OK, it started out buying everything for my 455 rebuild at one catalog who said I should use a 270H Comp cam. Heads are 6X-4 converted to bog valve, new ARP studs, Comp 995 springs and roller tip rockers 1.5s. Then, Comp said to send them back the cam it was not right for my engine and sent the XE 268H to me. Now, I am reading in Jim Hands book and looking at other engines where the Comp XE 274H is used alot.

Question: Before I install this new engine I can swap to the XE 274H like I see so much of. Keep the XE 268H I have (No Want A wuss engine) Or buy something else. Also, heads were never ported, just cleaned a little. Pull the heads and send to Spots for port work is an idea also. Engine was going in a first Gen Bird but now a 66 Le Mans. And my point being? Simple, before I install the engine I want a good Cam that will produce enough Vaccumn to supply brake booster. And, sound tough and run strong on a street engine. Carb for now anyway is sitting in a box and is a BG Speed Demon 750, with an RPM Performer Intake, and headers yet to be decided maybe using the RA ones by Company Who makes the nice ones. Or, Maybe DOug's. So Come one ya guy's you've helped for all the other stuf I had questions about. It's sure was a good way to learn that next time I'm ahead having someone good build it from the cround up for me. Nope, I can't do it myself because I'm blind and will be driving the car in really wide open spaces only. But, driving it hard. Thanks, and choices for the best Cam will win my vote and order it in the next few days. I, listen, debate, listen more, and then order now that I have gone through this. By the way, never listen to someone who's a salesman but not a user for the thing's they sell. < Mike >

OK, it started out buying everything for my 455 rebuild at one catalog who said I should use a 270H Comp cam. Heads are 6X-4 converted to bog valve, new ARP studs, Comp 995 springs and roller tip rockers 1.5s. Then, Comp said to send them back the cam it was not right for my engine and sent the XE 268H to me. Now, I am reading in Jim Hands book and looking at other engines where the Comp XE 274H is used alot.

Question: Before I install this new engine I can swap to the XE 274H like I see so much of. Keep the XE 268H I have (No Want A wuss engine) Or buy something else. Also, heads were never ported, just cleaned a little. Pull the heads and send to Spots for port work is an idea also. Engine was going in a first Gen Bird but now a 66 Le Mans. And my point being? Simple, before I install the engine I want a good Cam that will produce enough Vaccumn to supply brake booster. And, sound tough and run strong on a street engine. Carb for now anyway is sitting in a box and is a BG Speed Demon 750, with an RPM Performer Intake, and headers yet to be decided maybe using the RA ones by Company Who makes the nice ones. Or, Maybe DOug's. So Come one ya guy's you've helped for all the other stuf I had questions about. It's sure was a good way to learn that next time I'm ahead having someone good build it from the cround up for me. Nope, I can't do it myself because I'm blind and will be driving the car in really wide open spaces only. But, driving it hard. Thanks, and choices for the best Cam will win my vote and order it in the next few days. I, listen, debate, listen more, and then order now that I have gone through this. By the way, never listen to someone who's a salesman but not a user for the thing's they sell. < Mike >

Mike,
XE274H is parametrically similar to Ram Air IV (041). It employs XE technology, which is one of the better designs for "low" compression (under 10:1) engines. It has a similar power band to 041, while having better low-speed behavior. It also makes ample vacuum for power brakes.
Rather than trying to build an engine from catelogs, consult one of the "gurus" for a "package". That is, use a known combination that will achieve the power and drivability you require. Jim Hand's book has several good outlines for engine builds, including some of ours. You could find a combination in there, to meet your needs.
I hope you're a youngster, regarding your statement about sales people and what they well. This was a lesson learned MANY years ago... Maybe it was that I grew up in "the land of milk and honey", and knew as a child, they were just blowing smoke, hoping to get a slice of "my" pie.

Jim

I got the XE274 in my 400. Its great has quite a bit of lope which is what I was looking for. I'm not sure what it will do in a 455 as far as idle quality but I'm sure it will pull hard.

Mike,
I recomend the XE 274 to people who have 400's and it's a good cam for that but you need a bigger cam than that in a 455.

at the very least the Crane 280

Jeff

Comp makes an XE284, you could try that one.

Hi,
You did not mention your transmission type nor rear gear ratio. These are important considerations. I have just finished building a 455 with a XE268H cam. I have a wide ratio four speed and 3.55 rear gears.
Generally, the more duration a cam has, the higher the useful rpm band is.
What do you want the engine to do? Low end power, high end speed, etc.
I've read a lot of posts and topics on the subject on this forum. I think that I have made the right choice. The XE268H should be close to the Pontiac 068 cam.
Good Luck.
Mike
I hope to get the engines swapped over the holidays.

Chris,
I don't have the 284 myself but I have run it on two desktop dyno programs and believe it or not the numbers are pretty dissapointing.

That's why I recomended the Crane instead.

Jeff

I am running the XE 274 in my 455 powered 4000 Lb 1977 TA. The cam produces good vac. And has nice Idle at 800 RPM. I can idle it even lower but idle gets a little rough in gear. Power is good from off idle to about 5500 rpm's. My engine is only running about 8.5-1 Compression, and I really like the cam. I am planning a head swap to get compression up to 10.0-1 and adding some better head flow numbers. Im really wondering how much more power I am going to be making by adding 1.5 more points of compression and some good flowing heads. Im just curious how the cam will perform with the added compression seeing as how its designed to function well with low compression. I may have a used XE 274 in a few months, If i decide that i would be better served with a larger cam due to the compression and head flow. Any one out there running a 4000lb car with an XE274 in a 10-1 compression 455??? If so what kinda times you putting down.
My TA ran 13.26@101 mph last time out, with fuel and timing issues, but pulled a 1.82 60' which isnt too bad for a 4000lb sled from what I understand. Should be in the 12s next time i hit the track, since i have corrected the fuel and timing issues.
Mike

Jeff,

Just Curious, how did the desktop dyno compare the XE284 to the XE274?

Once you go past around 230-234 degrees duration at 0.050" on the intake, you will only go SLOWER unless you install some serious gears & stall speed.

I've ran as quick as 11.59 with just 231.

Hey Chris,
I did the compairson a few months ago for a guy here and I was recomending the XE284, when I put it on desktop dyno it came down on power by a few...I'll run it again if you like and this time I'll use Mike's (RR67GTO) engine as the example.

LouisianaGuy,

That cam will be fine with more CR as my friend has it in a .030" over 400 with E-heads and he's about 10.5:1...a bigger cam would serve you well.

I disagree with Lee as I'm running a 455 with a 242/[email protected] roller cam and my gears are 3.31's but I do agree with him on stall speed as I'm yet to install a good converter and it affects my 60 ft's 2.200...very bad but so far doing 13.0@ 110 mph

Shaker,

I failed to to mention, but the durations I mention are ONLY for flat-tappet hydraulic cams. IMHO, the "@.050" durations are NOT directly comparable between solid & hydraulic and flat & roller tappet cams.

Sorry Lee,
Yes your right...I blew right over that..
thanks.

Chris,
I got your email...would you like me to post the dyno results of your engine?
Jeff

shaker455,
Would you be willing to run the numbers on your desktop dyno for the engine I just had built?
455 +0.30" for 462 CID.
2-bolt mains with balanced rotating mass
Comp XE268H hydraulic cam and lifters.
CR= 9.34:1, flattop pistons with cutouts for valves.
Cast #15 heads w/ 1.96" Intakes and 1.77" exhaust. Gasket matched intake and heads ports.
Cast iron stock intake, 700-750 cfm Q-Jet.
Log exhaust manifolds with 2.25" pipes.
I'm interested from idle to 5200 rpm for HP and torque.
Thanks,
Mike [email protected]

Sure, I'll post it next

Hi,
Great, I'll be looking forward to it.
Thanks,
Mike

Jeff, did you get my response to your e-mail?

Mike, (runningbwdog)

Here's what I got with just the info you supplied as I could not find any other info on your # 15 heads w/ 1.96 intake valves...kinda small and big exhaust valve 1.770:

RPM scale starts at 1500rpm and ends at 5500rpm

Hp Tq
115 403
166 435
213 447
262 459
309 464
333 437
341 398
324 341
285 273

Jeff