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Old 08-11-2017, 12:06 PM   #1
rally
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350 build - where do I start?

I have a 350 currently in my 69 C10. It's a 14088548 block with 462624 cylinder heads. Apparently, the heads are not the best and the stock block is nothing to write home about either. I have an edelbrock 1406 carb on an edelbrock performer intake. The engine is paired with a th350 transmission and 3.10 gears on the back. Because of the rear 20" tires, according to what I've been able to research, the gears are effectively 2.90. This is definitely setup for cruising and I'd like to get more power out of it, but still maintain relatively decent MPG. I don't take the truck out very much but when I do I'm usually commuting on the freeway.

I bought Engine Analyzer to hopefully plan out a build before i start buying parts, but i ended up with more questions than answers. It seems the combos i enter into the program dont produce much more torque or horsepower, and i usually get warnings saying my rpms will be high and theres spark knock, among other things.

Where do I start with building an engine? I'm not an engine guy but I am not unfamiliar with turning a wrench. This would be my first build, and I don't know how to plan a build and figure out what parts work with others. Any advice other than the obvious reading?
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Old 08-11-2017, 12:42 PM   #2
68gmsee
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Re: 350 build - where do I start?

That rear axle ratio definitely does seem tall. I used to have a 3.08 rear ratio in my 69 with a th350 and it did fine for my purpose. In your case I agree that it's great for cruising at freeway speeds but if you want more pulling power I'd definitely would be looking for another rear axle ratio.

One more thing, I doubt you will get good gas mileage with these trucks unless you completely change to computerized fuel injection. Even then, it may gain you just a few more but nothing to brag about.
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Old 08-11-2017, 03:56 PM   #3
rally
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Re: 350 build - where do I start?

Quote:
Originally Posted by 68gmsee View Post
That rear axle ratio definitely does seem tall. I used to have a 3.08 rear ratio in my 69 with a th350 and it did fine for my purpose. In your case I agree that it's great for cruising at freeway speeds but if you want more pulling power I'd definitely would be looking for another rear axle ratio.

One more thing, I doubt you will get good gas mileage with these trucks unless you completely change to computerized fuel injection. Even then, it may gain you just a few more but nothing to brag about.
Thanks for the reply. I'm pretty sure you're right about the gas mileage. I tossed around the idea of going fuel injected, but I kind of feel like I should keep it simple for now. I don't take it out very often so I guess MPG isn't too important.

But where should I start when building the engine? I figure I'd keep the stock block and build on it. It sounds like the heads are prone to cracking when I looked up that casting number. Can I just buy any set of heads from a vendor and throw it on the block (assuming they're made for a 350)? Or what should I be looking for?

How can I tell a head/block/camshaft combo works together before buying them?
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Old 08-11-2017, 03:57 PM   #4
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Re: 350 build - where do I start?

One thought is to swap in a 700r4 transmission and either 3.42 or 3.73 or closest equivalent gears for your axle. Would give a bit more pep at low speeds and still keep the cruising ability at highways speeds.

What's your current mpg?

This posting has a wealth of info: http://67-72chevytrucks.com/vboard/s...d.php?t=736001
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Old 08-12-2017, 10:57 AM   #5
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Re: 350 build - where do I start?

Awesome, thanks for the links!

I calculated around 10 MPG with 100 miles round trip when I commute. About 90 of those miles is freeway.

I was thinking 3.73 with 700R4, too. But someone who owned the truck before me powder coated the frame, so I think to move the crossmember back I'm going to either have to remove the powder coat around the new crossmember location? Or have a gap where the crossmember used to be. If I can go with the 700R4, I would love to go that route. I haven't had much luck finding any, though, and wouldn't know how to tell if it's still good if I found one.
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Old 08-12-2017, 11:03 AM   #6
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Re: 350 build - where do I start?

Re. where to start.. If this is a learning experience for you, first buy a SBC rebuilding book. There are several in the market that basically start you from scratch.

After you get an idea of the process, just dive in. As an old mechanic once told me, "nobody is born learnt." In other words everyone has to start somewhere.

Don't buy parts yet. The next step is to dismantle the engine to see what you have. Take it out of the truck if it's still in there, remove the intake and exhaust manifolds and heads so you can see the condition of the cylinders. From there you'll have to follow the procedures to completely disassemble the block for machine work.

Also, keep in mind that if you intend to use parts again, be sure and label them so they can be installed in the same place again: pistons and rod bearing caps, crankshaft bearing caps and even the lifters and push rods. They should all be carefully labeled.

There's a lot more to it but this should give you an idea of the work involved. Cost? Depending on what you wind up having to buy (parts, tools, all bolts, etc.) It may be over $1K and even closer to $2K. Keep in mind that a GM crate motor will cost around the same.
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Old 08-12-2017, 12:49 PM   #7
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Re: 350 build - where do I start?

If you have a real desire to rebuild your engine, I agree with 68gmsee that your first task is to disassemble the engine and see what condition everything is in. Unless you're experienced and have the right tools, you'll need to take it to a machine shop to have everything checked. Once you know what's usable and what machine work you need you can start planning for parts and cost.

You may find that a crate engine is a better deal for you. All new parts and a warranty to boot. Unless you're dead-set on going all original, I have a fondness for the L31 Vortec crate engine. You can get one for around $2k. You'll get a roller cam, one-piece rear main seal, and the best heads Chevy ever put on a small block. If you go that way, you'll need a new intake. a mellonized gear for your distributor, an electric fuel pump, and a flywheel or flex plate with the 1-piece seal pattern.
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Old 08-15-2017, 05:37 PM   #8
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Re: 350 build - where do I start?

EDIT: I should add that all of the above advice here is great.

In a previous job I was a (not kidding) Decision Analyst. My job was to analyze investment decisions for a global energy company.

So my first question for you is... What is important to you? Or stakeholders, like spouse, whose support it will likely take to be successful?

1) If I had to guess I'd say most guys probably want reliability, performance, cool looks, fuel economy, all within a budget.

2) Or you might want power and be willing to sacrifice the others in pursuit of sub-11-sec drag times.

3) Or you might just want awesome looks and sound of a 350 with a 6-71 blower and open headers. And no hood.

Once you know that you can test all of your decision options against it. In other words, when I compare two different options, which one gets me more of what I want (power, reliability, economy, looks)?

In my case (still in progress) I wanted to go simple old-school, mostly follow the GM factory speed parts list available from '67-'72. That means my motor will be a clone of a Z-28 Camaro or LT-1 Corvette. Which makes it hard and tempting to veer from the path, because there are some really good cylinder head options (from Summit, and Dart, and others including the GM Vortec heads) to replace my crack-prone '624 heads (yep, I have the same ones as you). I want to get the best of the GM parts bin for that time frame so I'm stuck with the '186 Z-28/LT-1 heads. And I'm likely paying a $800-$1000 over what I'd pay for other pair of decent functional heads. But that's just me. Everyone has different preferences.

And this list of what is important to you shouldn't be taken lightly. You need to think about what you really want and weigh your options and test your priorities.

If I can offer the voice of experience, I'd encourage you to stick with something close to stock with your first engine. Something that you can find tune-up specs for or get parts for an any NAPA, or Car Quest, or O'Reilly's along the road. This recommendation is based on a '72 Ford F250 project I did several years ago. I went too wild with it and the 390 FE valve-train wound up being really temperamental and not fun.
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(Very) Slow-Going Build Thread: Stock 1970 Short Step with Stock 1970 LT-1

http://67-72chevytrucks.com/vboard/s...d.php?t=567340

Last edited by mattfranklin; 08-16-2017 at 12:46 PM.
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Old 08-16-2017, 02:15 PM   #9
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Re: 350 build - where do I start?

personally... I just started shopping for stuff and went from there.

For example. Cylinder heads - different: runner volumes, combustion chamber vol., aluminium or iron, etc... you have all these options and I just ended up researching out said options and decided what direction I needed to go. After months of obsessing about different combinations... I'll probably just go with the edelbrock RPM power package ;-)

I have a local machine shop who also does dyno work, I chatted with hom for over an hour about what direction to go. Another option to get an idea of what combination you go with.
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Old 08-16-2017, 04:37 PM   #10
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Re: 350 build - where do I start?

Is the truck driveable now? Would you want to consider keeping it driveable while you built the engine?

Are you open to putting a Vortec engine into it or would you want to stick with something closer to your original model year? Car Craft had a super economical buildup on a Vortec -- less than $500 to $1000 depending on what spare parts you had around. http://www.hotrod.com/articles/how-t...l-block-chevy/

~300 reliable horsepower on the dyno. If I were not following my "period-correct" vintage theme I'd be considering that.

BTW, there is a great book by David Vizard on rebuilding an old small block Chevy.
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(Very) Slow-Going Build Thread: Stock 1970 Short Step with Stock 1970 LT-1

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Last edited by mattfranklin; 08-16-2017 at 05:06 PM.
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