347 block prep and crank Q's

[h82crash]

Planning to build a 347 using a '90 roller block. Looking to make 400-425 hp @ 6K and do mostly street driving with an occasional autox. It won't see sustained periods over 6000 rpm. I'm not trying to cheap out but I also don't want to spend money on unnecessary grades of parts. FYI this will be in a roadster with T5 and 3.27 final.

So my questions.
I read, when using the stock block there is no need to use a forged crank as a cast crank is stronger than the stock block. True?

Also I've been told, for longevity, to 0 balance the rotating assembly. Unnecessary?

Do I need a forged crank for internal 0 balance?

What machining services will my block need? Thinking align bore, cylinder bore/hone, square deck, cam bearings, rod clearance. I guess the standard clean and inspect for flaws.

What else and what what should it all cost to prep the block?


Would like to build and assemble myself if it makes financial sense. If its close to a wash I'll go with a crate engine/short/long block.

[Gordon Levy]

1) Not true
2) 28 oz balance works really well. 0 balance really won't help longevity unless it spends all of it's time above 6000 revs.
3) see #2
4) Balance, refit the rods and check the journal, polish the crank and make sure it's round.

You will find building yourself will be in that same ballpark financially as a "crate" engine as far as cost.

[BigLeo69]

a stock ford crank will be stronger than some after-markets but the stock crank won't work for the 347

your stroking so purchase a good rotating assembly, machining of the block adds up, new parts still need to be checked
i have seen bearings in a wrapped box that were all right except one pair.
to do:magflux old block, clean thru bake/heat cycles,bore, line hone the main,could have to line bore the mains,"line hone" the cam bosses, checking deck ht,(mocking up rotating assembly and then disassembling) decking the block(piston to deck ht)cleaning again.install cam bearings balancing rotating assembly,
not part of maching but needs to be figured in: matching a cam,matching the rear-end ratio, matching a cylinder head for CR and piston clearance. theres more added to a build.oh then clean again prior to assembly.and the one thing you will be doing too is buying tools you will hardly ever use again.

i got about 8500 in the engine i hand-built thats maching costs too.it was fun

or buy a crate.............sell him one Gordon

[MJN]

Tom.

As Leo said if you enjoy the experience of building your own motor, have tools and the time then go for it.

I built my 331 and had a lot of fun doing it but at the end of the day when I added everything up I probably saved less than $500 by doing it myself and could have had a crate motor sitting in the car months before I was done with my own build. However I know what the bearing clearances are on every journal and the ring gaps on every ring, I know what the fasteners were torqued to and the gaskets that were used.

I had the machine work done locally and spent hours at the machine shop with the machinist watching and learning which was invaluable. I probably had more machine work done than was really necessary but now the engine is basically blue printed and even though for the power output and use it gets I doubt it makes much difference it makes me happy to know that I did it just as knowing that I built the roadster gives me a similar sense of satisfaction.

All in my machine work cost a little over $1,000 for the block (bore, hone, deck, square and align bore), heads (surface and seats cut), and balancing the rotating assembly.

[h82crash]

Thank you very much, guys. Good info. I already have more tools than I have room to store. I have everything needed to build a house, lay tile and brick, cut & weld, build a roadster, I could go on. I made the tools I didn't have when I rebuilt a VW engine. Not sure I want to buy any more tools. I've garage built three engines and none blew up, yea! This one I want to be sure its done right.

That said, I'm still firmly on the fence whether to build or buy.

Plus, this engine is a 6 months from now thing. Got lots of honey-do's to complete since I spent the last 9 months committed to finishing the roadster. In the mean time, I have this awesome looking FFR Roadster to drive.

[Big Blocker]

One thing about crate engines, most reputable builders will give you some sort of warranty . . . something you're not going to get with a home built.

On the other hand, you stated that you've built a few engines before with no catastrophic results so . . . I say go for it.
There's nothing like the bragging rites of "I built everything on the car, including the engine" for a great conversation starter at the local club gatherings.

Just my 2¢

Doc

[h82crash]

My decision is clear as mud.

[MJN]

Why not make up a spreadsheet with your desired engine specs and full list of components and talk to someone like Fortes who can give you a price for the parts and also the completed assembly then it's up to you to make up your mind if it's worth your time to do the assembly work yourself. Like Leo I would still do it myself

[trevor]

stock blocks are not as weak as everyone thinks. My block is stock. I am on my 3rd race season with 500 fwhp. Everything is forged inside with a 28 oz in balance. My rev limit is at 6500 where it spends most of its time.

[xsive]

I had a local race shop do the machine work, and I assembled it myself. I will admit I am a machinist, so I had the mics, bore gages, ect to double check everything. With a stroker kit, the crank and rods are better than stock, add ARP fasteners and you should be good to go. Nothing like firing up one you built yourself. If you feel confident in your abilities, go for it.

Don H

[Bob Cowan]

Cost wise, it's rarely cheaper to build it yourself. But, that only includes the initial build. If the car is purely a week end toy, and not too radical, a crate engine will last until one of you dies.

But, if you're going to beat on it, you're going to break it. That's just what happens. If you built it yourself, you can fix it yourself. Over a week end. At night. In bad weather.

As for machine work, you're essentially going to do the same procedures you would for a standard 302. Only the actual numbers will be different: bore, stroke, etc. Ring gaps, bearing clearances, etc , will be the same process. Follow the instructions included with your kit and it will work out.

The only additional step you might need would be clearancing the bottom of the cylinders for the added stroke. Most kits need that, but think I read about some that do not. Again, follow the instructions, and you'll be fine.

When I had my engine built, I wanted all new parts, including a new Dart block. So I had a pro do the initial short block assembly (Fortes). There's lots of measuring and adjusting needed during the initial build. The new block needs to be bored, decked, aligned, the cylinders need to be clearanced, etc. Get that solid foundation done by a pro, then my 10 thumbs can follow along.

Every overhaul after that I have done. It's probably not any cheaper. But I enjoy the work, and I can do it in my spare time in the winter. I check every ring gap, every bearing clearance, every side load, etc. It's meticulous and engaging work, and is a wonderful way to spend a winter evening.

Most of the actual hard parts come from the same place - Eagle rods and crank, JE pistons, etc. Probe has a good reputation for Ford kits. I know Mike and Gordon don't manufacture any of these parts

My suggestion would be to call Gordon or Mike (I called Mike), and tell them what you need. Let them build you the basic motor, as far as you want them to. You'll get exactly what you want/need, for a reasonable price, and they'll stand behind their work.

[edwardb]

I had a local engine/speed shop do the bore/hone, line bore, deck and balance on my 306. Then had them install the new rotating assembly. That way I was positive about the new bearings, rings, torques, etc. I built up the rest. I added the numbers up when done. I could have purchased a crate motor for about the same amount, but in general I have better parts in my build than similar priced crate motors and (like others have said) the satisfaction of doing it myself. I wouldn't hesitate to tear into it if there was a problem. So far (1200 miles) it runs great. BTW, while I'm pretty mechanical, my previous experience with engine overhauls was a single cylinder Honda motorcycle when I was in high school and a VW Beetle not too many years later. Just took my time, did a lot of studying, and it turned out fine. Really enjoyed doing it actually. It was a fun challenge. Not always just about the money.

[biga_93]

I have built three and have had a builder build three motors. As I get older my time is worth more than anything else. They always cost more than expected and all need to be work on more than you like.....if I wasn't so stupid I would buy a create motor next time. Especially if it was a street car. Another 2 cents worth which now a days buy much!

Sent from my ADR6400L using AutoGuide.com App

[ehodger]

Can you do the rod clearance on the block yourself or is that something else the machine shop needs to do?

[Bob Cowan]

Here's some pictures of my stock block with a 427 stroker kit installed. Noty a big deal, something you can do with a cutting bit and a drill motor. Very tedious work, though.

[Butch B]

I went with a "pro- built" short block. Was cheaper/faster than trying to do the short block myself.
hth
Butch

[2FAST4U]

Originally Posted by ehodger

Can you do the rod clearance on the block yourself or is that something else the machine shop needs to do?

I did my own clearancing. No big deal

[Gordon Levy]

Most of the kits out there now don't need to be clearanced anymore.