781/049 Angle Milling

[95ttoplt1]

We have a set of 781 that we are going to angle mill. First a little primer to save us all some time and effort as we have gotten nothing by time wasters in other forums.

Yes, we understand a piston swap can gain compression. Yes we understand aluminum after market heads are available. We understand the tertiary effects of the ANGLE milling(intake face, exhaust face, PTV clearance, Pushrod clearance, dowel location and depth etc). We understand there are factory closed chamber heads. So save yourself some typing. WE KNOW

Not to be rude, but I don't care that you flat milled your heads. Or angle milled a different casting than what we are asking. It seems reading comprehension is a super power these days hahaha

With that being said what we are looking for is

1. How much you were able to successfully ANGLE mill off a set of 781 or 049 heads and what intake valve size was used. Expressed in Thousandths off the intake and exhaust side, or in degrees.

2. How small you were able to get the chambers in CC.

Please guys I have asked in a couple different places and the most common answers are "I milled .040" off my heads and it dun runs good", "I had my AFRS angle milled and I love it" or "I stroked my BBC and got my compression up". Please don't be that guy. None of these are helpful responses, or even address the topic.

I'm hoping the crowd here is above such responses.

[Carnut1]

Truth is depending on exactly how high the valve seats are in the heads and the diameter of the intakes valves I do not think anyone can give you a 100% accurate number. I have seen these cut right to the intake seat. Doing so will lose some flow. 2.3" intakes can have less of a cut than stock 2.06" valves. By the way I am from NY so I love the attitude. Welcome to ST, giving more specs on combo and expected results will get you the info you seek. This board has very talented members. I personally would like to know the flow numbers you have on these at this point. Thanks, Charlie

[95ttoplt1]

Truth is depending on exactly how high the valve seats are in the heads and the diameter of the intakes valves I do not think anyone can give you a 100% accurate number. I have seen these cut right to the intake seat. Doing so will lose some flow. 2.3" intakes can have less of a cut than stock 2.06" valves. By the way I am from NY so I love the attitude. Welcome to ST, giving more specs on combo and expected results will get you the info you seek. This board has very talented members. I personally would like to know the flow numbers you have on these at this point. Thanks, Charlie

That is kind of what I was thinking. Measuring from the deck to the outer edge of the intake seat and then doing the trig.

Sorry, really no attitude, just frustration! Sometimes we find great info online from very intelligent people who are willing to share. It seems lately, more often than not, we just get people that like to flap gums regardless of the topic.

[peejay]

Truth is depending on exactly how high the valve seats are in the heads and the diameter of the intakes valves I do not think anyone can give you a 100% accurate number. I have seen these cut right to the intake seat. Doing so will lose some flow. 2.3" intakes can have less of a cut than stock 2.06" valves. By the way I am from NY so I love the attitude. Welcome to ST, giving more specs on combo and expected results will get you the info you seek. This board has very talented members. I personally would like to know the flow numbers you have on these at this point. Thanks, Charlie

That is kind of what I was thinking. Measuring from the deck to the outer edge of the intake seat and then doing the trig.

Sorry, really no attitude, just frustration! Sometimes we find great info online from very intelligent people who are willing to share. It seems lately, more often than not, we just get people that like to flap gums regardless of the topic.

I zero decked a 301 Pontiac once and it would pull 100mph with a lot of pedal left...

Just kidding. I understand your frustration and it's a lot of why I don't bother asking questions a lot of times!

[CGT]

http://www.mjpsoft.dk/port_area_instructions.html

Programs such as these can get you there. Rick360 on here is very familiar with them. He has calculated a couple for me and it turned out a very accurate prediction.

[Frankshaft]

I have done a 0-.100 angle mill. I am pretty confident, if you wanted to, you could probably do 0-.150 maybe .200. If it gets into the intake seat, bfd, recut it and sink it in a bit, blend chamber accordingly. A lot of it is simply trial and error to figure it out. There is no 100% cut in stone way to do it. Remember, you don't have to cut all the way across the head. From your post, your familiar with everything that will change, and need to be "corrected". Creativity and common sense come into play if your trying to max it out. Is this something you have to farm out? Or can you do it your self? Because that can make a big difference, angle milling is involved and sort of a pain in the ass, if your not getting paid for your time. Most guys hate doing it, because of all the extra involved that most don't understand, and don't want to pay for it.

[95ttoplt1]

I have done a 0-.100 angle mill. I am pretty confident, if you wanted to, you could probably do 0-.150 maybe .200. If it gets into the intake seat, bfd, recut it and sink it in a bit, blend chamber accordingly. A lot of it is simply trial and error to figure it out. There is no 100% cut in stone way to do it. Remember, you don't have to cut all the way across the head. From your post, your familiar with everything that will change, and need to be "corrected". Creativity and common sense come into play if your trying to max it out. Is this something you have to farm out? Or can you do it your self?

We are doing it in house.

When you say we don't have to cut all the way across. Can you explain that a little better? If we didn't come to zero at the intake face/deck intersection wouldn't that leave a peak longitudinally in the deck surface?

Thanks for the reply! refreshing to have a on topic response

[Frankshaft]

Basically, you can stop once the head gasket will seal the water. The part that hangs off into the lifter valley, is just hangin in the breeze so to speek. There will be a slight gap on the corners that you just fill with the right stuff gasket maker. About .007/cc. You will still have to correct the intake face angles.

[95ttoplt1]

Basically, you can stop once the head gasket will seal the water. The part that hangs off into the lifter valley, is just hangin in the breeze so to speek. There will be a slight gap on the corners that you just fill with the right stuff gasket maker. About .007/cc. You will still have to correct the intake face angles.

Awesome, just the info I was looking for.

So a .100" angle mill would cut 14.28 cc? Does that sound right?

Thanks so much for the info.

[utmost]

I agree with you, when we ask a simple question like yours and the know it all's ask why are you doing it that way, wouldn't it be easier to do such and such and this and that. that being said I have angle milled lots of heads with good results but it is a lot of work.

[ProPower engines]

When it comes to angle milling BBC heads as mentioned the part of the head gasket that just touches the valley area is not an issue. It makes it easier to get the head milled down faster then cutting the whole head and leaves the port bottoms untouched making the port work easier.
Un MLS type of gasket works better when using sealer on the valley area of the gasket to seal. I have used the composition Felpro gaskets but they seem to weep oil in a short time at the rear of the engine.

I rough in the Valve job then CC the heads to make sure I am close on volumes between the heads and measure the valve to deck clearance. I then compare the 2 heads and alter as needed to get the balance before machining. That way any touch ups will be the same amount on both heads.

[95ttoplt1]

When it comes to angle milling BBC heads as mentioned the part of the head gasket that just touches the valley area is not an issue. It makes it easier to get the head milled down faster then cutting the whole head and leaves the port bottoms untouched making the port work easier.
Un MLS type of gasket works better when using sealer on the valley area of the gasket to seal. I have used the composition Felpro gaskets but they seem to weep oil in a short time at the rear of the engine.

I rough in the Valve job then CC the heads to make sure I am close on volumes between the heads and measure the valve to deck clearance. I then compare the 2 heads and alter as needed to get the balance before machining. That way any touch ups will be the same amount on both heads.

Sounds like a good plan! Thanks!

[Baprace]

when you angle mill .000 - .100 you will get approx 75% +- CC's , you don't get 100% untill the cut has completley covered the chamber, then you can figure approx .007 per CC.

[pdq67]

Bringing another thread back from the dead..

How much flat milling per cc for a -206 head??

They should be stock at 96.7 to 98 cc's and I want to get down a lot lower to up my CR is all IF POSSIBLE??

Put them on a stock 454 P/U engine to raise their stupidly low factory CR so that a decent cam can be ran is all.

I would use correct length P/R's here..

A cheap increase in power by me..

pdq67

[F-BIRD'88]

PDQ67 Do not assume that your 206 or 215 heads are 98cc .
Many are larger than that oem stock. Cc your heads first.
Once you have employed the shim gasket the most you will
Further change the compression ratio is 0.45:1 cr for the dish piston 454 and 0.5:1 cr if the flat top 454 piston motor.
Either way the resulting cr will STILL BE TOO LOW..
It was a bad idea 3years ago and it is still a bad idea.
If a dish piston 454 the end cr will still be Less than 9:1 cr.
Now your stuck with useless heads with no VTP clearance for that cam you want to run. And still again usless when you realize that and then decide new pistons are needed..