I am wondering why people don't use just the small inner springs to break in the cam. Less spring pressure on the lobes. I know, I know, lot of work plugging the air chuck in the the plug holes, but It certainly would eliminate wiped lobes on start up.

 

The inner springs are usually to weak. I do use just the outer springs when breaking in a cam with dual springs. Yes it takes a little time to change out the springs but far less than changing a cam again.

 

don't think i'm supposed to post links to other sites but there is a good post on solid cam motor oil on a chevelle site. it's a sticky and tells which oils have the material solid cam motors need to keep from wiping out lobes and lasting longer. somehing about the oil formular was changed and this ingrediate was removed because no one was using solid cams anymore from the factory. using this oil might make your cam breakin a little safer and you would not have to replace the springs.

 

I never had any problems using the inner springs...the inners can't be that much different in spring pressure between SBC & BBC

 

My dual springs for my solid cam are in the 120 seat 320 open range. As I recall the inner springs were only about 100 or so open. I guess if you keep the rpms to minumum they would work. The outer springs were heftier. I guess either one will work just as long as it lightens the load on the cam.

 

I didn't do my homework,and fell prey to the lower zinc/phosphate oil,and wiped a lobe,so the 68 sits,and 75 is daily driver.Going roller whenever I do the engine again.

 

You have to keep the ZDDP additive in it if you use a flat tappet. I found out the hard way. I installed mine a year ago and it runs and sounds great. Always use ZDDP additive in it when I change oil. VR1 is what I use.

 

My dyno guy breaks in the big block flat tappet engines with 1.4 ratio rockers instead of the stock 1.7 ratio ones.

 

if high rpm's are not needed (6000 or below), are there any other performance advantages to a solid lifter motor?

 

original chevy cams don't have the breakin lobe wipe problems aftermarket cams have - has to do with way they harden cams or don't or something like that. zddp levels in current oils similar to that of the 60-70s oil and no problems then.... all reasearch I have done suggest it is cam manufactures problem not oil....doesn't hurt to be safe and use oil with higher zddp but you can still wipe cam with good oil and proper breakin.....been there, done that and only with the new aftermarket cams and the higher zddp level oils...my 2 cents.

 

Nearly all stock sb heads have only 1 vlv spring plus an inner dampner. The dampner would easily collapse if used by itself. It sounds like your thinking BB's George and haven't played with sb's much.

I recall someone does sell light springs just for break-ins but i don't have any names. I plan to keep the next set of used stock springs i have like on the LT1 in the garage with 175k mi on it and use those when a cam break-in is needed. The biggest pain is finding an user friendly vlv spring removing tool that can be used with the heads on. It better to have that tool staged for the job rather than go shopping on break-in day. It still adds several hours time to swap out the vlv springs.


cardo0

 

For some reason i thought Comp Cams and other mfg's sold dual springs for SBC...I know the factory were single w/damper.

 

Here are the small block break in rockers. 1.3 ratio. Comp makes a 1.2 ratio but they are full roller and big bucks. Not a good option for a one time deal but if you do it often these are the way to go. They come with polylocks so it helps the cost a little.
http://www.speedwaymotors.com/Camsha...hevy,3191.html
Too bad someone doesn't make an inexpensive stamped steel version for under $100. Bet there is a market for them.

 

I start to think there's something wrong with new flat tappet cams...
in my 68 427 motor (now stopped due to problem to a cylinder) I have an L88 cam and GM lifters and very high spring pressure. all the lobes are still there and fine...and I think the guy who assembled this engine in his garage 10 years ago put no attention to oil or zddp ...simply because I suppose 10 year ago there was no info about.
I think this engine has been run for a while with usual oils, then added ZDDP after a while.

I know of many vintage US cars here in Italy running fine with their stock cams and usual oils and they have many miles on them.

so where's the problem?

63mako. by breaking-in the cam with a shorter rocker arm , are'nt there problems in keeping up the engone running with such lower lift? i'm referring to my build...

 

Hi Aldo, been meaning to say Hi for a while. Where is the root cause of all these cam failures we hear about? Is it from poor manufacture of cams or poor manufacture of the lifters or reduced ZDDP in the oil? Or is it from excessive spring tension?
I have a stock replacement universal motor in my 74 and Valvoline emailed me that 30w was just fine and that is what I have been using for the last 7 years and the motor is just fine. Now I'm nervous and going to change to VR1 Racing oil which is $2.00 more per quart. My Vette is in a heated garage (55*F) so even in winter it leaves warm and after lunch or dinner it doesn't get that cold in two hours, so what is the problem?
PG.

 

The problem is a combination of things. First and foremost is the lack of ZDDP followed closely by faster ramp rates. The OEM cams had a lazy ramp rate. They had to warrantee these motors and engineering common sense says a gradual ramp rate using less spring pressure is a more durable setup. The newer grinds have faster ramps and a lot of times higher lift to snap the valves open and closed faster. The speed of the ramp rate determines the "Hydraulic Intensity". A faster ramp makes more HP. Also requires more spring pressure and puts additional pressure at the lifter, lobe interface. The new EDM lifters will help this. They put pressurized oil right to this point. Customers choose the cams that will produce best power. Dyno results are the goal. The cam companies give us what we want. A lot of people build a small block and put 1.6 ratio rockers on it. The hydraulic intensity dramaticaly increases more than you would think at the lobe to lifter interface. This is another reason for more recent failures.
Check out this article.
http://www.enginebuildermag.com/Arti...r_failure.aspx
The short ratio lifters are really ideal for break in. They drop loading pressure on the lifter to cam lobe through shorter lift and less multiplied spring pressure. The spring pressures increase the farther the spring opens. If this is reduced the pressure at the lobe is reduced. Also the rocker ratio determines the actual pressure the lobe sees by multiplying the spring pressure by the ratio of the rocker arm. A lower ratio = lower pressures and also a perceived slower ramp rate and less hydraulic intensity. All good things for cam break in.

 

Somting wong with the cams, a cam made out of concrete with .000001" of hardened metal on the lobes would be a problem. Spend the extra 40 bucks and get a billet cam and use oil with high levels of ZDDP

Concrete and billet cams, which one would you put in your motor ?


Here's my solid roller billet cam. Comp Cams charged me $40 more to make an custom grind small base circle cam with a pressed on iron gear to work with any stock distributor gear. It is a work of art. It looks light years ahead of their off the shelf stuff. They can make you these custom cams in week

 

Yes they all sell dual springs for SB Chevrolets but not for the stock spring pockets. The stock springs if I recall are 1.25 diameter. Most all the duals are 1.47 or 1.55 depending on spring rate.