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

OK, now I hope that I didn't just spend 5k + on an engine that gets a best of about 285 HP. Now when I could have bought a Cheeby box engine with 330 HP for what, 2k?? Tell me it ain't so Joe !! These numbers are not what I was thinking his engine would do. Considering it's pretty close to what I'm almost done building. < Mike > http://forums.performanceyears.com/g...icon_smile.gif

RR67GTO,

Those are not your numbers...there for runningbwdog.

I'll do you engine today.

Shaker455,
Thanks for doing a desktop dyno on my engine combination. I have a couple of questions.
Is this rearwheel hp? I'm a little surprised because the factory rating for this engine before I had it rebuilt was 360hp. Of course, that is at the flywheel with no accessories. The new standard gives lower numbers.
Would RAM Air style exhaust manifolds and 2.5" exhaust pipes up the hp and torque numbers.
Thanks again,
Mike

Mike,
The numbers are at the flywheel or back of the engine not at the rear wheels.

I used HP mainfolds and exhaust on your set up to get those numbers.

What's holding you back is your funky valve size and you could use headers...

Jeff

RR67GTO,

Here's your dyno numbers:

I could not remember how many cc's 6x-4's are ( some where between 91-96 cc's) but I used 9.5:1 for a CR and I used small tube open headers, first is with the XE-268 then XE-274.

Flywheel hp & tq

Hp 367@ 4000
Tq 507@ 3500

Hp 399@ 5000
Tq 509@ 3500

Thank you very much for the numbers. It looks like the 274 would be worth the extra time. And, if I had the heads ported and done well it should put me in the 400 HP range which is not bad for an old guy like myself. http://forums.performanceyears.com/g...icon_smile.gif

I'm also happy now that I decided to have the valves changed to 211 x 177 because I'd be looking at doing a complete new set of heads after learning more that I knew back then. Again, thank you very much. < Mike in Oregon >

No problem Mike

Here's 6X ported w/XE268 then XE274

Hp 406@4500
Tq 529@3500

Hp 437@5000
Tq 528@4000

Shaker455
I wonder if you could run the numbers on the 455 I am now building for my 67 firebird
Balanced stock rotating assembly
211/177 heads that flow @ 265/215 @ .500 lift
SRP pistons approx. 9.5/1 comp.
Comp hydraulic roller ground to 230/236
1.5 full roller rockers
Edlebrock Performer RPM
Speed Demon 850cfm annular carb
Have not got headers yet but will be 1.75 4 tube type with either 2.5" or perferably 3" x-pipe exhaust any recomendations on headers for a first gen bird?

That's a nice set up and I really like the flow of the heads. HAve you decided just where your going to keep this beast yet? I tried using a RPM intake under the hood of my 350 car after I had the first engine swapped for a warmed over 67 400. I learned how to put a dent in the hood from the inside out. http://forums.performanceyears.com/g...icon_smile.gif And then, one of the good people here told me how to use a couple of empty toilet papper rolls. BY placing one inside the other and sticking them over the air cleaned bolt (without the cleaner attached) when I closed the hood the two rolls would collaps on inside the other and when I opened the hood I could look at the rolls and see how much room I had. It was, far less that I would have thought. And because the RPM intake is a bit taller than the normal one A drop down air cleaner did the trick. But, that also meant having to use a manual choke. No problem, because soon I tired of the 400 in that light car and had a desire for an even bigger engine. That's why I first decided to build the 455. However, I came across a beautiful clean rust free Southern California Le Mans, and I changed my plans for the engines new home. I still own and drive the Bird, and ya know what? In the seven uears I've owned that white 68 Bord it's to only car that I have new or old that has never failed to start. And, get me there and back home again. I've collected so many emblyms and other small things for it since owning it I have a shelf ful of them. I'm a true first gen bird man and also own a high optioned 68 400 vert that's just getting done with a real frame off resto after having a real good frame on in 1997. Also decided to use much more of the nice aftermarket goodies on it this time around so it drives as nice as it looks. By the way, on the white 350 (now 400) white bird I own. I toook a set of 69 rear side marker Bird lights and mounted them in each of the front grills as front parking lights. It looks real cool, and before doing it with a set of decent grill inserts I tried it using a set of bad ones I had. Now, it not only has lights, it also has Firebird eyes, as my youngest Daughter calls them. And why they don't make some decent turn/driving light lenses for the 68 I don't understand. Parts are still a bit hard to get, and decent after market fenders are zilch. I tried two of them before going back to having a factory one cut and patched. Anyway, I would like to know how the car deals with the new engine when you install it. I have a new rear I had built for the 455 going in the Bird but it's never been nounted because the engine didn't go in. 71 Nova with welded tubes, new Eaton and NOS 3.23:1 gears built by a locla shop that does nothing else and has been in the same place for over forty years. Good day, and best wishes to all. < Mike from Oregon >

I'm keeping it under a 400 hood with a drop base and 3" filter but would like to do ram air setup may have to get a tall 400 hood need somone with experience with this stuff (ram air). Also really need to know what headers are best I have been looking at Doug's headers. Also are there any resonable aluminum radiators out there.

Hi shaker455 I have always wounderd how much hp & tq mine would show on the desk top dyno I have a 400 with fully ported heads xe274h cam 9.5.1 comp, rpm intake, headers, carb set up by the carb shop , dist set up by larry row. that is if you don't mind. Thanks alot Loren

Yeahhhh, that's more what I'm looking for. So now, I know what I need to get there. Sure I can run the engine as is and see how I like it. But, the season is over here for a while. Oe reason is I need to replace all that dired out S.Cali weather strip on the car because we get a lot of rain here. So, I can go for the few upgrades, have the heads ported and install the new cam. And, get the car ready for the spring by doing the weather seal and doing some upgrades with having the posi built (I already have everything ready to go) and replace the worn parts below the paint job. Thank you very much for taking the time to run the numbers for me. Good day friend and also the rest of you. And, of course your families as well. < Mike in Oregon >

Happy T day to you all!

455earlybird and macho t/a,

I'll be glad to run some number for you guys!

455early,

I need all of your flow numbers...not just there peak..also I need all the specs for your comp roller or give me the number and I'll look it up on there site.

What is your bore size and what heads are you running?


Loren,

I need more info from you as well,

Bore size, head #, head flow numbers,carb size,

thanks
Jeff

hey, here is your flow chart

wedge intake valve flow chart

port No : 2

valve dia : 2.110

gross valve area : 3.497

stem dia : 0.341

gross stem area : 0.091

net valve area : 3.405

first intake flowscale value : 150.0

leakage% : 0.0%

test pressure : 28

(L/D) ratio 0.05 0.10 0.15 0.20 0.25 0.30 0.35

valve lift 0.105 0.211 0.316 0.422 0.527 0.633 0.739

test flowscale 150.0 298.0 298.0 298.0 298.0 298.0 298.0

flowscale adj. 149.6 297.1 297.1 297.1 297.1 297.1 297.1

flowmeter 0.840 0.580 0.740 0.860 0.890 0.900 0.900

total flow cfm 125.6 172.3 219.9 255.5 264.4 267.4 267.4

leakage cfm 0.0

test cfm 125.63 172.33 219.87 255.53 264.44 267.472 267.42

test cfm/in 36.89 50.61 64.57 75.04 77.66 78.53 78.53

potential cfm 22.76 45.68 68.61 78.65 84.00 87.51 87.51

% flow rating 162.1% 110.8% 94.1% 95.4% 92.4% 89.7%89.7%

This is the Correct Exhaust Valve Flow Chart

port no : 3

vlave dia : 1.770

gross valve area : 2.461

stem dia : 0.341

gross stem area : 0.091

net vlave area : 2.369

first exhaust flowscale value : 158.0

leakage% : 0.0%

test pressure : 28

(L/D) ratio 0.05 0.10 0.15 0.20 0.25 0.30 0.35

valve lift 0.089 0.177 0.266 0.354 0.443 0.531 0.620

test flowscale 158.0 158.0 318.0 318.0 318.0 318.0 318.0

flowscale adj. 158.4 158.4 318.8 318.8 318.8 318.8 318.8

flowmeter 0.410 0.750 0.510 0.590 0.670 0.700 0.740

total flow cfm 64.9 118.8 162.6 188.1 213.6 223.1 235.9

leakage cfm 0.0

test cfm 64.94 118.78 162.57 188.07 213.57 223.13 235.88

test cfm/in 27.41 50.14 68.62 79.83 90.14 94.18 99.56

potential cfm 22.76 45.68 68.61 91.87 97.89 100.57 100.57

% flow rating 120.4% 109.8% 100.0% 86.4% 92.1% 93.6% 99.0%

the carb is a 750 cfm q jet the heads are 6x-4 I now this more than you need just making sure I give you the right info Thanks Loren

also I have 1.65 rockers thanks Loren

Loren,
Sorry my friend wrong info!

I need yourflow #'s per .100" lift...here's an example:

Intake lift flow
.100" 86
.200" 155
.300" 200

Every # you can give me for intake and exhaust ..

I'm lost All I know is whats on that flow sheet I'm not to good at all this stuff yetI will have to get some help to find this out.

all i was told was they flowed 267 at 600 lift when I bought them. sorry wish I knew.

Don't bother,
I'm just going to have to print off your info and decode it for a loss of proper words...LOL

But I see some of the numbers I need there just not in the right order and it look like they did not use a standard lift number like .100"-.150-.200 etc

looks like they went .105-.211 etc and it look like the total cfm list is your flow....ripping my hair out now!...LOL..I'll get it for you

I need you bore?

.030 over? head #? carb size?

Sorry Just your bore size?

I see you gave me the rest...for now I'll guess you .030" over and use those numbers

and I have you flow info

sorry about that it's .030 over Thanks Loren

Desktop dyno is a great tool but needs to be used precisely for best results.

For example, induction flow is not neccessarily equal to carb CFM. It is a measurement of everything from the cylinder head's intake port to the air cleaner. This number becomes more important with larger displacement engines. Jim Hand's book contains some measurements of the percentage losses involved with particular intake manifolds.

Also, the compression calculator is pretty slick but you need to know many specifications to get it right other than to just plug in 10.5:1 or whatever.

My biggest issue is the lifter type menue which extrapolates the shape of the cam lobe based on assumptions made about the type of cam selected. With cams like comp's XE series and Ultradyne around, can the lift rate on those be assumed to be the same as those used on the O41 cam??

What I would like to see with these vendor's who make recommendations and sell all of these cams, step to the plate and put these cams under the dial indicator and give us cam specs every .050 and host them on this site in a data base. Everyone would be able to compare and make decisions based on complete information.

Macho t/a,

Here's your results!...I like it!

Pk flywheel Hp and Tq using headers & open exhaust

Hp 532@6000
Tq 534@4500

Here' the the whole scale from every 500 rpm from 1500-6500

107 373
159 418
203 426
334 501
401 527
457 534
502 527
529 505

Shaker455
My cam is a comp cam that Jeff Kaufman is turning to 230/240 @.500 with a 112 degree lobe seperation it is a custom grind so I can't find other info but it should come with the cam. The cam seems to be right between a xr276hr and a wr288hr but as I said the lobe seperation is 112 unlike these other cams. I just don't have it right now I was hoping to have it any day. Also my engine is bored .030 over to make it a 462 approx. My flow at each .100 of lift are as follows intake 93@100 165@200 210@300 242@400 265@500 And 267@600 the exhaust side flows 59@100 130@200 158@300 180@400 195@500 and 200@600 Hope this is enough info

Oops...clicked too early

532 466
504 408

Formula8,
Yes I know what your saying, I have 2 dyno programs, Dyno sim and engine anaylzer, they serve as a goo reffreance not as an exact number.

Okay 455early your next

thanks alot thats pretty kool the guy that I copied off of had his on a dyno and said it had 476 hp 529 tq but he had 1.5 rockers and just street ported heads. so sounds good to me know that 175 shot nos I got should be plenty for a street car. Again thanks alot good people are hard to come buy but seem to be alot on this forum.

Sorry about the long user name I had signed up earlier as earlybird but then later when I went to log on there were pasword problem so I had to change my name. Thanks for all your help. Have a great holiday. By the way how do you put a picture of your vehicle on the forum and the other info under a responce I'm somewhat computer iliterate or if I spelled the word wrong maybe im just (owell I can't spell the word).

455earlybird,

The flow # are good but I need more info...sorry

whats the lift on the cam and the intake centerline?...comp is usally 106

And you first posted 230/236 then you posted 230/240?...is 230/240 right?