[wallyworm]

my valve spring installed height is 1.70, I have #48 heads and when I measure the installed height it is 1.58, I looked into valve spring seat cutters and the inside diameter on most are .620, but when I measure my valve guides at .670. looks to me like I am going to have to cut the valve guide down so I can cut the spring seat. I see valve seals are available in .620, any suggestions would be appreciated

[25stevem]

Please go over what you have posted.
You have stated that your valve spring installed height is both 1.700” and 1.58” ?

For a # 48 head 1.700” sounds more like it .
What is the overall length of the intake and exh valves you have?

[Formulas]

his target is 1.7 his current is 1.58 but i detect a situation where a auto machine shop should do these heads not a job for a novice

pockets need cut valve guides need cut to .530 dia. the guides height needs trimmed down to comfortably accept a viton seal, and since he is talking .620 guide dia he most likely has original guides which should be suspect for internal wear

[wallyworm]

the new valve springs require a 1.70 installed height, and i am measuring 1.58. intake valve is 2.11 x 5.095, exhaust is 1.77 x 5.11 ferrea stainless

[wallyworm]

i found valve spring seat cutters, and videos of it being done, seems fairly simple, was hoping someone else may have come acrossed this situation before, i am 2 to 3 hour drive from a good machine shop.

[25stevem]

Even though it’s more expensive if you do not have a good drill press set up at home and have to use a hand drill, then your better off buying two different cutters.

One that tops the guides and cuts there OD for a .530” Viton seal, and then another cutter to just cut the spring seats seats instead of the combo cutters that can be had.

Since you will need to cut from the spring pocket a total of .120” that’s starting to get iffy in regards to cutting into the water jacket.

I would get valve keepers with a .050” offset and then remove the remaining.070” from the spring seat.

When you top and cut the guide be sure to leave .060” tall section of the original guide to center the bottom of the spring.

When you get the cutters be sure the bottom of each shaft has a nice taper to it so it does not chew up your guides from rocking due to the use of a hand drill.

Also lube that guide shaft up really well, the cutter sections of both should be dry so they expell the chips.

Once you think your done be sure to check that you have enough retainer to seal clearance for the valve lift your running .

The valve seals you need to match that .530” cutter can be had from Butler performance.
It’s there part number pep-343530-16.

How much lift will you have at the valve with your set up?

[PAUL K]

.120 is quite a bit. There is water underneath the spring pocket. Might want to verify you will have enough material to make that cut. If the spring has a damper it will chew through the cast iron in short order.

[Jay S]

Most people just use longer RAM AIR IV length valves on those heads, instead of stock length to get to 1.7” IH.

But you can cut the spring perched (Compcams and Isky both sell them), change to deeper retainers, and/(+/-.050”)valve keepers to change the IH, sometimes it takes all the above.

[74SDformula]

Just about every pair of Pontiac heads I do get longer valves put in them. That way I can use a spring cup to protect the cylinder head. I also typically use 10 degree retainers/locks which make it easier to adjust the installed height.

[Half-Inch Stud]

Buy your own valve guide boss cutter tool and dyi all 16, for the save.

[74Grandville]

i'll switch it up and say what cam are you trying to run that is calling for those springs? might be able to go for a crower spring like the 68404 with 1.6 install hight and get the same result.

[Cliff R]

I would not cut the springs seats that deep.

Better to change the keeps, retainers or go to longer valves to get you where you need to be.......

[NeighborsComplaint]

You won't be able to cut that much out of the spring pockets. One alternative is to find a set of springs that install around 1.586" and cut the guides down for Viton seals.

The other alternative is to swap your short D Port valves (5.095" & 5.11" L) to RA IV length valves (5.213" & 5.2.3" L).

If you do the math (1.70" - 1.586" IH) you need to gain .114" for 1.7" IH
Intake side gain (5.213" valve - 5.095" valve) you gain .118"
Exhaust side (5.23" valve - 5.11" valve) you gain .120"

Dropped spring locks are only available in -0.050" so the above is as close as you're going to get without machining the spring seats and either shimming back up or using the dropped spring locks.

The .004" and .006" difference in installed height is nothing and most builders would be happy to get that close.

[25stevem]

For safety sake if your running factory stock valves which are two piece then get them the hell out of there a use new valves as posted in the RA4 length.

[NeighborsComplaint]

I'll add that if you stick with stock installed height springs (1.586"), even with the valve guides cut, you will be limited to just under .500" lift at the valve.