topsportsman1

I see so what you are saying is that you used the 31* @ .050 method OK

Another thing you need to do is make sure TDC is verified with your degree wheel using a stop or dial indicator,I prefer the indicator myself

One thing for you to consider is,to do your checking at the #1 intake lobe when doing it this way,,the way you have done it at the intake valve tip you can have some error,I'd reccomend doing it at the intake lobe,then check the clearances with lite springs like someone said previously.

If you can't get proper clearances that way,I'd reccomend setting the cam in with the centerline method and advance it till get sufficent enough exhaust valve clearance.,some where around 110 degree center line would be a close start

Robert1320

I am interested in finding out what worked out. I agree with the guys above.

bjuice

This is some good stuff here...JUST wanted everyone to know that has participated in this thread ..i am soaking all of this up.....anxious to see what the out come is....

a -lot of varibles thrown in here by some very experience fella's

Brian

gyrogearloose

It has been a long day. Ran all over and burned up $100.00 in gas. And talked to a 100 poeple besides everyone up here who is offering good advice. Took the head back to Chapman's to get it repaired, and had them install check springs on the other head so I could mock up the left bank and #3 cylinder again.
Yes I used the dial indicator to find TDC on #1 and it is correct. I also checked #3 TDC for the hell of it, and it is correct. (like the crank is going to be wrong.) Took the other pistons over to H. Doubaugh's shop to have the valve pockets check and realigned to the valve angle if necessary. Tomorrow I will check the clearance of #3 exhaust valve at 10° BTDC on the exhaust/intake stroke. that is the closed the piston will ever be to the piston now that I have the check springs on the valves. Will post tomorrow with results and any further developments.
Thanks for all the help todate,
gyrogearloose

gyrogearloose

Forgot to say that I asked if the valves were set back to the correct depth and the chambers were re-clearanced after the resurface and was told that they were.

edvancedengines

Hi again,
By no means was I saying that Chapman does not know what they are doing. I was meaning that it does not matter who sets up your valve springs including me, if they are not set up for your exact cam needs and no more extra clearance from coil bind than is the minimum necessary they could be done wrong. Also ask them about your exact springs with the cam profile and lift and rpm range you want and see if they are recommending this same spring.

How much valve to piston clearance do you have to the intake valves? You can possibly get some additional wiggle room there too like I said earlier, by changing your camshaft lobe Intake Centerline.

Ed

gyrogearloose

I didn't get anything done yesterday. (Some days I could just strangle some employees.) I checked the clearance of #3 exhaust valve at 10° BTDC on the exhaust/intake stroke of #3. With the dial indicator I have .765" clearance between the exhaust valve and the piston.* I again checked the cam timing at #1 and it is just where I set it. 31° BTDC @ .050. I again checked the cam timing at #3 It is the same as #1 as far as the intake and exhaust opening and closing.

Ed, I know, Not sure that I said my answer correct. Anyway sorry for any miss communitactions. The valve springs I used are Crane Part # 96848 and I also used the Crane rtoller lifters Part # 13552-16. I like keeping everything matched if possible. With the clearance I have between the valves and pistons, I don't think it is a clearance problem. Will look at the valve train componets tomorrow. Still not sure what I am looking for.

* I had to check back in my notes to see why I put so much clearance in the combustion chambers, but when I had the combustion chambers layed back, I was using 50cc domes. I am now using 42cc domes, which accounts for all the clearance between valves and pistons.
Still looking for any ideas,
thanks,
gyrogearloose

sp2816

That number doesn't sound correct. With your domes, duration on the cam, and valve lift, if you get numbers higher than .180" you had better measure again.
To check the clearance, you need to set the valve lash to .000" with the pushrods and the rockershaft on. Then you rotate the engine over to 10*BTDC on that cylinder (#3 would be 100* on the balancer). The camshaft will actually open the valve and start allowing it to close. Then the exhaust valve is depressed additionally by hand until it touches the piston. The extra distance the valve will depress down from the rocker is your clearance.
When you come up with your number this way, you can always add your valve lash to the number and come up with your running piston to valve clearance. Say you come up with it being .075" and your normal valve lash is .025", your piston to valve clearance is .100".

Hope that this helps,
Bill M

gyrogearloose

It has not been a good week. I don't know why I posted this number this way, but, .765=.0765. Please don't ask, because i don't have an answer for this. Anyway with the 50cc domes, it wasn't that much, but ok.
Now for the update. I talked to JE today to get replacement pistons for #3 & 7. It is a discontinued part. The replacement piston (#258236) is 35 grams lighter than the pistons I am using. They said They would machine two pistons for me, but it would be a minimum of 2 weeks. Which in realility is more like 1 to 2 months.
So we have decided to put the backup long block in the car and start over with the current engine.
So until I find the problem, I will not be posting to this thread anymore.
The race season is too short to be sitting out for 3/4 of it. Thanks for all the help and advise from everyone.

gyrogearloose

edvancedengines

I could probably get you a set of pistons custom made in 3 weeks. If not custom made maybe even quicker if it is a standard style of dome or combustion chamber configuration.

Another thought is that possibly Mike Panetta at Diamond could get you some together quickly.

I personally hate the JE pistons that they call nitrous pistons. Just a personal opinion. I also hate what looks to me like mountains sitting on top of a piston. I have been making mole hills out of mountains on pistons for a long long time. Even if someone does bring me an out of the box JE nitrous piston, I chop chop until I am happy.

Look at your burn pattern on your piston and in your combustion chamber. Look good at all the soot and crap. Now clean the piston good and wire brush the top hard with a brass brush. If you see any color where that color is , is your actualy burn pattern. I think you will discover that most of the previous colorations just washed off the piston, particuarily the piston dome and the quench pad of the piston will possibly look like it has never even seen any heat at all. If that is what you see or anything similar you can gain power with a different dome profile that works better with your chamber.

Wo cares if you lose a little compression if you are improving the flame probagation of the joining of the many different flame fronts to get a better burn. Actually I have done some pretty high compression stuff with domes that were not as larrge, particuarily with large swept volume engines.

You did have some very important measurements missing from your posts though. You never posted what the LSA was or what Intake Centerline you had it set up for. Even if you are degreeing in a cam using the .050 opening and closing numbers it is still advisable to check the Intake and the Exhaust centerlines.

Maybe your v/p clearance was enough, Maybe other guys would like an .0765 exhaust clearance. I don't.
Not to me it wasn't. I do not do exhausts less than .100 and I prefer .125. Intake is not so big of an issue and I do get them closer.

Ed