PROJECT: How would a Chevrolet dealer build a shop truck in the early 1970s?

[mattfranklin]

None of the bores show over 0.002 wear.
About half showed less than 0.001 wear.

Method: set inside micrometer for 4.032 (and later 4.031) and tried tipping it and jiggling inside the bore to see if I could make it change directions. At 4.032 I couldn't make it tip in any of the cylinders no matter how I tried. At 4.031 if I tried really hard I could make it tip in about half of the cylinders near the top of the bore.

[mattfranklin]

Just ordered a stock *forged* regrind crank kit for it from RockAuto. Maybe I can flex hone it, clean it up, and start to reassemble it over the holidays.

[mattfranklin]

Progress. Had a little time over Christmas break.

Starting to put it all back together.
Over the last several months the '72 front crossmember was cleaned and painted and installed in the '70 truck.

Torqued the cross member mounting bolts in this morning. One spec I found said the ones that go down into the frame are 90 ft-lbs and the ones that go out into the sides of the frame are 65 ft-lbs. Strange to have the identical 7/16" x 1.5" Grade 8 bolts that bolt together such similar material having such different torque specs.

Also, before the holiday break, the block was cleaned, deglazed, and painted (used the 1955 "orange-red" instead of the later 1970 appropriate "orange" because I liked how the darker color looked). Thread chasing and more cleaning today.

Also a shot of the hypereutectic pistons mounted on the resized rods and the forged crank kit from Rock Auto.

[DD1]

Nice job so far! Wish i had the patience and knowledge to rebuild my own engine. Would have saved me lots of cash.

[mattfranklin]

Originally Posted by DD1

Nice job so far! Wish i had the patience and knowledge to rebuild my own engine. Would have saved me lots of cash.

Thanks. I learn a lot from the things I read here -- including your build thread.

[mattfranklin]

Some engine progress...

I was amazed that I wore out two 7/16"-14 taps chasing out the head bolt holes. I used to think that as long as I was careful didn't break a tap they would last forever. I guess not. Now, I did use a cheaper brand of tap, "Vermont American." And the block is a high-nickel 3970010. So with better taps or a different block material they might have lasted longer.

I think one more good brushing of the bare block with hot soapy water and I'll be ready to start reassembling the short block, too.

Have not touched the heads yet.

[DD1]

Originally Posted by mattfranklin

Thanks. I learn a lot from the things I read here -- including your build thread.

Thanks! I have definitely learned a lot from this board as well. Keep on posting! Your build is interesting!

[mattfranklin]

A buddy stopped by last evening and we installed the new crank. Always better to have two sets of eyes checking things.

[mattfranklin]

Starting to push again and get a few things done. Unfortunately, brake parts vendors are sending wrong parts.

1) It looks like I got the wrong stainless line set from TheRightStuff. Supposed to get 7 pieces. Got 6. Only 2 of those work for sure, but 1 more might work. Working with them to get "the right stuff." ;-)

2) Ordered a prop valve from Inline Tube. I think that one is actually right (but we'll see).

3) Ordered bracket that holds prop valve to the master cylinder from Inline Tube. I ordered BRK08 which shows to be the right thing. Nicely gold/cad plated. UNFORTUNATELY, they double-booked that part number. And they sent me the wrong BRK08, but, hey, at least they charged me for the more expensive right one.

Murphy's Law strikes again, but we'll get through this.

EDIT: It turns out four of the tubes (of the required seven) from RightStuff.Com were correct. As soon as they send the three replacements, the tubes will all be good to go.

[RenoKeene]

Just found this thread. You are doing a very good job. I built mine with the same mindset as you, something the factory could have built within the 67-72 range. The dropped spindles didn't exist but almost everything else I used did. I kept the aftermarket stuff to a bare minimum, used mostly OEM or NOS.
Good luck with your build.

[mattfranklin]

Originally Posted by RenoKeene

Just found this thread. You are doing a very good job. I built mine with the same mindset as you, something the factory could have built within the 67-72 range. The dropped spindles didn't exist but almost everything else I used did. I kept the aftermarket stuff to a bare minimum, used mostly OEM or NOS.
Good luck with your build.

Cool truck! And thanks for the kind words.

[Boog]

Anything new?

[mattfranklin]

Originally Posted by Boog

Anything new?

Thanks for the interest and the question. I'm recovering from hernia surgery and scheming and planning my next steps.

Here's what I'm thinking about. Trying to figure out whether to to just reassemble my motor with the old heads. The engine had good compression before, but when I got the heads apart they were pretty worn. Ideally I'd get a pair of the '186 heads, the ones with the 2.02 valves and camel humps marking on the ends.

EDIT (adding more):
My budget is tight and I don't want to waste any money along the way as I search for a set of reasonably priced correct '186 heads. And I also don't have enough cash right now to splurge for the correct heads. (Remember the '186 heads are the period-correct ones for the 1970 Z-28 Camaro or LT-1 Corvette.) So, while I heal and save, I'll treat my current '624 heads as "practice heads." I won't put any expensive machine work or new parts into them (or at limit myself to parts I can swap over to the new heads). That way I can fiddle with them, install screw-in studs and guide plates using the tools from Comp Cams and not worry much about risking vintage iron while I learn.

This seems reasonable to me because it does not take very long to swap heads on a small block Chevy. I remember a time where it took me 20 minutes to strip down a dyno engine and have the heads lying on the workbench. Of course it will take a little longer to put back together.

[mattfranklin]

Just a teaser for now...
After a couple of stumbles (bought bad eBay heads and my clumsy work on machining the spring pockets for spring cups and striking water -- ugh!), I finally talked to an old-school machinist who knows these castings inside and out. He diagnosed the heads and said I'd be better off starting with heads that were less bad. He found me a beautiful set of untouched '186 heads. They are now at his machine shop getting new hardened false guides and a light grind of the seats.

Maybe pics in a couple of weeks.

[DD1]

Any updates?

[mattfranklin]

Thanks for the reminder, Darien. I should post something. Getting the heads together and on the engine. All torqued on weekend before last. Rockers installed this past weekend. Started to check push rod lengths, but checker push rod was too long. New tool should arrive this evening. Will check length and order a set.

[toolboxchev]

Love the thought process in your build. Yea those taps do not like the rust and crud they go through. I tried to blow them out with PB blasters or WD before running a chase through them.

Saw your other thread in engine and drivetrain, Its a tad bit hard to see what your looking at. I thought for some odd reason or perhaps ill advise that one would not have to anything with rocker contact when using stock parts?

I could be wrong, whats your thought on this?

[mattfranklin]

Originally Posted by toolboxchev

Love the thought process in your build. Yea those taps do not like the rust and crud they go through. I tried to blow them out with PB blasters or WD before running a chase through them.

Saw your other thread in engine and drivetrain, Its a tad bit hard to see what your looking at. I thought for some odd reason or perhaps ill advise that one would not have to anything with rocker contact when using stock parts?

I could be wrong, whats your thought on this?

Really good point. Most demonstration videos or articles I have seen use roller rockers. They *say* you can do it for stock stamped rockers (even Comp says that), but the pictures they always show are marks from rollers.

I have to use a bit of interpretation when I see the marks on the top of my valve stems. I do lots of repeats and get about the same pattern.

But there sure seems to be a big smudge with the stock style stamped steel rockers (Crane 11800-16). These are actually brand new Crane stamped rockers with stock 1.5 ratio, so I can't blame it on worn out parts. Trying to keep it in the spirit of a new stock restoration even if the original part numbers are no longer available.

[DD1]

Looks like you are making good progress. Engine rebuilding is not my strong point (or body work, or welding, or... ). Seriously, while I know my basic engine parts, I can't follow your engine work, but you seem to know what you are doing.

[mattfranklin]

Pushrods came in and I got some time. I experimented a little with an adjustable pushrod and concluded that stock length was just right.

Having been burned in the past with (Ford 390) pushrod issues I probably went overkill on quality of valvetrain parts, especially pushrods.

[mattfranklin]

Got valves lashed and headers on.

[mattfranklin]

Originally Posted by DD1

Looks like you are making good progress. Engine rebuilding is not my strong point (or body work, or welding, or... ). Seriously, while I know my basic engine parts, I can't follow your engine work, but you seem to know what you are doing.

I should have explained better. Ideally you want the rocker arm to push, on average, in the middle of the top of the valve stem. As the valve seats wear and sink the valve stem gets taller and you’d need a longer pushrod to maintain geometry. If the deck of the block or the mating surface of the head are decked or milled you’d need to compensate with shorter push rods. If the engine is old and lots stuff has been done you have no idea which way to go the cool trick is to use a dry-erase pen on top of the valve stem and color it in. Then you assemble things and rotate the engine through four revolutions or so. Then carefully disassemble and see the wear (or witness) marks of where it was contacting. If the wear mark is in the middle you are perfect. If it’s toward the intake manifold then the pushrods are too short. If the wear mark is closer to the exhaust side then the pushrods are too long. In my case I lucked out and stock length was spot on. There are some good videos on that and I think Comp Cams has a PDF of instructions for that.

[mattfranklin]

Primed the oil system *before* the intake went on just to make sure. I’ll do it again right before start up.

[mattfranklin]

I had just seen a couple of horrifying Facebook videos where something went wrong and their rockers were dry and squeaking. I wanted to make sure I wouldn’t be that guy.

I was looking to see that all of the rockers got at least a little flow from the pushrods.
They were all good.

[mattfranklin]

The PO has plugged the intake water fitting in a clever way. He cut off a lug bolt and drove it into the fitting. I put less than 100 miles on the truck before I tore down the engine, but I never saw it leak. Anyway, I just wanted to capture that bit of Roadkill genius before it went away forever.