Hi guys, I have an opportunity to purchase a set of these heads, the 185cc version for very cheap from a friend. I did some homework and found that they flow as well as, sometimes better than the heads I was considering for my 406 build (dart iron eagle 215, pro topline 220) I think the velocity of the smaller holley head sure would be nice. Plus they utilize a 20 degree angle rather than the normal 23, which I believe would be another benefit. Here is the engine:

406 sbc
Forged pistons with a measured 10.8:1 c.r. using a 64cc chamber.
Cam Motion custom solid roller (296/303adv 257/265@.050 .610/.609lift 107LSA)
Weiand Tunnel ram, dual 450 holley carbs

This is in a '71 chevelle, TH350, 4.56 gears and appropriate converter (whatever coan recommends)

One side of me says those heads will limit me, but the other side says that they may work well with a bit of port work, they seem to be a bit weak on the exhaust side.

Any thoughts on this? I wouldnt have considered them until the opportunity came up to buy them cheap.

Thanks everyone!

Adam, whats the application for your car? Weekend bruiser, daily driver, etc..

I'm guessing a street/strip weekend car. I think the heads could work if you port them (exhaust & intake). In outta-box shape they'll be done by 6000, probably closer to 5500. Just depends on how high you want to spin the motor. Looking at your 4.56 gears I'm guessing you'll want to be spinning the motor a bit. What size tire are you running?

Hi John! Thanks for replying.

I had originally planned on using a set of CNC Pro Topline 220's, but wasnt able to work out a deal. This opportunity kind of fell in my lap, and quite honestly - this needs to be as much of a budget build as it can.

The car will be street/strip for sure, how much strip will depend on my work and college schedule. I wanted to keep it around 6500 rpm wise, and probably won't ever see the high end of 5K on the street, I cant afford to frag the motor because if that were to happen, the car would sit for quite a while.

I know marooned runs a ported afr 190 head on his mid 11 second 383, so maybe I can get some more out of these systemax heads.

Thanks for the input. I'm going to do some more homework myself. I'll post whatever I find out.

I found on the chassis dyno that my engine with TFS 195cc heads had a really long flat power curve. Well, I came to the conclusion that while the big flat curve was good - maybe I was "head limited" and that is what was flattening the curve out. So when I pulled the heads, I calculated max RPM using the minimum cross-section and the math seemed to confirm that my 195cc heads were a slight limiting factor. I guess I'll see when I put the engine back on the chassis Dyno or run it in the 1/4 again.

Bottom line is this --- I'm sure they will work good in a street engine, you just might be leaving a little top end power on the table.

They actually work pretty good but you can't run a 1.55 spring in them so see what springs you will run and make sure they will be ok.