Re: some interesting reading about spring pressure
The Comp cams pro-mag rocker is 225 grams. That includes all the guts/bearings. Terry
The Comp cams pro-mag rocker is 225 grams. That includes all the guts/bearings. Terry
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Re: duke what do you think of this??
Am I figuring this out correctly??
3970627 spring will have closed pressure of 105# @1.88 and an open of 312# @ 1.415. Was this the typical replacement spring for bbc? Thanks, TerryComment
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Re: duke what do you think of this??
I called comp cams and talked to the guy on the phone. Nice guy. I asked him if they had any recommedation of changing spring pressure on bbc when using full roller rockers on a essentially stock bbc engine. I explained the valve train mass thingy and he sort of giggled at it. He said he just sells them because they are good. I'm just not that type of person. Anyway, the pro mag is made of 8650 steel and weighs 225 grams as a unit. I would like to know what one weighs without all the trunion bearings in it and shaft? Thanks, TerryComment
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used them on every BBC with stock cams
i ever worked on. i saw too many broken valve springs on early BBC including my 65 396 vette.Comment
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Re: used them on every BBC with stock cams
Are they anywhere near the limits of a standard camshaft regarding durability because of the spring pressure? When you by them, do they come with the dampener installed in them? I believe my valve springs had rotators under them? Should those be replaced? Thanks, TerryComment
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the orignal BBC valve springs were bad and were
replaced with the 627. they are dual spring with out a damper. i am not sure what year they started to install the rotators BUT if you has them they may not be the correct springs.i never worked on a SHP corvette engine with rotators.Comment
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Re: the orignal BBC valve springs were bad and wer
Hmmm, I think I saw rotors on them. I will take note when I start pulling it apart. Is a 390 hp considered SHP? TerryComment
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Re: the orignal BBC valve springs were bad and wer
i do not think the used rotators till after 71 when the went to unleaded gas. i can tell you are looking to get more performance from your corvette and you will need to go to aftermarket parts to get this and you may sacrifice some durability but the fun is to be quicker than the other guy. i never left any of my new corvettes stock or any of my other cars also. i had 8 miles on my new 1968 Z-28 when i redid the complete engine.Comment
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Re: the orignal BBC valve springs were bad and wer
It is hard to tell what I am up to. I will bullet proof the bottom end but there is a limit to that. It has 2 bolt mains and that is plenty for the HP it will make. But, it will be balanced and polished to death.
I might have a personal project. I am going to try to find actual rocker arm weights of Comp Cams pro-mag rocker arm body with the roller tip installed. I want to compare it to a standard rocker arm. I bet there may be hardly any difference gross weight wise. I also feel that under 6500 RPM, any small amount of additional weight they have is unimportant if you have a valve spring set-up that is dead-on the way it should be. Since my factory cam doesn't have boo-coo lift, I don't think the cam servival will be that big a deal. I think it is possible that what added tip weight there is is made up for in function (for the most part). I will learn more about spring rates to get a feel for where I am in the big scheme of things. I will probably search for a set of those GM spings you mentioned.
I am still looking at hydraulic lifters. I will not use an anti-pump up lifter. They make a lot of noice and I just don't like the set up. They may be great for all out balls to the walls or where hydraulic lifters are required but not for the majority of driving I will do. But I notice there are ball design and disk design standard lifters. I am interested in looking at them and there is a self metering hydraulic lifter that has a variable flow control oiling system. I will probably settle for a standard lifter with a heavy duty plunger retainer. Push rod will probably be 3/8 single piece chromoly with formed ends. I don't want push rods that look like noodles when I decide to have a little fun once in a while.
I will check or have the deck height checked and adjust accordingly with head gaskets. I will have the heads cc'd and even them up if they are grossly wacky. Rocker studs will be replaced and I will use new guides. I will carefully look thing over for metal flashing and sharp edges. I will use bronze guides. I am not sure on valves. I like the idea of a single piece valve. I have seen some stainless single piece valves with chromed stems. I like that idea.
I will use original rods that are nicely reworked. I will get ARP rod bolt and rocker studs. I will seal the studs just in case. I will use brass freeze plugs. I will use a factory configured piston, I am not sure which kind I will use. I don't know enough about rings yet but I am not worried about them that much. I will not use a gap-less ring because I hear and believe they do too good a job and promote cylinder wear. It is likely that I will use a factory oil pump after I check the clearances on it. I am uncertain about bearings but I will get some decent one. This seems sound to me. I don't think I should have to worry about the compression ratio as long as I stick with the stock configured pistons??? Thanks, TerryComment
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Re: the orignal BBC valve springs were bad and wer
Do most quality valve come with hardened tips? Keepers should be hardened also I assume?? TerryComment
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Re: the orignal BBC valve springs were bad and wer
needle bearing rocker arms move the pivot point up higher on the rocker stud than stock ones so the force on the stud is up higher and put more strain on the stud.with stock cam lift and stock springs there should not be a problem.any other combination of cam and springs i would use a stud girdle. remember if you use stronger studs they have a larger radius at the bottom of the stud and sometimes the stud slot in the bottom of the rocker arms must be clearanced to clear this radius.remember after market parts are not "bolt on" without a lot of checking.Comment
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Thanks, Terry *NM*
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Re: some interesting reading about spring pressure
Clem, I was reading about Rhodes hydraulic lifters. They are sort of interesting. They generate more vacuum in high lift cams at lower RPM (variable bleed off rate depending on rpm you are at). Kinda give you the best of both world. Slightly noisy at low RPM but not as noisy as mechanical lifters I and fully pump up solid at around 4000 rpm. I think it would have been interesting to see them in a 435hp engine. They may have improved low end drivability and maintained high end performance. The 3x2 may have liked it. Depending on the camshaft though, it may not have made a difference in vacuum though. TerryComment
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the vipers used them as std equiptment *NM*
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