Head/cam combo question

[Jeff95TA]

Currently leaning toward AFR heads w/ 56cc (I believe that's stock?) combustion chamber. Not sure between the 180cc, 180cc competition packaga, or the 195cc LT4 heads. Flow numbers are similar on the bare head 180cc & 195cc. I'm sure AFR can guide me, but do you guys have any input up front? I know the LT4 requires the LT4 intake (which I believe has more porting potential?). I've searched a LOT of old posts trying to get my info straight! (I hate asking the same questions which I'm sure I have.)

As far as the cam I'm looking at the Comp Cams XE305, 306, 502, or 503. They seem very similar and again I'm sure Comp Cams can guide me. The 500 series don't seem to have as much lift. Two things that are important for me: don't want to lose too much low end power or vacuum for the brakes. Does the 306 have too much duration?

I'm also planning on a new stall converter, and I'm sure headers are a good idea if I'm doing heads. I should know this, but can I keep my cat with full length headers? Am I wasting money on the heads with shorties?

Sorry for the length of this post, engineers like getting info on stuff they don't know well. Thanks!

[Injuneer]

I wouldn't limit the engine with a 180cc intake runner volume. At least go to the 195cc design.

I have really mixed feelings about the AFR heads, based on experiences a friend of mine had. It appears that all AFR did to make their LT1 heads, was take their standard 65cc combusiton chamber 1st Gen heads, relocate the water passages, and dump a big lump of extra metal in the combustion chamber to reduce the chamber volume. This causes the plug to be seriously shrouded by the extra casting material. In the opinion of a shop that I highly respect, this is the reason for the poor results with the AFR's "out of the box". They take substantial porting, by a knowledgable party to achieve good flow numbers. George Baxter tried the AFR's and hated them, claiming they lost him 50HP (out of maybe 700) compared to the Lingenfelters he had been using. In the end, he took LPE LT4's to the 925HP level, then found a rare set of Canfields and virtually reconstructed them to support 1,125HP.

Apparently Trick Flow decided to avoid the problem of reducing the chamber volume in their recently released LT1 heads. They simply relocated the water passages on their Gen 1 SBC heads, then kept them at 64-65cc to avoid facing the problem of reducing the chamber volume. But that limits them pretty much to blower motors.