Who has a Comp Cams Xtreme Energy XE250H Cam

#21
Anyone read that awesome article in Popular Hotrodding about how cams work and how to choose one? I'll see if I can find them, read um over and give you the jist of what the guy was saying about them.

The 1.7 rocker was something the guy said was good because it accelorates the valves open faster, meaning more time with higher air flow through the head. Makes a cam look like a bigger one.
 
#22
jikelly said:
Anyone read that awesome article in Popular Hotrodding about how cams work and how to choose one? I'll see if I can find them, read um over and give you the jist of what the guy was saying about them.

The 1.7 rocker was something the guy said was good because it accelorates the valves open faster, meaning more time with higher air flow through the head. Makes a cam look like a bigger one.
Click to expand...

I read that article and loved it
 
#23
ashford said:
a smaller cam dosent always mean better gas milage. in my falcon i had a 289 with ported heads and a crane 270 grind in it. in town it got about 14 mpg town and 21 on the highway with an auto. i blew it up(!$%#@$&) and decided i didnt need power for a cruiser and built a 302 with the same heads and went for a "economy"(245 grind)with a t-5, with very dismal results. 15 mpg town and 17 highway. it had absolutly no power at all, and wouldn't turn past 4000rpm. i eventually just dropped in a 5.0 HO fuel injection and all. 16 in town 19 on the highway.

on the other hand i have my capri. my last configuration(havn't done gas milage with new motor) was a roller 302 ported early 289 heads with 1.92 1.50 valves, e303 cam,625 road demon, t-5 and 3.08 gears. hold onto your pants here 6-8 mpg town 32mpg at 80mph a/f gauge in the green.
Click to expand...

how did the e303 sound?
 
#25
jikelly said:
Anyone read that awesome article in Popular Hotrodding about how cams work and how to choose one? I'll see if I can find them, read um over and give you the jist of what the guy was saying about them.
Click to expand...


Do you remember what issue that was? I would love to get a hold of it and check out the article.
 
#26
bad68coupe said:
From what i understand there is not beniefit of going full roller other than it is more stable at higher rpm's which i will only flirt with once or twice, why do you say to go full roller? what would be the best combination for gas milage, because when you think about it gas milage is nothing but effeciency, and when the engine is effecient it is also making power, i figure that up to a point they go hand in hand. I am just trying to do it right the first time.
Click to expand...

Roller cams are definetly NOT for a high RPM application. In high RPM's roller lifters will tend to float your valves. This is why when shops build race motors which will see a lot of high RPM (above 6500) they will never use roller lifters. Take NASCAR for example, their motors are built to hit 10K RPM they use solid flat tappet lifters. Now that may be a NASCAR rule that they use flat tappet lifters but in other applications like Daytona Prototypes this would not be an issue yet they still elect to use the flat lifters. Because of their very high tech use in these two applications I certainly wouldn't call them "old technology" but they certainly have been around longer. But they still have their uses.
To answer your question about when to use them and if they are more efficeint, they are more efficeint and allow for a steeper ramp on your cam. Full roller motors will also run cooler since there is less friction within the motor which causes heat. Not to sound like a commercial but heat will help to break down your oil. Now most of us change our oil on a regular basis so this is not much of an issue.
To sum up a really long discussion about all this, roller motors tend to last longer if you don't abuse them.

Hope that helps and answer your questions.
 
#27
Sharps-Nut said:
...My question now goes to 67topless whis runnning the cam. Is it at all choppy at idle?...
Click to expand...

I think it has a great idle (personal prefference of course), but probably not what you are looking for. It sounds lilke there is something going on under the hood, but doesn't sound like a dragster either. I can send you a link to to a dyno video that progresses from idle to WOT. Gives you a good idea of how it sounds sitting at a stoplight...

Scott
 
#28
I really don't think there is an engine builder in racing that would use a flat tappet if the rules don't require it. Hydraulic rollers are not much help for a mild cam. When rpm and spring pressure get high, there is a definate advantage. I have seen stock flat tappets go over 200K miles enough times to doubt that friction and wear, though present, are what kills motors or even present much friction. To run a HR in a non-roller block will cost plenty as well. For new parts including cam, lifters, springs and push rods, you will be nearing $900 or $1000. Call Comp Cams and get them to help you with what you need.
 
#29
Just finished my cam install - comp cams XE274H. Here is a video of it running w/ open headers. Sounds pretty mean now. We'll see w/ the mangaflow installed.

http://s65.photobucket.com/albums/h...current=tide015.flv&refPage=&imgAnch=imgAnch1

(this was cold start w/ no choke so it wanted to stall and it was hard since I had to keep the rpms down for the neighbors sake)

This one is w/ a basically stock engine and worn no-name turbo mufflers...
http://s65.photobucket.com/albums/h...rent=Picture069.flv&refPage=&imgAnch=imgAnch2

Trevor
 
#34
I am of the opinion that you should ditch the 289 and get a $100 junkyard special 5.0.

Used GT-40 heads, cobra intake, e-cam.
With 3.73s and a t-5 these motors typically get 17-18 around town and 25ish on the highway. Or stick with the stock cam and run 1.7 rollers . . . slightly better mileage. Put down 260rwhp 290rwtq.

If you want to stick with the 289, I would go with the xe256 if you want to stay comp. Port the heads or find some $500 big valve, screw-in stud 351 D0OE heads on EBAY. It seems like everyone has a set nowadays. You will have to mill those . . .

At any rate, you will need overdrive. Mileage and power do not mix with a c4.
 
#36
Yes 351w heads will fit, not sure about 351m or 351c heads, but (there is always a catch) you will need different head bolts since the 351 engines use head bolts that are a larger diameter around. So your bolts will be to small.

I have seen adapter bolts for the 302 engine so you can use 351w heads from ARP.
 
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