Did I do something wrong?

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BHB4408

BHB4408
Joined
Aug 29, 2022
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Novice racer, building my own 440 with 512 stroker kit. Trickflow 270 Heads with flat-top ICON pistons at a 12.1 ratio.

I degreed my cam. I did it multiple times, exactly like the cam spec's told me to, and exactly like multiple internet searches told me to, and it had me Advance to the #2 position on the lower timing chain sprocket, to get the 104 as suggested by Bullet Cams. Any other setting on the sprocket didn't come close. The head-gaskets I ordered will give me .040 piston to head clearance. With gaskets in and heads on, I'm using the clay method of checking Piston to Valve clearance, and I was expecting to find about .010 on the clay. But doing the test over and over on different cylinders, I'm getting about .22 (about a quarter inch of PTV clearance) on both intake and exhaust valves. Does that mean I've degreed the cam wrong, or is .22 something that I should be happy about?

Thanks for taking the time to help me out,
 
A couple more notes; The block is bored 40 over, with a 4.36 bore and the 512 stroker rods.
 
If you are running a hyd. cam you need to check it with a solid lifter and 0 lash. No slop in the system. ps how far are the pistons in the hole.
 
Novice racer, building my own 440 with 512 stroker kit. Trickflow 270 Heads with flat-top ICON pistons at a 12.1 ratio.

I degreed my cam. I did it multiple times, exactly like the cam spec's told me to, and exactly like multiple internet searches told me to, and it had me Advance to the #2 position on the lower timing chain sprocket, to get the 104 as suggested by Bullet Cams. Any other setting on the sprocket didn't come close. The head-gaskets I ordered will give me .040 piston to head clearance. With gaskets in and heads on, I'm using the clay method of checking Piston to Valve clearance, and I was expecting to find about .010 on the clay. But doing the test over and over on different cylinders, I'm getting about .22 (about a quarter inch of PTV clearance) on both intake and exhaust valves. Does that mean I've degreed the cam wrong, or is .22 something that I should be happy about?

Thanks for taking the time to help me out,

Sounds about right.

Did you use checking springs on the valves or the springs you are going to run?

If the former you’ll have even more clearance because all rockers have more ratio than nominal built into them.

For example, a 1.5 rocker should measure with checking springs 1.55-1.57 so that the ratio when the rocker is loaded will be 1.5.

If you did the measurements with zero lash you’ll have more clearance. Same if you didn’t use a head gasket.

That’s the problem with off the shelf pistons. The valve notches are almost always too deep.

It sounds like you did it correctly. Did you check the exhaust as well?

If it’s very tight then that’s a clue the cam isn’t timed correctly. If it has close to the same clearance you are golden.
 
Thanks everyone;

I'm using Harland Sharp 1.6 roller rockers, roller lifters, and a 671 lift cam. I checked everything at zero lash with head gaskets installed and the Trickflow Roller Rocker springs I'm going to run in the engine. They are the springs Trickflow recommend for roller rockers, that. I'm going to use in the engine. Yes, the PTV clearance is almost equal from intake to exhaust. I'm just making sure the 1/8" gap between my piston (valve pockets) and valves seems correct. I was expecting the gap to be tighter. Please continue to educate me. Much appreciated.
 
Sounds about right.

Did you use checking springs on the valves or the springs you are going to run?

If the former you’ll have even more clearance because all rockers have more ratio than nominal built into them.

For example, a 1.5 rocker should measure with checking springs 1.55-1.57 so that the ratio when the rocker is loaded will be 1.5.

If you did the measurements with zero lash you’ll have more clearance. Same if you didn’t use a head gasket.

That’s the problem with off the shelf pistons. The valve notches are almost always too deep.

It sounds like you did it correctly. Did you check the exhaust as well?

If it’s very tight then that’s a clue the cam isn’t timed correctly. If it has close to the same clearance you are golden.
440 source says they're notches a 4 ccs too.
My pistons are 6, I don't believe I had that much P 2 v clearance
 

For example, a 1.5 rocker should measure with checking springs 1.55-1.57 so that the ratio when the rocker is loaded will be 1.5.
Wouldn't that be caused by deflection rather than a change in ratio?
 
Wouldn't that be caused by deflection rather than a change in ratio?


Exactly. All rockers flex. All of them.

If you know a rocker will flex and you want a 1.5 under load you add ratio over nominal to get it.

If you build it at 1.5 and no flex it won’t be 1.5 under load.

This is an easy test.

Use checker springs and measure lift. Write down lift at the valve.

Put on the springs you are going to run and measure it.

The unload rocker ratio had better not be the nominal ratio or you’re screwed.

That would mean the ratio when the rocker is loaded is less than nominal.

If you are paying for a 1.5 ratio and it’s not you got screwed.
 
I get what your saying. I guess the way I would look at that is the ratio is the same but the loss on lift is due to deflection in the whole valve train including the rockerarms. For example . There is a loss in lift between checking springs and race springs. You replace a flexing pushrod with a stiffer pushrod that doesn't flex . Now when you check it shows an increase in lift from before. The rocker arm ratio wasn't changed but instead the system has less deflection than it did before.
 
I get what your saying. I guess the way I would look at that is the ratio is the same but the loss on lift is due to deflection in the whole valve train including the rockerarms. For example . There is a loss in lift between checking springs and race springs. You replace a flexing pushrod with a stiffer pushrod that doesn't flex . Now when you check it shows an increase in lift from before. The rocker arm ratio wasn't changed but instead the system has less deflection than it did before.


I’m pretty sure if a checker spring is flexing your pushrods the entire engine program needs an overhaul.

I can measure my junk with a checker spring on a .3875 lobe and it comes out to a 1.63 ratio.

Using my springs it comes out to 1.57 which pisses me off. I’ve talked to PRE about it. So did someone with more clout than me.

He got PRW to update the rocker.

Also of note if I shorten the pushrod .060 the ratio goes down to…I think 1.55. I don’t have my notes here with me.

Shorten it another .060 and the ratio starts dropping like a rock. This is because of the angle of the adjuster going through the rocker.

The further down the the adjuster is, the further the adjuster is from the centerline moves.
 
It sounds to me like you did it right. If you read the KB web site, their description of their valve reliefs in the KB and Icon pistons is "extremely generous" or some such.
 
Got it.

How did you determine it was pushrod flex and not the rocker.
Same way you would check rocker flex. Replace the suspect component with a stronger one and look for a change in lift. On a stud type system you can see the flex in the stud when you loosen the girdle.
 
Same way you would check rocker flex. Replace the suspect component with a stronger one and look for a change in lift. On a stud type system you can see the flex in the stud when you loosen the girdle.


Ok. That’s how it’s done.

And yes, studs flex like crazy.
 
Thanks everyone;

I'm using Harland Sharp 1.6 roller rockers, roller lifters, and a 671 lift cam. I checked everything at zero lash with head gaskets installed and the Trickflow Roller Rocker springs I'm going to run in the engine. They are the springs Trickflow recommend for roller rockers, that. I'm going to use in the engine. Yes, the PTV clearance is almost equal from intake to exhaust. I'm just making sure the 1/8" gap between my piston (valve pockets) and valves seems correct. I was expecting the gap to be tighter. Please continue to educate me. Much appreciated.
If you said already I apologize, but is this a solid roller?
 
Thanks everyone;

I'm using Harland Sharp 1.6 roller rockers, roller lifters, and a 671 lift cam. I checked everything at zero lash with head gaskets installed and the Trickflow Roller Rocker springs I'm going to run in the engine. They are the springs Trickflow recommend for roller rockers, that. I'm going to use in the engine. Yes, the PTV clearance is almost equal from intake to exhaust. I'm just making sure the 1/8" gap between my piston (valve pockets) and valves seems correct. I was expecting the gap to be tighter. Please continue to educate me. Much appreciated.
I did mine today.
With the 1.6 harland sharp rockers
Camshaft lift is .704 , 272-284 advanced 1.5°
Checked at .020 lash
I run a .051 gasket
6 cc piston notches
I milled my trickflows .080
Those are the specs.
My p to v clearance was .110 on the intake & .130 on the exhaust .
Just by adding what I subtracted in surfacing it sounds to me like you did it correctly.
 
I did mine today.
With the 1.6 harland sharp rockers
Camshaft lift is .704 , 272-284 advanced 1.5°
Checked at .020 lash
I run a .051 gasket
6 cc piston notches
I milled my trickflows .080
Those are the specs.
My p to v clearance was .110 on the intake & .130 on the exhaust .
Just by adding what I subtracted in surfacing it sounds to me like you did it correctly.

If you want to go down the rabbit hole, measure lift at the valve with the springs you run and then measure it with checker springs.

The former should end up at 1.6 ratio and the latter should be 1.65ish.
 
If you want to go down the rabbit hole, measure lift at the valve with the springs you run and then measure it with checker springs.

The former should end up at 1.6 ratio and the latter should be 1.65ish.
I will do the measurement off of the retainer, I just need to make a base for my dial indicator.
I tried but couldn't get the reach from the China wall
 
I will do the measurement off of the retainer, I just need to make a base for my dial indicator.
I tried but couldn't get the reach from the China wall
Use a piece of flat steel. Drill a hole in the edge of the metal and bolt it to the valve cover rail. This will give you a sturdy work surface for your magnetic base dial indicator.
 
If you want to go down the rabbit hole, measure lift at the valve with the springs you run and then measure it with checker springs.

The former should end up at 1.6 ratio and the latter should be 1.65ish.
As long as we understand that the rocker arm ratio doesn't change. Instead lift is reduced due to deflection of the valve train components caused by the increased resistance from the stiffer valve spring. That’s what I think is happening anyway. :)
 
Use a piece of flat steel. Drill a hole in the edge of the metal and bolt it to the valve cover rail. This will give you a sturdy work surface for your magnetic base dial indicator.
That's an idea, I was going to make something that bolted to my exhaust flange.
 
As long as we understand that the rocker arm ratio doesn't change. Instead lift is reduced due to deflection of the valve train components caused by the increased resistance from the stiffer valve spring. That’s what I think is happening anyway. :)


That’s not what happens. If the valve train is flexing that much turning it over by hand there are issues.

Every rocker arm manufacturer builds extra ratio into the rocker because the all flex.

With checking springs the ratio should be higher than nominal by a good amount.

The good rocker manufacturers also take into account pushrod angle and rocker offset.

My Norris rockers both loaded (320-340 on the seat and 8xx over the nose) were 1.6. Unloaded the exhausts were 1.66 and the intakes were 1.69.

Rockers flex.
 
Rockers flexing is still flex in the valve train. Not a change in ratio.


Call Jesel and tell them that. The rocker can and does flex apart from everything else.

Make the call and then come back here and let us know what they say.

Rockers flex. It changes the ratio.

I can’t say it any simpler than that.

That’s why my Norris exhaust rockers had .3 LESS ratio than the offset intake rockers. The account for the offset.
 
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