Decking the block ?

this is on my dove-a block i asked the machine shop to take off .005 for zero deck with the diamond flat tops for the scj's i got from Lem, i talked to the machine shop yesterday and he asked me do i want to go to the high side,low side or split it in the middle ? he said because rod length varies, i only measured number one at tdc and put a piece of flatstock across it and the thickest feelergage i could slip under it was a .005 ,i did check it on the center of the piston,so what should i tell him just take off .005 or see what he says first and whats better high,low or split it ?

nuclearcobra wrote:this is on my dove-a block i asked the machine shop to take off .005 for zero deck with the diamond flat tops for the scj's i got from Lem, i talked to the machine shop yesterday and he asked me do i want to go to the high side,low side or split it in the middle ? he said because rod length varies, i only measured number one at tdc and put a piece of flatstock across it and the thickest feelergage i could slip under it was a .005 ,i did check it on the center of the piston,so what should i tell him just take off .005 or see what he says first and whats better high,low or split it ?

high or low side of .005" ????? does he mean the height- low/high on block deck height ? corner to corner not even

Hell,he's the machinist,let him tell you what needs to be done.If he don't know,find a new machinist.

The machinist is not designing/building the engine, YOU need to do the work figuring out what deck height will bring the pistons to the place YOU want them. 1/2 of the stroke plus the rods center to center length plus the compression height of the piston will give you the deck height for zero down (flush). If you want them .005 down, add .005, if you want them .005 OUT...subtract .005. YOU give him the deck height YOU want, then it's up to him to cut them parallel and square. Before cutting, it's good to re figure the compression ratio as decking is 2-3 times GREATER change than milling the heads.

I checked the number 1 piston it was .005 in the hole so i said take .005 of the block and when i talked to him yesterday he asked me that ? about hi,low or in the middle thats what threw me off i mean its onle .005, he said the rod length can vary a little so decking it .005 some could be at 0 deck and some could be in or out of the hole by a few thousandths so if some are out of the hole and some in i guess you can split the diffrence like maybe taking off only .003 vs. .005 and does it really make that much of a diffrence .002 to say .005 i mean Lem had a post about compressed head gaskets that they can vary cylinder to cylinder a little even tho all the bolts got the same torque,maybe i should call him and say make it .005 and thats it, i was doing it for a new surface as well seeing how im bolting on brand new heads.

Thanks guys for the replys i told him let me know what he comes up with before he cuts the deck i might just leave it like it is.

56Tbird wrote:5 in the hole is safer, my old block was 7 out of the hole....new A460 we left 30 in the hole for the next combo...Runs the same numbers. I'd rather have the valve and piston clearance myself after seeing the results of my engine..It'll work at zero just fine ,but make sure and check valve to piston clearance. The MLS gaskets Lem sells can be bought at different thicknesses to get your clearance where you need it.Good luck..

X2

you'd be better off with it like it is and never know it's got .005 on it.

Ideally I would install the four corner pistons and check the height on them then mill the deck to get the desired number.

bigblok2000ranger wrote:Ideally I would install the four corner pistons and check the height on them then mill the deck to get the desired number.

Yes exactly , that's how i do it . Blocks are not always square to begin with. In saying that the 460 blocks i've had have been pretty good .

good connecting rods will not very more than .001 in length, so part of what is said above makes no since to me

Their brand new eagle h beams i got from Lem.

I'd four corner it and be sure,it's you're time, not his so it shouldn't cost any more to do it right. Sounds like you're building a stout engine, I'd want to make it as perfect as I could.
Good luck,
Jr.

Just got off the phone with the machinest and i'm leaving it alone and it'll save me some moola to boot. So i should have everything back in a few days all thats left is pressing the pistons back on the rods for Billys motor, all my stuff is done the decking was the last thing for my motor so now thats out mines finished. I still might be able to try my new combo this year cause theres a few tracks that run into december a few hours from here, i never thought it would've takin this long i mean i bought the heads/pistons and other parts from Lem back on june 16th, man time flys by three week delay here and two there then cracked block then cracked crank then wrong balance crank then balance man takin 3 weeks to get started when he said it'll be done in a week ,it all adds up but the bright side is i sure have saved some bucks not racing much this year i think 5 times total compared to last year everyweekend plus some. I had the cobra two to race all year and its a blast but i have raced that car since 95 untill three years ago when i bought the 84 mustang and put the big block in it and raced that for two years and got hooked on the big motors plus its nice to have the cobra two registered again after sittin for 3 years to take a put here and there when i want to. So soon i'll be posting pics of these two builds very soon and pics of Billy's car (action jackson) also as his car is a total build from scratch all thats done so far is the rear and k member are in.