[Bob Turner]

My research continues as to why I don't have as much power as I should out of this motor. Some of you may have read my other posting regarding my anger:

http://www.hotrodders.com/t52657.html


I was trying to compute the compression ratio. I had asked the machine shop to dial in 9.3-9.4 to one.

I am pretty sure that I have flattop pistons (I am trying to find out now from the machine shop) with a zero deck on the block and for sure- 118 cc 1973 049 cylinider heads. After adding in a 10cc amont for the valve reliefs on the pistons, I have calculated a 7.86 CR.

Can you mill heads down from 118 cc's to 95 cc's??????

If so, what are the problems (other than doing the intake also) with this?

Thanks to all.

Bob

 

[Deuce]

Can you mill heads down from 118 cc's to 95 cc's??????

If so, what are the problems (other than doing the intake also) with this?

Bob [/B]

IF you could cut the heads 23 cc's.......very doubtful......

The intake manifold would have to be cut even more.........to get the bolts to line up. I suggest another set of heads with a smaller chamber with the 98 cc range........

 

[lluciano77]

Angle milling will net you even more cc's, but again, the intake will need to be cut to match.

 

[k-star]

heads

Your not going to make it with those heads .... If they have the 2.19/1.88 valves in them you will cut into the intake seat at about .050 or so. If you do the angle mill you can go deeper before you get into the seat but then you need to do all kinds of fix up stuff,,, Like cutting the intake face,re-spotting the bolt holes,, depending how hard you angle cut them you will need to fix the holes in the heads....

I did not do the math but i seam to think that you will need around .125" straight cut to get them to 100cc's

I would recommend a different set of pistons...Or let it like it is and bolt on a pro-charger......

Keith

 

[[email protected]]

Go to an early set of heads (pre 70). Not the real small bathtub chamber (65-66) , but the 68-69 closed chamber head. Have hard exhaust seats, and 2.19 intakes installed. Relieve the chamber just a bit towards the spark plug hole. Mill it .030" and bolt on some horsepower.

I know that the "Experts" will tell you that these heads are too shrouded, etc. But for a good street head, that won't be turning 6800 rpm constantly. These are the ticket with flat top pistons.

Yes, there is some valve shrouding, but the effect is only noticed at over 6500 rpm and if you are constantly running at this speed or above. You won't be for long, as the local gendarmes will have your description posted in every cruiser.

 

[Bob Turner]

Thanks for the replies.

I will either buy a set of closed chambered 427 heads or pull the motor and have the dome pistons installed.

No sense in ruining those 118cc heads...

Will have an update in the near future!

Sincerely,

Bob Turner