Hello, I have a 1980 K5 with a 1993 GM factory replacement engine. it doesn't have the power I think it should. I did a compression test on each cylinder, and they all have 120-122 PSI. not the best, but it does run well, just lacks power. I put some oil in one of the cylinders and the PSI came up to 140-145 PSI. much closer to a strong engine. I know the rings are getting worn. I plan to pull the engine, get some better heads, put a "RV" cam and now will re-ring and change out the bearings. I am going to check for ****s and giggles the gear ratio? It may be a combo of a weaker engine, and high gears. I will document the progression here. the engine that in it is a 4 bolts main, solid 350, so I have a great starting point. picture for reference... and who doesn't like pictures of a square body blazer!!!

 

Yes, be sure top keep us posted. It'll be interesting to follow along!

 

The "Oil In The Cylinders Test" says the engine's tired. It appears to me (I'm making an extension in logic here) that it's not an individual or pair of cylinders as you reported they are all pretty close and came up rather equally from dry to oiled.

With that last line, I double-down on a tired engine.

What size are those tires? They look like 37s --- no? That can contribute to a bad seat-of-the-pants feeling of a weak engine, especially coupled with stock gears.

If your stock gears are now what mine were/are yet, I have 3.07:1 and with 245/75R17 tires, and I am happy.

I stroked a 350 to 383 -- and generally think it was a waste of time and money if I wasn't going to add headers (I didn't) or install pop-up pistons (I didn't) or put in a really serious lope-stick (I didn't do that either).My story may not be the same as yours, but I did a triple-angle valve job (I do not believe in any less than 3-angles to get the contact position and width correct) - added sodium cored valves (exhausts only) and went to oval (1.77:1") rockers for a larger ratio.

Add on a new Rochester Q-Jet
on a Weiand Low-Plane Street Torquer manifold
and HEI
and Cloyes chain and gears, etc,
a Melling HP oil pump,
Jahns Teflon-button pinned Eutectic pistons -
Crower 3/4 cam (3/4 means it runs optimally on a 3/4 mile dirt track -It pulls my firewood trailers well, hauls full-length trees for 1/2 mile or so out of the woods climbing over previously-made stumps, rocks, etc. I recently changed my Gov-Lok in the rear differential for an Eaton 912A556 Detroit Truetrac 8.5" - staying with my 3.07:1 gears.I have decided if --- in the future --- I need to rebuild this engine --- I'll likely go with a Crate Vortec 5.3. Those 5.3s make a lot of serious horses and there's years to go for parts for them, unlike the SBCs currently in our trucks (mine's a 1986).

 

I have 33's on it. I am going to check the gears before doing anything drastic. good info on all that you have done. I just want a good running strong blazer. good looking rig you have there. I totally agree on the Vortex engine swap. they are perfect for what I want, I just don't know if I want to do that yet.

 

IMO --- if I had the time and the druthers, I'd for sure go FI if you somehow stick with a SB from the '80s.

Not too sure I like the Holley system though.

Stay with the stock gears for now and I'd dump the 33s --- I had them and they'd sure-as-hell get me stuck a lot!

Now I'm running 245/75R16 LT and I won't ever go back to big fats at all.

I would not re-ring and re-piston any engine --- it's a lot of work, cost and really if you don't at least bore it a bit to clean up and make them round again, it's a waste of patience and reliability too; you don't need an oil-pumper at this time.

Be moderate on cam choices --- no matter how much you like loping engines, because they need to get "on the pipe" we used to say and that means lots of gas and a fussy throttle that makes you keep the engine boiling to get any performance below 10,000 RPM --- understand?

3.07s are good for most work --- I seldom use 4L - but it's there and that's a radical gear change if you follow that logic.

What I shot for, and basically GOT, was a good street-able D/D with good gas consumption and in 4L I can still climb walls.

You do you, though --- we live or die by our choices --- not that you might actually die --- but regrets, we all have.

Go slow and make it a project over a longer period of time so you can savor and enjoy the individual things you do --- so you can say: "That was fun".




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"I would not re-ring and re-piston any engine --- it's a lot of work, cost and really if you don't at least bore it a bit to clean up and make them round again, it's a waste of patience and reliability too; you don't need an oil-pumper at this time.

Be moderate on cam choices --- no matter how much you like loping engines, because they need to get "on the pipe" we used to say and that means lots of gas and a fussy throttle that makes you keep the engine boiling to get any performance below 10,000 RPM --- understand? "

I like working on engines, it is a lot of work for sure. if I went that route, I would send it to a machine shop and get it cleaned up for sure.

Oh, I am not going to go crazy on the CAM, I know what you are talking about. I have a 70 Nova that I built a crazy 396 (.060 over) engine with all the goodies. I want a nice running well powered K5, that occasionally, if I want to burn rubber I can

Thank you for the input.

 

I had a buddy with an 85 K5 Blazer and he stuck 1 ton military front and rear axles in it, a 505-ci Chevy BB with a moderate cam and twin turbos, running 15# on the street.

There's a severely updated THM400 and I forget which transfer case he uses, but it has just 2WD and 4WD options.

He can light up all 4 for over 1/4 mile on the street.

Yeah --- he's nutz!




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sounds very stout!

 

.... and scary! I watched it pull onto a freeway, and the acceleration was intense!

After the smoke cleared, there was a lot of new tire rubber on the road.

He's crazy ,,, cap "C".

 

I don't need that in my K5... LOL