Guys,

Ive got AFR 315 heads with solid roller springs (and one of Harolds SR cams). I have an adjustable pushrod.

Got a few questions about checking out the top end of my 540...

1) I belive that i need to establish pushrod length before checking PV clearance, right?

2)Once i get the correct length,do i need the actual pushrods that ill use in my motor to check PV clearance or can i just use the adj pushrod? (i think i can just use the adj PR but wanted to ask)

3)Do i still need to use checker springs (im not using hydraulic lifters... but my SR springs might be too much for the adj pushrod)?

If so, where can i get the checker springs? summit and jegs dont seem to have them....

4)How do i determine which pushrod ends i need to use? Is this based on application? or personal preference? this is a street 540, afr 315, 257/263 @050 725 lift SR from UDHarold, Isky Redzone lifters from Mike Lewis (wolfplace)...

what would you guys recommend?

5) when checking PV clearance, do i use my head gasket (will the test ruin it?) or valve spring shims (.030)?

sorry for the long post... just didnt want to have 15 posts going at once.

thanks guys
jeff

From a post by GRN69CH.

Easiest way to do preliminary checking - assuming motor is already assembled. Bring #1 to TDC. Take rocker off #1 intake, get measurement off of fixed point on head to retainer. Open intake valve until it hits the piston, take new measurement, this is your P/V clearance at TDC. Hopefully it is at least .250". For comparison, when I assembled my motor, I had .400" P/V using the above method.

Using A Comp XE as comparison, closest lobe is XE290 [290/252/.614]. This lobe will have .115" lift at TDC when installed at 106ICL. Backing out .024 lash and mult x 1.7 = .155" valve lift at TDC plus .060 clearance = .215" for this lobe. The Lunati may be a little faster and is 2* more advanced, so you will have to check. But my guess would be .250" or better and you will not have a problem. It is real easy to check though.

I did this with a dial indicator and took readings from 15 BTDC every 5 degrees to 10 ATDC. Closet for me was at 5 ATDC. Checking springs give you about .020 less than you actually will get from your actual springs.

Checker springs are not very strong. You can buy a spring from the hardware store the approximate size of your valve springs. 1.5 by 2-3 inches.

I just added the amount of gasket to the total clearance, ie with my .095 clearance plus .020 gasket gave me 115 and with a conservative addition of .020 using actual springs I have more than adequate clearance at 135.


I all depends on type of pistons you are using and the valve reliefs.

Read this about "radial clearance" and the issues associated
http://www.chevelles.com/forums/showthread.php?t=160962&highlight=clearance

Probably just need the standard ball style pushrod ends. Make sure you check your valve train geometry with a sharpie and witness marks to get the proper pushrod length. You will need the lifters you are going to use and the adjustable checker pushrod and springs are fine. Once set up rotate your engine over by hand and check how wide your mark on the valve tip is. Prefer around .060 or less and centered or slightly inboard.

Guys,

Ive got AFR 315 heads with solid roller springs (and one of Harolds SR cams). I have an adjustable pushrod.

Got a few questions about checking out the top end of my 540...

1) I belive that i need to establish pushrod length before checking PV clearance, right?

2)Once i get the correct length,do i need the actual pushrods that ill use in my motor to check PV clearance or can i just use the adj pushrod? (i think i can just use the adj PR but wanted to ask)

3)Do i still need to use checker springs (im not using hydraulic lifters... but my SR springs might be too much for the adj pushrod)?

If so, where can i get the checker springs? summit and jegs dont seem to have them....

4)How do i determine which pushrod ends i need to use? Is this based on application? or personal preference? this is a street 540, afr 315, 257/263 @050 725 lift SR from UDHarold, Isky Redzone lifters from Mike Lewis (wolfplace)...

what would you guys recommend?

5) when checking PV clearance, do i use my head gasket (will the test ruin it?) or valve spring shims (.030)?

sorry for the long post... just didnt want to have 15 posts going at once.

thanks guys
jeff
=
1 You can do both if you want but you will need to use checking springs with the adjustable pushrod or you may break it
I always use checking springs when I am doing geometry or initial p/v clearance & the spring I am going to run if the clearance is close.
Intake will be closest at about 10° ATDC.
Exhaust at about 10° BTDC, both on overlap.
This varies a bit with lobe design.
You are going to need two adjustable pushrods for a rat unless you have the Jesel one.

2 See one :D

3 If you check with light springs you will gain clearance with the real springs by quite a bit, things move around a lot

4 I would use 3/8" .120 or .135 wall pushrods with the standard ends.
7/16" would be better but probably will not clear the heads without grinding so use the 3/8"
If you have trouble finding them just call
You can find springs at the hardware store that will work or Comp has checking springs,
I can get them if you have trouble finding them.
You want the pushrod length to be what gives the narrowest sweep somewhat centered.
I do not care if it is exactly in the middle of the valve tip, it can be to the top or bottom as long as it is as narrow as you can get it.
You need to use some common sense here, you obviously cannot have the rocker tip running off the tip of the valve :sad:
But the cute little pictures that show the pattern directly in the middle of the valve tip are not necessarily correct.
The more the tip of the rocker is sweeping back & forth, the less it is pushing the valve open, simple as that.
Check geometry with hot running clearance.

5 Yes you should & no you won't, you can also check with no gasket & add the thickness.
You don't need anything trick, just put the head on with the gasket you are going to run with a couple of bolts.
Another "trick" is to install the head with no gasket, rotate the engine & see if the piston hits.
If it clears with no gasket you can be sure you have enough piston to head clearance.
This is assuming you do not have positive deck of course.
This should not be an issue with your pistons nor should p/v clearance or radial clearance on the intake but we always check anyway even of we know the combo.
=====edit==========
Also be advised not all pushrod manufacturers measure pushrods the same
Trend & Comp both use a "gauge length" so the pushrod end to end will measure longer by about .017 than what the catalog says
An 8" pushrod will measure 8.017 give or take with calipers.
Just tell who you order from how you measured & you should be fine.

See what happens when you go eat breakfast before posting an answer :D
Garry pretty well covered it already,,

your closest V/P clearance will probably not be at TDC. The method posted above will not, not, give you your real P/V calearance because it starts with the valve closed. The valves are not closed at TDC so that measurment indicates more clearance than is really there.

You can get the ultra-double-triple-trick-superwhammy checking springs at an Ace or Truevalue hardware store. It's just a coil spring big enough to fit over the valve seal and tall enough to hold the valve closed. Assemble the valve train and check the V/P clearance every 5 degrees from 20 before to 20 after. I use the head gasket, two bolts just past finger tight. I have a flat piece of steel strap as long as a BB head, drilled for V/C bolts, bolt on and use it hold a magnetic base indicator stand.

You can mark the tops of the valves with a Sharpie, the rocker will leave a visible mark in the ink. I like to see the pattern in the middle 1/3 or 1/4 of the valve tip.

Any shops that work on diesels also has soft valve springs from the diesel valves that are good checking springs.

hey Mike, I learned it all from talking with you and reading a ton of posts.:beers:

hey guys,

do i check pushrod length with the head gasket in place too or can i do it with no gasket and add the compressed gasket width to the puhrod length?

thanks guys
jeff

http://www.jegs.com/webapp/wcs/stores/servlet/product2_10001_10002_756197_-1

better with your gasket installed

ok, ill use the gasket and like Tom said, a few bolts just past finger tight so i dont screw the gasket up

thanks guys.

yeah, the dowels actually locate the head, the bolts just keep it from falling off and landing on your toe. :) Of course, have to add the inevitable comment: "Don't ask me how I know this....." It was a 428 F*rd head, broke my big toe and blew the toenail right off. I've discovered it takes the biggest part of a year to grow a new big toenail.

yeah, the dowels actually locate the head, the bolts just keep it from falling off and landing on your toe. :) Of course, have to add the inevitable comment: "Don't ask me how I know this....." It was a 428 F*rd head, broke my big toe and blew the toenail right off. I've discovered it takes the biggest part of a year to grow a new big toenail.


OMG! All these years I thought that I was the only dimwit that did that!

I laughed so hard that coffee spewed out my nose!:D

You're absolutely right. It takes about a year for a big toenail to grow back. Unfortunately, I now have a DOUBLE LAYER toenail that takes a Dykes cutter to trim.:yes: I broke THREE toes, however.

Randy

Choosing a push rod length can be tricky. I also found if you order a say .100 longer then stock they actually are about .080 longer, not the actual .100
Also to error on slightly the short side is better then to error on the long side. You want the rocker tip to start on the inside of the valve stem and roll towards the center of the stem or slightly over center at full lift.
You do not want to start in the center and roll towards the outside with lift.
If you start on the inside of center and roll towards the center it puts less side loading on the stem.
You also have to watch about being too short and actually having the rocker touching the retainer on the spring.
Custom pushrods that you shorten yourself and press on the ends are NOT easy to do. I do them for customers but I have special equipment and use liquid nitrogen and they still give me problems.
I also use COMP cams pushrods but they force you to buy sets. If you want a .100 over intake you must buy the matching exhaust even if you don't want them.
Remember to error slightly on the short side is better then to error on the long side.

nah, if there's a dimwit stunt out there I've probably pulled it least once. That's why I'm so ummmmhhh experienced! :)

Experience is valuable, it allows you to immediately recognize when you're making the same mistake again. :)

Choosing a push rod length can be tricky. I also found if you order a say .100 longer then stock they actually are about .080 longer, not the actual .100
Also to error on slightly the short side is better then to error on the long side. You want the rocker tip to start on the inside of the valve stem and roll towards the center of the stem or slightly over center at full lift.
You do not want to start in the center and roll towards the outside with lift.

If you start on the inside of center and roll towards the center it puts less side loading on the stem.

You also have to watch about being too short and actually having the rocker touching the retainer on the spring.
Custom pushrods that you shorten yourself and press on the ends are NOT easy to do. I do them for customers but I have special equipment and use liquid nitrogen and they still give me problems.
I also use COMP cams pushrods but they force you to buy sets. If you want a .100 over intake you must buy the matching exhaust even if you don't want them.
Remember to error slightly on the short side is better then to error on the long side.
=
The bold part above is a very common misconception & not always correct.

I will repeat this.
I do not care where the pattern is as long as it is on the valve tip & as narrow as you can get it while still keeping it somewhat centered.
The best pattern may or may not be in the center or starting from the intake side.

While the ideal pattern would be perfectly centered & very narrow,, the valve could care less where it gets pushed from as long as you keep the side loading to a minimum.

If I have two choices, centered & wide or off center & narrower I will always choose the latter.

If you are traveling across the tip you are not pushing down on the valve regardless of where the pattern ends up, you are pushing sideways.

Again, do not believe everything you see in some catalogs regarding rocker geometry & pattern position ;)

BTW, although I don't use them to often, you can buy any comp pushrod in singles if you wish.