For a free motor - suggestions?

[TwoFiftyShifter]

My 84 K10 has the original 305. It burns and leaks oil, and I'm running a plow and 308 gears. The 305 is tired, and inadequate.

My father said I could have the spare motor in the garage. It's a 1971 400 small block. Ran when pulled from a station wagon.

My plan is to freshen up the bearings, use the Q jet from my 305 and throw some headers on there.

Sound good? I will need a standard shift flywheel as well. Hoping to not spend a fortune here.

[school boy]

think about a mild cam, the factory cam is a baby. other than that, free is free and cant beat that.

[ChevDog1]

I love 400SB's! I've built a few of them. Common problem is cracked heads. Just get a set of heads from a 350 and use the 400 head gaskets as a template to drill the steam holes. And as mentioned above, give it some cam. 400's can take much more cam than a 350 before it starts to have drive ability issues.

Good luck, and keep us all posted!

[nekkidhillbilly]

the qjet is gonna need tuned for that motor.

[Old Truck Man]

The stick flywheel for a 400 is a tricky item. The only early chevy externally balanced stick flywheel is for a 454. There where not any small block 400,s that came from the factory with a standard flywheel. A 454 flywheel will not balance on a small block 400. What we did is have a machine shop take the balance weight from the 400,s auto flywheel and install it on the stock neutral balance stick flywheel. I don't drill any holes in the heads when changing them. Instead I fill the steam holes in the block. I pack them tightly with JB weld.

[MikeB]

Externally balanced flywheels for 1985 and earlier blocks are readily available. However, the entire rotating assembly will need to be balanced, because these flywheels are generic for use with a 383 (stroked 350), and may not be even close to what 400 crank, rods, and pistons would like.

http://www.summitracing.com/search/p...lance/external

Make sure you get the right diameter for your bellhousing and starter.
The smaller diameter 153-tooth model can be used only with 10.5" clutch. The 168-tooth model can be used with 10.5" or 11" clutch. The 400's OE starter probably works only with the 168-tooth flywheel. Most aftermarket starters are drilled to work with either flywheel.

Don't go crazy on a cam. In fact, for plowing with a 3.08 axle, I'd sure stay close to stock, say no more than 194/204 duration. All a bigger cam would do is steal torque from lower RPMs to add horsepower at higher RPMs, assuming you had heads, intake, and exhaust to make it all work.

What kind of manual trans does the truck have now?

[TwoFiftyShifter]

Thanks for the input. She has the 465 tranny. Flywheel seems to be a definite snag here.

[rfmaster]

The way to guarantee a good balance take your existing 400CID flexplate and replacement flywheel, clutch and pressure plate to a machine for a balance. Provided that original flexplate provided a good balance balancing replacement flywheel and clutch is an easy job for a machine shop. Currently, there are a lot 383 applications which use 400 flywheels and harmonic balancers, so finding a suitable replacement flywheel for your 400 should not be too difficult.

Mike is correct - stay tame on the camshaft, such as CS1103R, as long as compression is stock: 8.0 to 8.5. However, if you can increase compression above 8.5 to 9.0:1 then go with slightly longer duration camshaft, but keep LSA around 112 deg for it to have decent idle. CR1014r is good choice for a bit more performance over stock.

//RF

[MikeB]

Originally Posted by TwoFiftyShifter

Flywheel seems to be a definite snag here.

If price is important, you might want to check Craigslist and eBay. You are looking for an externally balanced flywheel for a 383 built with a 2-piece main seal block.

The 86-up 350 blocks are all externally balanced, but the flywheel will not bolt up to a pre-86 crank.

Regarding your trans, if these are the ratios...

First Gear - 6.55:1
Second Gear - 3.58:1
Third Gear - 1.70:1
Fourth Gear - 1.00:1

...then even in second gear, a stock 400 will probably push your house! And the trans can handle lots of torque.