Speaking to mechanic about rebuilding my 350
 

I have a really nice 1972 K5 4x4 with matching numbers 350 now at about 107k miles or more on the engine and trans. I went to see my mechanic and spoke with him about a rebuild and adding about 75-100hp over stock. I said I would consider stroking it and aluminum heads. I want to do it with the factory block and spend whatever is needed to make sure it never blows ( forged everything) top machine shop etc and preserving the matching numbers. He wants to put my motor in storage and put a stroker engine (he already built that is a deal honestly) in saying thats the only way to really protect the original matching numbers engine and add plenty of HP. I feel like he is saying what he thinks is in my best long term interest. What do you all think? What would you do if you want to add a noticeable amount of power and didnt mind spending 4-6k?

Thanks PG

Re: Speaking to mechanic about rebuilding my 350
 

Number matching really doesn't matter in these trucks. If you want to preserve the original engine, take it and put it in storage. 4-6K you could build a 406ci motor

Re: Speaking to mechanic about rebuilding my 350
 

I had the original 350 rebuilt in my k5 and added a roller cam - the block did not need to be decked so the stamped code remains intact. If you rebuild the original motor skip the decking if possible. Not many k5s have an original drive train.

Re: Speaking to mechanic about rebuilding my 350
 

I would put in an L31 Vortec - in fact, that's what I'm doing. A basic Vortec 5.7 with the HT 383 cam should get you in the neighborhood of 330 HP and 400 ft/lb of torque. It's a whole lot less than 4-6k. And in my opinion the Vortec can't be beaten for reliability.

Re: Speaking to mechanic about rebuilding my 350
 

I would pick the way that works best for you. If you have the cash/time and not concerned about price rebuild the existing and add the horsepower with original motor. The ready to go will work just be sure to store the original motor or just rebuild to stock and put in storage In case you ever want numbers matching original

Re: Speaking to mechanic about rebuilding my 350
 

Totally agree !!
Let's face it, the old engines were great 50 years ago, but they were junk. It's 2018, and if you want lots of power, fuel efficiency and excellent reliability then scrap that old 350 and put a late model fuel injected engine in it. If you still want more power, then put a single turbo on it. Other than nostalgic reasons, there zero reasons to still be using a carburetor. If you're determined to use the original block, at the very least put fuel injection with timing control on it, but IMHO rebuilding a 50 year old engine is throwing money in the wind.
The engine in my truck is a (LM7) 2003 5.3/4L60E that I got from a donor truck that I bought for $500. It had about 120K on it, and all I did was external gaskets and rebuild the transmission. Been driving it for 2 years and it runs like a top and gets the same mileage as the new trucks. With such a short wheel base, I wouldn't want any more power.

Re: Speaking to mechanic about rebuilding my 350
 

I opted for a GM Performance Crate 350/357. I got the fully dressed engine complete with intake, holley carb, and serpentine kit with alternator and AC. Complete and ready to install, brand new block and parts with zero miles, and 2-yr / 24000 mile warranty - all within your price range.

Re: Speaking to mechanic about rebuilding my 350
 

all great opinions so far..... how are you planning on using this truck, wanting more power for using in what way ? Nice sound to turn heads, tire smokin power and all the kids in the hood want to be you some day ?

How would your old transmission hold up to more power ? Every one wants more power but it requires to look at other items on the truck to support the power increase.... Just wondering. I build engines, trans, diff's, so I guess its hard to give you my wallet to spend 4-6K on just an engine... Good Luck !!!!

Oh... one more thing I wanted to add....with 50 year old technology wears out the engine over time, the introduction of OD transmissions and fuel injection makes it possible to pick up a 120K mile LS engine for cheap because the engines last longer, no longer driving the vehicle at 70 MPH turning 3000 plus RPM.... so nowadays you can have the gas mileage plus the HP with combinations of OD trans and rear gears...

Re: Speaking to mechanic about rebuilding my 350
 

My Jimmy had more mileage than that on it when my dad bought it in 1977! My original motor let go at 248k when the timing chain broke and that was 1987.

Obviously, your money your truck do what you want. But I don't think numbers matching matters at all on the trucks. There were so many made and only a few engine options that there are many available. Unlike the muscle cars that not that many were made and a rare car with the original motor DOES matter.

Midyear Corvettes (63-67) are an interesting study as the Resto-mod cars bring more money than the numbers matching restorations unless it is a SUPER rare car ala '67 L88, big tank cars, fuelies, etc.

If you don't want to deal with electronics then I think the Vortec L31 is an easy bolt in that utilizes all your existing accessories yet gets you much better heads and the hydraulic roller.

But if you are willing to jump off in EFI and wiring etc, it seems hard beat a 5.3 or 6.0 with a cam swap. But accessory drive can be a PITA and $$$$.

Re: Speaking to mechanic about rebuilding my 350
 

If you ever sell your truck, matching numbers may make a difference. It does on all the other cars from the 70's, why not the blazers?
Pull your motor, stick it under a bench or in a corner and drop in something else. You have lots of options and can do whatever you want, but that original motor will still be sitting there and not loosing any value.

Re: Speaking to mechanic about rebuilding my 350
 

Thanks everyone good things to think about I am still on the fence as to what I will do. I will report in when things happen. Thanks PG

Re: Speaking to mechanic about rebuilding my 350
 

I hope it is okay to resurrect this old thread. I am looking to rebuild the original 350 engine in my 1972 Blazer 4WD and want it to look all original when done. I prefer to use the heads, intake, carb, exhaust manifolds and valve covers as original. I know this will leave me with limited options to improve performance. I want to increase horsepower and maintain good torque. Current spec is 175HP and 290 lb-ft torque at 2400 RPM. What is the best I can hope for keeping it like I want? I'm thinking all I can do is look at the cam, lifters and pistons.

How did you build yours? Any thoughts on what I should be thinking? I appreciate any help.

Re: Speaking to mechanic about rebuilding my 350
 

Check out cam MC222135 https://www.enginepro.com/downloads/..._CamShafts.pdf

Hydraulic roller w smooth idle that will boost torque. My builder went w MC22238 and that probably wasn’t the best choice for me. I wanted to keep it simpler and boost torque but had no intention of using it as a hot rod motor. I just had a valve keeper fail and a stud partially pull so look at screw in rather than pressed in rocker arm studs.

Re: Speaking to mechanic about rebuilding my 350
 

Also consider a bore and stroke to 383 with a balanced cam / roller assembly, while maintaining that 100% stock look, will significantly increase in HP and torque.