Best way to prep a short block for the machine shop?
 

I’m getting ready to drop off a short block I purchased that was running prior to me purchasing, I’ve torn it down to the basic short block/rotating assembly. It looks to be low miles since the previous rebuild and overall very clean with no wear. I’m having new forged rods installed, rotating assembly balanced, new rings, cylinders honed and the crank polished with new bearings as necessary.

The machine shop wants to assemble the short block after they do their part so what should I do to prep the block before I drop it off? I’ve asked that they hot tank it and check it before they do their part obviously. Should I pull the galley plugs prior to them getting it, freeze plugs, possibly have them replace the cam bearings with roller cam bearings? I’m trying to do any operations first so that when they’re done with it I can finish the cam, heads, etc paint it and install it in the car.

i take my blocks in bare, no reason to pay labor for them to remove crank n rod. toss your pistons n rods in the scrap if stock. cam bearings and freeze plug installation is pretty much standard procedure when a machine shop cleans/ machines a block. i myself would not spend the money on roller cam bearings in a stock block...stock bearings will do the trick just fine for stock block potential.

Pull all galley plugs, have them tap & thread the front two openings behind the timing chain for shallow pipe plugs. They will need to “fit” the cam to make sure it rotates well after the cam bearings are installed. Assuming this is a shop knowledgeable with Pontiac engines?

Post #3 got it. Basically remove all them pressed-in parts. And can review my recent activity below:

Expecting my 421+060 block back next week; bored+honed+deck-level cleanup cut, +lifter bore hone,+ washed.

Dropped-off completely bare, with primer and light paint on exterior for ease of cleaning the grit, with #1+#5 Main Caps and +060 pistons for fit.

Pick-up: i will clean oil passages, add galley plugs, add freezeplugs ( HD gray silicone on chilled plugs), cam bearing pressin, respray paint. Bag for Late Spring Assy.

Pop out the oil galley plugs and the freeze plugs.

Hopefully during the last rebuild the oil galley plug below the Dizzy got removed, if not have the shop do that.

If it’s a recent rebuild that was likely hot tanked before then as long as the oil galley passages are clear then there’s no need to either hot tank the block or bake it as some shops do to clean it.

This will save you from the cost of replacing the cam bearings which should still be fine if the Cam comes out easy.

Just spray it down at home to remove oil with some brakecleen outside.

Have the shop open up the oil pump feed hole in the block some so they can grind a taper into that passage and the the pump side will then have a lip to block some reversion pressure that’s bad to have.

If the car is Auto. Look over the flexplate carefully for signs of beginning cracks.
This way you will not waste money on having to possibly get another one after the balance job.

Also look over the freeze plugs in the end of your heads.
If they do not have a size stamped on them then they are likely still the original ones.

If so then you want to replace those end ones at least because there almost nothing more aggravating then to have to yank a head because a original rear end plug has finally rotted out .

if your gonna do the screw in galley plugs...buy the dril bit and tap and do it yourself that way you can make sure to stop the threads shallow enough to garauntee the plugs cant be tightend too much below flush. thatswhat i did on all 4 of my blocks so far.

that plug in back steve mentioned sucked azz for me. only 1 out of 4 was ever removed so it came out easy with the tool butler sells. the 2nd block i broke that tool,but bought the snap on socket and it came out....the other 2...drill bit and pipe nipple extractor...honestly this was easiest.

theres no reason not to replace this plug with drilled plug for extra oiling of the cam gear....also in my opinion its well worth the time saved to just buy the butler one they sell already drilled. in my case especially since i had a few to do i bought 5 or 6 plus some standard plugs for the front galley plugs.

If you do bring them a bare block just make sure to bring them the bearing caps. That is the one thing my shop was very happy I had for them.

Yes, the machine shop will want the main caps and the fasteners you are going to use. This would go for the head studs or bolts your going to use as well. (If they are going to hone with a deck plate). They will want to torque the main caps on and measure the housing bores. Then line hone if necessary. Then they will bore/hone with the main caps torqued in place. This will pull/push and stretch the cylinders similar to their shape when operating.

It’s my local shop that’s been building everyone’s engines for years, they aren’t specifically Pontiac although they’ve done a few for the guys in the local club so anything that I can do or remind them about is helpful. When I asked the owner how he preferred to do the work he said he’d prefer they assemble the short block vs all the parts individually which I felt was really the right way to go if that’s his preference.

Since you do not know what’s in the motor now spend the bucks for a HD oil pump driveshaft.

Also pick up a pre-drilled oil galley plug for the trans side of the block.

This kit is a cheap way to go even if you do not use the other two front of block plugs.

Also maybe consider you to deburr the block before the machine shop gets it.

Are you considering an oil cooler or remote filter? If so, I would also have the oil passages where the filter housing bolts on tapped for pipe thread. While you can bolt on an adapter at that location it is easier and reduces the chance of leaks if you thread fittings straight into the block.

My experience I like to take out all the soft,freeze plugs. Why I found on one block years ago someone just drove the old plugs inside! I like to mark 'my'block and heads with my name. Sometimes I've marked the main caps,location in the block. Yes I'd drill and tap the front plugs its simple just take your time with the tap, tap in maybe 1 turn then back out then in and back out.

This is a good idea……

LOL My shop pulled at least 6 extra plugs out of my block.

Please explain these 6 extra plugs?

There’s only a possibility of 4.

they were previous knocked in plugs!
(not pulled out then new installed)


:eek:

Ah, so where taking about knocked in freeze plugs .

I don’t know why folks have so much of a problem removing freeze plugs with the block out.

Hit them to rotate them 45 degrees and the get a small Crowbar behind them.
In 3 minutes you got the 6 of them out.

Do a neutral balance, and replace the balancer & flexplate/flywheel. It's just common sense.

Stud the mains. Heads too depending on the build level.

Personally, I would replace the valley pan, windage tray, and use an aftermarket oil pan.

Compare cost of machine work to rotating assembly to a rotating assembly stroker kit. For a few extra bux you get a stroker, and can sell the crank to further offset the cost(s). Some kits already come balanced, fyi.

What is the block and heads that are going to be used?



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I am amazed by the number of freeze plugs I find inside blocks and even heads. It just makes sense they are going to block/reroute water someplace inside there. As you said, they are generally pretty easy to remove. Every now and then is not room enough to rotate them for removal. But you have to do whatever it takes to get them all out. Also every single oil gallery plug needs to be removed. Have an aftermarket SBC in the shop right now. A "Motown" block, 5 billet steel 4-bolt main caps. It has 19 screw-in oil gallery plugs!! Makes a Pontiac with 4 seem very simple.