Block Prep 101
 

Hey all. Well I'm here once again to pick the brains of the Engine Masters. Looking for feedback on things that can be done to squeeze horsepower out of things other than heads and cams: namely the block. I've done a fair amount of work to this block so far, but I'm at a stage where I'm going to be dealing with the more tolerance sensitive areas so I want to be absolutely sure I'm on the right track. I'm including some pics of different areas of the block and would like to get some ideas on what can be done to improve them:

Start with a garden-variety '69 cast 400 block
http://memimage.cardomain.net/member...07_35_full.jpg
http://memimage.cardomain.net/member...07_36_full.jpg

Is this the area that's considered the "bulkhead?" I've heard it's good to get things smooth here
http://memimage.cardomain.net/member...07_37_full.jpg

What about in this area?
http://memimage.cardomain.net/member...07_43_full.jpg

Is there anything that should be addressed here?
http://memimage.cardomain.net/member...07_44_full.jpg

I rounded off the front return holes to have a smoother "waterfall" effect on the oil.
http://memimage.cardomain.net/member...07_46_full.jpg

Is there anything specific that could/should be done to the timing chain cove area?
http://memimage.cardomain.net/member...07_45_full.jpg

I've heard of three methods used to address these drainback holes: (1) plug them, (2) install oil restrictors, (3) install screw in "vent tubes." Of those three choices, which would be the best method to reduce windage on the cam/crank in a street engine?
http://memimage.cardomain.net/member...07_40_full.jpg

I've heard that these holes should be enlarged, but how much? How big is too big? Would quarter-size be about right?
http://memimage.cardomain.net/member...07_38_full.jpg

Are there any other areas of a block that weren't mentioned that should be addressed? Any particular methods, procedures, "no-no's" that should be taken into consideration? Just trying to make the most of what I have. Thanks in advance...

Re: Block Prep 101
 

How many hours you got into polishing that block? I've never seen anything like it!

Re: Block Prep 101
 

Jesus, how much time do you have to polish things!!!!

What casting number did that block start out as?

I'm hoping that you don't have any cracks in that block or it's going to make a nice coffee table.

http://memimage.cardomain.net/member...07_43_full.jpg

See the casting flash around the bottom of the bores at the back of the block... make sure you remove that.

http://memimage.cardomain.net/member...07_38_full.jpg

This area can be enlarged to about the size of a quarter or half dollar. You might also want to bolt on a set of heads and see how the rear oil drain back holes meet with that step near the top of that pencil.

As for the holes in the lifter valley. I plug them and just use the front and back oil returns with screens epoxied over them. I also make sure they are large enough returns so they can't get blocked off by debris.

Too bad you don't live in NC, you could always get a job deburring NASCAR blocks in your spare time. lol

Bret

Re: Block Prep 101
 

Yeah - like bret said, you need to get that block magnafluxed first, those blocks love to crack on the deck from the steam holes to the bolt hole or bore. Also in the main webbing.

Nice polish job:thumb:

I sometimes do vent tubes in the valley, most of the time I plug them, then enlarge and radius the outer drainbacks, install screens to keep broken valvetrain parts out of the bottom-end. The restrictors you are talking about are not used in the valley, those would go in the lifter feed oil galleys to restrict oil to the top end on a solid lifter application. Take the filter adapter off and clean that area out.

One of my important bottom-end prep area's is the main caps, smooth and polish the tops of the caps to get rid of stress risers as they can crack, then on the rear main, radius and polish the oil feed hole area from the pump mount surface.

Remove the front and rear oil galley plugs and brush them out real good, then tap the front ones for 1/4 pipe.

Re: Block Prep 101
 

I don't think he could stop at just deburring them! :eek:

Re: Block Prep 101
 

I've been working on this piece off and on for 2 years now. I'm a patient man. :)

The number on the rear bellhousing flange is "3951511" and the stamp on the front deck is "T0105 CGR". On the inside of the rear bellhousing cove there is a "511" with an "A" right next to it.

Good call. I think I might try rounding off those ledges so the oil doesn't have to go up an incline before it goes over the edge.

In reference to this, I was given a tip on another board. Here's the quote:

"The other area is the oil filter pressure relief valve. I would install a plug in it so all the oil gets filtered. This will ensure clean oil at all times just be sure to use a good quality filter and change it regularly."

Is this good advice or no? It sounds logical but I'm wondering what the consequences would be if something went wrong? That is, if anything could go wrong? (Murphy's Law, knock on wood...)

What circumstances/conditions would sway you to do either/or?

This is some awesome info guys. Once again, thanks for the help. :bow:

Re: Block Prep 101
 

Nice work! How did you go about polishing the block?:D

Re: Block Prep 101
 

Yes - I do a 1/4 pipe plug in the filter adapter of performance stuff.

The idea behind the vent tubes is that while keeping oil from draining onto the crank, they allow crankcase pressure to equalize:shrug: I have not seen any gains by using them over pipe plugs, it's a customers choice kinda thing, they want the nice shiny part in the valley where they will never see it.

Re: Block Prep 101
 

What did you use to do that? I can’t imagine what that took

Cold/thick oil or a plugged up filter could result in an exploding filter canister, but that shouldn’t be an issue for something that gets regular care and isn’t going to be beaten on with 50wt when it’s ice cold…

Re: Block Prep 101
 

He didnt really want advice, he wanted to show off the FREAKING AWESOME SHINE!!!;) :eek: :bow:

Re: Block Prep 101
 

Anything you can use to polish aluminum, you can use to polish iron. There's really no special trick or method involved in doing this. The only thing I can say that would differ in the case of iron is that due to the fact that it's such a dense metal, you can't really afford to skip abrasive grits like you can with aluminum. Example: a typical sanding sequence for aluminum might go 80, 120, 220, 320, etc., whereas with iron it goes more like 36, 40, 60, 80, 100, 120, 150, 180. It's just basic common sense that the further ahead you skip in the grit range, the more time and more media you're going to consume to complete the next step. This phenomenon is just about tripled with iron.

Another thing that may become a temptation for someone who is getting frustrated with slow results would be to use something like a rotary carbide burr in a die grinder to speed up the abrasion process. The catch-22 to this is that the margin for error is significantly decreased. If you look more closely at the picture of the timing chain cove area, you'll notice that it has a much wavier "funhouse mirror" finish than the other areas. This is because I used a carbide burr in that area. (Wasn't too concerned about it looking pretty, just getting smooth.) It's also much more difficult to tell where your errors are after using a carbide burr because the surface is still rough enough that it doesn't reflect light very well. So in essence, you won't find out how good or bad a job you did with it until you're much further along in the sanding process and gotten the surface smooth enough to see light reflections. For a more even and uniform surface, I highly recommend sticking strictly with sanding media. (Roloc discs, cartridge rolls.)

After 320 grit, you're pretty much stuck with having to continue with old fashioned hand sanding. I searched pretty extensively for cartridge rolls that went higher than 320 and the few companies that I found who made them all catered to the jewelry business and their bits were ridiculously priced. (Like, $2.50-$4.00 per cartridge roll.) Seeing as how I was burning through approximately 20 sanding rolls to finish one grit, I just stuck with regular sandpaper. After exhausting 360-1,200 aluminum oxide, I switched over to a special brand of sandpaper called Micromesh which ranges from 1,500 to 12,000 grit.

Buffing stage was standard protocol: tapered felt bobs with black, white, and then blue compound. I found that the tapered bobs worked better than standard spiral sewn buffing wheels because you could hold more pressure against the iron with them, which sped things up a bit.

In a nutshell: this is the only part of this thread that isn't "Advanced."

Re: Block Prep 101
 

How are you going to leave the outside of the block so it won't rust? Clearcote of some kind?

Re: Block Prep 101
 

I'm going to apply an intermediate coat that is POR-15 equivalent to seal out rust for the hot tanking/machining stage, and the final finish is gonna be done by these people:

http://www.americanpowdercoating.com/samples.htm

Re: Block Prep 101
 

That's cool. Hope it all works out for you. You know i hate to tell you this, but you can hardly see the engine block at all on a 4th gen car when it is installed, but I'm sure you're aware of that.

Re: Block Prep 101
 

2 things on the powdercoat...

1. You could have saved yourself all the time AFTER doing the 180 grit rolls with 2 coats of powder. They will even out and flow just like it's polished even on a rough casting.

2. They will probably glass bead or rouch up your finish to get rid of the polishing compound.

Go look at a spray bomb clear engine paint and try that on some spare cast iron and see how that looks for ya.

Bret