Need a bit more oomph...

[7900_Blazer]

I have a 1985 K20. It appears the previous owner put in a crate 350 - likely the lowest horsepower/torque engine - it doesn't have a ton of guts. A few months ago I swap out the SM 465 for an NV4500. It has an edelbrock cab (unknown which carb).

I'm about to swap out the front clip (rusty fenders - easier to replace than fix); and having easy access to the motor, I thought I'd add something - anything to give the engine a bit more power/torque.

I've considered adding a cam but am unsure which cam to swap in. I don't really have the $'s for heads... unless I can find something 'better' but inexpensive. I've also considered adding a better intake... but unsure.

If you are so inclined, could you provide specifics - exactly which cam you ordered or which intake you've had good experience with etc...?????

Much appreciated.

 

[TotalyHucked]

Well, you need to know what you have before we can give recommendations. Find the numbers on the engine and post them up here. Also any pictures of the engine/front of the heads/intake/carb/etc. Gotta know where to start before we know where we can go.

You can't just slap a random cam in or intake on willy nilly that worked for someone else and see an improvement, the whole combination needs to be thought out so that it works well together. For example, the Texas Speed Bald Eagle cam I have in my 10.2:1 compression 5.3 would not work well at all in a 8.5:1 compression 4.8, it's wayyy too big with wayy too much overlap and duration.

 

[Ricko1966]

Biggest bang,for cheap bucks is going to be gears,cam,and headers/better exhaust. You already have a 4 barrel manifold a different one might make a little difference,but not much, camshaft you need to make a realistic decision as to how you are going to use the truck. Putting in a cam that makes more top end horsepower,usually results in a loss of low end power. Example you put in a cam that makes great horsepower from 2500 to 6000 rpm but you are geared so most of your driving is under 2500 rpm,you aren't going to be happy. Tell us what you are going to use the truck for. A toy? 4 wheeling?Pulling trailers? Just used as a passenger car?

 

[TotalyHucked]

^This.

Depending on how you use the truck, gears would be my first choice. If you have something like a 2.41/2.73/3.08, changing to a 3.55 or 3.73 would be your best bang for your buck. But again, until we know more about what you already have and how you plan to use the truck, we can't make any recommendations.

 

[Catbox]

Instead of swapping the cam, how about buying a mixed set of 1.6 / 1.5 roller rockers.
Put the 1.6 on the intake for a bit more lift and the 1.5 on the exhaust as they already flow well enough for most cams in the area of your crate engine.
In the past I have had to buy two sets, one of each and then split them.
Now you can buy a set that is already half and half.

Put them all on and set the lash, then rotate the engine by hand to make sure things are not colliding.
Most of the stock engines I have done this too have plenty of room for the extra lift, so it should not be an issue.
But it could.

The best way is to pull a head off and put some playdoh in there.
Strap the head all the way back on and rotate the engine.
Then pull the head and measure your valve to piston clearance.

The 1.6 will provide a bit more time to fill the cylinder and thus provide a little more pep in your step.

Make sure if you do this to measure your rocker stud to see if it is 3/8" or 7/16" as well as self aligning or not.

 

[SquareRoot]

That's almost exactly what I have. 85 K20 bought with a new GM crate engine. I think the lower version is 260 hp (don't quote me). It sucked for power. I added Vortec heads, PF-4 EFI, Comp Cam, NV4500, Electric Fans, headers, dual exhaust and lots of other stuff. Power is now sufficient for how I use it. Lessons learned along the way:
1. Vortec's are good for the money but I wouldn't do it again. There are better heads for similar $$$
2. Sniper TBI was nothing but a headache. If your gonna go EFI, go with true port injection and step into the modern world.
3. Comps 4x Extreme Energy cam is ok but I could have done better. Consult the pro's, they will make better decisions for you.
4. Converting from Auto to NV4500 (or 4l80) is hands down the best and most practical upgrade for these 3 speed bricks. Don't even consider a 700r4. bad
5. Headers and dual exhaust was a waste of money and space. A single exhaust (3"+) is more than a truck 350 will ever need and saves a lot of space underneath. That matters with a t-case and dual fuel tanks. Holley's new cast manifolds are 10X better than long tube rust magnets.
6. Gears- K20's are heavy. You now have 5 gears. You need 4:10 or better yet 4:56 gears. They give you the best of everything. I have used both. Depending which version of trans you have (92-94 or 95+) one is slightly better than the other. The early one will cause you to start in second gear and hit third getting thru an intersection. It gets annoying. Don't even think about a mechanical locker with a manual on the street! Bad-like worse than a 700r4 bad.
After all that and the umpteen thousands of dollars it costs I can proudly say I now get an honest 15 mpg. I'm proud of that until I get in my 21 Duramax and get 30mpg. That's a kick in the balls but hey it's about the fun factor. I couldn't own an EV and feel good inside...

When you get all that done we can talk about Vintage Air and Dakota Digital, lol.

I have a 1985 K20. It appears the previous owner put in a crate 350 - likely the lowest horsepower/torque engine - it doesn't have a ton of guts. A few months ago I swap out the SM 465 for an NV4500. It has an edelbrock cab (unknown which carb).

I'm about to swap out the front clip (rusty fenders - easier to replace than fix); and having easy access to the motor, I thought I'd add something - anything to give the engine a bit more power/torque.

I've considered adding a cam but am unsure which cam to swap in. I don't really have the $'s for heads... unless I can find something 'better' but inexpensive. I've also considered adding a better intake... but unsure.

If you are so inclined, could you provide specifics - exactly which cam you ordered or which intake you've had good experience with etc...?????

Much appreciated.

 

[1lejohn]

The heads on your crate 350 are the biggest problem. They sux. https://www.summitracing.com/parts/cca-k12-249-4
See the attached link to what I think would be a good upgrade to your truck.

 

[DoubleDingo]

I had the low-end crate 350 in two different trucks.

Mean Green (1965 C20 with sm420 and 3.54 Dana 60) I installed an edelbrock performer intake and tuned the timing for peak performance, and that truck could break land speed records.
The other truck was my dad's 1979 GMC Sierra Grande K15. It had 3.73 gears and the sm465. Tuned it similarly to Mean Green. Neither was hurting for power. Could have been better, yes, but it was sufficient for sure.

 

[7900_Blazer]

Well, you need to know what you have before we can give recommendations. Find the numbers on the engine and post them up here. Also any pictures of the engine/front of the heads/intake/carb/etc. Gotta know where to start before we know where we can go.

You can't just slap a random cam in or intake on willy nilly that worked for someone else and see an improvement, the whole combination needs to be thought out so that it works well together. For example, the Texas Speed Bald Eagle cam I have in my 10.2:1 compression 5.3 would not work well at all in a 8.5:1 compression 4.8, it's wayyy too big with wayy too much overlap and duration.

Thanks for a starting point… I’ll work on getting pics once I get back to my shop.

 

[7900_Blazer]

Biggest bang,for cheap bucks is going to be gears,cam,and headers/better exhaust. You already have a 4 barrel manifold a different one might make a little difference,but not much, camshaft you need to make a realistic decision as to how you are going to use the truck. Putting in a cam that makes more top end horsepower,usually results in a loss of low end power. Example you put in a cam that makes great horsepower from 2500 to 6000 rpm but you are geared so most of your driving is under 2500 rpm,you aren't going to be happy. Tell us what you are going to use the truck for. A toy? 4 wheeling?Pulling trailers? Just used as a passenger car?

Thanks for the feedback- The truck has 4:10’s… I would use it mostly as a daily… (I have a Duramax for any substantial towing)… most of my driving is under 2500 rpm… so lower end torque is the desire.

 

[7900_Blazer]

The heads on your crate 350 are the biggest problem. They sux. https://www.summitracing.com/parts/cca-k12-249-4
See the attached link to what I think would be a good upgrade to your truck.

Much appreciated on a cam direction… You mention that the heads are the biggest problem, thoughts on a direction for heads that won’t break my marriage?

 

[Confused]

If you don't go hydraulic roller I don't know that I would trust a flat tappet cam. Heads would certainly help. 64cc or smaller ups the compression and will wake it up even with the stock Cam. 1.6 roller tip rockers for fun.Use the added flow of new heads.

Sure a used aluminum intake (performer,action plus,etc) is an upgrade but not necessary.

How is your exhaust?Single? dual? stock muffler ? Even a stock exhaust will benefit from a long case straight through type(magnaflow,dynomax ultra flow,etc) muffler.

Have you tuned the distributor curve? HEI have notoriously slow advance curves. Don't need a ton of initial advance with a small cam but getting the curve all in by 2000 or 2500 rpm will surely help it.

 

[legopnuematic]

Contact a cam MFG, I used Howards for my 76. You provide them all of your information, vehicle weight, gears, engine compression, etc, then they will recommend one or a few cams suitable for your project/needs/desired outcome.

All four of my vehicles have flat tappet cams in them and no issues from any of them. Roller cams are nice, but they can have their own problems and if you don't have a later roller cam block, $$$.

 

[ChuckN]

Much appreciated on a cam direction… You mention that the heads are the biggest problem, thoughts on a direction for heads that won’t break my marriage?

It may be true that your heads aren’t the best, but if you’re not pulling it past 4000, your money is best spent elsewhere IMHO.

The cam selection mentioned is something I would look at myself if I was in your shoes- mild, shouldn’t result in any low end power loss and would be a noticeable improvement since I wouldn’t be surprised if the stock lift is likely less than .400- the rocker arm idea is a good one too.

Either way, make sure you run a high zinc oil for these old flat tappets- you probably already know that. Best of luck, and as always, these are just my two cents.

 

[Rusty Nail]

Meh.
I dont like complicating things unnecessarily.

I vote for 1.5" primary full-length headers and some cool mufflers with an "H"pipe.

I'd blow off everything else and focus your time, attention, and money towards that one. single. modification.
Quite frankly you will not beat that overall improvement to your truck for the money - ever.
Do it up!