Topic: Any idea on compression ratio?

[a700guy]

picking up this 836 block and pistons stamped rc eng, also comes with RC ENG cam (one end is stamped 27B, the other RC 315), using them in my 72k engine.

Ideas on approx how this combo will run?

[a700guy]

Also I see in the pics one piece oil ring, where about is best going to find new rings with 3 piece?

[mick7504]

Some helpful info here on the RC 315
http://forums.sohc4.net/index.php?topic=65562.0

These guys may be able to help out with rings.
http://www.totalseal.com/

Mick

[a700guy]

thank you for the cam info mick, it looks kike a good one if I can figure out which specs to degree too!!

[754]

Real easy to tell difference, between 10.5s and 12s., lot higher dome..

If you do not want to run a cam with .012..  12 thou clearances, and change your mind, I call dibs, am interested..
 754..

[a700guy]

I suspected these are 12.1 pistons, so I guess that assumption is correct.

I also assume this cam is a good match to keep cylinder pressure in check for premium unlead?

[NitroHunter]

I also assume this cam is a good match to keep cylinder pressure in check for premium unlead?

Yes.
Degree to the 104 L/C, it will be the same intake & exhaust.
You'll have to get hold of a burette and get to cc'ing for the REAL CR answer.    There are web sites (I think RSR is one) that have calculators whereby you can figure actual dynamic CR based on static CR & intake valve closing point.
Spend the time to get it jetted correctly, tune the ignition timing to the 'ping' of your chosen fuel... and you will love the power this cam makes. At least I did.
Of course good head will make things even better - but I guess that goes without saying. 

[a700guy]

I asked this elsewhere but no one seemed to have an opinion, would I be better off opening up the chambers in the hondaman hemi style for better flow from the head since I have plenty of compression to spare, obviously I would cc the chambers, but I would do this and match them anyway, clean up the ports, possibly angle the floor, etc.

[NitroHunter]

Opening the throats to 90% of valve seat diameter is important, nice ports won't show much flow improvement without doing it. I'd have a real head shop / porter guy handle this, the job gets done correctly and the results will speak for themselves.  
Zero decking the block will give several benefits as well. George Bryce wrote on this years ago as a primary source of otherwise missing horsepower. An example big HP Comp motor benefitted by 15 HP... so I would take his word for it.  

I don't have an answer for the SOHC chamber style based on any dyno results, only what others far smarter than me have shared.
 A hemi head exposes alot of surface area but unshrouds the valves. RC did lots of 'em and I have one too. I also have had ported stock style heads that ran great. More important to remember is that 200+ psi cranking pressure always wakes up a motor. I ran 240 psi on 93 unleaded - tune carefully.

All the 4 wheel drag stuff I've played with have hemi heads (well, except the jet) and I figure since Allen Johnson, Brad Anderson, Minor Bros, etc make the chambers that shape...  One motor has 6.3:1 CR, another has 12.4:1 CR. Different applications & fuels, but both hemis.

Do the math before grinding.
 
Again this is all just my .02
 

[a700guy]

I may send it to someone, but it pains me as people send me their 4 stroke 4 valve dirtbike heads and 2 stroke cylinders to do.

I would need to run By RES and sweet talk Ron into letting me use his flowbench to check my results, but in the end it could be less pain to pay someone who already has a baseline and knows what port measurments and shapes work well for this engine.

Valve shrouding is what I really fear with the stock chambers, I have been kicking port diameters around, but I am on the fence about going too large with the stock 72 carbs, I have alot to do beside the engine and high end carbs are at the end of my list right now.