Valve spring sanity check

louisb

louisb

Senior Member
Hi All,

Setting up my valve train on my flathead and I wanted to run the numbers by you guys since this is my first time. This is a 276 street engine with the usuall dress up goodies.

Valve Train Components:
Potvin 3/8 cam
Stock springs (sealed power)
Chevy OEM 1.5 valves (sealed power)

Measuring the springs at 2" gives me from 48 to 53 lbs. This should be okay for a motor that tops out at 4500 rpms?

installed height is 2.40".

Does this sound right? If so I will need .40 in shim height. Is that correct?

Thanks,

--louis
 
louisb said:
Hi All,

Setting up my valve train on my flathead and I wanted to run the numbers by you guys since this is my first time. This is a 276 street engine with the usuall dress up goodies.

Valve Train Components:
Potvin 3/8 cam
Stock springs (sealed power)
Chevy OEM 1.5 valves (sealed power)

Measuring the springs at 2" gives me from 48 to 53 lbs. This should be okay for a motor that tops out at 4500 rpms?

installed height is 2.40".

Does this sound right? If so I will need .40 in shim height. Is that correct?

Thanks,

--louis
Click to expand...

Hi Louis, I would say you need more particulars here?? Part numbers maybe?

Thanks, Gary in N.Y.

P.S. A .400" shim on a Flathead just ain't happenin! (I don't think)
 
.400 shim seemed like a lot to me too which is why I asked.

The following are Sealed Power:
Valve Keepers - 115
Valve Guides - 428
Valve Springs - 393
Valves - 1199

Retainers came from Speedway and have number - 910-15318

just in case I did it wrong, I put the assembly together but not in the engine and measured from the guild to the retainer. Comes out to 2 4/10.

Thanks,

--louis
 
louisb said:
just in case I did it wrong, I put the assembly together but not in the engine and measured from the guild to the retainer. Comes out to 2 4/10.

Thanks,

--louis
Click to expand...

You're gonna have to insert each assembly in its bore, install the keeper, then measure installed height.
 
Generally stock valves will give 2.125 installed spring height. The chev valves have longer stems. Ive used as many as 3 060 shims to get 70-80 on the seat with isky springs which is where you want to be with that cam. Stock springs will close the valve but I would upgrade. Off set split keepers will also gain you some...
 
Okay so it is a stock ford 2 piece keeper and it goes in the groove closest to the end of the valve right?

Thanks,

--louis
 
The offset split keepers? yes goes in valve stem groove. they look just like the stock ones but the groove is slightly off center to raise the spring retainer.
 
40cpe said:
You're gonna have to insert each assembly in its bore, install the keeper, then measure installed height.
Click to expand...

This is how it's checked, in the block, as it would be if running. Horseshoe clips, retainers, and locks.

Thanks, Gary in N.Y.

P.S. That part number spring, VS-393 should yield about 50# @ 2.000" (if Speed-Pro hasn't changed their original specs). This should be OK. I keep those springs in stock but none of your other numbers? Our guide number is VG-614 or VG-614B, same guides but the "B" denote bronze-lined.
 
40cpe said:
You're gonna have to insert each assembly in its bore, install the keeper, then measure installed height.
Click to expand...

Okay that makes more sense. I come up with 2.125 when installed in the bore. So I should need 2 .060 shims.

Sorry if the questions seem dumb. My first engine rebuild so I will probably have more.

Thanks,

--louis
 
There is no need to put it together as an assembly to check installed Heights.Install the guide with the horseshoe clip in the block.Drop a valve in the guide install the retainer and keepers. Straighten everything up hold the valve closed and take your measurement from bottom of installed guide to the retainer and there u have it.It will take a telescope gauge to get the measurement .Not rocket science just plain old measuring.A bit time consuming but that goes with the territory on the first few.No telescope gauge make up some go no gauges with welding rod and have at it.Think outside the box.If you need 2 spacers that isn't the proper setup either.Buy some compensated keepers and you will probably get by with one shim there is some proper measuring that must happen.

R
 
Thanks Ronnie that is what I ended up doing after trying it with the spring in. Who makes compensated keepers?

Thanks,

--louis
 
Hi Louis, you say "double-grooved" valves?? Are these "longer-than-stock" Chev type valves??

I ask because this entire setup using the Chevy valves creates way more grief than necessary, we stopped that method years ago!

I've put this up here many times, there's not a bunch of room on the guides to be "stacking" spring shims. A single .060" alone may be a stretch! You really DON'T want to lose the spring register on the bottom portion of the guide with excess shims?

Thanks, Gary in N.Y.

P.S. If this is your issue? there are keepers (valve locks) that we use for the Chev's/Flatheads (same locks) that are either -.050", Std, or +.050". This may be an option in your case. If we find we need the longer (Chevy) valves to get the job we done simply use lash caps (adds .080" to the valves) in conjunction with the OEM (Flathead) lengths, this removes ALL the spring height headaches! Much of this is affected by the cam "base-circle"?
 
Hi Gary,

Yes they are the longer OEM Chevy valves sold by Sealed Power. I am using a reground cam which is why I went with those valves. (After getting a headache from reading a few dozen threads on here with a bunch of different opinions.)

Thanks,

--louis
 
louisb said:
Thanks!
Click to expand...

Hi Louis, there may be one better option left which would require NO shims and NO headaches.

I believe the Isky 185G spring will fall right into place there and solve the entire issue! Possibly won't need to mess with any shims OR the shorter locks and in the end you will have a much better spring for a performance type build.

The cost of the Isky's isn't all that bad considering $30.00 for the locks that MAY still not work! I believe their springs are around 75.00 or so! You are really better off with the least shim thickness you can put in there under the springs! Like I said, you may not need a single shim this way.

Thanks, Gary in N.Y.

P.S. I can be much more accurate on this but not until Monday when I'm at the shop. This route sounds simple to me?? Your call in the end for sure though!
 
Sounds like a simple solution which is usually the best. I had thought about LZ springs but not the Isky springs. If it looks like that will work and you can supply them shoot me a pm.

Thanks,

--louis
 
Aren't the Isky springs comparable to Zephyr springs? I used the Chevy valves/LZ springs with one .060" shim on each valve and a few springs with an additional .030 to get in the 50# range.
 
The issue here is the amount of spring pressure. Will the Potvin 3/8 cam operat to 4500 RPM with only 45 to 50 lbs of spring pressure. The L-100 will operat to over 5k with it, but may have a different profile. As cheap as I am I use shims to get this pressure and ther are a bunch of my engines running around this country with stock springs chevy valves and 2 .060" shims. I'm not suggesting this is the right way to do it, just one way to skin a cat.
 
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