I have a 406 short block and need a little help on picking a cam. I have Cast Iron vortec heads with stock components and an Edelbrock performer intake (#2116). I calculated the C.R. to be slightly under 10:1 with these heads. I need a cam to help me out with detonation (93 octane) and give me good power to about 5000-5500. Comp Cams recommended the 268HE (because XE series builds cylinder pressure and thats not what I need), he said this cam would help bleed off excess cylinder pressure. Anyone have a better idea for a cam i could use. I am on a strict budget so I don't want to go roller. And any idea what type of dyno numbers this setup would produce.

 

My last 406 had around 10.0 compression using 76cc heads and flat top pistons with a 214-224* 112 cam. I ran 93 octane and didnt have any problems with detonation.

I think the Duration that comp suggested would be just what you are looking for it should pull to 6000 with that cam. The smaller cam I mentioned above would pull to 5500 with a standard 2101 performer.

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Black 90 IROC, L98, A4, 323 gear. SuperRamed 406 in the works!

 

i dont think comp cam make such generalizations between cam so similar. Not only does the advance curve come into play but so does gearing and abient temps. Both cams have 110lsas which will bleed off cylinder pressure at low speeds. I think the XE268 would work fine. If you can, put the heads on the block with no pistons or crank. Scribe a line around the cylinder bore. Then roll back the chamber to the scribed line. That will improve flow at low lifts and also add about 2 cc of chamber volume. Get a loose converter and play with advance curve and you should be ok.

 

Thanks for the replies fellas. Will my stock rear hold up to this combo (91Z w/3.23)?

 

for a little while. It depends on how you drive it. the old 7.625 inch ring gear is stronger than people think, but it will crater evenutally.

 

My recommendation would be the Comp Extreme Energy XE 274 cam. You will need to bleed off some cylinder pressure with the cast iron heads to keep it away from detonation. The cam though is only one part in the combination. The quench area is one other important area. If you are not familiar with this term, it is the area between the deck of the cylinder head and the top of the piston at TDC. The ideal quench is .040".
Also in my opinion the Edelbrock Performer manifold will kill performance in that motor. Go with the Performer RPM!

www.geocities.com/dzperf

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D&Z Performance
"Putting Power to the Pavement"

 

trouble with the 274 is that it will probably cause retainer to guide problems with stock vortec heads. The lift is .49 I think, thats pushing it a little.

 

i will probably be running vortecs on my wife's 383 and i would like to know what rockers i have to use. i am also planning on using that xe274, i think the stock valve springs will hold up. please advise me as to rockers and guide plates.

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88 S10
Dropped 5/5
18" Boyd Coddington Timeless 5s
406 balanced with 6" Eagle H-beam rods, 10.25:1 JE SRP pistons, Comp 284XE cam; 240/246 @.050, .507/.510, Dart 200cc Ironeagle heads, Victor Jr. intake, Holley 750 vac sec.
12.20 @ 115.25 mph

 

The issue on the Vortecs is not the springs, it's the guides. They're so tall the bottom of the retainers hits them.

The 274 will probably not work on them. Although, you could get some .050" offset keepers and some .050" shims, and then it probably would... but I believe it would still be wise to put some real valve springs in there if you intend to put very many miles on this motor at all. Remeber, those are replacement truck heads, in GM's eye they're just service parts for broken trucks, not performance heads.

I had that cam in my std bore 400 and really liked it. I'm sure it will work just as well in a .030" over one. I have a XR282HR in it now, which I like better. I also have heads that will support some lift, so I have better springs and 1.6 roller rockers on it.

Those heads do not come set up for guide plates. Remember, they're not performance heads, no matter what the flow #s are; they're replacement truck heads. So, to run them without machine work, you need self-aligning rockers. Comp makes some steel 1.5 SA roller rockers now, those would be the best bet.

Many people have experienced severe valve train damage at valve lifts over .480 or so with those heads. Exceed the limit at your own risk, the odds aren't very good.

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"So many Mustangs, so little time..."
ICON Motorsports

[This message has been edited by RB83L69 (edited August 13, 2001).]

 

thanks for the advice rb. maybe i will use the xe268. this is not going to be a race car or anything, so the 268 is probably a better bet for someone without a lot of experience with hotrods.

so, i just buy the sa rockers from comp and bolt the heads on? i am planning on getting them from paceparts drilled for the old intakes.

 

this might sound way off, but another combo i did recently to get rid of detonation was an L82 (late 70's early 80's vette engine) cam. it's specs are almost identical to the LT1 cam. check it out. it can also be gotten from summit, jegs, even local autozone. this was put in a 10.9 to 1 355 with cast iron heads and no problems since putting it in as long as he gets good gas and stays with 92 octane and more. anything less pings, but it works.