks should start out with a head swap, since its hard to get anything good out of the stock smog-era heads.  You might also want to take a look at this Engine Masters episode on Youtube to get an idea of where you should be headed. https://www.youtube.com/watch?v=f7mvgf6_p1g&t=829s

Do you know the stock gear ratio in the truck?   With an unmodified TH350 (stock stall converter) and 33s or 35s, you really need at least 4.10 gears.  These were common on 3/4 ton trucks, but 1/2 tons often had higher gears (3.07, 3.42, etc.).  Finding a donor truck with the right ratio and swapping both axles is often the simplest choice.  If you are willing to swap torque converters, a higher stall converter (2500-2800 rpm, etc.) would get your RPM up faster and give you more on the low end as it kicks in.

When you compare cams, don't be confused by articles where the engine is going into a Camaro or other vehicle that is much lighter than your truck, or into a car that has a 4 speed (where you can rev it up and drop the clutch).  You want more power, but don't want to kill your low end torque.  With your Vortec heads, a cam in the range of 214-218 @ .050 is usually a good choice, and should make up to about 325-330 HP if you also use long tube headers, full duals, and a good carburetor.  Many vendors refer to this as an RV cam.  You could use more cam (e.g. 225-230 duration @.050) and get more total horsepower, but would probably lose some of the low end torque you need. 

Make sure you check the total lift on any cam you buy, to ensure it will work with the Vortec heads.  Scoggin-Dickey heads may have been reworked to allow for more lift, but stock Vortec heads can only handle about .450 lift before springs bind.

Bruce

Offline bd

  • Global Moderator
  • Senior Member
  • *****
  • Posts: 6438
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline ArtO89

  • Newbie
  • Posts: 5
  • Newbie
Re: ‘80 K10 Cam Help.
« Reply #5 on: May 28, 2018, 02:42:04 PM »
Thanks for the info 75gmc, and bd good stuff too. Also I am probably going to go with the Edelbrock performer rpm as my intake and I am currently looking at this kit for the cam https://www.jegs.com/i/COMP-Cams/249/SK12-210-2/10002/-1. These are the heads I plan to go with https://sdparts.com/i-23901396-sdpc-sd8060a2-vortec-sb-chevrolet-cylinder-head-with-0-525-valve-spring-upgrade.html will these work with one another and how do I go about on selecting lifter rods and the rocker arms?

Offline Mario

  • Newbie
  • Posts: 60
  • Newbie
Re: ‘80 K10 Cam Help.
« Reply #6 on: May 29, 2018, 10:00:39 AM »
I like to run a 6" connecting rod to increase piston dwell near TDC.  I prefer competition cams, and roller lifters because the cam profiles are better.  Also, set the cam timing to 4 degrees advanced (with respect to the crankshaft).  For trucks it helps tremendously!  You'll need a pair of adjustable pushrods from Competition Cams to establish the correct length that you need.  They'll have the instructions that you need to follow.
Mario
Santa Cruz, NM
1972 C10 4x4 350 350TH NP205
1981 K20 355 NV4500 NP208 GM14SF GM10
2005 3500 Duramax Allison 5spd