Put on your blindfolds, into the inner and outer world of valve springs we go!

-
MOPAROFFICIAL

MOPAROFFICIAL

Oogliboogli
Joined
Jun 1, 2016
Messages
13,341
Reaction score
17,353
Location
Popcorn stand
So you got your new Fast rate cam and you're stoked. You flip the lid and pull out the instructions... and it tells you that it requires a prticular valve spring... oh?...okay.. a double spring as a matter of fact. You read further into the instructions and it tells you to break the camshaft in by removing the inner spring and only running the outer springs...
.............Uh oh..........
But wait, do you even know what the outer spring by itself rates? What seat pressure? Open pressure? ....well? Do you??
You don't...
Unless you have a rimac aka "spring tester".. you have no idea what the pressure is or if it's even sufficient for a cam to survive a break in. ..or how about the little "womp womp" of throttle you give it ..before shut down and inner spring reinstall...
Well.. you would be shocked to find out that the outer spring alone is MAYBE 90lbs seat and 175-190lbs open/full lift all the way to coil bind!
Proper break in procedure, not necessarily psi , is what's most important. Proper lube, fuel primed,oil primed, instant spark... are the main keys to that procedure of a properly built and ready to run engine.
Consider the idea that you could very well be doing harm to your brand new camshaft by only running the outers.

Example...a common 140lb @1.80 315 open spring 'assumed made by the same manufacturer p*****r and reboxed by Hughes, engle, paw..'yes they're that old' and maybe even Howard's...'

80lbs psi installed ...
175-180lbs open @500

Would you break in a .573 lift solid with less than 250 open? Even less than 200?
Let alone 80 seat.
2200-3000 rpm.

Be safe out there.
Know what you're doing before you do it.
 
Last edited:
I’d break in a cam with 80 on the seat. Why not? There isn’t a lot of load on the engine and the rpm shouldn’t get high enough to be a concern.
 
Yes. RPM is what will hurt something with spring pressure that low. There is no reason to brake in a cam over 2500 anyway. Run it for 15 minutes and put the inners back in and another 15 minutes and it’s done.
 
I always vary between 2500 and 4000 on break in. You want a ton of splash.
 
Are these blindfolds?

download.jpeg
 
RustyRatRod said:
I always vary between 2500 and 4000 on break in. You want a ton of splash.
Click to expand...
Splash is correct.
2000-2800 is where I break'em in. 3000 in some cases.
Hyd flat tap chevy low lift dinosaur grinds are all about 1800-2200. Stock 340, same...but you aren't gonna control squat imo on a fast rate, it's right at the edge of launch. One blip to goose it for any reason to keep it from dying or what have you and slap. Bunch of bs.
120-140lbs seat , no problem. Save yourself the trouble with changing the inners.
Not even 180 open in some cases.
You could squeeze your fist with more pressure.lmao.
 
MOPAROFFICIAL said:
You could squeeze your fist with more pressure.lmao.
Click to expand...

A lot more accurate statement than many realize.

And when I say 4K RPM, I mean for an instant, varying. That's just how I've always done it. Our auto shop instructor showed us that and it's always worked for me. I have YET to wipe a lobe. Knock on wood.

But back to the valve sprAng subject....I've also broken in a good many with dual sprAngs and never taken the inner sprAng out. Never worried about it. The key is, I believe, not letting it drop below a certain RPM. "WHATEVER" that may be.

I guess my attitude has always been, if something goes wrong at break in, I want it to happen RIGHT NOW, rather than on the road.
 
Subscribed with a few questions. Will be assembling a mild 318 build when the block gets back from machine shop jail. 9.7-1 compression, 302 heads and a melling grind 68 340 automatic cam. The 302 heads have the stock single springs in them. Pretty weak springs. I purchased melling VS-380 springs with inner damper coil. Supposedly these are 340 springs. Plan was to break it in with the springs already on the 302 heads and then swap in the VS-380s.

As OP posted unless you have some sophisticated equipment, you dont know what open or closed or seat pressures are. Cam manufacturers like edelbrock typically manufacture power packages. Use their cam, lifters, springs as an engineered matched setup, no issues straight out of the box. I have built engines before back in the 1990s and even one for my pops lil red express around 2002 and never had cam lobe wipe out issues. Now I'm reading about the oils not having zinc, or ZDDP in them. Inferior parts etc. My head got to spinning, I said to myself damn, should I have just gone roller cam now?

Back then I'd build them up with the springs I was gonna run. Typically use the cam break in lube, get it started, and run it 20 minutes varying RPM from 1800 to 2500. After which I'd set the idle, fine tune the carb and timing, and drive it around the block. I'm going to want to do this one the same way, but not wanting to wipe out a cam lobe either. This brings me back to the beginning of my post. Since I will be using a melling flat tappet cam and melling lifters, Should I just break it in with the lighter single coil 302 springs, then swap em out for the heavier springs after the cam is broke in. Or install the heavier 340 springs on assembly, and just use an oil with ZDDP additive and send it like I always have done? I'm mostly a body and structure guy, but can build an engine. I just dont do it very often like some of you Gurus do.
 
Last edited:
moparmat2000 said:
Subscribed with a few questions. Will be assembling a mild 318 build when the block gets back from machine shop jail. 9.7-1 compression, 302 heads and a melling grind 68 340 automatic cam. The 302 heads have the stock single springs in them. Pretty weak springs. I purchased melling VS-380 springs with inner damper coil. Supposedly these are 340 springs. Plan was to break it in with the springs already on the 302 heads and then swap in the VS-380s.

As OP posted unless you have some sophisticated equipment, you dont know what open or closed or seat pressures are. Cam manufacturers like edelbrock typically manufacture power packages. Use their cam, lifters, springs as an engineered matched setup, no issues straight out of the box. I have built engines before back in the 1990s and even one for my pops lil red express around 2002 and never had cam lobe wipe out issues. Now I'm reading about the oils not having zinc, or ZDDP in them. Inferior parts etc. My head got to spinning, I said to myself damn, should I have just gone roller cam now?

Back then I'd build them up with the springs I was gonna run. Typically use the cam break in lube, get it started, and run it 20 minutes varying RPM from 1800 to 2500. After which I'd set the idle, fine tune the carb and timing, and drive it around the block. I'm going to want to do this one the same way, but not wanting to wipe out a cam lobe either. This brings me back to the beginning of my post. Since I will be using a melling flat tappet cam and melling lifters, Should I just break it in with the lighter single coil 302 springs, then swap em out for the heavier springs after the cam is broke in. Or install the heavier 340 springs on assembly, and just use an oil with ZDDP additive and send it like I always have done? I'm mostly a body and structure guy, but can build an engine. I just dont do it very often like some of you Gurus do.
Click to expand...
No guru here.
Break it in with the new melling springs.You'll have no issues.
Stock 340 springs are only around 90-100 lbs seat and like 240 open @lift. 318 springs are 80 seat and maybe 180 open...but are very short and coil bind right above the 340 lift iirr.I'll have to check again. .395 lift....With the old stock hp cams. I've fired them and raised the idle speed to 2400 and just walked away and sat down for 20min. That cam will rev 5800-6000 rpm with that spring, why? Because it's only around .429/.441 lift! Rpm, yes that's a 'FACTOR' ..but not the only one.
I was going to do a video but got too busy.
Think i still will this weekend.
 
Thanks for the refresher and specific information it's always good to go over this stuff for us old flat tap guys.
 
Using the automated BreakIn Cycle on the SF-902 is the only way to fly for me. Cycling from 1800-2400 RPM in 1 minute is the way I like to break in flat tappets. I do remove the inner springs for this and haven't lost a cam since using this method. J.R.

thumbnail_20210731_115940.jpg
 
I’ll add, with a flat Tappet it’s crucial to detail the lifter bores on assembly and make sure the lifters are free to rotate. With a hydraulic flat, it’s crucial to prime the oil system before cranking. And (most people don’t) crank in a bunch of timing.
 
RAMM said:
Using the automated BreakIn Cycle on the SF-902 is the only way to fly for me. Cycling from 1800-2400 RPM in 1 minute is the way I like to break in flat tappets. I do remove the inner springs for this and haven't lost a cam since using this method. J.R.

View attachment 1715773806
Click to expand...


There is a shop down here in east county, el cajon iirr that has a machine they use to spin up for break in.
 
Last edited:
TT5.9mag said:
I’ll add, with a flat Tappet it’s crucial to detail the lifter bores on assembly and make sure the lifters are free to rotate. With a hydraulic flat, it’s crucial to prime the oil system before cranking. And (most people don’t) crank in a bunch of timing.
Click to expand...

Many blocks are cooked and it leaves a rougher finish everywhere that isn't freshly machined. It's always a good idea to lightly 'finger twist' hone with some 500-800 grit paper in the lifter bores before cleaning & assembly.

Always makes sure they spin easy.
Always check the oil feed hole sizing in each lifter bore. They are sometimes not as big or have a ton of flashing like the late 70's 318's.
 
MOPAROFFICIAL said:
Many blocks are cooked and it leaves a rougher finish everywhere that isn't freshly machined. It's always a good idea to lightly 'finger twist' hone with some 500-800 grit paper in the lifter bores before cleaning & assembly.

Always makes sure they spin easy.
Always check the oil feed hole sizing in each lifter bore. They are sometimes not as big or have a ton of flashing like the late 70's 318's.
Click to expand...

Someone told me you were good at finger twisting.
 
TT5.9mag said:
I’ll add, with a flat Tappet it’s crucial to detail the lifter bores on assembly and make sure the lifters are free to rotate. With a hydraulic flat, it’s crucial to prime the oil system before cranking. And (most people don’t) crank in a bunch of timing.
Click to expand...

RIGHT! That's another reason I add some more RPM. Higher RPM tends to persuade lifters to rotate.
 
You must log in or register to reply here.
-

Back
Top