CAM SELECTION
Cargo Master
Joined: Feb 2003
Posts: 2,341
Likes: 5
From: Sacramento
BTW, I was browsing online and found some vids of cars and trucks with the 268 Comp cam. After seeing the vid on you tube of the bumpside with the loud flowmasters, I was surprised to hear an engine run with that cam in it and w/o the flowmasters. It really doesn't sound that radical.
Laughing Gas
Joined: Nov 2003
Posts: 898
Likes: 1
From: southeren Oh
.....
I would go with the Comp 268, but am concerned with mileage. Although it does impress me with the 110 lobe angle. If you don't have flowmaster 40's, that cam sounds tame, loping yes. But with 218 degrees duration @.050", that tells me performance will jump at the expense of mpg.
The other alternative is the Isky 262. With a LSA of 108 degrees, I know it will have that lobing sound. But it actually has less duration @ .050" than the comp 260! And the 108 LSA means less vacuum, a narrower power range, but greater low-mid range.
For me it always helps me make up my mind to hear other peoples experiences and opinions. BTW, I will be dropping back to the 1.6 rockers with the new cam. I am also concerned with what I have been reading about the Isky cam being 30+ year-old technology.
I would go with the Comp 268, but am concerned with mileage. Although it does impress me with the 110 lobe angle. If you don't have flowmaster 40's, that cam sounds tame, loping yes. But with 218 degrees duration @.050", that tells me performance will jump at the expense of mpg.
The other alternative is the Isky 262. With a LSA of 108 degrees, I know it will have that lobing sound. But it actually has less duration @ .050" than the comp 260! And the 108 LSA means less vacuum, a narrower power range, but greater low-mid range.
For me it always helps me make up my mind to hear other peoples experiences and opinions. BTW, I will be dropping back to the 1.6 rockers with the new cam. I am also concerned with what I have been reading about the Isky cam being 30+ year-old technology.
252,256,260 sounds like you wouldn't see much diffference in the three.
I'd go with a 268 comp.
Don't worry about a cam design being 30 years old, after all that good 300 engine was designed 45 years ago.
Senior User
Joined: Jul 2007
Posts: 105
Likes: 1
f250 restorer I have the comp 260 and have a dual in/ dual out flowmaster 40 on mine. It has a very little lope to it. my motor doesnt really take off until about 2200 rpms, but when it does it does and doesnt back down. you know all the things i have done to my engine. I thought i would just give you some info. I know you want the lope, but will a 6 cylinder lope like a v8 with the same size cam? You should just take a break and enjoy your engine and truck.
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Lead Driver
Joined: Mar 2008
Posts: 7,188
Likes: 384
From: Near Los Angeles
f250 restorer I have the comp 260 and have a dual in/ dual out flowmaster 40 on mine. It has a very little lope to it. my motor doesnt really take off until about 2200 rpms, but when it does it does and doesnt back down. you know all the things i have done to my engine. I thought i would just give you some info. I know you want the lope, but will a 6 cylinder lope like a v8 with the same size cam? You should just take a break and enjoy your engine and truck.
Don't you have r.rockers on yours? Are they the 1.6?
Senior User
Joined: Jul 2007
Posts: 105
Likes: 1
Ya I got roller rockers, 1.6 harland sharp. I sit and think about all the stuff that I should have done, and could do, but the engine is running so good I would probably screw something up in the process. I wish I would have went with the comp 268. I finally pulled the intake I built out from underneith the table and started cleaning it up. I dont mean any disrespect at all about what I wrote. I think you are an insperation to alot of guys and gals on here, including me.
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Lead Driver
Joined: Mar 2008
Posts: 7,188
Likes: 384
From: Near Los Angeles
Clifford cam specs
Very interesting: When you start looking around at cam specs!!
Cam companies measure duration differently, that is why it is important to look at the duration @ .050". Case in point, the Comp 260h cam. At .050" it has a whopping 212 degrees duration! That is actually more duration than the Isky 262H (208 degrees), or the Clifford 264H (which actually has LESS duration @ .050" than the Isky 262H, making 206 degrees @ .050"!) That makes the Comp 260H a real wolf in sheep's clothing, IMHO.
The only cam in that range that makes more duration is the Comp 268H (218 degrees @.050"), and has the same mild mannered 110 LSA.
Cam companies measure duration differently, that is why it is important to look at the duration @ .050". Case in point, the Comp 260h cam. At .050" it has a whopping 212 degrees duration! That is actually more duration than the Isky 262H (208 degrees), or the Clifford 264H (which actually has LESS duration @ .050" than the Isky 262H, making 206 degrees @ .050"!) That makes the Comp 260H a real wolf in sheep's clothing, IMHO.
The only cam in that range that makes more duration is the Comp 268H (218 degrees @.050"), and has the same mild mannered 110 LSA.
Postmaster
Joined: Dec 2006
Posts: 3,603
Likes: 10
From: Spokane, WA
Yup...can't go by the "advertised" duration or anything else that's 'advertised". Now what would be interesting to see is the difference in running with the Comp 260 or 268 while retaining the BBC 1.7 rockers.
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Postmaster
Joined: Mar 2005
Posts: 2,949
Likes: 6
From: Earth
Jeez Louise, that's a freaking street rod cam! How does she do down low? Seems like it wouldn't really start barking until ~2,500 rpm...
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Lead Driver
Joined: Mar 2008
Posts: 7,188
Likes: 384
From: Near Los Angeles
Now what would be interesting to see is the difference in running with the Comp 260 or 268 while retaining the BBC 1.7 rockers.[/quote]
That is what I was thinking. I would get loads of duration--10 degrees more than I now have! with slightly less lift than I now have. What lift would that be? .482"? "Very interesting." I'll ck with Comp and see if my Isky springs will work.
That is what I was thinking. I would get loads of duration--10 degrees more than I now have! with slightly less lift than I now have. What lift would that be? .482"? "Very interesting." I'll ck with Comp and see if my Isky springs will work.
Cargo Master
Joined: Feb 2003
Posts: 2,341
Likes: 5
From: Sacramento
It's surprisingly tame, even with the choppy idle. Its operating range is about 1500-5k. My tach is broke. It will pull decently just off idle. A little annoying with the 4 spd and 3.25 gears. The duration is the same as an Isky 280 at .050 lift.
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Lead Driver
Joined: Mar 2008
Posts: 7,188
Likes: 384
From: Near Los Angeles
Thanks for all the feedback, guys. I think at this point I am going to hold off doing any mods to the engine until I get the ZF trans installed. I don't like to manually shift an auto trans--bad experience--and believe that to maximize performance, to really feel the engine open up, you need a manual trans. I know I could adjust the trans to shift later, but it's not the same. I just think I'll have a much clearer idea of the performance of this engine with a manual trans.
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Lead Driver
Joined: Mar 2008
Posts: 7,188
Likes: 384
From: Near Los Angeles
Would using the Comp 260 cam, with its 212 degrees duration @.050", and my 1.7 rockers with over-size valves, be too much for my engine/intake? Does my DP intake flow enough for it, or is it too much for my engine?
I have 9.3 c.r.
I have 9.3 c.r.