Another OHV M90 build

[Dono]

When I measured my valve guides it came very close. Like JD said you can get away without having them cut down but it is very close. Not sure if you are taking your own measurements and calculations but I have all my cut measurements to fit the 988 springs if you need them for reference.

Thanks,

I was sure you posted these in your build thread. I'll go look for them.
I'm not doing my own measurements. I don't have the right tools, and I don't trust myself with that fine of measurements.

egr pipe is off the manifold. Heat and a wax candle.
The area was heated and, a wax candle applied to the area so the wax would wick in to the threads.
I'm not sure if the wax helped, or the heat, or both. I'm just happy its off.

I also spoke to Glenn about my home made egr tube (I am using copper water pipe and the solder keeps wicking out, Tried jb weld and it disappears also). He says the only real fix is threaded pipe. That's not good. I don't know how I'll adapt the two ends to the gas pipe, or how I'll cut the pipes to the right length and thread them without a pipe threader.

 

[Dono]

So, how is this verbage when speaking to the machine shop? I don't want to sound like a complete idiot.

For the Comp 988 dual springs to fit the 4.0 ohv heads, I measured that:
-Cut spring seat .042"
-Cut valve guide .025"

machine the pocket for the 988 spring which has an outside diameter of 1.385".
Comp Cam specifies that there needs to be .0010" to .0012" pocket clearance.
Valve guide cut is required for the .475" ID

Check for valve keeper hitting top of valve seal. The top of the head that the valve guide seal mounts on may be too high.

 

[jd4242]

So, how is this verbage when speaking to the machine shop? I don't want to sound like a complete idiot.

For the Comp 988 dual springs to fit the 4.0 ohv heads, I measured that:
-Cut spring seat .042"
-Cut valve guide .025"

machine the pocket for the 988 spring which has an outside diameter of 1.385".
Comp Cam specifies that there needs to be .0010" to .0012" pocket clearance.
Valve guide cut is required for the .475" ID

Check for valve keeper hitting top of valve seal. The top of the head that the valve guide seal mounts on may be too high.

You get those specs from comp cams?they are saying or recommending the guild be trimmed down.if you just give them these specs they will know every thing that needs to be done.i don't think all that is necessary but they can tell that at the shop.like i said i think my ID and the guild didnt need to be cut just the seat pocket.

 

[Dono]

Not much new. Heads are still at the machine shop. Hopefully tomorrow.

I sucked it up and ordered new push rods.
The ones I have measured about 5.495. Not long enough. Id have ticking noises from the motor, and that would make me very unhappy.
I think someone handed me the push rods when I was working somewhere else at the office and set them down while I was concentrating on other things.
Watch this....Tomorrow they will turn up. Thats the way it works.

I couldnt take the risk, as Im without a vehicle right now.

I have done my house cleaning, including cleaning up some valve cover threads on my lower intake that were cross threaded. Im not sure about the egr pipe, it looks like the header is in the way of the egr pipe, not sure on placement. We will see once the heads are back.

Not much else I can do till I get those heads.

 

[Dono]

Cracked head...
This is going to set me back at least a week.

 

[jd4242]

Cracked head...
This is going to set me back at least a week.

What for real?those are new castings right?who made those?don't think I've head of an aftermarket cast cracking.i have seen them have cracks from the factory,but not crack after you put them on.that sucks!

 

[Dono]

This was a clearwater head.
I just called Enginequest. A new 98tm casting is $150.00 +shipping. Coming from chicago.

No vehicle for me for another couple of weeks. ****.

 

[vroomzoomboom]

whoa! where was it cracked, between the valves? it wasnt using, or loosing antifreeze was it? wasnt detonating? this sucks balls!!!! on the bright side (sorta) looks like you found the dead cylinder......even though i hate saying it.

 

[Dono]

whoa! where was it cracked, between the valves? it wasnt using, or loosing antifreeze was it? wasnt detonating? this sucks balls!!!! on the bright side (sorta) looks like you found the dead cylinder......even though i hate saying it.

I did have detonation issues.
I overheated the motor this summer. That must be what did it. Fan quit, and I wasn't watching my gauges.
My coolant reservoir was empty when we were pulling the motor. Must have been a small leak somewhere.

The shop tells me the crack is between the valves in a cylinder. I'm going to go get the bare head from them.
Ill be able to inspect it, and also I'll want the old head to match up the porting and polishing. ****...****...****.

I didn't count on this, as you can imagine.

 

[vroomzoomboom]

oh wow, no....we didnt count on this. hell, if i had a spare ohv kicking around i would say, screw it for the time being, toss it in so you have something to drive for the mean time. yea, this isnt good.

 

[Dono]

Id use a casting from the donor motor you gave me, but the factory castings are so prone to cracking, I don't want to use it.

Im surprised engine quest would ship to Canada, last time I called them they wouldn't.
Id have bought 95tm heads. oh well.

 

[jd4242]

Id use a casting from the donor motor you gave me, but the factory castings are so prone to cracking, I don't want to use it.

Im surprised engine quest would ship to Canada, last time I called them they wouldn't.
Id have bought 95tm heads. oh well.

I think last time you emailed their ebay distributor,he won't ship to Canada .i would have suggest you run the same cast on both sides but sure it won't really matter.any reason you didnt order one from clear water?

 

[Dono]

small crack at the valve seat. This would be on the #1 or #4 cylinder.
You have to look close.

I would have gone EQ the first time since everyone has such good luck with them. I could go with another clearwater head, but EQ heads are closer (Chicago, as opposed to Florida) and I think its worth trying a EQ head since clearwater's haven't worked out so good for me. This crack could have happened with either manufacturer, tough to know for sure.

So, I'll get the bare head, and polish the combustion chamber, and clean up the exhaust (I'll make the head look like the cracked one (minus the crack). Then take the head to the machine shop. They will measure, and shave the head to match the other one.

I'm glad they checked the heads. The cylinder that had weak compression was cylinder 2, so the crack is a second issue with the motor. Its a bad news, good news thing. Better to find it now, than have to pull a head again.

Tim's offer to help put the old motor back in is greatly appreciated, but I'm far to lazy for that. This is a bit of a setback, but This motors going together and will be good and strong.

 

[Dono]

Here's a better pic.

 

[vroomzoomboom]

sumoufabith. i have to be honest, when you said you were going to send the heads out just to have them checked, i though it was kinda a waste of time. now seeing that, i am glad i kept my big fat mouth shut.

 

[jd4242]

Wait that's not a bad crack.those can be replaced.those are pressed in.

 

[vroomzoomboom]

look between the valve seat, and spark plug hole

 

[jd4242]

look between the valve seat, and spark plug hole

Is cracked All the way to the plug hole?i really have bad eyes and on the phone?

 

[Dono]

I hear what you are saying. I thought you could replace the valve seat ring also.

Im not a machinest, and the machine shop is reputable, so I'd say for whatever reason they dont want to.

I can't see the crack going right to the plug hole with my eye, but maybe under magnaflux they could see it? In the picture it looks like it does go to the spark plug hole, but thats just the shadows in the pic.

 

[Dono]

sumoufabith. i have to be honest, when you said you were going to send the heads out just to have them checked, i though it was kinda a waste of time. now seeing that, i am glad i kept my big fat mouth shut.

I thought I was being over cautious also.
With the valve out, the cracks there, but you'd never see it with the valve installed.

Anyway, right or wrong, theres a new head casting on its way. I'll hive the combustion chamber a polish and slight porting (Like the other head) before taking it to the machine shop to be shaved, and fitted with the new valve springs and old si valves.

The machine shop says even a slight overheating can cause this and they see so many heads that are cracked, they check the heads no matter what the customer says. They feel its their reputation on the line. The desk guy just smiled and said 'You should see the look on guys faces with the heavy equipment that has a cracked head $8000.00 makes jaws drop.'

Im getting over the delay. Not much I can do about it. JD, I'll be on the couch watching football and drinking beer on your birthday.