New advice building a 350

[gabet40]

I'm finally getting back in the game, and am looking for some advice on which direction to go. I'm planning on getting another 69-72 4x4 Blazer, but don't have the space for the vehicle yet, so I'm going to begin building the engine.

- New or Used? - my assumption was that I'd buy a basic crate 350 block, then modify and build on from there. Is it wasted money to bore out a new block?
- Power is Power, right? - would I build a high performance engine different for a 4WD than I would for, say a Camaro?
Thanks!

[James the III]

Originally Posted by gabet40

I'm finally getting back in the game, and am looking for some advice on which direction to go. I'm planning on getting another 69-72 4x4 Blazer, but don't have the space for the vehicle yet, so I'm going to begin building the engine.

- New or Used? - my assumption was that I'd buy a basic crate 350 block, then modify and build on from there. Is it wasted money to bore out a new block?
- Power is Power, right? - would I build a high performance engine different for a 4WD than I would for, say a Camaro?
Thanks!

Why not start with a crate 383?

[ka_jd7and1]

Originally Posted by gabet40

- New or Used? - my assumption was that I'd buy a basic crate 350 block, then modify and build on from there. Is it wasted money to bore out a new block?

IMO, yes. No reason to spend $1600 on a crate engine, then have to pay for machine work and/or new pistons. You would be better served getting a junkyard block and building it up.

Originally Posted by gabet40

- Power is Power, right? - would I build a high performance engine different for a 4WD than I would for, say a Camaro?
Thanks!

Parts of it, yes. At a minimum, you will have a different camshaft for each of those vehicles.

[gabet40]

Originally Posted by James the III

Why not start with a crate 383?

I guess just lack of knowledge. I also like the idea of getting moderate fuel mileage from a small block when I'm not mashing on the gas pedal. I'm not 100% set on boring it out, but if I am, I guess you're right that a new 383 would be the way to go.

There are a lot of other ways to build power other than boring out/bigger block, so I guess I would just be missing out on some bottom end power to stick with a 350, right?

[gabet40]

Originally Posted by ka_jd7and1

IMO, yes. No reason to spend $1600 on a crate engine, then have to pay for machine work and/or new pistons. You would be better served getting a junkyard block and building it up.



Parts of it, yes. At a minimum, you will have a different camshaft for each of those vehicles.

Thanks, and just for my education, how do the camshafts perform differently between those two vehicles?

[ka_jd7and1]

Originally Posted by gabet40

Thanks, and just for my education, how do the camshafts perform differently between those two vehicles?

The cam will depend on what vehicle the engine is going and the purpose of the vehicle.

A low RPM 4 wheel rig vs a 7,000 RPM drag car, a heavy vs light vehicle, etc etc.

[gabet40]

That makes sense. I was afraid of that. Reason being that I trying to decide between my blazer project, or the wife's camaro project, and was hoping to put off the decision and build an engine that would fit either....

[truckster]

Originally Posted by gabet40

That makes sense. I was afraid of that. Reason being that I trying to decide between my blazer project, or the wife's camaro project, and was hoping to put off the decision and build an engine that would fit either....

You can certainly build an engine that will fit either.

I'm a fan of torque down low whether it's in my Camaro or my Blazer. I very rarely redline my Camaro. It's torque that gets vehicles moving, whether they weigh 3582 lbs. (my 79 Camaro) or 3677 lbs. (my 72 Blazer). The weight difference between the two is not terribly significant.

On the other hand, I'm more likely to tow or go off-road in the Blazer (neither will happen in the Camaro on purpose) so it's nice to have the extra grunt on the low end. But I'm more likely to do burnouts in the Camaro, so it's nice to have the extra grunt on the low end.

Unless you're racing or towing you're not going to need to build an extreme engine. And as far as boring a new block, that doesn't make any sense to me at all. If you're talking about taking a 350 block .030 over, that's only going to net you 355 cubic inches, not enough to notice any appreciable gain in torque or horsepower.

Unless you really feel like you want to build a motor (which I can understand) you can probably find a crate motor that's going to give you what you want for less money. Look at the L31 (Vortec) 350 crate engines - they're likely to be all you're going to need in a Camaro or a Blazer.

[gabet40]

Well put truckster - I appreciate your feedback, and envy your inventory.
I'm surprised how small the weight difference is. I agree on boring out the new block.

I see your point on buying the package already built, but there's a big part of me that wants to build the engine bolt by bolt - even though it probably going to cost more and be more prone to human err. Makes total sense right?

[truckster]

It makes perfect sense to me.

I would probably start with a Vortec block. That gets you the one-piece rear main seal, a roller cam' and really good heads. The ones from 1 ton vans have better exhaust valve seats.

[gabet40]

Sounds good. I feel a little more edumacated. I'll keep yall posted as I get it going.

Thanks!!

[gabet40]

https://www.summitracing.com/parts/nal-10105123

??

[Captainfab]

For a little more than twice the cost of that new bare block, you can get the same block with the rest of a long block included and a L31 engine to boot.

https://www.summitracing.com/parts/nal-12530283

I know you said that you wanted to build an engine yourself and that's fine. But IMO starting with a block like that doesn't really make sense for what you are wanting to do. My suggestion would be to search locally for a good used L31 long block or complete engine to rebuild.

[gabet40]

So here's the update. The wrecking yard down the street sold me a long block out of a 99 3/4 ton for $100. I've got quite a bit o clean up to do on it, but its 4 bolt main, 1 piece rear seal and roller cam. Plus now I have a good excuse to buy a nice Dremel kit.....
They also threw in the heads, although I'm not sure I'll even use them, nice to have em just in case.

Heres the pics

Any feedback?

[Marv D]

The 99 would be the L31 Vortec truck motor. I wouldn't be surprised to find the heads need more work than they are worth new, but just have them checked out THOUROUGHLY before spending anything on them to refurbish

So here's the thing no one has brought up. A 'NEW' casting will move around and 'settle' with heat cycles. If you bore and power hone a 'new' casting with a torque plate and put it into service,, within a couple hundred heat cycles the bores will no longer be 'perfect' round. That's why you hear about a 'seasoned' block. One that has seen thousands of heat cycles has shifted and deformed as much as it's going to . You spend $500 to bore and hone a well seasoned block with a power hone and a torque plate,, it STAYS round. Not to mention the deck of the block twisting and warping.

Obviously a ROUND cylinder will hold a ring seal better than one that has deformed. Do a meticulous build with a properly bored/honed block, proper cross-hatch for the ring material, file-fit moly faced rings with a proper gap, and you can get 2-3% leak on the engine stand, and that improve to 1% after the rings have a few seconds of conforming to the bore face.

Just saying a crate motor with all new components is usually a nice long lived engine. BUT they are normally mediocre ring seal (3+% leak after breakin isn't uncommon at all) and it can only get worse from there.

Cylinder pressure is POWER. You burn the fuel to make the cylinder pressure. The more that is leaked past poor cylinder sealing (rings or poor valve job) is power and gas given away.

All that to say,,, a seasoned casting with factory roller cam was a wise WISE choice iMO. HOWEVER,, the pictures show a buttload of rust in the cylinders. I'd get it apart and it spend some quality time at the machine shop being jet blasted, and checked to see IF it is going to be salvageable. That much rust in a cylinder wall may be a $100 paperweight. It could be the LAST hole to see the boreing bar that says what ya got

[Captainfab]

That's a decent deal as long as those rusty cylinders clean up at .030 or .040 at the most. There is nothing wrong with Vortec heads. I would have those checked out and see what sort of condition they are in. I just don't understand all this talk about rebuilding a set of used heads costing more than a brand new set. Maybe if you have to replace every valve and every seat, but even then. Around here the base cost on rebuilding a set of small block heads with a good 3 angle valve grind is ~$300.00. Parts are on top of that.

[Marv D]

I agree, IF the guides are good!
High mileage motors that has seen poor maintenance seldom fall in the 'good' guide catagory. As does motors put together with poor valve train geometry side loading the guide because of a cam swap without paying attention to what it effects. New cast iron guides will double that cost,, and that is what get's you close to $600-$650 (and replace vs repair cost).

[gabet40]

Good feedback. I appreciate it. Started taking nuts off the piston arms and one of the non rusted pistons slid right out and fell to the floor. I'm hoping that's an indication that the engine wasn't sitting long, and the rust is fairly recent and hasn't penetrated the other cylinders too much.

[garyd1961]

There may be some advantage to a seasoned block when building a motor for the track but I doubt it makes a real difference when building a street motor.
It's probably going to cost you twice as much to build that block than what you could have bought a crate engine for.