PISTONS AND COMP RATIO

[hotrodharley]

I BOUGHT A NEW SET OF DIAMOND FLAT TOP PISTONS FOR MY 540BBC BLOWER ENGINE I'M BUILDING.AFTER BUYING I DECIDED TO GO ALKY ON ENGINE.NOW I'M BEING TOLD I SHOULD HAVE AT LEAST A 11-1 COMP...PISTON INFORMATION IS 4;50 BORE--COMP HEIGHT IS 1.520--EFFECTIVE VOLUME= -3.0CC

I HAVE A TALL DECK[NEW DART BLOCK.NO MACHINE WORK DONE YET ON IT.]..4.25 STROKE CRANK..6.353 RODS..BRODIX HEADS WITH 119CC CAMBERS RIGHT NOW[I'M GOING TO HAVE CBOGGS DO THE PORTING AND FLOWING ON THEM]

MY QUEST IS CAN I GET THE COMP I NEED WITH THESE PISTONS AND IF SO HOW DO I GO ABOUT IT?

OR SHOULD I SELL AND BUY DIFFERENT PISTONS?

[edvancedengines]

Get Curtis to angle mill your heads.

Might need to touch up valve notches on pistons some too.

Ed

[hotrodharley]

THANKS ED;;will curtis know how much to cut on them and will i need my intake also milled then to match heads?

[zipper06]

I BOUGHT A NEW SET OF DIAMOND FLAT TOP PISTONS FOR MY 540BBC BLOWER ENGINE I'M BUILDING.AFTER BUYING I DECIDED TO GO ALKY ON ENGINE.NOW I'M BEING TOLD I SHOULD HAVE AT LEAST A 11-1 COMP...PISTON INFORMATION IS 4;50 BORE--COMP HEIGHT IS 1.520--EFFECTIVE VOLUME= -3.0CC

I HAVE A TALL DECK[NEW DART BLOCK.NO MACHINE WORK DONE YET ON IT.]..4.25 STROKE CRANK..6.353 RODS..BRODIX HEADS WITH 119CC CAMBERS RIGHT NOW[I'M GOING TO HAVE CBOGGS DO THE PORTING AND FLOWING ON THEM]

MY QUEST IS CAN I GET THE COMP I NEED WITH THESE PISTONS AND IF SO HOW DO I GO ABOUT IT?

OR SHOULD I SELL AND BUY DIFFERENT PISTONS?

Might be a better move to sell those and get another set. i did the calculis and you have 9.04 with those pistons and 119cc heads, useing .062 gaskets. I don't know how much you can mill the heads to get 11 to 1 ratio. Yrs. ago i was running 13 to 1 with a 1471 littlefield @ 30% overdrive.
Alcohol likes lot's of compression to preform at it's best, but be sure to get blower pistons/dropped ring land.

JMO

Zip.

[edvancedengines]

If your intake fits now, it will fit after Curtis does the angle milling on them. He will cut mostly one side of the head to reduce chamber cc and will alter the bolt holes and the under head spot facing of the bolt heads plus correcting the intake port angles.

Your valve to piston clearance will become less and the valve angle of the valve relief in the piston will not need to be so steep.

Talk it over with him.

Ed

[edvancedengines]

O'boy,
If zip is right angle milling won't do it.

O'well

Ed

[zipper06]

O'boy,
If zip is right angle milling won't do it.

O'well

Ed

Ed i used this calculator and it's actually 9.02 with "0" deck and 3 CC valve reliefs, and .062 gaskets.

http://www.wallaceracing.com/cr_test2.php

Zip.

[hotrodharley]

thanks ed and zip;;i listed them on rj for sell or trade so hope i can get what i need.
don

[edvancedengines]

Those 6.535 rods are a little short but can be made to work in this. I can do you up a pistong that might give you something extra in performance and in durability when you get to that point if you are interested.

I would still get Curtis to angle mill your heads though. There are nothing but positives with this. No matter whose piston you use it will need less dome and also less valve angle too.

Ed

[zipper06]

I'm with ED on this, there's nothing that increases the flow better than angle milling the heads.
Work with ED and Curtis on this build and i'm certain you'll have the baddest 540 on the planet. I have total respect for both of these builders and they know what they are doing.
In fact i'm going to talk serious to Curtis about doing my heads for my 383 blown motor, it's already been 4.62 @ 2600lbs when it was a 358" motor. Next i'm going to talk to my Doctor to see if i have the B?lls to drive it in an 1800lb Anglia.
Good luck and i think you made a wise choice to get new pistons. I can only hope that i helped in this decision with the formulia that i posted.

Zip.

[hotrodharley]

i made mistake on my posting..my rods are 6.353;;ed did i understand right..you can do me a set of pistons?and yes zip you have helped me a lot on this as ed has also..i'm for sure going to have curtis do my heads..i'm on disabilty due to illness so got to do this build right th first time and be dependbly at same time..i'd love to be able to say i have a 1000hp++on the street..that's my dream anyhow..not sure how close i can get there..i do and will race also.only street use i'm talking is at car shows and local cruises..

[edvancedengines]

I still don't understand your rod size?
No one makes that size rod unless it is a custom made rod.

Ed

[hotrodharley]

sorry about that ed;;;;rods are for sure 6.535;;;;i was looking at part no# on box early and jump gun posting rod size..

so rods are 6.535 length and crank is 4;25 stroke and have a fresh new dart 10.20[tall deck]sportsman block