|05-28-2006 07:02 PM|
|lelandl||One big thing is proper cam lube and proper break-in procedure. Many guys think it is a waste of time to take the 20 minutes to break in a cam. I actually had one "engine god" tell a friend to set the lash and take the car out and race it. "If it's gonna blow, break in won't help." I have not lost a cam in any engines I have done and I adhere strictly to break-in procedure and dumping the break-in oil after 30 minutes.|
|05-28-2006 06:26 PM|
SBC are notorious for lifter bore wear and dumping oil pressure out the lifter bores. More than .0015 is asking for trouble. On race prep engines we rebored the lifter holes. New lifters are available that have lubrication holes in the lifter face. Chevy blocks of the 70s-90s were often horrible on lifter bore angles and even cylinder bore angles. I have seen 350 block cylinder bores that were more than .050 out of square with the crankshaft. Makes me wonder how they ran 100,000 miles. I did one that was so bad that it could not even be bored .060 over to correct the angle so it was junk.
Could be lifter face angles, too. CompCams has now adjusted its cam lobe face angle to allow for more lifter rotation with heavier springs, this to assist in the reduced lubricity of the modern oils. Use Rotella T, racing oil, or synthetic.
|05-23-2006 09:14 AM|
|al37ford||The initial cost of a roller retrofit can be cheaper than the standard flat. After THREE wiped out camshafts, 2 Crane & a Comp, we bench broke in the FOURTH rebuild and found the lifters spun properly using stock chevy springs but going back to the stock Edelbrock the lifters did NOT spin which translates to a quick lobe wipe out! Several reasons found , including the new environmental oil composition but the main reason apparently was that the lifter bores were not perfectly square with the cam surfaces. Likely a bad run at the factory! Worked ok with stock stuff but NOT with higher performance. I haven't read it yet but am told the June issue of HotRod mag. has an article addressing same.|
|05-23-2006 12:49 AM|
Every build I do I say to myself; this engine should really take advantage of a roller cam's technology and blah blah... Then I actually price one. In terms of return for your dollar its not really worth it. I actually had a tech at Comp Cams talk me OUT of buying one. In truth, until you buy the cam, the retro rollers, pushrods, bronze distributor gear, thrust bearing, and all the other associated goodies it can be $1200 or more just in parts. That's a huge cost for another 20 hp.
If you want to do a roller engine and save a ton of money, just find an 87 or newer 350 core that is already a roller block and swap your new parts to that block. I think you'll find that since the newer core engine already has all those parts (and the cam and lifters are cheaper) that you'll save tons of money doing it that way.
|05-22-2006 07:52 PM|
First engine build - would a roller cam be a better choice?
This may be a dumb question, but here goes... I'm building my first engine. It's a 383 (it was a 350 stored for ten years) with new forged pistons, stock-resized rods, new cast steel crank, rebuilt O41 heads, and a Summit .224/.234 .468/.488cam. Although it would take me out of my "budget build" mode, is there any benefit in putting in a retro-fit roller cam assembly?
It seems like so many people I hear from who have a problem following a rebuild have problems with wiping lobes on the flat tappet hydraulic camshafts. As a rookie, it seems that you want to turn the motor as few revolutions as possible when rebuilding and then starting the motor so you don't clear off any of the assembly lube/grease. As a beginner, I can see me turning the motor over so many times to get the proper valve lash, etc. set up because I won't trust my first attempt.
Anyway, it almost seems that a roller camshaft in spite of cost would make the rebuild a lot more trouble-free. I appreciate any input from you rebuild-veterans out there. Thanks!