JP86SS

iTrader: (1)

I'm putting my motor back together (trying to anyway) and have been running into issues with the valvetrain.
The heads need to get cut on the spring seats and the guide bosses to fit dual springs. While I have them at the shop I was planning to have them milled by 0.030" to 0.035".
These are 64 cc heads on a stock 87' 350 roller motor bottom end.
What would the comp raise up to using the recommended 0.040 gasket if I went that far?
EDIT: Approximate Milling Guidelines: .0065 per 1cc

Any mating surface problems with the intake?

The other concern was the valve spring diameter is larger than stock (1.437) and it appears the roller rockers are going to hit the edges. Not sure, haven't mocked it up fully yet with the new cam in it.
I'm going to buy new stainless valves and was wondering if I should get them +0.100 longer to move the rockers up.
Sound like a good plan of action?
TIA,
Jp

305sbc

iTrader: (3)

Milling .030" would raise your compression approx .5
Calculate it exactly though to be sure.
http://www.rbracing-rsr.com/compstaticcalc.html

Taller valves could make the problem worse. Easier to just use a longer pushrod.
Many people just grind some clearance on the bottom side of the rocker to clear. I've run them like that with no problem, but some people end up breaking a rocker.... not the end of the world though.

five7kid

iTrader: (14)

If you are set on using the .040" compressed thickness head gasket, it makes more sense to zero deck the block than it does to mill the heads. That would give you the "ideal" quinch area. If you want to know exactly what your CR would be, cc the chambers - mill to get them where you want them to be (64cc, right?), rather than assuming what they are.

My "58cc" chamber heads turned out to have 64cc chambers. That's not all that unusual, from what I've gathered.

JP86SS

iTrader: (1)

Decking the block is really not an option (motor still in the car)
this just started as an intake swap and has gone from there.
First cam, then springs, retainers, 10 deg locks, new comp roller lifters, $ and $ and $ ...
Seems like I'm going backwards, but its all for the greater good

Figured I could bump the CR a little since they have to be cut at a machine shop anyway. I will do the longer PR. Easier for me to get everything right that way. CC on the heads is 64 to start with and I polished the rough spots so probably a pinch more at this point. nothing major, just smoothing the rough casting bumps but not totally smooth. I don't want to have them cut to the limit and risk clearance so I'm looking for some guidance.
The factory spec of 9.3:1 would be nice to bump up to 9.6 or so anyway if its not going to cause alignment issues with the intake, etc. Already have the 0.040 head gaskets.
The two things I don't know is the piston relief volume on the stock pistons and my deck height. Been guessing the deck at 0.030 because it is a stocker.
Got a guess or something close to use in the calc for those two??

305sbc

iTrader: (3)

Stock deck is usually around .025"
Valve relief depends on how many you got.
A lot of stock pistons have 4 releifs plus a huge cut around the outer edge.... adds up

It's not uncommon to have to have the intake manifold milled .020 to .030 to realign with milled heads. You just have to mock it up and see how far it's off. Every case is a little different.

JP86SS

iTrader: (1)

See how things keep snowballing
I'm thinking to just leave it as is and just cut for the springs and seals. Don't really want to oddball the parts for such a small gain at this point. It is just a street motor with a little umph!
I'll probably just have them take a flattening cut if needed.

Just wish I had a mill, a lathe, a flow bench, and a blower!
Christmas is coming but I don't think those will fit in the sleigh this year.
Back to the porting dremel for me

Thanks for the help.
Jp

five7kid

iTrader: (14)

Why aren't you using steel shim head gaskets?

JP86SS

iTrader: (1)

Sorry for the dumb question but,
What does that do for me ?
Are they thinner?

five7kid

iTrader: (14)

They reduce the gasket thickness from .040" to .015-.020". Reduces the head gasket volume from around 9 cc to around 3-4 cc (depending upon the specifics of the gasket you choose).

Zed'er

Any compression calculator that doesn't allow you to enter the complete head gasket dimensions, thickness and bore, isn't going to be accurate. You are relying on their assumption of what ever bore they decided to use. Better off doing the math yourself, using your specific gaskets.

Better explained here:

http://www.speedomotive.com/auto_math_101.htm

If anyone uses Excel, I have a handy little calculator with a few different gaskets made up I can e-mail.