I have been running a set on my autocross car since I built it. I don't have flow numbers but it looks to be very nice port work, matched to a felpro 1206 gasket. It also looks like they have been angle milled as all of the headbolt holes have been spot faced at an angle and also look to be slightly elongated at the top. It is also loaded with titanium valves. 2.08 intake 1.625 exhaust, I would say that someone spent a good deal of money on these at some point in the past. The engine I have right now is a 12:1 350 with a small solid lifter camshaft and it makes very good power from about 3000 RPM all the way to 7000 RPM. I was just reading David Vizards head porting book and while he didn't get great numbers (250CFM at .600 lift) he also said that he put very little time into them and the ports where only 185 CC. I think 250CFM with that small of a port isn't to bad. I believe out of the box Brodix Track I's with 215 CC ports where only at 250 CFM, Fully ported Sportsman Iron heads with 215 CC ports where flowing 285CFM, CNC ported AFR 220 cc ports where flowing allmost 300 CFM and ported 18 degree heads of most manufacturers where in the 310-315 CFM range(All at .600 and 25" vacuum) The best flowing 23 degree SBC head he tested was a fully ported Pontiac aluminum head and that was in the 305 CFM range. From the looks of it I think a bowtie head with the ports enlarged to 210-220 CC(Where I think my heads fall) and ported by someone that know how should flow in the 290 CFM range pretty easily. I know Bowtie Phase VI heads are a little dated and so is the book I am reading but from the looks of it, with work, these seem to flow as well as anything that was available at the time. Just wondering the potential of the bowtie heads and if anyone has experience with them. Honestly I am just trying to get to the 600 HP range on an 11:1 roller cammed 383(Or larger) that still will make decent lowend power. If I don't need to buy different heads to do that I will be happy. BTW, I was just looking at the AFR site and the CNC ported 210 CC heads are flowing 305CFM, the 220 is at 317CFM the 227 was at 319CFM and the 235 at 224 CFM all at .600 lift and 28" Vacuum so there have been some fairly big improvments over the years since this book came out as it was taking an 18 degree or better head to reach those numbers before. Not sure how much of a difference there is between 25" and 28" of vacuum either.

Have you heard anything yet? Im in the market for some good porting books and possibly some heads. that 600 # sounds really nice. are you using a single plane intake for AX?

I would like to get them on a flow bench and see how well they flow. I know nothing about porting but like I said, someone put a large sum of money into these heads and from the little bit I do know the port work looks to be very nice, I am sure it was done by someone who knows what they are doing.

As far as books, I feel the Vizard book has a lot of good info but it is more then 10 year old info so it is dated but I guess airflow theory really dosen't change much. AFR seems to get some great numbers out of 23 degree heads even back then.

Yes I am running a single plane Victor Jr intake on my autocrosser. My car dosent lack any lowend torque and the Victor Jr has been proven to not lose much lowend torque from a dual plane.

A little old...but
I have 2 sets of these and with your intake you'lll make 600hp if the cam will.
The the owner of the local head porting company CFO for the roundy round guys here in so cal, told me that on high continues rpm's the 049 bowtie heads have soft aluminum that could drop the seat inserts, so see if they are pined.

If you look at when the phase 6 head was on longer product it marks the LS entery.
I have never heard of anyone disapointed in a bowtie head...but I a drag racer.

I pulled the heads off today and took a closer look. On one end the heads are stamped LEO 62. I assume that is the initials of company that ported them. The first and so far only thing that came to mind is Lingenfelter Engineering. Any thoughts?

The intake ports are a Felpro 1206 size, actually a touch bigger but the 1206 is the closest match. The exhaust ports are square and are very close to the header bolt holes some of the ports are even touching the header bolt holes. I am sure the heads have been angle milled but they must have also machined the intake side to match because my untouched intake seems to match fine allthough I probably should use thick intake gaskets. I remeasured the valve sizes and they are 2.10 intake and 1.625 exhaust(Titanium).

I took some pictures but haven't uploaded them to my picture host yet. Might get that done later tonight. As far as 600 HP, I believe they have that potential but right now I am running a small .540 lift 300 degree(Approx) Solid cam and only a 600 CFM Holley DP so my guess is I am at the 450 HP level right now. Need to get a roller cam and 750 DP. Believe me, I am not disapointed with these heads. Right now I have more power that I can effectivly use.

Pictures #7 piston

#7chamber

Exhaust port

Intake port

Intake closer

Lingenfelter uses LPE, not LEO.

Any ideas on who LEO is then?