|02-22-2012 07:59 PM|
|1969chevyss||I'm going to take all the factors into consideration but I've already ordered the isky mega 264 with lifters. The xe268 probably would have been good for me with my mild build but why take chances especially at this stage in the build.|
|02-22-2012 07:18 PM|
Well, you can say what you want about failures being caused by incorrect installation, but how do you justify the professional engine builders that went from no failures to several failures overnight? Then just about as quickly as the failures started, they have went away. There's still old stock from a couple of years ago being sold that should have been trashed, so we are still seeing a few failures with everything done right.
I don't believe that the cam blanks were the problem, but the white box lifters being sold during that time period. A crap lifter will take out even a good cam quickly. I may be wrong, but anyone heard of an installation with a set of Rhoads lifters going bad during that time period? Same cams, but different lifters didn't seem to have any problems.
Many years ago I ran a 268H cam in my (Pontiac) 455. Really great mid-range, but power flattened out about 4,500 RPM. Cam specs seemed like the power curve should have went much higher before running out of steam. Installed a Crower cam with close to the same specs and the power curve went 1,000 RPM higher before leveling off.
|02-21-2012 05:39 PM|
I bailed on Comp years ago.
If you're building a SBC, they probably make fine street cams.
If you want your junk to run like its supposed to, then look elsewhere.
For catalog cams, I only use Isky.
For race engines, I only use custom grinds.
|02-21-2012 03:06 PM|
|02-21-2012 06:37 AM|
easier to blame the maker of the cams
|02-20-2012 05:52 PM|
This is the cam I have in my pickup right now with a 355, th350 and 3.73 posi 12 bolt, summit hyper flat tops, steel shim head gasket and fresh 993 heads with small valves, Holley streetmaster intake with a divider installed and a 600 Holley it runs very well it actually surprised me and my buddies, I'm fixing to install vortec heads this spring after I clean them up and cut the guides down for positive seals, I run the cheap lifters all the time from competition products, or summit using diesel oil and Zddp and never had a problem. I have a comp 4x4 extreme in my 454 and it hasn't went flat broke it in with the outer springs only. I think cam failures are mostly installed wrong and the people don't want to admit they don't know what there doing.
It's close to the comp 268H and has a very nice idle.
|02-20-2012 02:51 PM|
Here's a checklist to help you out.....
|02-20-2012 12:31 PM|
|1969chevyss||I called Isky this morning and they recommended the 264 Mega. This camed will give me more low end torque with a noticeble lope at idle but nothing to extreme. He said he have heard from people that the 264 Mega out perfomed some xe268h. The Mega 268 would fit my combo as well if I was planning on changing the stock gears and converter. I'm glad I brought this issue up now and not later causing me to tear the motor down for a flat cam. I know it is still up to me to break in the cam right and use the right oil additives.|
|02-20-2012 12:51 AM|
Shorter duration, will. VERRY easy to over cam a 302. a larger than stock cam requires a higher towing rpm. ( gears )
50FT/lbs difference betweent eh real and virtual simulation is huge.
You best reconsider your inputs for the engine modeling choices.
This graph shows the basic effect on a engines torque curve when the cam is advanced or retarded. A duration change basicaly moves the whole torque curve up or down the rpm range.
A torque out put GAIN increase requires a increase in total engine AIR flow.
improved volumetric effieientcy or a reduction in friction or a increase in compression or engine CID.
|02-20-2012 12:07 AM|
Well I dont think the desktop dyno can be too terribly far off. Its only 50ft lb over what my engine is rated at stock. The engine IS stock but will be getting headers and exhaust and a K&N filter. Who knows what else. Also I might have to advance the cam a little to push the torque curve down - I am planning on doing some towing with this truck. About 6,000 worth.
Still yet, even if i only gain 30 ft lb, that puts me equal to a chevy 350 of the same year. 350s tow OK.
Big thing tho is still the fear of wiping out a cam. I know the engines are a good bit different between the SBC and SBF.
|02-19-2012 11:58 PM|
You best take the desk top computer simulation program with a big grain of salt.
Especially if the rest of the motor is stock.
It ain;t that simple.
The biggest effect of installing a larger cam in the stock motor is it shifts the torque curve up in rpm. Ususally always at the expense of low rpm torque.
The smaller the CID of the motor the more dramatic the effect and the neg effects of any cam choice.
its very easy to over cam a 302.
Moderator: Consider starting a new thread for Torque454 and 302 Cam stuff.
|02-19-2012 11:43 PM|
Does any of this stuff apply to the FORD 302 HIGH energy cam (not extreme energy)? I am looking at a comp cams 31-255-5 computer controlled cam, which on the camquest dyno software puts me at 330 ft lb, which is more than a stock 351 (which is what I am going for).
However I am scared to death about changing the cam. I cant afford to rebuild the engine if I wipe a lobe out....
|02-19-2012 07:48 PM|
|Formulajim||I had a cam fail in my Pontiac 400 it was a xe275h. I,ve been a mechanic all my life, this is the first cam that failed. I went to a roller, hope for the best. Comp gave me credit for the old one but I had to pull the motor and rebuild it. Pain in the rear! Oh and $ .|
|02-19-2012 06:40 PM|
|02-19-2012 06:34 PM|
|1969chevyss||I have no problem machining the guide bosses for more lift if I have to. I was originally looking at the comp xe262 so maybe the isky 264 would work for me. I'm not sure what grind cam I have in my 350 now until I pull it out of the car but the sound is good enough for me with the custom exhaust I have. I'm calling isky in the morning and ask out the 264 and 268 grinds.|
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