Last 200 six Compression Ratio question

[pikesan]

Hey all,
I searched and found a bunch of info on calculating compression ratio including comments from Mr. Falcon Performance, David. I used the compression ratio calculator (here: http://www.falcon6handbook.com/compcalculator.asp) to figure out where I'm at. I just want to confirm. (you know, discuss twice, cut once!)

It's a 78 200 with 77 head. My plan:
Zero deck the block. - Does the D8BE6015-GD block need 0.025" milled off for ZERO deck height?
Take the 62cc chamber head to about 52cc like the older heads - I'm planning to take about 0.050' off the head - does that sound right?
How much to mill the head depends on the gasket's compressed height - isn't it about 0.050 or - How much does gasket thickness vary mfg to mfg?
When all done, I'm shooting for ~9.0 compression ratio. (it works out using the compression checker above)

More questions:
I heard I can use stock push rods. Taking 0.075" off, I'm ok up to 0.125" right?

Anything else I need to know?

By the way, working with Bill down at B&B machine in Mesa, AZ. Dude's been very cool and helpful. Haven't seen there work yet, but so far:

Thanks for any help! I'll post pics as she comes together. Looking forward to building the engine with my pops!

 

[FalconSedanDelivery]

The only way to know what you need to take off the block is to trial assemble , if you cut more than .060 you will need shorter push rods .

 

[MPGmustang]

the deck will be a mistery, I've heard some had to cut .065 off and others found there's at .005 height. Honestly you want the machine shop to measure the deck height.

The head is where you can really get some really good performance out of, if I were you I'd have CI prep the head with bigger valves and a porting job, they did beautifully on mine. and I highly recomend it. then give back to the build shop and they'll just install the head.

but back on topic, the CR is as striaght forward as it could be. you just need to tell the machine shop what CR you want, they should be able to measure and do the math for you, your lifters can soak up to .125 shaving, you'll be fine.

if you have a dual grind cam, you might consider higher compression as it tricks the engine that it has more CR than it really has. look up here for your cam, and read about it in relation to your cam grind. cam and CR really do go hand in hand.

http://www.classicinlines.com/200Z.asp
http://www.classicinlines.com/CompressionR.asp#SDChart
stock cam specks

 

[FalconSedanDelivery]

Respectfully Dissagree , Ford made pushrods in .060 increments for a reason ( service parts ) over .060 will not place the pushrod in the correct preload , no way .125 will be ok . but you do what u want , or want to hear , seems to happen a lot on this forum

 

[CZLN6]

Howdy Pike:

And thanks for the kind words. We all share what we know and what we learn. This is a team effort.

To your questions, every block is slightly different. Most 200 blocks are around .025" deck height. The other variable is the replacement pistons when rebuilding the block. Most after market pistons are made down an additional .005" from stock OEM specs So to find the true deck height of the pistons you will need to do a mock assemble with the new pistons and bearings in place to be absolute. Just doing the math will get you close enough.

.050" is a good guess to reduce the chambers of a late style head to about 52 ccs.

The stock OEM steel shim gaskets measure .025". After market head gaskets vary from .045" for a Victor to .055" for a Fel Pro.

Yes, a mill cut of .075" is safe to use stock push rods. In reality, the additional thickness of the new style head gasket makes it only .050" difference.

Sounds like you've got it going. keep us posted on your progress.

Adios, David

 

[pikesan]

Thanks guys! I like sharing what I know too and that includes sharing that I don't know what to do!! :rolflmao:
So David it sounds like I'm on track... I think I can get B&B started then. I'm not trying to squeeze every bit I can from this motor so I think 20 of the block and 50 off the head and with the thicker gasket I'll have a conservative hop-up done.

My Chandler buddy... I hear what you r sayin about the performance mods. Classic Inlines has some great parts, but I'm on a budget here. With all the required stuff I need to finish the car it'll be a stretch so I'll keep it simple on the engine mods. Ya know?

On the push rods I'll take a look and see where I end up. If the base circle of the cam is a few thou smaller that's headed in the right direction right?

Thanks again

 

[69.5Mav]

pikesan

If you've got the pan off you could install a windage tray and a crank scraper. If the crank is out you could have the machine shop knife edge the crank as well as ballencing it. Should be good in all for 4-5 HP.