Moparts

Block questions- deck surface and square specs street/strip

Posted By: radar

Block questions- deck surface and square specs street/strip - 08/18/18 11:28 AM

Howdy!

My local machine shop is not the fastest but their work always checks out good and I trust them. I just got done waiting for my third go-around there with the 512 I’m building. The block has been checked out, bored, and honed.

I figured I’d mock up and measure everything then take it back to the machine shop for one more few week wait. The problem is that everything I mock up or measure keeps coming right into spec where I want it. This is a new experience for me- the small blocks I built all needed a lot of work.

So I’m considering building this thing. The only thing I am not sure about is the deck/head gasket situation. Three out of four corners the pistons are .003 below deck. The #8 deck is .004 thicker. As far as quench goes I’m happy with .043”-.047” on the even holes and all at .043 straight across the driver’s side deck.

Obviously it’s not perfect but I was surprised how close it is to square and zero deck. The block has a shot peened finish which is something that I haven’t worked with before. The decks are nice and flat even with one .004 out of square on the even side. I plan to run aluminum stealths on 1009 felpros with 10.25:1 compression.

For a hot street motor am I good to screw this thing together? Or is my surface finish too rough or deck too far out of spec?

What do you think?
Posted By: sgcuda

Re: Block questions- deck surface and square specs street/strip - 08/18/18 12:52 PM

The problem is that in order to clean it up, you will end up with less than .043" on the even deck. It will have to be skimmed from one end to the other, so you might end up .040"-ish on that side, unless you clean both sides evenly. For a street motor, I think I would leave it and start building it. For Felpro gaskets, your surface finish is probably fine. If you were using an MLS type gasket, I might take a closer look.
Posted By: CSK

Re: Block questions- deck surface and square specs street/strip - 08/18/18 03:57 PM

I would NOT use 1009 gasket, they can have an issue, the fire ring hanging into the combustion chamber, check that VERY close, I would use Cometic
Posted By: merpar

Re: Block questions- deck surface and square specs street/strip - 08/18/18 04:17 PM

I would go with the felpro 1009's. I've used them for years and never had a problem. Even on 12.5:1 comp. Used Cometic once and had water leaks with very good surface finishes. Guess we all have different opinions and experiences. The felpros will work. And for a 10.25:1 motor .004 won't matter at all. These aren't facts, just my opinion.
Posted By: 4406bbl

Re: Block questions- deck surface and square specs street/strip - 08/18/18 04:29 PM

X2 on the 1009. Figure out your head gasket then decide on how much to deck it. I would shoot for .040 piston to head and use a cometic gasket with bigger bore size than 1009. Maybe use a .051 cometic and mill block about .014.
Posted By: 4406bbl

Re: Block questions- deck surface and square specs street/strip - 08/18/18 04:33 PM

1009 is a great gasket on most blocks, some have issues with overhang.
Posted By: 65Fury440

Re: Block questions- deck surface and square specs street/strip - 08/18/18 05:40 PM

My block had too much overhang for the 1099.
I used these.
https://www.summitracing.com/parts/fel-1...IhoCY9wQAvD_BwE
Posted By: 4406bbl

Re: Block questions- deck surface and square specs street/strip - 08/18/18 05:47 PM

Will thise work with aluminum heads? There is also a 1039 big bore wire ring .051 thick felpro that should work. You would want to mill block to hit.040.
Posted By: radar

Re: Block questions- deck surface and square specs street/strip - 08/18/18 07:41 PM

Thanks for all the thoughts. How cool is it to stay up late blueprinting and have this community to bounce questions off of- with a batch of well informed suggestions waiting to read by lunch the next day?!

I will check the fire ring on the 1009. I had a radical shovelhead harley with heads that were difficult to seal with blue felpros- cometic mls or straight soft copper was the answer but I have had good luck with .040 felpros on aluminum head smallblocks and steel shims on iron head rebuilds.

I never had a block shot peened before- this 400 block had about three gallons of hemi orange spraypaint on it so my machine shop said peening was the way to go to get it clean. The block is impressive looking like a new casting but the surface is definitely rough compared to a fresh cut deck- more like as cast type finish.

If the 1009 hangs over I will look into a cut and a thicker gasket to get me back to .040 but for a street motor the temptation to screw it together is pretty compelling. Of course I don’t want to leave power on the table or have nagging doubts about shortcuts but for the street I will probably have room to really let a 512 eat almost never so I don’t want to get bogged down if I can be driving.

Thanks fellas
Posted By: radar

Re: Block questions- deck surface and square specs street/strip - 08/19/18 06:55 PM

The head gasket doesn’t overhang the bore in the block or the head’s combustion chamber. The rods all checked out good on both ends- bearings and bushings. The source kit doesn’t need any whittling on the oil pickup boss- #1 rod and cap screw clear by a mile.

Looks like the mockup phase of this engine build is about done. It’s crazy I think I had around $6000 in my last 408 LA build. This motor is coming in at more like $4000 and should make more power at lower rpm!

Big blocks are awesome.
Posted By: 4406bbl

Re: Block questions- deck surface and square specs street/strip - 08/19/18 07:30 PM

If no overhang then I would run them. Hard to beat big blocks with $1000 heads with a smallblock thats cheap. What rocker gear pushrods and intake are you running to come in that cheap? Heads cost to much to get to 600 hp with a small block. But a 408 with iron ported late w-2 heads, cheap, would do you in for 5 grand. and the mains will stay in the block. Just having fun with you.
Posted By: BSB67

Re: Block questions- deck surface and square specs street/strip - 08/19/18 08:02 PM

If you're going through this effort, why not square deck the block, and then see what you have?

Give your machinist the deck numbers for all 8 holes and tell him you want zero deck, the best he can.

Sounds like either the even side deck is machined on an angle, or #8 rod is shorter. What are #6 and #4 hole numbers?
Posted By: 4406bbl

Re: Block questions- deck surface and square specs street/strip - 08/19/18 08:46 PM

The last untouched 69 block I did was that way, 1 side perfect, other .001 low in front, .004 high in back. I used same rod and piston in each hole, wrote my measurements in valley and had it milled. All .001 in hole when done, started .017 or more. I was also going to leave it but wanted that .040 quench for the closed chamber heads. If I get around to it mocking another 1970 today, be interesting to see where its at. Its a winter project but with machine shop wait may take that long...
Posted By: 4406bbl

Re: Block questions- deck surface and square specs street/strip - 08/19/18 08:50 PM

I might add, machinist said the deck was also off angle wise the other direction also a little. Other side was fine.
Posted By: 4406bbl

Re: Block questions- deck surface and square specs street/strip - 08/20/18 02:35 AM

1970 hp block it is from my 6bbl car, numbers block. Both front cylinders are .016 in the hole, both rears are .017 in the hole. Never milled. An .024ish head gasket would mean no milling. 1009 will not work on this block, has chamfer, the non hp 69 was fine with 1009 same.030 over bore and pistons. So it is real hit and miss.
Posted By: radar

Re: Block questions- deck surface and square specs street/strip - 08/20/18 03:38 AM

It was the same rod and piston measured in all 4 corners when I measured deck height. The compression ratio will decrease on the even cylinders (2,4,6,8) from 10.16 to 10.09, so seven hundreths of a point. I decided I’m willing to deal with it and I’m sure I won’t notice any lost horsepower on the street. Quench will still be in a healthy .042-.046” range with a .039 gasket which should combine with just 10.1static CR for a good pump gas motor.

But yeah if I was only building a motor and not getting stretched thin building a hotrod to put it in I would be decking .013 on the driver side, matching it on the passenger side, and shopping for a .050 gasket. I’m also a little greedy for time because I don’t have a mock up block and still have to fabricate motor and trans mounts and build a floor firewall and trans tunnel.

Radar
Posted By: wyrmrider

Re: Block questions- deck surface and square specs street/strip - 08/21/18 08:09 PM

X2 on the surface advice if cometics- will not hurt with felpro
consider the .028 gaskets if it save some milling
I'd run .030 total quench depending if tight fitting piston with some skirt
else .035 for looser forged piston .040 max
I had a big chamfer- ended up with the pistons out .015 and ran a .050+ marine gasket (Victor or McCord I forget) did have a stainless center
915 heads - D Dish milled in 6 pack pistons- old school
Posted By: moper

Re: Block questions- deck surface and square specs street/strip - 08/22/18 12:20 AM

Originally Posted By radar

I never had a block shot peened before- this 400 block had about three gallons of hemi orange spraypaint on it so my machine shop said peening was the way to go to get it clean. The block is impressive looking like a new casting but the surface is definitely rough compared to a fresh cut deck- more like as cast type finish.


SO - the decks were not cut after the airless shot cabinet? Did they protect the main bores and lifter bores?
Posted By: radar

Re: Block questions- deck surface and square specs street/strip - 08/27/18 07:17 PM

Howdy

Delayed response- I went camping for a week with my family. World’s End state park in northern PA is awesome but there is no cell service for miles which is also kind of awesome.

The pistons are forged and set with 5 thou clearance to the bores per mfg spec. They are pretty short for the 400/512 stroker. I would be nervous about running a super tight quench but I’ve only built a handful of v8 motors with quench. On paper I am super happy with how my motor is measuring out. I think 10.2 compression, .044 quench, with aluminum heads and a mild flat tappet should help steer me away from ragged edge tuning nightmares on the street.

The last motor I built was a 318 for my ramcharger. I did a stock shortblock, fresh top end, headers, RV cam, aluminum dual plane, and a four barrel with msd ignition. Kind of like a home brewed tow package. I really enjoyed how easy it was to put together and tune. This motor I am trying to go a step hotter but use the cubes to move my power way down the rpms where stamped rockers and wimpy springs will happily do the job. I probably would have been perfectly happy with a smog 440 but if I’m going to rebuild a motor it is real hard to argue with 440 source stuff- 72 extra cubes, forged bottom end, and stealths for small money.

The bearing and lifter surfaces did get covered when it was peened but not the deck.

I have heard the big blocks often need the cam bearings shaved by a cut up old cam so I decided to install the cam bearings after the mains were torqued in case the block moves around and got another nice surprise when the cam stabbed in and spun nice and smooth.

Hopefully in a few weeks I’ll have this thing hung in the chassis ready to break in.

Thanks for your thoughts and questions I am always learning more about this stuff!

Radar
Posted By: dogdays

Re: Block questions- deck surface and square specs street/strip - 08/27/18 09:17 PM

Everyone responds like there is NO CHANCE of something going wrong in the decking operation. Plus they will spend your $180 as if it were pennies.

If it's not a class race engine where you're scraping every hp, I say put the doggone thing together and burn some gasoline! (and rubber).

R.
Posted By: an8sec70cuda

Re: Block questions- deck surface and square specs street/strip - 08/27/18 09:22 PM

Originally Posted By dogdays
Everyone responds like there is NO CHANCE of something going wrong in the decking operation. Plus they will spend your $180 as if it were pennies.

If it's not a class race engine where you're scraping every hp, I say put the doggone thing together and burn some gasoline! (and rubber).

R.

iagree No way would I be concerned about the deck heights being off that tiny amount.
Posted By: radar

Re: Block questions- deck surface and square specs street/strip - 08/28/18 01:25 AM

Thanks fellas. I had to laugh when I re-read my above post “a step hotter” than my 318 hahaha. The 318 in my ramcharger is probably an honest 250hp/350tq and I was just amazed that it has awesome manners and now pulls above 2500rpm. And that is in a super heavy truck!

I can’t see this motor having less than 350hp/400tq at the wheels which I already know is fun in a 3000lb hotrod.

I’ll throw some stuff on youtube when I get it together.
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