Just buttoned up my BBC bracket motor tonight after installing the new heads (Dart Pro 1) and fired it up

We are putting it in the dyno Friday. I am not too confident of any gains at this point. I lost a full pont of compression over the old heads (nicely ported 325cc rectangular port stock castings). The head guy I use was too busy to get to the new Darts (325cc) so I just bolted them on "out of the box". They will come off for milling and porting this winter, regardless. Wish me luck!

Rich

 

good luck wit it

 

Thanks!

 

Rich if you have no gains with out of the box heads that ought to make you all kinds of excited, just think of what you'll have when they get worked over by a pro.

 

Good luck, post up some results and details

 

youre out of buffalo i see are u gion to rhineback this year for the good guys show wit any of your hoops

 

No, I am pretty far from there.

Rich

 

Those are great castings to start with, but they really need port work to shine - especially the chamber.

 

Yes, from looking at them that's kind of what I figured. The valves are shrouded with the stock chamber and the finish is rough. My head porting skills are pretty rudimentary, or I'd have done it myself and like I said, my usual guy was not available. In retrospect, if I'd known he couldn't do it, I would have bought the CNC version and just had them milled to get the CC size I wanted.

It's going on the chassis dyno this afternoon, so I will have a back to back on OOTB Pro 1's vs. a ported stock casting, if anyone cares. The lower CR will confound the results a bit, so it isn't a clean experiment.

Rich

 

It worked ok. Made ~10 more hp (~20 corrected for the air) and ~35 ft-lb more torque in spite of the lower CR.

Rich

 

So how much do you think a good port job and some more compression is worth? Are you going to get a new cam for these heads?

 

This motor makes ~600rwhp through a 5,000 stall converter. Assuming this is 20% drivetrain loss, it's at ~750hp now. Going from 12.5 to 13.5:1 ought to be worth 1% or so. IOW 5-10hp. Porting should net maybe 25-30CFM. A reasonable rule of thumb is ~2hp/CFM on a V-8. So, that ought to be worth 50-60hp. That would put it over 800hp, pretty decent for a "small" (469ci) bracket motor. For comparison, look at Reher-Morrison's 509ci bracket motor. That one's 810hp from 509ci. http://www.rehermorrison.com/ If I can get the same, or more, hp/ci as R-M on a comparable bracket motor, I am pretty happy.

I specced out the cam I am using now. Keep in mind this is not a ***** to the wall setup - it is designed to go two seasons with up to 100 passes/season w/o rebuilding. That means keeping the r's down. Peak hp is about 6,800rpm and I shift at 7,100. The cam is kind of interesting. It is Comp lobes 4208/1481 on a 110 LSA. This works out to 272/280 @ 0.050" with 0.690" lift at the valve. These are aggressive lobes that I picked to get decent area under the curve while keeping the lift under 0.700". I have a big urge to experiement, but I think I will keep the cam the same unless I decide to go bigger on the motor. I do have a Dart block waiting for me to decide what to do with. I could get a set of new pistons for the 4.500" bore and just transfer everything else over. That would give me a 509 and with some porting, the 325cc castings I have would be perfect. Hmmmm.

Rich

 

I think you will be pretty happy if you get into the heads, Is this the motor you run after market EFI on? If so what TB are you using?

 

nice numbers, good luck with it

 

I am using an Electromotive TEC3r EFI with a Super Vic manifold and a 2000cfm throttle body (Holley).

Rich