I have searched for this subject but came up empty... A friend of mine brought me a set ove heads to change over valve springs, retainers, and valve seals, (he changed out his cam) and the comp cam he is using calls for comp cam springs # 981-16, the problem is the head seats are machine for 1.500", and the springs are approx. 1.250" O.D.??? WTF now? Is he screwed? Can I install them as is? I'm at a loss here and he doesn't have the money for new heads, Comp doesn't list another compatible spring for this cam(I dont have the cam specs) but I think its a comp cam # XE-274 H... Oh ya, and another question, what is the best way to remove the inner spring,(required for cam break-in)? any help appreciated..
You will need spring seats. These are raised at the center hole so the spring is located by the inside diameter. I don't have my cam catalog here. But most 1.25" springs just have a flat wire damper inside. Removal of this damper is difficult and will not help in cam break in. If the spring seat is that big. Do you have the correct spring height set?
you should use the right springs.....i have never had to remove inner spring for cam break in just make sure it fires right away and then do the usual cam break in procedure.
Sounds like you need "Spring Cups" on the valves to machined seat problem. REMEMBER HAMBERS Modern Oil is lacking Zinc,Phosphates,Phosphorus,etc. You must run Royal Purple "Break-In Oil" or another special oil for break in of the cam. I use it exclusively. If you smell it then you'll notice that it smells exactly like Rear End Grease.The reason is because it has the extreme scuff resistant compounds that make it slippery as parts smear against each other as they work. I've read many modern books and if you are running very stiff valve springs you really should break in the cam as you suggested,, without the inners or whatever the manufactuer recommends. Then after the break in period you can add them back (still bolted on the block). All you're doing is buying time with properly assembled parts. After all that is said and done you still need protection from scuffing,,I run "Rotella" a diesel oil designed for the long haul as it's for the same type flat tappet cams as in the Old School type of engines. Roller cams are a whole 'nuther story. Imagine this applies to tillers and mowers etc,,any old engine that smears it's parts to opperate.Oh yeah,,over fill the crankcase a couple of quarts to sling the oil from the spinning crank to the new cam 'n lifters as it all breaks in.
Be careful. The new Rotella is "watered down" compared to what it used to be. The EPA just started clamping down on the diesels in the last 2-3 years.
There are several oils available in both synthetic and petro based that still have a heavy load of ZDDP. One of which is Amsoil's "Premium Protection" synthetic, available in 10W-40 &20W-50 " (I'm an independent Amsoil dealer). With the advent of the new diesels equipped with particulate filters and catalytic converters in '07, the oil companies had to change the oil additive package for '07 & later diesels. Some companies, Shell apparently among them, chose to go to the new additive package with reduced ZDDP for all the diesel oils they market. Amsoil chose to continue marketing a high ZDDP oil for pre'07 diesels, which I use in my '03 Duramax, and introduce a new oil for the '07 and later trucks. Also available from a HAMB vendor is a ZDDP concentrate to add to whatever oil you prefer. As to the OP's original question, if you go to Comp Cams online catalog, go to the tech section of the catalog and look up the valve spring specs for the specific cam your customer has. Then you can look over in the 1.500" springs and maybe find a spring with similar #s of pressure. Otherwise I expect they would have the cups to install the 1.25" springs in the big pockets. Dave
Lets start off with the stock type spring you are using dose not have an inner spring it is a dampener.You should use a spring cup that was mentioned above but you will need to measure the guide od to see what size it is. Most common is .570 od. Once you get all your parts together you will need to measure the install height of the combination of valve retainer spring seat keepers. For that spring the install height should be 1.700. If you have more you will need to add shims under the spring cup if you have less you will need to use +.050 keepers or a plus retainer. Spring pressure for that spring will be 105 to 115 closed open pressure will be 285 to 300. If cam is new use a crane gray cam lube on the cam lobes only and the bottom of the lifters only use 30w on the lifter sides. Use Joe Gibbs or Brad Penn break in oil and break the cam in for as long as the water temp don,t go over 200 i prefer to let the cam break in for 30 plus min. The engine must start right up no prolong cranking. and run between 1800 and 2500 rpm changing rpm every 10 minutes. Manley part # for the spring cup 42142-16 Ps: Comp Cams has break in oil now to.
Mike, good advice on break-in oil and procedure! I should have added that even though I sell Amsoil and get it at wholesale, I bought Gibbs break-in oil to start off the engine I'm installing in my "A" roadster/SBC. The Amsoil Premium Protection synthetic won't go in till the cam is broken in and the rings are seated. Dave
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