H72 or H89 head? - going to get one rebuilt.

[rbastedo]

I have several cylinder heads available on my shelves, I'm going to have one rebuilt.

It's going to be for the motor with the dual SU MGB carbs on it, I can pull the head that's on the motor now and get it rebuilt or take that's already loose.

Does it make any difference which one I take to the rebuilder?

Anything I should tell the guy - (he does remember the 70's / 80's so he's not completely without a clue)?

[rbastedo]

I actually have an H89 and an H85 on my shelf.

Looks like the main difference between the two is that the chambers on the H85 are way deeper than the ones on the H89.

Any reasons I should choose one over the other?

[datzenmike]

ggzilla???

[ggzilla]

H89 is the 2nd best factory head. Only A12GX head makes more power. H72 machined for US market is a mediocre smog head.

 

They are all the same compression so that doesn't matter. If you use flat top pistons the closed chambers are more powerful and more fuel efficient both. I'd go with 79mm flat tops, only $400/set brand new. Or buy used ones from Peter Zekert.

[rbastedo]

Thanks!!

[rbastedo]

H89 is the 2nd best factory head. Only A12GX head makes more power. H72 machined for US market is a mediocre smog head.

 

They are all the same compression so that doesn't matter. If you use flat top pistons the closed chambers are more powerful and more fuel efficient both. I'd go with 79mm flat tops, only $400/set brand new. Or buy used ones from Peter Zekert.

I happen to have two extra sets of used flat tops.

Kinda keep everything, throw nothing away sort of mentality here.

Usually gets me in trouble, sometimes it's so worth it though.

:devil:

[rbastedo]

Here are some pics of my H89.

Should I ask them to do anything besides clean it up, make sure all the parts are good, replace anything out of spec, regrind?

Anything they can do to improve it without charging a lot of $$?

 

 

 

[ggzilla]

It looks good, was running correctly by the coloration of the valves.

 

I would put a level on the face to check for flatness. If you can't fit a .004 feeler gauge, it does not need to be milled flat.

 

Turn upside down, fill chambers with water. If it holds overnight the valves are sealing and does not need a regrind.

 

Next, check for loose guides which is the most common wear. Remove a spring, push valve down 1/8" and wiggle side to side. A noticeable amount causes oil smoking on engine startup.

 

Clean it up and install it.

[rbastedo]

Awesome! I'll do that.

 

Don't know if you remember I came over to your place in Bellevue a few years ago.

When did you make the move to Maui? I wish I knew, we visited about a year ago.

[ggzilla]

Been here for a few months now. PM me next time you come over here.

[rbastedo]

Think a gasket set from O'Reillys will work ok?

They will have a set for me by this afternoon.

I am hoping that there's no serious damage inside, pull head, clean up, new gaskets, torque down, adjust valves, drive.

I'm an eternal optimist eh?

[ggzilla]

A-series usually don't need much.

 

Orielly sells good stuff

[rbastedo]

There's some old gasket stuff on there, I'm afraid of gouging the aluminum.

Any ideas on how to clean it up? Use permatex? Any sealant anywhere?

[ggzilla]

I use a gasket scraper, chisel or a sharpened putty knife. All work good without gouging the aluminum.

[ggzilla]

No sealers are needed except in the corners of the oil pan gasket.

[rbastedo]

No sealers are needed except in the corners of the oil pan gasket.

 

Will it be a problem if I use some anyway? Permatex ultimate gray or whatever it's called - the high temp stuff?

[ggzilla]

Yes it can be a problem. I don't use it and my engines dont leak.

[ggzilla]

Yes it can be a problem unless you are very careful. I don't use it and my engines dont leak.

 

As long as you are using quality gaskets you'll be OK, such as Nissan, Payen, Fel-Pro or VictorReinz.

[rbastedo]

Yes it can be a problem unless you are very careful. I don't use it and my engines dont leak.

 

As long as you are using quality gaskets you'll be OK, such as Nissan, Payen, Fel-Pro or VictorReinz.

 

OK - I'm convinced, thank you,

[rbastedo]

I'm documenting this with pictures for myself.

It's clear to me my memory cannot be trusted, so pictures will be the only way I'll be able to recall any of this in the future.

 

It turned out that I had put an H72 head on the thing last time.

Also apparently I had forgotten to bolt down the bottom of the intake / exhaust at all.

The HG was severely blown.

 

I cleaned everything up, transferred studs to the new head, installed the water connector in the back and mounted the H89.

Torqued it down, installed the rockers, torqued down, adjusted valves.

 

Tomorrow I will bolt up the intake / exhaust and the thermostat and put in new plugs, change the oil, reinstall the radiator and coolant and see if she fires.

I suppose I'll notice a difference between the H72 and the H89?

(I hope so!)

 

What is the thing on the front left corner and where is it supposed to go?

Can I remove it and plug it?

 

[ggzilla]

Noseemun

 

I doubt if you could feel the difference. But with the flattop pistons after tuning I expect you might be able to run 2° more advanced and that will make a difference.

[rbastedo]

I screwed up.

There are water passages in this head that are plugged in the old one.

I'll need to remove the intake / exhaust and fix that, this time I'll fill it with water before bolting up the manifolds.

Feeling like a dummy. :rofl:  (again)

[ggzilla]

My manifold covered the passages, but others won't. Best to plug them.

[rbastedo]

I've got a twin 1.5" SU manifold, it doesn't plug them.

PITA to remove it and everything but it has to be done.

Taking a personal day tomorrow, I'll get 'er done yet.

[rbastedo]

Sorry I never posted again until now.

 

It's been running great for over a month now, I retorqued the head bolts at about 500 miles.

This past weekend we took it up to the Mt' Vernon / Anacortes area for our club's annual Tulip Rallye.

 

It drove great all the way up there, and the 100 or so miles of the Rallye itself it did without trouble.

After lunch we started home, got on the freeway and suddenly it started cutting out.

I found I could drive about 50MPH and as long as I didn't go uphill it would run, once I started up any hill at all it would start coughing and sputtering.

I pulled off and checked my rocker arms, made sure the bolts were tight and re-gapped the clearances to be sure.

Still cutting out on the freeway.

 

At one point it was really bad, I found I could just put the gas pedal down hard and it would speed up but cutting out still and the temp rose quite a bit.

I pulled off again, engine still running, pulled the cap and poured in some coolant.

This is when I got the bright idea to turn on the heater, it was blowing hot air so I know hot water was circulating.

Leaving the heater on I could drive on the freeway without cutting out at 65MPH.

Only the steepest of the hills caused any trouble, it cut out again just once.

 

I know this could be a lot of different things, from coolant leak hitting something vital to something internal in the engine.

At least we made it home without a tow.