[austenpowers]

ok im at a cross roads ..... could you tell me if it is a good or bad idea to machine .050" off the deck of an engine block ...... namely ford 5.4ltr boss 260
is it done often

im chasing compreshion . and to get it i need .050" off the block

the machine shop seem ok with it . but im positive they have not done many or any blocks of this nature

is there any rules of thumb i need to put in play

[SWEET2KSTANG]

can you? yes. do i recommend it? not on a street orientated car. imo, the best thing to do is to call in a set of pistons and have it added to the top of the pistons.

[slow02gt]

+++1

[cruizer]

Could you get heads with a smaller combustion chamber or shave the heads instead?

[SWEET2KSTANG]

you can shave the heads, but it takes quiet a bit to get make a difference in the compression ratio.

[CobraStang161]

why dont you just get a different dish piston?

[SWEET2KSTANG]

flat top's still dont yeild squat for compression in the 5.4's.

[CobraStang161]

Originally Posted by SWEET2KSTANG flat top's still dont yeild squat for compression in the 5.4's.

perhaps i should of elaborated, i mean call up CP and get a custom piston that will yield desired CR

[limited]

I would not shave the block or heads unless it is to square up the deck or if there is warpage. It really effects a lot as in chains, intake manifold fit etc. Do as mentioned and get the piston/rod combo that does what you want

[tbirdscwd]

I agree with all these posts so far pretty much. It is a lot better of an idea to get the right CR by choosing the right rods/pistons for your combo. I don't know about the 5.4, but shaving the heads or deck makes our already PTVC prone engines to have an even smaller amount of clearance which would require you to nothc the pistons to run any sort of decent cam

[SWEET2KSTANG]

the 5.4 sits in the deck, and is why he is hunting down a set up to bring up the compression. its not that big of a deal to dial the timing chains and intake manifold when you shave them down.

[tbirdscwd]

Originally Posted by SWEET2KSTANG the 5.4 sits in the deck, and is why he is hunting down a set up to bring up the compression. its not that big of a deal to dial the timing chains and intake manifold when you shave them down.

If that is the case, I wouldn't think twice about shaving the deck surface down a bit down a bit

[SWEET2KSTANG]

you have to get good tensioners, and a way to dial in the cams. the crank gears are prefered method, but the cam gears can be used as well. this also depends on how much is shaved off as well. the deck on the 5.4's are able to take quiet a bit, but not enough to make that primary way of getting the compression.

[austenpowers]

Thanks guys for all your answers ,comments and questions . im in aus and dont know alot about this engine as do my machine shop .... it started back at a combo from modxxx. i wanted a cr of 9 to 9.5:1 because im boosting this engine and they set me up hbeam 4340 rods and 11cc dish manley pistons wich put me in the 8.7:1 cr area and was really conserned about it being a street car a driving like a dog off boost (and the turbos arnt going strait on eighter).

they told me there was a problem as the deck was way down (i now know this is normal for 5.4) and i want 9.5:1 cr that told them that .050" had to come off the deck wich started the this thread,,,,,

so if i take .008 off the heads and .010" off the block this bumps the cr to 9.125:1 wich im happy with and its not the .050" as first thort .......

so its been a learning curve for both me and my machine shop (im just about to leave and educate them now)

thanks once againe this is a verry valuable forum keep up the good work

pleas comment

[slow02gt]

if thats all you want... then just go with flat tops and it will put you where you want to be...thought you wanted a all motor car...nex ttime be more specific..

also sounds like you probably would have been better off getting a shortblock already built since the machine shop you are useing dont know anything about mod motors...

[SWEET2KSTANG]

+1 on the flat tops. if you would just get flats, then you wouldnt have to worry about shaving anything.

[austenpowers]

yip you guys are right flattops would put me where i want it.... but money spent funds running out for the build so im working with what i have....

its a bit of a regretfull purchase, well,,, im shure i will be happy with the final outcome..... i did spesify what cr i wanted but i also specified what hp i wanted too so maby the pistons rods and cr was based on all those things i specified. it will work ok and now i have room for more boost i guess.

im gunnah be strapping on 2 wizzers but dont make me tell you what they are as im a bit ashamed of them however there a start

thanks

[SWEET2KSTANG]

if your boosting, then dont worry bout the little bit of compression difference. you can make that up with a little more boost.

[austenpowers]

well im more worried about the off boost performance and down low torque
this is where a cr would help off boost....... its been 16years since my last turbo car and it was a to you guys "pinto 2ltr" to us and the pom's a rs 2ltr escort ...... (loved that car) was crap off boost though.....

im shure i will have great resaults but have a long way to go

[SWEET2KSTANG]

you arent looking at much difference in off boost tq with minor compression difference depending on heads,cams, and turbos size set up.