measuring head and block deck. Got feeler gauges and straight edge.

[Stainbox12]

I recently purchased a straight edge and a set of feeler gauges, to measure the deck of the block and the head. I´ve been having problems pushing coolant with my new cometic gasket. My head was milled but the block wasn´t. I had overheating problems, but now that i installed everything the gasket and torqued down everything properly, i still have overheating problems. I guess that the block is warped. I would like to measure the block deck for straightness, and i know this is done with some feeler gauges and a straight edge, but not sure about the procedure, if anyone knows, please let me know. Thanks.

 

[bluegs03]

Here is the procedure you take the straight edge and lay the straight edge from corner to corner, then measure along the staight edge and see where you can shove the biggest feeler gauge through measure both corner to corners. the top middle and bottom of the cylinder head. Im gonna try and make a diagram so bear with me!!



\------------L
| O O O O |
L_______\


so thats my cylinder head. The O's represent where the valve ressed part is. You want to put the straight edge so that it touches both \'s and then use the feel gauge. Then put the straight edge so that it touches both L's . Then for shits and giggles put it where the _________ 's are and where the O's are and try and find the biggest feeler gauge thingy you can stick under the straight edge.

Hope this helps feel free to PM me with any further questions.

 

[KYNgsx]

Here's another picture

 

[Freerevving]

That's a good diagram

Just use the second to the smallest feeler gauge, put it under the straight edge in those areas, push down lightly on the straight edge... if you can pull the feeler gauge out, you have a low spot

You could have a crack in the head... or less likely, in the block

 

[Stainbox12]

Ok, i know now how to measure it, but i still have a question. Whats the max Clearance allowed? i know the manual says that the head and block can be resurfaced .008. But that doesn´t tell me actually if when im measuring with the feeler gauges how much of a gap can i have. Per example if i take the smaller feeler gauge .001, and it goes inside in some places, does that mean i have a .001 worth of warpage in certain part of the surface? I guess, but either the block or head can be used still? whats the allowed clearance for the surface? Thanks a lot.

 

[Stainbox12]

That's a good diagram

Just use the second to the smallest feeler gauge, put it under the straight edge in those areas, push down lightly on the straight edge... if you can pull the feeler gauge out, you have a low spot

You could have a crack in the head... or less likely, in the block

Now, that explains a little more in the detail the allowed gap. Can someone confirm? my smallest feeler gauge is .0015 the second one is .0002.

 

[Freerevving]

I'd say .001 is acceptable, .0015 is too much... but I don't know what the factory tolarances are

I have always used the .0015 in the past...

 

[Stainbox12]

I'd say .001 is acceptable, .0015 is too much... but I don't know what the factory tolarances are

I have always used the .0015 in the past...

Ok, to my understanding then you mean you can get inside a feeler gauge which is .0015 in some areas or all the areas and thats acceptable. I´ve found from my measurements if i did it correctly then, that even the .010 can get inside in some places. I measured the block. I guess its warped then.

 

[Freerevving]

no don't do that... using the .0015 feeler gauge:
you put the straight edge on top of the feeler gauge, pushing on the straight edge lightly, with the straight edge aligned as in the diagram...

If you pull on the feeler gauge and it comes out easily, then you have a low spot greater than .0015 at the location of the feeler gauge

If you feel a slight tug, then the low spot is about .0015, which can be acceptable in some cases.

With a level surface, the feeler gauge requires a hard tug to be removed from under the straight edge. Just be sure that the straight edge is perfectly straight (true).

Keep lifting the straight edge and move the feeler gauge to locations along the straight edge.
If I say straight edge one more time it'll be rediculous... straight edge

okay sorry if I sound like I'm trying to be a teacher or something.. you probably know most of this

and yes, I see what you're saying if you can fit a .010 under the straight edge, then you've got warpage... you might even be able to see it from the side

 

[Defiant]

Here's a dirty secret: I stopped having heads cut in the eighties, when it occurred to me that I'd never seen one come off "flat". If the cams turn freely, I just bolt them down. I've not had a problem with it.

 

[Stainbox12]

Here's a dirty secret: I stopped having heads cut in the eighties, when it occurred to me that I'd never seen one come off "flat". If the cams turn freely, I just bolt them down. I've not had a problem with it.

I know, what you are saying, but my head got warped because of overheating. Im gonna send it for a pressure test, should that reveal cracks? I still don´t feel like pulling the whole engine yet.

 

[Freerevving]

Here's a dirty secret: I stopped having heads cut in the eighties, when it occurred to me that I'd never seen one come off "flat".

Machining has come a long way since then. I also find that hard to believe, as I've managed to get flat surfaces using this measuring method and using equipment that's been around since long before the eighties...

If the cams turn freely, I just bolt them down. I've not had a problem with it.

Not a good idea IMO, but I see what you're saying... Measure your head! make sure they got it flat

I know, what you are saying, but my head got warped because of overheating. Im gonna send it for a pressure test, should that reveal cracks? I still don´t feel like pulling the whole engine yet.

Yes... I was going to mention pressure testing, but forgot... That should reveal any major cracks... Dye testing can be done to reveal fine cracks that enlarge when he head gets hot, but pressure testing is enough 99% of the time.

Didn't you say that the block is warped?... that's very common on V8's and severely overheated engines... I would expect that that is your problem. If you measure .002 or more on the block, and the head is flat, then I would send the block to get it decked while they pressure test your head

BTW on this last head, the resurface I payed for is amazing... I've never seen anything like it. $35 and it looks like it was done by a laser beam. I can faintly see the tool marks if I look closely in the reflection

 

[Stainbox12]

Thanks freereving for following my post so closely, it definitely helped. I wasn´t sure how to use the feeler gauges, and when i did it the first time i did it wrong, and surfaces where not clean, thats why the bad numbers. I can now pull out a .002 feeler gauge out of the middle of the block. Now, im not convinced if the block is warped or not since im using a level and im not sure if its straight enough. So ill send the head first, see what happens with it, and go from there. Thanks, for the help.

 

[Freerevving]

Hey no problem

yeah you're right, a level could be off by 2 thousandths, a lot of people expect them to be a straight edge, but there is a difference... I wouldn't trust it, but it tells you that there's a good chance the surface is concaved

 

[dsmpat95]

I beleive for a Cometic headgasket it needs a 40ra finish on the metal surface to seal properly, you can ask your machinist.

 

[Zex4g63]

Almost every block I machined this past year had a dip in it. As stated don't shave the head on less it really needs. And if the head is warped it means the valves seats are warped so get a valve jo as well.

 

[D_Eclipse9916]

When you guys are quoting measurements (i.e. .002 and .0015) are you speaking in terms of inches, or metric terms?

 

[Defiant]

In American machine shops, things are still measured in thousandth and ten-thousandths of an inch.

By Congressional decree, the US will change to all-metric in September of 1966.

 

[BoredDSM]

In American machine shops, things are still measured in thousandth and ten-thousandths of an inch.

By Congressional decree, the US will change to all-metric in September of 1966.

thats just to funny.