Summit Cam K6900 vs. Original Factory Cam

-
Got2Gnow

Got2Gnow

Active Member
Joined
Mar 8, 2011
Messages
25
Reaction score
0
Location
Metro-Detroit
My very original 1971 Swinger (318, 2-bbl, auto, 3.23:1 gears, electronic ignition, 2 1/4" dual exhaust (factory manifolds & FlowMaster 40s) (~115,000 miles)) will be getting an LD4B intake, 1406, new Cardone water pump (8-vane), and a Summit True Roller Timing Set (SUM-G6603) soon.

With all this going on, I was thinking about adding the Summit K6900 Cam & Lifter kit. My biggest question is how much of a difference is there between the factory cam and the Summit cam? Is it worth the money and effort? The car is used for local car gatherings and visiting ice cream parlors with the wife and kids.
 
Extremely interested in what opinions you get here. We have pulled 2 failed and flat summit cams out of smallblocks recently. Id much rather reccomend you a lunati or comp at discount than see you run that cam. But thats your call my friend.
 
Ive used their cams in the past with no problems but its been at least 5 yrs. That grind should be a nice step up and fit your combo well. I think the stock grind is around .390 lift and maybe 185 to 190 degrees at .050 lift. Don't no exact numbers but that's close. Sounds like fun ride.
 
Summit cams are made by anyone that can fill the bill the cheapest. Use break in and a diesel grade motor oil that still has zinc in it. No synthetic oil! Your supposed to watch the pushrods for rotation, even "help them along" if they are not turning. That tells you the lifters are turning. Now doing this during a variable 1500-3000 RPM is a little more than I would be comfortable doing but that is what Crane recommends. I would stud the valve covers and get some cheap 70's valve cover wing bolts so I could start the motor with them off, observe the pushrods (put a line with a sharpie on the side or something) for rotation, then put the valve covers on in a hurry and snug down so you dont drip oil on the headers. Or you cold use a cheap set with the tops cut out.
[ame="http://cranecams.com.au/pdfs/Reasons%20&%20Causes%20for%20Cam%20Failure.pdf"]403 Forbidden[/ame]
 
pishta said:
Summit cams are made by anyone that can fill the bill the cheapest. Use break in and a diesel grade motor oil that still has zinc in it
Click to expand...

The last flat cam we pulled from a sbc was ran with comp break in oil, and failed during break in. The other used the zinc additive. Sbf' made it 1k miles.
. both hyd summit cams. Obviously we dont sell them. I know tons of guys get by with them...but these castings are rough....never seen slag between lobes like these.
 
Had good luck with Summit's house brand camshafts, usually with the lower lift grinds,& used stock valve springs ( reducing valve spring pressure, obviously..) That was a decade ago,who knows now...
 
My understanding has always been that the Summit cams are simply reboxed Crane grinds. I have used several of them through the years and they always have Crane numbers stamped on them.

Also, regarding the lobe issues, I have not seen a flat lobe on a Summit cam. I am sure there have been failures, but rest assured most of those come from user error. As long as you cover your bases with good break in oil with plenty of zinc content and make sure the engine fires off quickly and keep the RPM up on break in you shouldn't have an issue.

I don't run a big business but I have used several of them in the past and had good success.
 
rustyratrod said:
my understanding has always been that the summit cams are simply reboxed crane grinds. I have used several of them through the years and they always have crane numbers stamped on them.

Also, regarding the lobe issues, i have not seen a flat lobe on a summit cam. I am sure there have been failures, but rest assured most of those come from user error. As long as you cover your bases with good break in oil with plenty of zinc content and make sure the engine fires off quickly and keep the rpm up on break in you shouldn't have an issue.

I don't run a big business but i have used several of them in the past and had good success.
Click to expand...

x2...
 
I think you'll like it and you definitely need a camshaft to take advantage of the larger intake and carb. You will also have to upgrade the valve springs to something like the Comp 901-16s.
As far as cam install and break in... You need to verify lifter rotation. You do that by marking the tops of the lifters and placing them in the bores on the cam with only WD40 on them. Then rotate the cam and look at each lifter mark. If one doesn't rotate in it's bore, swap them around until they all do. I would not use pushrods for this. I always go right to the source and look at the lifters. Once I verify they move, use the Crane camshaft lube paste on the lifter bases and lobes being careful not to get it on the lifter sides or bore. Assemble everything but the rockers and pushrods. Do them last. If you check piston to valve clearance, assume you have to reapply the break in paste. Pre-oil the and get fuel up to the engine without using the starter. I fill the bowls through the vents. Make sure the distributor is installed properly. Make sure the cooling system is close to full and have fans blowing air over the radiator. Then fire it an get the rpms up immediately past 2500. Keep it there for 15-20 minutes, varying the rpm up to 4K, but never below 2K.
If you follow all the steps, the cam will be fine. If it doesn't start for a bunch of turns, or you have to shut it down for leaks or whatever, or you turn it over with the key to get fuel up and oil pressure up... You are asking for a cam failure.
 
I'm contemplating almost this exact upgrade.

I'd love to hear before and after specs, esp MPG and 1/8 mile stats.
 
You must log in or register to reply here.
-

Back
Top