First Generation Firebird-L Mailing List
.........................................................................
Mike / Kelly,
I agonized over my cam selection - as aI always do - (and even e-mailed Jim
Hand). In the end I went with a Crower 60243 grind. Here are the specs as
compared to your XE274
Crower 60243:
Duration at .050: 228/235
Lift: .479/.494 (but I have 1.65 rockers s probably
more like .520/.540 for me)
LSA 112
Comp Cams XE274:
Duration at .050: 230/236
Lift: .488/.491
LSA: 110
As you can see, these two cams are in a similar ballpark. A lot of the
answer to your question probably lies in the rest of your combo.
My combo is:
67 Firebird Convertible (aka - heavy)
TH400 with BOP GM25 converter
3.08 or 3.23 rear gears - man I'm embarassed I cannot remember which one!
Motor is:
455 bored .060 over - ie.. 468 cubes
9.5:1 compresssion (maybe a tad more...pistons are positive deck)
SD Performance ported 6X-8 heads (chambers cut to reduce compression) - 260
cfm flow
Crower 60243 hydraulic cam listed above
Cat stainless 1.65 rockers
Cheesy headers (new ones are still in box)
Holley 750 cfm 3310 with Vacuum secondaries
Normally, I would have honestly gone with a smaller cam for a street driven
cruiser for my combo above, but I wanted to maximize my ported heads. If I
had it to do over again I probably would go with a smaller cam - maybe
something in the 224/226 duration range. Day one my combo felt a bit doggy
with part throttle driving, etc. However, some carb and ignition tuning did
wonders for it. I played with the weights and/or springs in my HEI
distributor and got the advance to come in where I wanted it and further got
the vacuum secondary spring kit from Holley and adjusted that.
Unfortunately, as soon as I rebuilt the motor and did the tuning I parked it
in preparation for the paint and body phase (that was 2...or was it 3) years
ago!
The morals of this story (as always) are:
1. The combination is key
2. Better to under cam than over cam
3. Carb/Ignition tuning seems like black magic, but most of it is pretty
straight forward and can do amazing things
As an aside (and related to tuning), my TH400 shifted way too early when I
first got the car and I ended up installing the B&M governor kit to get the
shift points right...another huge improvement.
Regarding the XE274 I believe the ramps on that cam are pretty aggressive
and account for a lot of the good feel some folks have with that cam. It is
still pretty big, and certainly a lot of folks have it. A 4-speed car will
absorb that cam a bit better than an auto...would probably pair it up with a
mild stall in an auto for sure.
Oh and Jim Hand recommended a smaller cam for my combo as well...
I'm sorry...what was the question again?
Later,
Chris
----- Original Message -----
From: "Kelly R" <[email protected]>
To: "'First Generation Firebird-L'" <[email protected]>
Sent: Friday, July 24, 2009 11:52 AM
Subject: RE: [FGF] Comp Cam Inquiry
First Generation Firebird-L Mailing List
.........................................................................
Too late for me to change my mind now. The turd is already buttoned up
inside my motor. ;-) I have heard the RAIV is great for 400's but that the
additional cubes makes it milder in a 455. what do you like for a 455?
I saw the XE274 mentioned a few times in 455 recipes in Jim Hand's book
and
he comments well on it except it being a rougher idle (which I like) so
that
was why I went with it.
What cams have the rest of the forum members used in any 455's? good, bad,
or ugly.
Kelly
http://www3.telus.net/public/68bird/
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Joe Paoletta
Sent: July 22, 2009 8:16 PM
To: 'First Generation Firebird-L'
Subject: RE: [FGF] Comp Cam Inquiry
First Generation Firebird-L Mailing List
.........................................................................
I hate to say, I used the XE 274 in my last 400 and it was a turd.
Used a 4 speed and 3.90's
The RA IV is a MUCH better cam. Lots of mid range and tough idle.
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