Ken Ruether

I've been trying to find flow data for stock 081 or 416 heads but haven't had much luck.

So far I have only found data for ported 416 heads but I'm not sure if the valves they used were for 1.84" or 1.94" or what level of porting they received.
The flow data I found was as follows.
Intake
.200 .300 .400 .450 .500
119 172 202 207 207

Exhaust
.200 .300 .400 .450 .500
93 127 143 168 169


Anyone have flow data for 081 or 416 castings in stock form?

How about flow data with backcut 1.94 valves and maximum porting?

What kind of flow can you get from these heads with backcut 1.60 exhaust valves and maximum porting?

Will the 1.94/1.60 combination work on these heads if used on a 305ci?

Thanks
Ken

F-BIRD'88

Search my past posts... Its all there...

Ken Ruether

Wow, you sure have a lot of post's and a lot of great reading.
I found the information I was looking for.

I have another question for you. Out of all of the different 1.94"/1.60" valves on the market, which valves flowed the best for you on 081 heads?

Thank you for your help.
Ken

robertg

iTrader: (2)

https://www.thirdgen.org/techbb2/sho...hreadid=150604

above is a very good thread that i have had bookmarked for almost a year now.

F-BIRD'88

I actually got the best results with common stock replacement
but larger 1.94x1.60 valves in the 416 heads. The reduced stem diameter performance valves work too.
A 30 deg back cut helps. The 081's are basicly the same.
A race valve is not nessessary to get good results.
It's all in the porting effort.

Ken Ruether

What kind of improvement in flow can be expected if reduced stem dia valves are used instead of stock replacement 1.94"/1.60" valves.

Thanks
Ken

F-BIRD'88

Only few CFM at best on this application. And only at very high lift.
There is more to be gained with concentration on porting, valve job and a 30deg back cut on the valves.

I ported two sets of 416 heads. The set with the standard stem valves actually flowed a little more.

I wouldn't run all over town looking for under-cut stem valves for this.

Ken Ruether

Thank you for all of your help.

Just for the heck of it, I ran the ported flow numbers through Desktop Dyno last night.

With 500 cfm on the intake and stock exhaust with mufflers using a Comp Cams XR258HR but increasing the lift to .500" on intake and .550" on exhaust a 305 will put out almost 400 ft lbs of torque. Not bad for what some consider to be junk heads.

I found that the XR258HR gave the best performance (with eather stock or ported 081 heads) of all of the out of the box spec XR line of cams.

Take care.
Ken