‘77 C10 hp increase

[Rich77]

Hello all,

I've got a '77 C10 "Scottsdale" w/long bed. It has a 350 4/bbl. As it's currently set up, it's a dog. It probably has 145hp. My plans are to get it in nice shape and get enough hp in it to replace the tires every other year.
My buddy, who owns a custom car shop, told me to just buy a crate motor and call it a day. I know that may be easiest, but I don't have the cash for that right now. I'd like to slowly work on this truck. I don't need to get it done any time soon.
I don't know enough, not even enough to be dangerous, except for wasting my money.
My initial thought was headers, heads, intake manifold, distributor (?), radiator, alternator, etc...
My buddy says it doesn't matter what I change it will still not have hp.

If I could find a 383 Stroker, or 355, or even a big block, to trade for I'd probably do that. But finding an appropriate trade partner is difficult.

As you can tell, I don't know squat.

So, what do I need to do to this existing 350 to rack up some hp?

 

[C10MixMaster]

A cam swap will probably give you the best bang for the buck. something like Comp cams cl12-210-2 cam kit should be mild enough to work with your stock motor and give you some more hp.. A manifold and headers will help to. Anything more you should consider doing a complete motor.

 

[Dutch Rutter]

I just got though rebuilding my sbc350. Nothing too crazy but it'll light up my 33" tires. Sounds nasty, runs and drives flawlessly. I'd say its in the 350hp + or - at the crank. And this is a k20 mind you.. so something along these lines would move a c10 pretty well.. all in all cost me $1800 total. But I did already have most of the major parts in great shape, and required little machine work.

Some will say to swap in an LS which is an option but does require know how and alot of work.

Also sounds like you need new buddies.

 

[dvdswan]

Well, depending on how tired the engine is now, I'd look for good used short block, long block or complete engine big or small. Tear it down, have it vatted and build your own. Take your time, read up on engine builds, and build what you want. Long run is you know what you have and the satisfaction of shreading tires.

 

[eskimomann209]

Or yank a vortec engine out of the Gmt400’s. slap the intake manifold to covert it to carb. I think that’s the cheapest fastest route to a really good engine. Cam it too and woooo hoo loookout

 

[Shorty81]

Maybe all your 350 needs is a good tune up and carb rebuild. A good running 350 moves a 2 wheel drive 1/2 ton truck pretty good.

 

[Rich77]

Well, a buddy gave me some heads off of a 400. Those might help??

I can also get a Xe274h flat tappet cam kit at a nice price.
Do you think that cam is too much?

 

[MikeB]

Maybe all your 350 needs is a good tune up and carb rebuild. A good running 350 moves a 2 wheel drive 1/2 ton truck pretty good.

Yes, and check the ignition advance -- not just at idle but all the way up to 3000 RPM. I won't go into details here, but there is plenty of info on the Internet.

Next up is a good exhaust system. If you don't have dual exhaust, get some price quotes or buy a kit. Back in the day I had a truck with a stock 307, single exhaust, and stock muffler. Upgrading to duals through "turbo" mufflers made the truck feel like it had gained 25% more power! And it did gain 2-3 mpg. And that was with stock 2" rams horns manifolds and 2" pipes. What you want is 2-1/4 or even 2-1/2 inch pipes. In fact, even a single exhaust system using a size or two larger pipes than your stock system + a performance muffler would make a difference. I think some vendor out there makes a "Y pipe" for squares using 2.5" head pipes into a single 3" pipe for connection to a 3" system.

Speaking of exhaust manifolds, make sure your heat riser valve works, assuming you have one. And if the truck has a catalytic converter, make sure it's not clogged.

Finally, I would NOT dump money into cam, heads, etc. unless the short block is in good shape, which means good cylinder pressure, good oil pressure, and little or no oil consumption. (Of course low cylinder pressure could mean leaking valves or valve seals.)

 

[78C10BigTen]

Or yank a vortec engine out of the Gmt400’s. slap the intake manifold to covert it to carb. I think that’s the cheapest fastest route to a really good engine. Cam it too and woooo hoo loookout

They dont have provision for a manual fuel pump do they?

 

[78C10BigTen]

Yes, and check the ignition advance -- not just at idle but all the way up to 3000 RPM. I won't go into details here, but there is plenty of info on the Internet.

Next up is a good exhaust system. If you don't have dual exhaust, get some price quotes or buy a kit. Back in the day I had a truck with a stock 307, single exhaust, and stock muffler. Upgrading to duals through "turbo" mufflers made the truck feel like it had gained 25% more power! And it did gain 2-3 mpg. And that was with stock 2" rams horns manifolds and 2" pipes. What you want is 2-1/4 or even 2-1/2 inch pipes. In fact, even a single exhaust system using a size or two larger pipes than your stock system + a performance muffler would make a difference. I think some vendor out there makes a "Y pipe" for squares using 2.5" head pipes into a single 3" pipe for connection to a 3" system.

Speaking of exhaust manifolds, make sure your heat riser valve works, assuming you have one. And if the truck has a catalytic converter, make sure it's not clogged.

Finally, I would NOT dump money into cam, heads, etc. unless the short block is in good shape, which means good cylinder pressure, good oil pressure, and little or no oil consumption. (Of course low cylinder pressure could mean leaking valves or valve seals.)

Good info! Im kinda in the same boat as him... im starting with a new distributor, wires and plugs first though.

 

[MikeB]

Good info! Im kinda in the same boat as him... im starting with a new distributor, wires and plugs first though.

Many HEI distributors have vacuum canisters that were designed to meet emission standards of old. I've seen some with as much as 20 degrees vacuum advance (to compensate for very low initial + centrifugal advance).

So if you dial in, let's say, 35 degrees total advance (initial + centrifugal) you end up with another 20 vacuum advance when cruising, causing detonation as you lightly roll on the throttle at cruising speeds. For most guys the fix is backing off on initial advance, which hurts performance. Adjustable canisters can help, but they control rate of advance, not total advance. You can also modify the limiter mechanism to reduce the pin "pull" to around 1/8". The best bet is a different canister like the one below.

NAPA Echlin #VC1838 (a.k.a. AR12) is widely regarding as a good all around performance canister because you can use it with 35 degrees total or more.

It's specs are:
Starts at 7-9" hg
Max advance at crank is 10-12 degrees at 7" hg

I'm not sure the picture is accurate, but its slot is short, limiting travel and therefore vacuum advance. The internal spring determines when it starts "coming in".

https://www.napaonline.com/en/p/ECHVC1838

Good article here with more info than I can provide, as well as specs for several more vacuum canisters.

http://www.vetteclub.org/warehouse/tech/Ignition/distributor.pdf

 

[MikeB]

They dont have provision for a manual fuel pump do they?

Some do, but not all. My truck has a 1997 "880" block with manual pump provision. It originally came with Vortec heads and, of course, EFI.

 

[eskimomann209]

Some do, but not all. My truck has a 1997 "880" block with manual pump provision. It originally came with Vortec heads and, of course, EFI.

Yep yep yep. some do some don’t. Kinda gotta look for the block off plate.
when in doubt electric pump?

 

[Matt69olds]

If the engine is mechanical sound (good compression, good oil pressure, decent leak down test) make sure the distributor is tuned right. Factory HEI were calibrated for emissions, not the best performance. Make sure the engine can breath, a good exhaust system is mandatory. Make sure the fuel pump can keep up with engine demand. Once all that is confirmed, then tear into the engine.

As cheap as cylinder heads are, I’d install aftermarket heads. Install a good cam, new timing chain, it should run pretty good. If that’s too much work, or the engine is tired, then a crate engine would probably be best.