[RUDOLFSSON]

What's considered ok here ?

Anyone with experience or cross sectional photos ?

I need to refresh the pockets on a pair of heads with ported runners.. seems like previous folks used no steel shims at all

Also pondering the idea of machining the pockets in a non ported pair a bit larger and deeper about .050 - 0.080 ".

Heads discussed... the old faithful: Edelbrock RPM Performers



Thanks in advance.
KRISTINN

[Half-Inch Stud]

Hard shims on Spring bottom are a must. No spring to Al-head contact allowed.

[steve25]

What spring installed height are you in need of?

What the overall lenght of the valves you are using?

Are you in need for more then about a 1.80" installed height?
What's the story behind the heads ?

I ask because it's highly unprofessional to not at least have a .010" shim under the spring so that it does not chew the heads up, this also would lead me to believe that the heads where not professionally ported so I would tend to think that not much if any was removed from the roof area.

The simple fact is that with the way these round port heads are cast the roof is already too tall off the floor as they come out of the box in regards to the stock flow numbers the Intake ports produce.

I have a cut away picture that I can dig up and post later today, in stock form there should be 1/4" of meat in the spring pad seat.

[chiefbigb]

I have seen roller springs eat a .015 shim up. The shop I use wants a minimum.030 to start with.

[PAUL K]

It's not a problem to widen the spring pockets on the first design heads. We usually refrain from cutting the spring pockets more than .050 if the head has been ported.

[steve25]

If you have springs cutting there way into any hardened steel shim then the springs are not quality controled right in terms of the deburring process.

That being said many a time I have spent a hour with the flat wire type springs further rolling over the sharp edge that still remains on them.

[chiefbigb]

I believe if they are thin enough rpms and high spring pressure will eat them up. That's the rule of thumb they use with over 40 years experience in drag pulling truck and round track engines. Most of my stuff gets spring locators installed.

[steve25]

This picture may offer you help, but this is one of the digital tools I use porting and gauging work .

[RUDOLFSSON]

The ported set came from Indian Adventures ... what a joke !

Today that cyl. head pair belongs to my father, the runners are near identical to the 330/340 cfm programs I've molded and scanned from other sets....
We've had that pair numerous times on our workbench since we discovered how horrific they came from Dick D. .... and yes we run steel shims on all our stuff.
..... anyhow, I'm machining these for dual conical springs 7245-16 // touch up on the floor of the pockets, I guess around .020" deeper and bring the diameter up to 1.66" ish.

The other pair has stock runners and seat pockets. 1.95" INT /1.92" EX Install height in them as is. My springs I had set up for these are @ 2.0" … I’ve yet to check them in on our pressure tester to match with pockets. I might end up @ 1.95” IH.
They need at least about .050” to be cut down and diameter to go up around same amount… this is for a turbo application... I wanted to cut all the heads at the same time in one of the 5-axis cnc centers @ work.

PS. Many thanks for the pictures Steve and all the input guys! Nice metrology equipment !!

Thanks,
KRISTINN

[Tim Corcoran]

I like to use hardened spring locator and locate the shims under the seat.

[Tim Corcoran]

Originally Posted by Tim Corcoran

I like to use hardened spring locator and locate the shims under the seat.

I meant to say I put the shims under the spring locator. This also stabilizes the spring and prevents it from walking around.