496 - AFR315 Heads?
 

Building a bracket 496 in a 2000 Lb car that I race at higher altitudes. Kicking around the AFR315 CNC heads. Has anyone used them in a combo close, or have any experience with them in other BBC applications?

Any advice will be welcome.

Re: 496 - AFR315 Heads?
 

Wilson,

I am glad to see an engine only thread. Please keep us posted as it progresses.

Re: 496 - AFR315 Heads?
 

My first thought is 315 is a touch small for such a light car. Personal experience with a 468 and Dart Pro1 325 cc out of the box was very impressive. Of course cam,intake carb size etc ... are all important factors. I also have a 496 that I originally bought the Dart Pro1 heads for but never got around to using them as my old 468 worked so well with them we just left it alone.

Re: 496 - AFR315 Heads?
 

I used a set of these on a 540 street engine with 9.98 compression, an out of the book Comp Street Roller (on a steel core) and a 950 Quick Fuel.
This thing surprised me with just about 750 HP (746 at 5900 and still at 743 at 6500) and 715 Lbs at 4900 rpm.)
This thing was still at 600 Lbs at 6500 rpm!

A very good cylinder head if you plan to keep the RPM between 6500 and 7000.

Re: 496 - AFR315 Heads?
 

I do agree for a sea level motor these heads might be a bit small. I race at altitude. Good DA for us is 6300 Ft. So I am trying to be just big enough on the ports, while having good velocity. The planned top end on the motor will be about 7300. So I am a bit challenged for good air, my thoughts are I would be better off with a little smaller head than one that is too big.


The rest of the combo will be almost the same as my 468, RM roller, 454R, 14:1, 1050, 180 glide, 4:30 gear, 6300 stall.

Re: 496 - AFR315 Heads?
 

I haven't used the AFR 315's ,but I can tell you the 357 Magnum CNC heads are the best bang for the buck ,so I would expect the same from the 315's.
the smaller runner should work well for your application ,help keep the velocity up.

Re: 496 - AFR315 Heads?
 

I have done all my home work and have decided to do the AFR 315 heads. I had the cam ground and it is on the bench. The main challenge with the AFR 315 heads is going to be the pistons.

All the head guys tell you, "Yep all the piston guys have our chamber profile" , but when you call the piston guys they always start fishing backwards. So the next challenge will be either custom pistons, or getting some big dome off the shelf pistons and milling the heads and fitting the domes to the chamber to get the compression up.

I am torn between 14:1 plus, or a bit lower compression and better flame travel. I would like to get both, but I am not sure I can. Anyone have any input regarding this?

Re: 496 - AFR315 Heads?
 

http://www.chevelles.com/forums/13-p...498-build.html

You might want to pay attention to the modifications made to these heads in this thread. I realize you race at higher altitude, but 13.1 will make plenty of power.

http://www.chevelles.com/forums/13-p...reshen-up.html

Re: 496 - AFR315 Heads?
 

HP Hunter – Thanks a bunch for posting those two threads. Lots of good information in both, which helps me feel much better about the path I am going down. While there are some differences in each approach, I think the expected results should be in the same ball park. I have been getting some flak from my local engine builder about my head choice… He is a Brodix guy. Good heads, I have Brodix on my 468.

If I get anywhere from the low HP number to the high HP number minus the 20% loss for my altitude, I will be very happy. I feel that is very doable based on the results of those two builds.

It will be interesting to see just what the final outcome is based on the different parts I am selecting. My cam is 274/278 .765 lift on 108LC installed at 106. The 315’s are a little bigger port, but my car is a lot lighter. I am going to run a 454R manifold and I will take my Gary Williams 1050 off my 468 and put it on this motor. I don’t think I am going to be too far off. I am getting excited…

Thanks again Sir

Re: 496 - AFR315 Heads?
 

At the very least:

1. Check the valve seat run out
2. Vent the heads, a MUST
3. Open up the oil return holes
4. Check for back flow @ .750 lift

Hopefully AFR has addressed these issues.

Re: 496 - AFR315 Heads?
 

Thank you for the suggestions. Just to make sure we are speaking the same language:

Check the valve seat run out? Not quite sure what you mean by that… Are you saying make sure the seat is concentric with the valve? I never run a new set of heads without checking the guide clearance, the seats and the stack height and opening and max lift pressures. Not to mention making sure the valves are all the same height in the head and the same length. I always try to get the coil bind as close to .080 - .060 as I can. I don’t know how critical that is for a low rpm (7200) bracket racer like me.

Vent the heads? Are you saying have breathers with an exhaust extraction? Which I do.

Open the oil return passages…. Very understandable, and I wouldn’t have paid much attention to that without the heads up from you… Thanks.

Back Flow? Are you referring to reversion? I do run and ET Genie because I slow the car down to run 9.0 in Div 6 and for the Heritage race. I have found that it not only serves as a great power reducer, but when running all out, serves as a good reversion plate when using a .5” open spacer under the ET Genie.

I assume you have had some extensive experience with AFR heads. Thanks for sharing you experience.

Any other suggestions you would like to provide will always be welcome. Thanks again Sir..

Re: 496 - AFR315 Heads?
 

Pictures of the vent holes behind the intake face. This video will explain the run out. AFR was working on fixing these issues.

https://youtu.be/N3jn2ER455Y

Re: 496 - AFR315 Heads?
 

Thanks. That is a question I am going to ask. I would expect better from a new set of heads... You have now messed with my head... LOL

Re: 496 - AFR315 Heads?
 

Just trying to help you, you will find its a simple fix, you just have to do it. Some people might ask how a S/S 295 HP 350 runs mid 9s @ 3100 pounds..........well its the details.