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Topic Review (Newest First)
08-15-2012 02:09 PM
Mr. P-Body cridder,

First, note the date on the thread. It was "dead" before I ever came around here... (:-

XE268H has a little less duration than 270H. BBCs have exhaust ports that could be considered a little TOO "good" for the intake. That is, the balance of flow is a little lop-sided to the exhaust. So, it goes to follow, a cam with a little more intake duration and less exhaust duration WILL make more power.

That said, the XE cams (the smaller ones like the XE268H) are more for "low compression" drivers. The XE268H will work well in a 427-up with a stock torque converter. These cams are for a different purpose than the Magnums. We DID build a 396 a few years back with a solid roller XE grind. A 3,700 lb,. Chevelle went 12.10s with it. Oval ports, 92 octane. Good runner!

The point? XE cams have their place in the "pecking order". Good stuff when used "as intended".

Jim
08-14-2012 11:40 PM
Cridder
BBC ex268

Quote:
Originally Posted by curtis73 View Post
I like comp's cams. I have heard all kinds of comp bashing but I assumed it was a Ford vs Chevy type of argument.

I have a Comp XE268H in my BBC and love it.
Im running the same cam in my BBC 461 with heavly reworked 049 heads and big tube headers and i dont think it makes as much power as the 270 magnum that it replaced.
Im not so sure the 268 is the best choice for free flowing heads and 2 1/8" headers as i think it may be over scavinging with the much longer exhaust duration. the 268 makes 488 horse in a 454 HO crate motor, i should have 500 horse but i wonder.
What are you running for heads?
04-07-2010 07:15 AM
SSBlazer
Quote:
Originally Posted by Custom10
Was this preload procedure done to 1/8 turn with the engine hot or cold? thanks

It should't make a differance with hydralic lifters. I adjusted them with the engine cold. I used the #1 firing, rotated the crank 360, & then adjusted the rest.
04-05-2010 05:18 PM
6426yy I'm running a Comp 4x4 XE 270 cam in my 454 and it is nice and quiet.... The valve train anyway.
04-05-2010 10:39 AM
techinspector1
Quote:
Originally Posted by gongsi1234
comp cams XE cams

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图片代码


i saw a thead where someone use one of the XE cams from comp and had all kinds of valve train noise, and then a bunch of guys replied with post, baching the XE line, i had plans on putting the XE274 cam in my 385 but now im second guessing my self, i dont want all kinds of crazy valve train noise that makes the motor sound like crap

is this a cam i should stay away from?

if so what are some other cams that will work well with a 385, cast crank, scat rods, kb 18cc dished pistons, 0 deck with 200cc/ 64cc/ 2.02/ 1.60 heads?

the car is 3450lbs with driver, street/strip, 4.10's with beefed up 700R4
Your static compression ratio is 9.75:1, so most any cam with around 225 to 235 degrees duration @ 0.050" will work well. Personally, I don't like the extreme cam grinds as I feel they apply excessive pressure at the lifter/lobe interface. I also don't care for increased ratio rocker arms for the same reason.
Here is an example of a hydraulic flat tappet cam that I might choose for your motor, that is if I were going to use a flat tappet cam. I refuse to use anything less than a roller camshaft any more due to all the flat tappet failures I see and hear about....
http://www.summitracing.com/parts/HRS-112031/
A roller hydraulic like this one might be a close choice....
http://www.summitracing.com/parts/HRS-110325-08/
WARNING: you should always counsel with the technician at the cam grinder's place of business for a recommendation before you purchase a camshaft for your motor.
04-05-2010 10:13 AM
Custom10
Quote:
Originally Posted by SSBlazer
I have a 94 chevrolet truck with a TBI injected 383 with the Comp Cams XFI & lifters. I have had valvetrain noise issues since day one. Ticking noise/sewing machine noise that seemed to get worse when the engine was warm. I first adjusted the preload at 1/2 turn. It was quite when the engine was cold & then slowing start making the sewing machine sound. Then I readjusted them to 3/4 turn but the noise was louder so I backed them down to 1/2. The noise was never there when the engine was cold. Then I found this http://www.compcams.com/v002/Instruc.../COMP4-115.pdf. I adjusted them again but at 1/8 turn. No noise. Some mornings I will hear one or two that will tap for about 3 seconds. I will make sure that I read the instructions first from now on. I hope I didn't mess anything up. Only time will tell.
Was this preload procedure done to 1/8 turn with the engine hot or cold? thanks
04-05-2010 02:44 AM
gongsi1234
comp cams XE cams

comp cams XE cams

--------------------------------------------------------------------------------<a href="http://www.ecplazazone.com " title="连接名"><img border="0" src="http://图片地址" width="862" height="266" alt="图片名注释">图片名</a>
图片代码


i saw a thead where someone use one of the XE cams from comp and had all kinds of valve train noise, and then a bunch of guys replied with post, baching the XE line, i had plans on putting the XE274 cam in my 385 but now im second guessing my self, i dont want all kinds of crazy valve train noise that makes the motor sound like crap

is this a cam i should stay away from?

if so what are some other cams that will work well with a 385, cast crank, scat rods, kb 18cc dished pistons, 0 deck with 200cc/ 64cc/ 2.02/ 1.60 heads?

the car is 3450lbs with driver, street/strip, 4.10's with beefed up 700R4
04-04-2010 09:49 PM
SSBlazer I have a 94 chevrolet truck with a TBI injected 383 with the Comp Cams XFI & lifters. I have had valvetrain noise issues since day one. Ticking noise/sewing machine noise that seemed to get worse when the engine was warm. I first adjusted the preload at 1/2 turn. It was quite when the engine was cold & then slowing start making the sewing machine sound. Then I readjusted them to 3/4 turn but the noise was louder so I backed them down to 1/2. The noise was never there when the engine was cold. Then I found this http://www.compcams.com/v002/Instruc.../COMP4-115.pdf. I adjusted them again but at 1/8 turn. No noise. Some mornings I will hear one or two that will tap for about 3 seconds. I will make sure that I read the instructions first from now on. I hope I didn't mess anything up. Only time will tell.
03-22-2010 05:08 PM
Fast 4 Door First I want to thank EVERYONE for keeping this thread alive. I Like to get as many opinions, facts, and true experience before I make a decision on how to help or correct the issue at hand. From what Info I have gathered both from this thread and from locals, I have come to the conclusion that..

1 - as far as lash adjustment goes, Less is more , even if it is a bit noisy. So I am going to leave it at 1/2 turn.

2 - The noise is typical of my particular setup.

3 - I am going to try a different wt. oil

4 - It runs great, lots of power, if it ain't broke, don't fix it.

And last, PLEASE, if you have more to add to this thread, add it

Thanks again
03-22-2010 09:38 AM
Custom10 I have the comp XE as well #12-235-2. Posted on this very thread with same noise issue. I run mine at 1 full turn now, tried many different preload settings and set with engine running as well, checked geometry, have good oil pres, springs, heads etc etc. Not sure about others but in my particular application the noise is most prevalent when the engine is hot. On start up she sounds just right then once at operating temp the ticking begins and is most annoying at idle. I just did an oil change to 10W-30 from 15W-40, the heavier oil was better (helped as attested by FBIRD88). However with the 10W-30 in my case there is also much less or no noise on start up. So just a thought here...when an engine is cold the oil is "heavier" so the hydraulic pressure in the lifter has more of a effect on cushioning (for lack of a better term) the valve train. The heavier weight oil affords this principal on a continual basis even when its at operating temp so the 15-40 is best. I have had a few guys ask me if i was running a mechanical cam, my XE sounds very similar. Anyhow on my new 383 I am switching to another cam, it won't be an XE...a change is as good as a rest they say.
03-22-2010 07:49 AM
Montebrian As far as a "loss" of power from the one full turn...I'm not worried about it. My car made 364 horses and right at 400 torque on a in ground Dynojet chassis dyno, Peak torque was at like 4900 and peak horses was 5850rpm. So that is rear wheels horsepower numbers, not flywheel.

If you tighten them too tight your valves wont close....Thats what happens if you go too much more than one turn. Most factory manuals from GM stated one full turn from zero lash as the official adjustment number for most factory 60's and 70's cars.
Its nuts if Comp told you a half turn themselves, Their own literature on the instructions actually says one full turn (So they must not even read their own directions)

If your adjusting your valves on a warm motor that was recently running, give the lifters time to bleed down, otherwise going from a half turn right to a full turn will unseat the valves and it will crank over with no compression for a minute until the oil bleeds down.


I have in the past done Comp Cams on small block Chevy's the Magnum Series 280 cam at a half turn and never had a issue. But the XE cam was different. (Although the Magnum cam seemed more likely to bend pushrods I had to change out a few hardened Speed-pro's and eventually switched out to all 4340 Chromoly Manleys to solve that issue)


I think every cam has its pro's & con's. Factory stuff is the only ones that should be expected to be perfect right out of the hole.
03-17-2010 10:26 PM
Fast 4 Door [QUOTE=cobalt327]There is no reason to go more than one turn- if you want to try less than one full turn, that's fine too.

But judging by what I've just read, one turn is where I would set them at.

Thanks again cobalt, one turn it is tomorrow.. if I can sneak out to the shop that is.. will post result
03-17-2010 10:20 PM
cobalt327
Quote:
Originally Posted by Fast 4 Door
Thanks cobalt, that was an easy one .. so think I am safe at one full turn? although it seems to be getting (enough) oil, if I crank her down will she get more? sorry to ask the same question so many different ways, I'm just afraid of doing damage to something. rather be on the safe side, maybe go 3/4 and see what is up?
There is no reason to go more than one turn- if you want to try less than one full turn, that's fine too.

But judging by what I've just read, one turn is where I would set them at.

But, no- there is absolutely NO damage from one full turn- provided that you start at a correct Zero lash.

Most agree that jiggling the p-rod in an up-and-down fashion will allow zero lash to be 'felt' easier than by twisting the p-rods between fingers and thumb- and is how I've ALWAYS done it, even before it was 'cool'.
03-17-2010 09:43 PM
Fast 4 Door
Quote:
Originally Posted by cobalt327
The short answer is- there is no need to go any more than one full turn.
Thanks cobalt, that was an easy one .. so think I am safe at one full turn? although it seems to be getting (enough) oil, if I crank her down will she get more? sorry to ask the same question so many different ways, I'm just afraid of doing damage to something. rather be on the safe side, maybe go 3/4 and see what is up?
03-17-2010 09:18 PM
cobalt327
Quote:
Originally Posted by Fast 4 Door
So, Comp. is telling me not to go over the suggested 1/2 turn. I have read (mostly here on this site) everything from 0 lash to 1 full turn. I guess my new question is, how far is too far and how do I know that I have gone to far, will the spring bind ? How much play is there in these hydraulic rollers?
The short answer is- there is no need to go any more than one full turn.
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