rithsleeper

So trying to get a perfect tdc check and now I bet I have to pull the head. I got just a generic summit racing piston stop and started having trouble turning the engine backwards because it would just start backing off the main crank bolt. So I figured would turn it till the balancer read 350* and screw the piston stop in till i felt it hit the piston then I only had to turn the engine clockwise and would hit it again around 10*..... But it went smoothly past it. Yes I have 600lb springs and its pretty tough to turn the thing to begin with. So I tried pulling the stop out again and it was not turning. I had to put a socket on it and finally got it out and the thing was bent. It was hard to back it out too. It didn't damage the threads but I'm worried the it scratched my piston or valve as it backed out.

What a pos. More tools that break. I didn't think there was much to a piston stop and watched a video of two people using them and one was the summit video and I don't think I did anything different. In fact I feel I should have felt the stop earlier because I was going for 10* off not like 5* so now I'm going to break this engine down again! Brand new pistons an Afr 220 this better not have messed something up...

If there is a nick in the valve or piston could I try to smooth it best I can and be ok or will I still have detonation from a hot spot unless I replace...

Did I think about something wrong? The piston is at top of stroke only at 0 right not 0 and 180... When trying to get it out I turned it to 180 and it still wouldn't come out all the way so I turned a bit more and it became loose... Coincidence?

C409

...... You should have removed the rockers from that cylinder ... an opening valve may have contacted your TDC tool and likely bent it ... and , if you really muscled into it you may have bent the valve also ... there are ways to check the valves without removing the head , but I wouldn't try to remove the TDC tool without pulling the head ... it might garf the spark plug threads ........ After re-reading your post , you probably bent the tool with the piston ... the spark plug angle is pretty flat relative to the piston top and you may not have screwed the tool in far enough to contact the piston deep enough in the bore ... especially easy with dished pistons ........ If its the brass tool , it probably didn't do any damage to the piston ......

WVZR-1

Piston is at TDC twice per complete combustion/exhaust cycle.

bjankuski

As noted, piston stops do not really work. The piston stop is almost parallel to the top of the piston, so they are very easy to bend and the valves will hit them if you are not on the compression stroke.

65Z01

Yep, you need the VC off to verify compression stroke.

rithsleeper

Well that's what it was hiring when backing it out but I know the piston bent it. I am just going to pull the whole head.

Can I reuse the manifold and head gasket? They are brand spankin new and that is another $100 in gaskets right there....

I ran the engine for about 30 min....

JackDidley

Angle plug heads can cause that. The stop is not pointed directly at the piston.

ANTI VENOM

Don't feel too bad, I did the same thing. Didn't even know I hit it. It was like I never hit the stop until I tried to remove it. My tool bent and the valve definitely hit it as well. I did numerous leak downs and checked against other cylinders and mine appears to be fine. I hope you fare as well.
Good luck.

JrRifleCoach

You could buy a cheap bore scope from Harbor Freight.
And save yourself the time and money pulling the head.
http://www.harborfreight.com/digital...era-67979.html

WVZR-1

That's a great idea. I believe I'd do it before all else!

rithsleeper

That is a great idea and very good investment for everything. However I'm still back to the original problem of verifying tdc... A piston stop didn't work with the angle I wanted..... Removing the head would allow me to slap a gauge on it. Should I retry the stop with a different brand?

cv67

If you did a leakdown test may show if you bent something up or not without tearing it apart

rithsleeper

How can I varify tdc some other way than the piston stop that doesn't stop the piston?

cardo0

Yea after bending my mail order piston stop i made a bunch of my own. I took some old spark plugs and broke out the ceramic/cut off the electrode. Found a tap to make course threads inside, used a good old stove bolt with a big head and enough length for what i want. Used 2 nuts between plug casing and bolt head to lock up the length i want then file off the sharp threads at the end. Much stronger than the aluminum thing i had bought before but u can still bend it (plug case is fairly weak) if not careful.

U need to come up to the piston stop slow enough not dig into the piston and not to bend the stop bolt.

Hope this helps.

BTW i could send u one if i can find them in my storage but really if u have large enough taps u will have your own in and hour or 2 depending whether u crush a few plug cases in the vise.

Silver96ce

You can use a "whistle" -

http://www.ebay.com/itm/S-G-Tool-Aid-Top-Dead-Center-Indicator-33650-/360935776773?hash=item540972e205&item=360935776773&pt=Motors_Automotive_Tools&vxp=mtr
I bought one like this and it worked fine for me.

DanZ51

Not sure if you found a solution yet but here's a suggestion: find a dial indicator that utilizes a a swinging contact probe.



There are hundreds of these on flea-bay either used or new (low quality) for cheap. The accuracy is not a major concern for your needs as you're only looking for a highest reading. Probe contact length will be limited but for your purpose you could tape a heavy gauge wire onto it to extend the length down through the spark plug hole. This is all speculation at this point (as I've haven't done it, yet) but I think this would be the solution you're looking for, for about $25

GQ-ROD

https://www.corvetteforum.com/forums...er-wobble.html

When i removed my distributer, i used a summit racing piston stop. Worked great for me, i marked both points that the engine stopped with tape then divided the distance between both marks to get my true tdc mark.

Had the same problem with the balancer bolt backing out, so you can just use the alternator bolt with serpentine belt still attached to turn the engine in either direction, this worked better for me, though in the thread i posted others disagreed.

Take all the spark plugs out to make it easier on yourself to turn over the engine.

A wooden dowel peg is good to use if your spark plug angle is parallel so much that a stop is no good, as are all the other methods listed.

leesvet

IIWM...

I'd get a hollow bolt or tube that would screw into the spark plug hole and adapt some clear tubing to that and stand it UP next to the valve cover.

Fill it with lt oil.

rotate crank and watch the fluid rise and fall. Will work compression OR exhaust stroke.

use sucker pump/tool to remove the majority of the fluid before d/c and removal.

rithsleeper

I created a sucker thing for the dial. I hollowed out a plug and put a 1/8 pipe fitting barb in and rtv'd it in to seal it. I am letting the rtv set. I got some long bolts that fit the crank pulley 3 bolts and will use to put a pry bar between. It seems like the oil thing will work but will need several tests since the pressure seems to build weird when I tested just sucking up oil in the tube. I still have not verified 100% if the valve is bent but I doubt it is.

I did end up buying the inspection camera from harbor freight. It is super quality picture but won't fit into the spark plug hole. I can however see a scratch on the piston top just a tiny nick. I'm more worried there will be a piece of metal scratched on the valve that will heat up and cause detonation like carbon deposits do sometimes.

I will do a compression test if I can't get the oil tdc thing to work. Then I'll buy one of those swing arm dial things. That would be a good solution.

leesvet

After actually THINKING about it, the more I think this would work best on compression stroke....

'cause,

the hole for the tube ( plug hole in combustion chamber) will be at a similar or equal level as the open valve(s) and that will make getting a level in the clear tube hard to establish since the fluid will have to rise a long way over the (open?) valves to a place high enough for you to see it...see?
fluid seeks its own height...so it would NOT rise in your gauge if there was an open valve.

On compression stroke, the fluid (oil) has no choice but to rise in the clear tube so the level should be very easy to observe. It will fall when the piston does, and rise again as the piston does. It will follow the piston, precisely. It has no other option.

I get this idea from an old "tuning" system used to sync multiple carbs on bikes 40 yrs ago...the vac draw pulled a little ball up/down in a tube so you could see if that carb needed to be closed or opened a bit to get it in sync with the others....same principle here except you're using fluid as an indicator.