Engine Question about Upcoming Build

[Spilfner]

Hello everyone. First time poster, just recently found the forum and I’m looking forward to digging around on here!
I have a question concerning an upcoming rebuild/restore of my dad’s (now mine) 1983 K10. I’ve been googling and researching various things over the past couple weeks, so forgive me if this is a stupid question...but for some reason I can’t find an answer that satisfies me.
During this rebuild (mainly a project for fun/nostalgia), we will be pulling the engine and cleaning/repairing what is necessary. It has the 305, and was still running a few years ago before it got parked and somewhat ignored. Now, I also have access to a 350 from a 1977 C10 (pretty sure that’s the year) that I could move over and use instead.
My question is: Is there a good reason for this swap? From the numbers I find online, there isn’t much power difference between a 1977 350 and a 1983 305 (at least in trucks). I’m not really building this for power anyway, so this is more of a question of curiosity. I also see that 350 engines from that era have significantly more power in other vehicles...is that simply due to different components of the engine?
Sorry for the long post, and thanks to anyone who can share wisdom.

 

[Paladin]

There's no replacement for Displacement! Welcome to the site. We're picture Hoes here, let's see it.

 

[Shorty81]

There's no replacement for Displacement! Welcome to the site. We're picture Hoes here, let's see it.

What he said !! Welcome from the Buckeye State.

 

[PrairieDrifter]

Personally I’ll never touch a 305. Why? Because 350’s are just as easy to find and more powwaa lol. Best bang for your buck to get some horsepower out of these old smogger engines is to throw a set of aluminum heads on. The biggest downfall of our motors are the heads in my opinion.

 

[Spilfner]

Personally I’ll never touch a 305. Why? Because 350’s are just as easy to find and more powwaa lol. Best bang for your buck to get some horsepower out of these old smogger engines is to throw a set of aluminum heads on. The biggest downfall of our motors are the heads in my opinion.

I know heads are a huge upgrade. Even though it's probably not ideal, that's one of the few things I DIDN'T want to replace. Holy moly are they expensive, lol.

 

[PrairieDrifter]

I know heads are a huge upgrade. Even though it's probably not ideal, that's one of the few things I DIDN'T want to replace. Holy moly are they expensive, lol.

This is true. But realistically when you look at it, it’s your best option considering rebuilding stock heads back to stock is 600-800 dollars or so depending, and to upgrade them at all with the rebuild will cost as much as a set of aluminum heads.

Also considering the factory heads are worst part of the engine. You can bolt on anything you want on top of the heads to make it go fast but a motor can only flow as much as the heads can. And sadly the factory ones don’t do the job well lol.

And you could do vortec heads but you’ll probably be in it for the same amount of money, or close at least

 

[75gmck25]

Go with the 350 if its in good condition, since almost all the aftermarket parts are designed for the 350.

I realize heads are expensive to start out, but head flow and compression are the basis for all other upgrades. If you use a good flowing 64cc Vortec or aftermarket aluminum head you will have the flow needed for other mods. If you stick with the old heads it will put a cap on your overall performance. There is no other mod that will fix poor flowing heads.

Bruce

 

[RoryH19]

Go 350 as everyone has said. There are tons of aftermarket parts.
Also that year may have 4 bolt mains.
You could run the numbers or pull the oil pan to verify.

 

[Charlie]

 

[Doppleganger]

You must be registered for see images attach

 

[illmanners]

Brandon,

Welcome aboard and congrats on the new (to you) pickup. Here's hoping you can get a bunch of trouble-free miles out of it and have a bit of fun along the way. I'll try to answer your questions as you posed them. You've indicated that this is not going to be a "power" build so lets look at the facts as you've presented them and hopefully, you can decide from there. The stock 305 in an 83 K-10 is 165 HP model, and the 77 C-10 350, rolls out at 155 HP, so an obvious decrease in hp due to limited smog equipment and low compression on the 77 350. Given those facts, now it will depend on the miles and condition of both motors. I'd start by doing a compression test on the 305 first and then the 350 to determine which engine is in the best condition and then move on from there. If you are not going to build a hot rod and (as you said) are not looking for power, if the 305 is in good condition, it should provide you with the necessary power for your needs. If you want to upgrade, as already stated by other, the 350 is the way to go for all of the reasons already mentioned. Please bear in mind that horsepower is seldom free, so be prepared to spend some money on upgrades. A good place to start there is with a crate engine version of a 350 as long blocks are still available at under 2000 bucks and in today's economy, that's good deal for a new 350.

You also noted that there seemed to be some horsepower differences in 350's throughout the 70's, which is due to various reasons. The vehicle is was installed in from the factory was the largest factor. In most cases, a 350 installed in a passenger car was a higher HP figures than one installed in a pickup as both vehicles were designed for different purposes, plus performance 350's were available in the Camero's, Corvettes, Chevelle's and Nova's. From 145 HP all the way up to 370 depending on vehicle. Full-size Chevrolet's had similar results as well.

Here's the basics on compression test if you are not familiar with it:

Compression can be checked two ways: manually with a compression gauge or electronically with an engine analyzer. The manual gauge method is the only one available to most do-it-yourselfer's.

To check compression, all the spark plugs are removed. The ignition coil is then disabled or the high-tension lead is grounded. The throttle is also held open. The engine is then cranked for a few seconds using a remote starter switch or a helper while a compression gauge is held in a spark plug hole. The maximum compression reading is noted, then the process is repeated for each of the remaining cylinders. The individual cylinder readings are then compared to see if the results are within specs (always refer to a manual for the exact compression specs for your engine because they do vary.)

If compression is low in one or more cylinders, you can isolate the problem to the valves or rings by squirting a little 30 weight motor oil into the cylinder through the spark plug hole and repeating the compression test. The oil temporarily seals the rings. If the readings are higher the second time around, it means the rings and/or cylinder is worn. No change in the compression readings tells you the cylinder has a bad valve.

With electronic testing, a computer analyzer "estimates" compression in each of the engine's cylinders by measuring slight variations in engine cranking speed. The results correlate well with actual gauge readings and can be completed in a matter of minutes without having to remove any 1. What's more, the analyzer prints out the results of the compression test making it easy to see and compare the actual numbers.

Hope that helps and good luck..Please keep us posted.

 

[MikeB]

Regardless of the horsepower ratings, just about any 350 will have more torque over a broader RPM range than just about any 305. And torque is what moves trucks.

For not much more than it would cost to do a decent rebuild on a 350, you can get a brand new GM crate engine with a warranty from a Chevy dealer.

\https://www.ebay.com/p/16031831284?...device=c&mkcid=2&chn=ps&campaignid=1498383093

You must be registered for see images attach

Some guys make fun of this engine, but I owned a 69 C10 with one, and installed them in 3 other cars and trucks over the years. With 2-1/4" to 2-1/2" dual exhausts and a 500-600 CFM carb, it is a very nice pickup truck engine. Heck, I put one in a 55 Chevy car and the owner was surprised that it made so much power. He was looking for a smooth, torquey, reliable engine for his cruiser and got more than he expected. BTW, the engine will accept a dip stick on either side. Just read the instructions carefully.

 

[4WDKC]

Use the 350 and contact local machine shops to see if they have some heads for sale that someone never came back for, Personally I wouldnt mess with anything stock other than the alum 113 heads, TPI heads if cheap enough, vortecs are going to cost you about $600 plus you will need a special intake at this point go aftermarket and check the machine shops like I said.

 

[Frankenchevy]

Regardless of the horsepower ratings, just about any 350 will have more torque over a broader RPM range than just about any 305. And torque is what moves trucks.

For not much more than it would cost to do a decent rebuild on a 350, you can get a brand new GM crate engine with a warranty from a Chevy dealer.

\https://www.ebay.com/p/16031831284?...device=c&mkcid=2&chn=ps&campaignid=1498383093

You must be registered for see images attach

Some guys make fun of this engine, but I owned a 69 C10 with one, and installed them in 3 other cars and trucks over the years. With 2-1/4" to 2-1/2" dual exhausts and a 500-600 CFM carb, it is a very nice pickup truck engine. Heck, I put one in a 55 Chevy car and the owner was surprised that it made so much power. He was looking for a smooth, torquey, reliable engine for his cruiser and got more than he expected. BTW, the engine will accept a dip stick on either side. Just read the instructions carefully.

If you don’t mind an electric fuel pump and a different intake manifold, a brand new vortec long block is the same price.

 

[DoubleDingo]

Welcome.

350.