I have set of AFR 205 heads for my T/A that I am going to install with a stealth 2 cam and a set of long tubes with cats. The cam is a 224/220 dur @ 50 with a 581 lift cut on a 116 lsa. The heads are right out of the box and have 66 cc chambers.The short block is a stock 346. I've been told this should give me around 10.2:1 compression. I've been told by some that I should mill them to get the ratio up a little and others told me to leave them, I need some opinions on this. The car is going to get tuned and will run 93 pump gas all the time. Thanks

 

Drop the cam numbers in a DCR calculator and aim for 8.5:1 or maybe a tad less this will tell you what chamber cc you need. Also consider checking P2V clearance before milling to make sure its all good. Use 0.040 gaskets to maximise quench and minimise knock.

 

Depends a bit on your future plans, i.e, turbo or blower or bigger cam- but in general, yes, you should mill. I'm just a follower of logic, don't claim to be an expert but do a search on AFR 205s or search Tony Mamo and you will see a trend of how people are setting theirs up. There is a DCR calculator floating around too that you should check out, along with the info on gasket thickness, quench. Milling will cost you ~$100 to $150 vs the savings and significant benefits left on the table.

 

yes mill them .024 as recommended by Tony Mamo himself.

 

Wheres this calculator at?

 

You should def. mill them. If you go forced induction, you'd prolly want more cc's than 66 anyways. I think a lot of turbo guys shoot for around 72. I'd mill them per Tony's recommendations.

 

There is a good one here http://www.kb-silvolite.com/calc.php?action=comp

 

I would mill them for sure...

Just leaving power, torque, fuel economy, and throttle response under the table if you don't....all of which you will be searching for at a later date....trust me on that.

At a minimum I would shave them to 63 cc's (.018 mill)....with an .040 gasket that will get you right at 11.00 to one....I would even consider going to 62 (.024 total mill)....that gets the CR around 11.25 to one. which should still work great with the fact you have 93 octane available.

Higher compression makes an engine more efficient....you want as much as your gasoline will tolerate before detonation creeps into the picture...

Let us know how your final combo pans out...

Tony

 

So 11.25 to one is about the limit of 93 octane? I have 63 cc 243 heads that I think bring me to about 10.8 to one. I'm thinking of milling them more to get me higher compression.

 

I'm jealous of all you people in states with 93 Octane. here in cali we can only get 91.

 

+1 ...............those lucky bastards

 

I'm with Tony, I would do a .024 mill for 62 cc chambers.
11.2 neighbourhood is well liked by that cam.
There is no PTV issue , been there done it.

 

Guys dont forget DCR is what determines chamber pressure not SCR. You need to double check on that.