Cam 3143 and which springs?

[Markus 38206]

Which springs have I to use for the mech. cam 3143 resp. 3904362? Due to a lot of book I should use the GM spring 3970627. Can I also use the L88/ZL1 spring 3916164 or gives this problems? Why is the L88 spring so much cheaper than a LS6 spring and why has the LS6 spring a ratio of 450lbs/in. and the L88 much less (only 317lbs/in.)?

Or is there any good replacement spring available for the 3143 cam?

[Clem Z.]

Re: Cam 3143 and which springs?

to get the correct over the nose pressure with the higher lift of the L-88 cam. if you use the L-88 springs you will not have enought pressure at full lift with the 143 cam. the 627 springs are correct for the 143 cam and they are of a very good quality and include a plastic oil shield in their retainers. the 627 springs were the replacement for the orignal BB springs because they had trouble with them breaking,i broke 1 driving my 65 396 home to PA from the st louis factory in 1965 and broke 2 more before i get the new 627 springs.

[Markus 38206]

Re: Cam 3143 and which springs?

Thanks Clem, you are takling about retainers with a oil shield. Are those retainers included in such a spring kit? Is there someting against to use my existing steel retainers and locks?

[Clem Z.]

Re: Cam 3143 and which springs?

it has been 4-5 years since i have bought the spring kit but the retainers with the oil shields were included. yes you can use your retainers if they fit the springs but you will need a oil shield(umbrella) or a positive seal to prevent excess oil getting down the intake valve stems.i do not like positive seals on street machines because they do not allow enought oil at idle to the exhaust valve stems causing the valves to sometimes stick in the guide. even on race engines where i used a positive seal on the intakes i used a umbrella type seal on the exhaust.

[Markus 38206]

Re: Cam 3143 and which springs?

Thanks Clem for the intersting news. I have already bought an put on this teflon seals. I hope I will not get any trouble. By the way, it seams that I have to put a large number of spring shims below the spring to get 1.88" install height. Is this a problem? A first look told me that I need about 0.12" shims on the intakes even I have used stock lenght valves.

What do you think about the rockers. Should I use stock HP rockers from GM or would you recommend those with rollers at the valve from comp cams? Actually there are gold crane needle bearing rockers on it but I will throw them away because I would like to put on the orignial rocker covers.

[Craig S.]

Re: Cam 3143 and which springs?

Markus - the cam kit with 16 627 springs doesn't seem to reference including the umbrella seals and the retainers, it calls them out separately. I am guessing it doesn't include them in the package. It is hard to fit the roller type rockers under stock covers. I managed to shoehorn a set of comp cams super magnum rollers with roller tips and posi locks under stock dripper type GM covers on an LS6, but, the power steering "dent" on the LH side was the very minimal type, not like the correct covers for the mid sixties cars. You probably can get away with the comp cams roller tip rockers that still have a ball fulcrum. I may go with those on my 66 L72 buildup, but haven't decided yet. Craig

[Clem Z.]

Re: Cam 3143 and which springs?

if you used the all teflon seal i would recommend that you run a 3/8" reamer thru the exhaust seals to allow some more oil to reach the stems/guides. also i would recommend that you use moly kote to lube the stems and guides for the startup. also make sure the shims you use are hardened,check them with a file for hardness. you only need the hardened ones next to the springs as you can build up with just standard shims but make sure the top one that the spring sets on is hardened.these are available from GM part# 3875916 for the .015 thick and part# 3891521 for the .065 thick ones