Piston confusion

[bluestang67]

Took this pic , I pulled the one on the left from my 84 HO 5.0 engine . The one on the right I pulled from the 69 block why would you want a recess not stock right . . The recess in the one from the 69 looks like some Sealed power one's I seen on ebay , they are beefier when the pin goes thru . Think is the recess has to for compression drop right , If I am correct from reading they would give me a 8.9-1 CR . Really was looking for the mid 9.5-1 ratio , sad thing 3 of the pistons from the 84 have broken ring lands . But the flat tops wit reliefs would be the better set right ????

[vara4]

Flat tops with reliefs are the better ones.
Kurt

[pat mccarthy]

my seal power piston book is at the shop. if you know some one that has one its great to have it will tell you your CH and what the CR would be and the deck of the block .the flat tops with no dish will give you more CR if the CH is the same . K B on line can help you and they have the silvolite cast piston line and i like them for very very mild builds.if you can not find it i can look them up and get you the seal power number

[bluestang67]

Pat speaking of deck height whats points do I use to measure from to get mine .

[pat mccarthy]

Pat speaking of deck height whats points do I use to measure from to get mine .

i have a big mic go from main bore to deck then sub 1/2 of the main housing bore of the over all from measurment or when i deck a block i use the BHJ tru-deck has a face plate that has a set height for the set up plate and you used that to measure up to the deck with a in side mic and add that up see that plate theres a height stamp on it

[bluestang67]

HM largest mic I have is 6 inches , but I think its a stock block that has never been decked.

[pat mccarthy]

most of the time the pistons are down in the hole 020

[bluestang67]

Well I can see why you do such good work . Machine work looks polished up .

[pat mccarthy]

Well I can see why you do such good work . Machine work looks polished up .

thanks i like to deck the blocks first with the BHJ then i set up off the deck when its were it needs to be then bore the block so every thing is as right as i can make it most all the time its waaaay better then stock . most of the fords are not to bad .hate to say chevys can be way off . but i do alot more chevys heres a photo of a block getting bored but first the block get s check so boring head is 90 to the deck of the block

[bluestang67]

Pat if you where closer , it would be in your shop for sure .

[hotrodstude]

a lot of rebuilders back in the 70's and 80's used dished pistons on there rebuild to lower c/r so the engine could run on lower octane fuel.are the pistons oversize???

[bluestang67]

HRS no they are standard bore . Funny thing they have a Ford part # on them .