Miata Turbo Forum - Boost cars, acquire cats.

Miata Turbo Forum - Boost cars, acquire cats. (https://www.miataturbo.net/)
-   Engine Performance (https://www.miataturbo.net/engine-performance-56/)
-   -   99/00 1.8 BP Head inspection (https://www.miataturbo.net/engine-performance-56/99-00-1-8-bp-head-inspection-70069/)

BogusSVO 12-24-2012 03:49 PM

I never straightend one with the cams in.

I do not see any reason to do it like that.

curly 12-24-2012 08:25 PM

Only reason I see is to try and keep the cam journals in line. If you've never had a problem with it I'm guessing you either line bore after or it doesn't affect the cam journals.

shuiend 12-24-2012 08:34 PM

So a random question for you Bogus. Is it possible to set correct valve clearance with the head detached from the block? I know in the FSM it says to put the cams at specific spots when measuring, so I was wondering how you do that without the Timing belt on to hold them in the correct locations.

Savington 12-24-2012 08:58 PM


Originally Posted by shuiend (Post 962309)
So a random question for you Bogus. Is it possible to set correct valve clearance with the head detached from the block? I know in the FSM it says to put the cams at specific spots when measuring, so I was wondering how you do that without the Timing belt on to hold them in the correct locations.

Not directed at me, but it's totally doable. You just need to set the lobe pointed away from the lifters you're checking, and that sets another set of lobes pointed straight down at a set of lifters. You can't do it with the head laying flat on a bench (at least not without being careful), but you can definitely get the cams to stay where they are without the TB. I do the valve lash on our new motors before the TB or cam gears go on.

BogusSVO 12-25-2012 09:53 AM


Originally Posted by curly (Post 962305)
Only reason I see is to try and keep the cam journals in line. If you've never had a problem with it I'm guessing you either line bore after or it doesn't affect the cam journals.

The cams would still flex in the bores, they are not ridged enough to help with alignment.

With this head was warped .012 across the bottpm, but the intake cam bore was still perfect, and the exhaust side had about .002

I could see more issues having the cam in with the bolts for the caps , galluing and ripping the threads out.




Originally Posted by shuiend (Post 962309)
So a random question for you Bogus. Is it possible to set correct valve clearance with the head detached from the block? I know in the FSM it says to put the cams at specific spots when measuring, so I was wondering how you do that without the Timing belt on to hold them in the correct locations.


Originally Posted by Savington (Post 962321)
Not directed at me, but it's totally doable. You just need to set the lobe pointed away from the lifters you're checking, and that sets another set of lobes pointed straight down at a set of lifters. You can't do it with the head laying flat on a bench (at least not without being careful), but you can definitely get the cams to stay where they are without the TB. I do the valve lash on our new motors before the TB or cam gears go on.



Like Sav said, as long as the lash you are setting, the cam is on the heel you can set it.

Hot_Wheels 12-26-2012 10:21 PM

nice to see your back! we bolted my head up and still waiting for the fabricator to finish up so we can get tuning! Is this Aarans head?

BogusSVO 12-27-2012 11:43 AM

HW.. No, Not Aarons head....His is getting much more involved....

Just a customers sent in for some play time. :D

Dang.. I was wanting to hear some reports on how yours was doing!!

BogusSVO 12-27-2012 01:11 PM

2 Attachment(s)
The straignting worked.

.005 is a tad "sticky" going under, and a .006 will not go.

Attachment 62937

Now to carry on with the head build

EO2K 12-27-2012 01:24 PM

Damn! What kind of temps are we talking about?

BogusSVO 12-27-2012 01:34 PM


Originally Posted by EO2K (Post 962849)
Damn! What kind of temps are we talking about?

Not as much as you would think.

Get the head too hot and all the machined areas will distort, like the cam bores and bucket bores.

No more than 350* and longer than it takes to bake a 20lbs turkey!

It spent 7 hours in the oven.

shuiend 12-27-2012 04:53 PM


Originally Posted by BogusSVO (Post 962853)
Not as much as you would think.

Get the head too hot and all the machined areas will distort, like the cam bores and bucket bores.

No more than 350* and longer than it takes to bake a 20lbs turkey!

It spent 7 hours in the oven.

So do you have an oven at the shop, or do you take it home to do that part?

Zabac 12-27-2012 05:50 PM


Originally Posted by shuiend (Post 962907)
So do you have an oven at the shop, or do you take it home to do that part?

I would not put anything with anti-sieze in my home oven.

BogusSVO 12-27-2012 06:12 PM


Originally Posted by shuiend (Post 962907)
So do you have an oven at the shop, or do you take it home to do that part?


I have a gas fired one at the shop I clean heads and other parts in.



Originally Posted by Zabac (Post 962917)
I would not put anything with anti-sieze in my home oven.

I do not think the anti-sieze would be what i worry about, but the burning smell of oil and carbon burning off.

TheScaryOne 12-29-2012 06:50 PM

This is relevant to my interests. Subscrib'd.

Bogus, do you always just bolt down the center of the head when you straighten them like that?

BogusSVO 12-30-2012 04:40 PM

You bolt down where the worst of the warp is, and commonly that is the center.

Jebrccars 12-31-2012 03:43 AM

very interesting.

EO2K 12-31-2012 12:44 PM

I'm sure there is some mystical art in selecting the shim stock thickness and then torque spec to the plate as well. That looks like a big ass chunk of steel right thar.

This is what I was thinking when I asked about "straightening" earlier. I honestly didn't think you were going to deck 0.012" off this thing. Do you find that you have to line hone the cam bores after the the trip to the oven?

BogusSVO 12-31-2012 12:50 PM

It is a big ol' cunk of steel. lol

The line bore of the cams is fine, no need to line hone. They were not far off to begin with.

No measurable distortion on the intake and less than .002 on the exhaust.

Jebrccars 12-31-2012 06:22 PM

I wonder if I can find a local shop as good as you.

slmhofy 12-31-2012 06:51 PM

I couldn't. That's why you're looking at it.


All times are GMT -4. The time now is 12:54 AM.


© 2024 MH Sub I, LLC dba Internet Brands