I'm looking at getting new cylinder heads (along with cam etc) for my 350. I've been thinking about AFR 195's. The problem is I'm thinking of changing to a new 406 short block in the coming year. My question is this:- Can I order the machine steam holes for 400cid engines (AFR#1260), and use it on a 350 block engine in the meanwhile? Will this have any adverse effects? Your input would be much appreciated.

Also, would AFR # 1094 195cc Street Comp package heads flow enough for a moderately built FI 400cid engine?

AFR say on their website that the 195's have an "ideal operating range of 2000 rpm to 6500 rpm....... and is the perfect street head for 350 cid to 400 cid engines from 1955-86".

The steam holes make no difference on a block without them. Go ahead and get them. Or, drill them yourself when the time comes.

They should work fine a 400. Just watch the compression ratio.

Thanks RB83L69!

What should I be watching as regards the compression ratio? Do you mean due to the cc size on these heads so that compression isn't too low? Am I missing something else?

yeah it will work fine, just on your non 400 block use a head gasket that doesnt have steam holes.

I've just completed my 406 installation. I opted to use the new Brodix RR200 cylinder heads. They advised me to NOT drill the 400 steam holes as the coolant passages are larger than what Chevy designed on the original 400 heads. I did however need to modify the head gasket by opening up the holes for the coolant passages.

So far, the motor is running extremely cool. My compression is 11.0-1.

So the regular small-block coolant passages are larger than usual on teh heads you used, and they actually encompass the area that the steam holes would have used?

Or they just arent needed but you need to modify the headgasket so you dont pop a headgasket?

The coolant passages are larger and redesigned in the cylinder heads. On the gasket, passages need to be opened up to allow more coolant to flow through.

Brodix has a technical bulletin on this modification. I did like the fact that the heads did not need to be drilled.

Take a good look at these heads. I did some extensive research prior to purchasing them. Once I received my heads, I took them to a local shop and flowed them. I don't always trust what the Head Manufacturer tells me.

We found that the intake flowed what Brodix claimed (nearly identical). The exhaust was a different story. The exhaust blew away the Brodix numbers. Brodix does not flow heads with a pipe. We flowed mine with a 13/4" pipe. Very impressive exhaust.

the pipe is probably why your numbers on the exhuast look so much better. The pipe will give you a lot better numbers on the exhaust. That is kind of comparing apples to oranges.

Ben

I believe that most cylinder heads are tested with a pipe. I have seen differences with and without but not as dramatic as these. Don't get me wrong, I was very pleased with the results.

If the numbers on the exhaust were that low with pipe, my cam choice would be much different.

I've got some 400 heads(3978493) on a .030 350ci(355ci) now it ran fine for years in a boat till the boat sank. Just use a head gasket without the steam port holes.
The 190cc AFR heads are some fine heads. Chevy High Performance tested some a while back and they outflowed a lot of larger CC heads. Check out there website. http://www.chevyhiperformance.com They have a very large head flow database there. Not sure about the 195cc head but it should be a great head for 383ci up motors though. I'm a firm beleaver that AFR makes some of if not the best heads on the market.

Thanks for all the comments guys!