Should I have it decked??

[DanM]

When I take my block in for work (bore/hone, plugs, cam bearings, etc.), I'm wondering whether I should have it decked for flatness or not?

My mechanic said that lots of people opt not to have it decked and get away with it just fine. He said that a cast iron block like this generally doesn't go anywhere (in terms of warpage).

My other thought was that, when I get my rotating assembly all done, I'll test fit it, and I may or may not need to have more material shaved off the block to achieve the compression I want (probably mid 9s), depending how everything sits. In that case, it would be silly to have it decked now, then find out I have to take it back in to have another 30 thou shaved off once I test fit it all....

So should I hold off on milling the block for now, until I can test fit everything, and go from there?? Or is there a 99% chance I'll have to have it done anyway, in which case I may as well just do it now....?

Thanks
Dan

[DAVID GAGNARD]

Dan;

When I build an engine I like to have my block "decked",not all the way till the pistons are at the top,but at least one pass on the machine to insure the deck is perfectly flat for head sealing purposes...... Once my block is bored and honed I DO trial fit all the pistons and crank and check the piston to deck clearance on all eight cylinders,then decide how much or how little to deck..... My last engine was cut the bare minimum it took to get a clean flat deck surface,came in less than .010.....My compression was where I wanted it to be so I told the machinest to take off as little as possible..... The engine before this one,I had the deck cut .030,which is a lot,but with the pistons I was using I needed that much for my desired compression ratio...

So far,by doing this step, I have never had any head gasket sealing problems,I feel it's cheap insurance,some people do it and some do not,I just prefer the peace of mind and the shop I use for my machine work charges very little extra since he does all my other machine work on my blocks....

Just my opinion......

David

[DanM]

Thanks, David.

So either way, you'd suggest having the block bored first, bring it back and do a test fit, and THEN decide if and how much it needs to be decked?

Dan

[DAVID GAGNARD]

Dan;

Exactly right,the shop I use just told me to bring my stuff (crank/rods/piston/rings/bearings) to them and they actually test fit everything for me,minimum charge,I figured it was quicker and easier than hauling the block home,test fit,and bring the block back.....

Tell you machinest what you would like to do and see what extra charges would be....

David

[DanM]

David,

I'd actually prefer to do it myself. Not that I don't trust the machinst or anything ... but I'm trying to learn as I go through this, so I'd prefer to do it on my own. :-)

Edit: Can I paint the block before I have it decked? Or will decking it ruin the paint job??

Dan

[DAVID GAGNARD]

Dan;

Nothing wrong with putting it together for a trial fit yourself,only way to learn..... I trust my machinest with my stuff,he has a college degree in Industrail Technology and is one of the few CNC trained guys around here and my cousin to boot.......top notch machinest,born and raised in a machine shop,then went to college to really learn the ins and outs of machine work and engine dynamics,can make just about anything from nothing if you give him an idea of what you want........


I prefer to wait until my engines are fully assembled before painting them,just my personal preference.....then I use an old set of valve covers just to cover up the top of the heads before painting.......


One other thing I'd suggest for anyone building an engine,once you have the crank/rods/pistons/cam installed and before you bolt on the heads,I like to install my timing chain cover and harmonic balancer,then bring # 1 piston to TDC and check my timing pointer and adjust if needed,that way I know everything is spot on...... I have seen some bolt on timing pointers that are slotted and can be moved 2 to 4 degress depending how you bolt them on.....Once this is done,I then outline the outside of the timing pointer with a felt pin just in case I have to remove it so it will re-installed in the same postion.....

David

[mylesdw]

One other little thing to watch out for: on my SBC the engine number was stamped onto the deck surface on a pad that sticks out from the head. After decking, the engine number was gone and I didn't have it written down anywhere!!!

[KrAzEcJ]

What about balancing? It's always been worth the 150$ or so to have your new rotating assembly balanced, its just good insurance for longer bearing life so be sure to take your flywheel and balancer your planning on using to your machinist. And if your heads need a little milling along with your block deck be sure to take in your manifold so he can mill it to match.

[trularin]

Decking means the guy makes sure the right side is the same height as the left side. Makes good sense to have the deck cut to add a little to the compressiona dn to make sure the deck height is uniform.

Have the block align honed, not bored. Have the CAM bearings fitted to the CAM (unless you are having roller cam bearings installed ). If you are having it punched, you will have to provide studs for the torque plate ( unless you are using bolts ). Measure these before you surrender them as they will stretch and you will want to know how far they did.

Heck, have the block tanked in Caustic Soda before any machine work is done. Then you can polish and prime to your hearts content.

Balance the entire assembly to the nut.

Man, this list can be longer than this, in a instant.

Just my quick thoughts about your deck question.

[TonyMadrid]

Decking is always a good idea to insure an even plane surface for mating the heads to the block.

You made no mention of what size & year block you have. If you have a 351W, keep in mind that the earlier blocks had a shorter deck height to begin with, by about .020". This is important and critical to piston selection so you will have ample valve to piston clearance.

Tony