Valve clearance

[pitaSHO]

What is the valve clearance in a stock motor? How much can I deck off the block and heads before I end up with an interference motor? My engine is in the shop now for balancing, rod resizing, and micro polishing. I may have him deck the block while it's there, but I'm under the impression that this is not recommended. I would also deck the heads when I do the head work. The builder said I was probably looking at .008 to .010 total; .004 for the block and .005 for the heads.

Thanks.

Chris K.

 

[rubydist]

as I recall, the biggest issue with decking is not that it becomes an interference engine, but that if you remove much it impacts valve timing (changes length of timing belt) which is bad. at .008-.010" you should be okay.

 

[pitaSHO]

I've seen pics of other motors (yamahaSHO and nik97 if I remember right) that showed pics of their blocks, at least, prior to assembly, and they decked them, but I don't know how much or if the heads were done. Jason?

 

[SHOtime2511]

IIRC .008 is the max.
I wouldn't bother if you don't have to.

 

[MerkXRTurbo]

See if you can get your hands on a precision straight edge (if you know a good wood worker or machinist they might have one they'd let you borrow). Clean the decking surfaces and check the flatness with the straight edge and a feeler gauge.

 

[pitaSHO]

I won't do it if it's not necessary, for sure, if for no other reason than cost. That's a spendy little piece of work to be done. At the same time I want it to be right, but I'm sure I'll be fine without it.

 

[yamahaSHO]

I've seen pics of other motors (yamahaSHO and nik97 if I remember right) that showed pics of their blocks, at least, prior to assembly, and they decked them, but I don't know how much or if the heads were done. Jason?

I had the heads decked, not the block. I told the machine shop to take off the bare minimum if they found them to not be perfect. I also started out with brand new heads so they barely touched it. If you want to take off more, you can't fix the timing with adjustable gears.

 

[MerkXRTurbo]

If you want to take off more, you can't fix the timing with adjustable gears.

Did you mean to say that you can fix the timing with adjustable gears???? Because it seems to me like you would be able to.

 

[yamahaSHO]

Yes, FMiPhone.

You CAN fix cam timing with adjustable gears.

 

[jayro]

I would have them check the block and heads, but from what I have seen the heads and block usually don't need decked.

 

[AREA 91]

If I remember correctly, max off the heads was .003

FWIW, I have never had to deck any heads or blocks in all the SHO's I've built.

You can't deck the block and heads enought to have a valve clearance issue with stock cams.

 

[AREA 91]

What is the valve clearance in a stock motor? How much can I deck off the block and heads before I end up with an interference motor? My engine is in the shop now for balancing, rod resizing, and micro polishing. I may have him deck the block while it's there, but I'm under the impression that this is not recommended. I would also deck the heads when I do the head work. The builder said I was probably looking at .008 to .010 total; .004 for the block and .005 for the heads.

Thanks.

Chris K.

WAY too much!!!

 

[pitaSHO]

Thanks for the info. I'm going to leave the block and heads alone. What about a three-angle valve grind with Tri Flow cams? This car may see boost some day and I only want to build this motor once, so I'm just trying to prepare for future mods while not diminishing from power gains I could see from the cams with stock internals and the usual bolt-ons.