Hi all,

You might have seen my other thread on heads choice. I am upgrading my engine with some AFR heads, 1.6 int and 1.5 exh roller rockers. Now I want a new cam too.

Here are the specs again:
400 SBC, 4-Bolt, std bore, stock bottom end, flat top pistons, Holley 3310-3, Edelbrock Performer manifold, 1.625 headers, 2.5 inch Flowmaster H-Pipe Exhaust /w deltaflow mufflers, th350 /w 2400 tork master, 2.73 12 bolt posi. AFR 195 Street's with 74 CC (~10.2:1 with flattops)

I want this to be a torque monster to match my 2.73 gears and 2400 stall. Redline will be at 5500 rpm aprox. I have heard good things about the CC 268 HE cams.

What is the difference between the HE and the XE? Is there a voodoo cam that would work better than the CC 268 cams?

Thanks,
Olli

IMO, of the three cams listed, my personal choice would be the Voodoo 268.

The Voodoo line incorporates the latest design technology.
The Comp XE line of cams generally tend to have a somewhat noisy valve train with aggressive lobe profiles.
The HE line is really old school...

I installed a Voodoo 262 in my '67s 350. Big smile on my face everytime I drive that car! :waving:

Are you sure you get 10.2:1 with flattops and 74cc heads?

Are you sure you get 10.2:1 with flattops and 74cc heads?

Well, thats what what I calculated with Dyno2003, yes. 9.98 with my 487x heads (76 cc) and 10.18 with 74cc heads. Do you think i messed up?

Here's the Data:
4.125 bore
3.750 stroke
821.24 cc cylinder volume
89.42 cc combustion volume
400.9 ci total

I used the following data:
Head chamber volume: 74 cc
Head gasket bore: 4.200
Head gasket thickness: 0.039 in
PDB: 0.03 in
I had to guess PDB, as i haven't had the heads off before. I thought 0.03 would be the standard value for a 400 sbc. Please correct me if I'm wrong. I'd appreciate it.

Anyways, anyone else for the Voodoo 268? Does it have the same torque curve like the 268 HE?

Thanks,
Olli

Ollie, I get the same numbers as you if I assume the pistons are truly zero volume flat tops. Most flat top pistons have valve reliefs cut into them that adds volume and lowers the compression. Sometimes as much as 6cc depending on the piston. What pistons are you running?

Tom, I don't know. I bought the engine as is. Flattop pistons is all i know... :(

I didn't think of that, now that you said it I'm pretty sure that you are right and it has a lower compression than i thought. Could be that it is more in th 9.3-9.4 range with the current heads.

With the 74 cc heads that would put me around 9.6:1. :sad:
And with the 68cc AFR heads cr would be somewhere between 10.2 (6 cc pistons) and 10.8 (0 cc pistons). I think 10.2 would be ideal. But who knows, I don't want to end up with 10.5 - 10.8 depending on gasket and not be able to use a 268ish cam. Dang... Ok, now my head hurts. :clonk:
I need to know what is in there. I know best thing would be to remove the heads and measure everything, then make a decision on 68cc or 74cc heads. But it will take ~ 8 weeks to ship the heads over here. Summers are short over here, I don't want to miss this one like the last ones. I got her back on the road only last August for the first time and I want to drive her!!! Dang. Maybe I should wait for the fall. Just thinking out loud.

But back to the cam : (given I'd get around 10:1 cr in the end ;-)

I just saw that the Voodoo cams are a little bit "hotter" than the comp cams, if you compare them by the advertised duration. Would you recommend using the LUN-60102 (262) or the LUN-60103 (268)? Or shall I stick with the CC268HE? I want maximum performance with my 2400 rpm converter and 2.73 posi. I MIGHT go with a 3.43 Posi later. As I said, I do not want to take her above 5500-5800 rpm with the stock bottom end.

Thanks!

Olli

It'd be interesting to see what your pistons look like. My motor was originally built with what I thought were flat tops with 4 valve reliefs. Turns out they were flat on top, but were shorter than normal, sitting down below the deck a bit, lowering my compression. I didn't calculate your comp ratio, but just eyeballing it, seemed a bit high for 74cc heads. That might be a good thing however. I'd guess 10:1 might be a bit much with factory cast iron heads. You'd be happier at 9.5:1 I would think.
The Voodoo 268 sounds like a nice cam. I hear that it doesn't like your (and my) highway gears.