checking piston to valve clearance

[ed hess]

Piston to valve clearance

After reading procedures for adjusting valves and checking piston to valve clearance i came up with a question about piston valve clearance.
Adjusting the valves is simple enough after reading the procedure.

Using comp cam 09-412-08 cam which is commonly used here.
J&E piston of an unknown part number (they came with this motor), and i cant id them from the ones shown in their catalog.

Comp cams directions say if your lifters are hydraulic then you must use solid lifters to test the piston to valve clearance.

The cam that was in this motor (sig erson) had a .480 lift on exhaust and intake. The comp cam 412 has .500 lift on Intake & Exhaust.

Previously rockers were crane gold 1.6. I will be using comp cam pro magnum 1.6 rockers.

Since the lift will be more now I need to find out what solid lifter to use
for this test.

Anyone who has actually checked their piston to valve clearances that might recall what they used?

Wondering if any old set of solid Chevy small block lifter will work here. If so then I can probably borrow some locally?


ed

 

[ed hess]

guess i will answer this question myself

So i called comp cams...guy told me to buy lifter no 818, in a quant of one the part number is 818-1. Also said i really only need check intake and exhaust on no 1 cylinder.

ed

 

[myclone]

You really dont have to check the piston to valve clearance unless you are running lotsa lift (412 is not), severely milled heads (I doubt that), high rpm (doubt that too), or alum rods (doubt that three). You can check it if it makes ya feel better though (I aplaud your attention to detail though).

You didnt have to buy a lifter to check it. Take off the #1 cyl intake and exh valve springs and install the ~$9 valve "checking springs". If you use the clay measuring method put your clay on the piston now. Install the head with no gasket and ~4 head bolts snugged down. Install the reg roller lifter, push rods, and rockers. Snug the rocker nuts down to ZERO lash. Turn the crank over a couple of times, yank the head, make a cut in the clay with a sharp razor where the valves made an indention, remove on half of the clay, and measure the remaining half thats on the piston top.

If you dont use the clay method then do the install of the checking springs, lifter, pushrod, head, rocker etc. and bring the eng up on TDC on the intake stroke. Mount a dial caliper on the head and zero it against the retainer. Push down on the rocker compressing the spring until the valve contacts the piston and note the measurement. Do the same for the exhaust. There is your piston to valve clearance for each.

The reason this works is the checking springs are just heavy enough to hold the valve in position but not compress the spring inside the lifter so you can use one of your lifters that are in the eng.

HTH

 

[warmpancakes]

actually the 412 cam is 500 total lift with 1.5 rockers , according to comp cams. Ken

 

[jwaller]

yes and .533 with 1.6 rockers...

 

[ed hess]

myclone

Piston no 6 had a very small mark on it from an exhaust valve when i tore this down. Machine shop will be checking and measuring everthing for damage!!!

Although the guy ran a lower lift cam but with 1.6 rockers as i will.

Guess you missed where i said the 412 has more lift than the cam he had used!!

Since it was only 1 piston showing this i would think it was a bad spring on just that one cylinder.

But i cant id these pistons from je to anyting in their catalog.

The pics showing the piston tops and the area from the upper ring to the top of the piston dont match to anything in the catalog.

I did ask the machine shop to see if they could determine the comp ratio on them. They said something about cc'ing the heads, and shipping a piston off to J&E.

Since nothing appears to be done in the norm in this block i think it would be a mistake to assume anything this guy might have done here.

Besides with the cost of all this shit...can ya really blame me?

the lifter was like 15 bucks.... no big deal huh here.... just as easy, no easier than changing springs.

I do plan on the clay method...


ken

Yeah i read the lift spec on comp cams webiste for total lift. but then with the 1.6 rockers i think if my memory is correct that equates to .533 or .513, or whatever.

Last motor i did i didnt go thru all this, but i think the total cost when i did that was like 2-300 parts, and the same for machine work. lil triumph spitfire.

If i count up all the bolt ons i bought for this, vortecs, cam, bottom end,
911, headers, turbo.... and on and on its probably like 10k if not more by the time its all goes together.

It cant hurt to take your time and cover your ass. Especially when all the local wussies keep saying..."i wouldnt do that myself, you should take it to someone who does it all the time and pay them.

And my answer: What kind of warranty do i get on a motor from them?

zip
nuff said.

ed

 

[myclone]

Again I aplaud(sp?) your effort and attention to detail.

1. You found a valve mark on the piston from a valve huh? My money is on weak valve spring on that cylinder + the engine was over revved. Valve float makes all kinda weird things happen. Any body tells you valve float doesnt cause weird stuff tell em I said they are stupid.

2. I dont blame ya on having everything checked since youve found so much interesting stuff with this motor. I personally dont see a prob with a .500 lift cam and dished pistons in the piston to valve clearance dept but in your shoes I guess Id check everything out just to be safe and help me sleep better.

3. IMO (repeat my opinion) .500 lift is not that radical. If the lobes wont fit in the block then you have about the right lift IMO. :wink: (thats a joke btw)

 

[ed hess]

myclone

One bad spring and valve float probably caused by to much oil presuure in the lifters.

Remember my posting about the extra high oil pressure he was running.

Put it all these considerations together and it makes sense.

CYA
Btw I dont know how to do this any other way, otherwise i wouldnt be able to take my mind off thinking about it.

ed

Also save the applause till its done
Ive got a few more questions to come for sure.