Valve Springs

[Finallall]

I'm rebuilding my 3.8 carbed N/A peoject and need to know what you guys are suggesting for valve springs. I'm using the Edelbrock kit. Heard something about 105lb springs and 980's but need more info.

Please help.

Thanks AJ I thought I was posting in B4 black.

 

[dr_frankenstein]

the comp 980s would be a good choice,

strong enough to let you spin a bit, but light enough to not destroy the cam.

I would install at 1.70 height for about 100 lbs on the seat and 230 open. great for the street on a daily driver.

if you want a bit more RPM i would go for a slightly heavier spring such as the comp 981, which installs at the same height, but is slightly heavier at 105lbs on the seat and 275 open.

depending on how you plan to drive, you could shim the springs for more pressure if float is encountered.... but the cam you have should die off at around 5800 so I dont think it will be a problem.

A.j.

 

[Finallall]

Thanks for the reply. So these springs should be OK then? I'm using the 204/214 Cam.
COMP Cams 980-12 - COMP Cams Valve Springs - Overview - SummitRacing.com

 

[dr_frankenstein]

yes they should be good to go, but comfirm your retainer to valve guide clearance. as well as coil bind height.

you can use the stock retainers and locks with these.

A.j.

 

[Finallall]

yes they should be good to go, but comfirm your retainer to valve guide clearance. as well as coil bind height.

Can you tell me a bit more about this procedure? I've never done it.

Thanks.

 

[dr_frankenstein]

Can you tell me a bit more about this procedure? I've never done it.

Thanks.

hmm...... how to explain this.....

lol

well you could mock assemble your engine, then install cam and two lifters on a cylinder. put a dab of assembly grease on lifter to protect cam.

get a light spring from the hardware store to replace the valve springs in the head. its just there to apply light tension to the valve and the retainer and locks. dont forget to install your valve seal!

put the head on the block, with a gasket - and snug it down. assemble the pushrods and rockers on the two lifters you installed. add a little oil to the parts just to keep action smooth.

now roll the engine over, until the cam has come to full lift on the intake.

now the rocker will have rolled, and the valve should be open.

looking threw the light spring from the hardware store.... get a feeler gauge and measure between the valve retainer and the top of the valve guide seal.

that is your retainer to Guide clearance.

at the very least, it should be .060

.065 makes me feel better though.

and do the same for the exhaust side as well.

from what I remember in the buick powersource manual, any cam over .420 lift. will have an issue if your using PC type valve seals.

I hope this helps, please tell me if your totally confused.

A.j.

 

[Finallall]

No this makes perfect sence. I am using an 87 block and heads tho. Do I still need to do this?

 

[charlief1]

hmm...... how to explain this.....

lol

well you could mock assemble your engine, then install cam and two lifters on a cylinder. put a dab of assembly grease on lifter to protect cam.

get a light spring from the hardware store to replace the valve springs in the head. its just there to apply light tension to the valve and the retainer and locks. dont forget to install your valve seal!

put the head on the block, with a gasket - and snug it down. assemble the pushrods and rockers on the two lifters you installed. add a little oil to the parts just to keep action smooth.

now roll the engine over, until the cam has come to full lift on the intake.

now the rocker will have rolled, and the valve should be open.

looking threw the light spring from the hardware store.... get a feeler gauge and measure between the valve retainer and the top of the valve guide seal.

that is your retainer to Guide clearance.

at the very least, it should be .060

.065 makes me feel better though.

and do the same for the exhaust side as well.

from what I remember in the buick powersource manual, any cam over .420 lift will have an issue if your using PC type valve seals.

I hope this helps, please tell me if your totally confused.

A.j.

Good explanation Aj. I don't think I could've done better.:biggrin:

No this makes perfect sense. I am using an 87 block and heads though. Do I still need to do this?

Absolutly! the final assembly has to be checked to make sure the machinist didn't make a mistake. If you don't then you can damage the piston and valves not to mention bend the push rods. LilSpann didn't check his and he bent the valves as well as the pushrods. To use an old carpenters addage, "measure twice and cut once".

 

[dr_frankenstein]

OK Kool.......

I was confusing myself try to explain it.

LMAO

and I was half cut already too. had to actually go out in the garage and think about it for a sec.

A.j.