What are the odds of a 1974 2.7 L engine heads coming off cleanly?

[tdskip]

Good morning gentlemen. I have a 2.7 L with a good bottom end but leaky top end. I wanted to ask about the Hail Mary of doing the top and refresh without breaking anything on the case in the process. This came from a non-thermal reactor car, but....

0%?
25%
50%

I pay my taxes and well give up my seat on the bus for someone that elderly people or those who are pregnant that helps my odds.

Thanks!

[Flat6pac]

If you’re going toretorque, probably need timeserts installed and that requires total disassembly because the magnesium breaks and chips in very small pieces and heavy dust.
Bruce

[tdskip]

Hi Bruce. So is there such a thing as just a top and rebuild on a 2.7?

Not arguing, it's a question.

[Flat6pac]

The problem is the the mag cases are getting old.
Now, yours, 40 years old, you’re betting on the studs holding.
Years ago, I recall having the heads holding on the build, several months later
Head studs are pulling,
It’s been a crap shoot for years...
Bruce

[Cairo94507]

tdskip - You already know what you have to do. Just pull it apart and clean it up and replace the bearings, rings, re-seal and do the timeserts so you don't have issues down the road. Hard not to go down the slippery slope, but you can do it. Cheers. Michael

[tdskip]

Good morning Michael!

It has been great to watch your progress with Ken.

OK, OK, just really playing out my options here but looks like doing it right is the only way to do it right.

[911pcars]

Do you have any history/docs on the engine?

That might provide some needed context for any future work.
Suggest performing a leak down test before proceeding to pinpoint whether it’s merely a valve job or an engine rebuild (the bottom of the slippery slope).
The cost to refurbish this engine version might exceed other engine options. Check the archives for lengthy discussions on the subject.

Sherwood

[tdskip]

Good morning and thank you for the response. Don't have much history other than that it ran and pulled well before it was removed, so I think it's likely the bottom is OK. It's from a non-thermal reactor car, so that's a plus. I'll do a leak down test before deciding what to do, I am aware that the scoring a 3 L that occasionally come up on a good price maybe more cost-effective.

Thanks!

[Eagledriver]

If you don’t take the heads off, you won’t have a problem with the head studs. Unless you have a leak between the cylinders and heads or pulled head studs, you can just put new gaskets on whatever is leaking. As others have said, if you pull the heads you’ll have to do the bottom end as well.

-Andy

[tdskip]

Originally Posted by Eagledriver

If you don’t take the heads off, you won’t have a problem with the head studs. Unless you have a leak between the cylinders and heads or pulled head studs, you can just put new gaskets on whatever is leaking. As others have said, if you pull the heads you’ll have to do the bottom end as well.

-Andy

Good point. Short of valve guides, what can be done to tighten them up without having to disassemble? Basic question, I know, but working on these engines is still new to me.

Thanks, and hope everyone is having a good weekend.

[Eagledriver]

Things you can reseal: oil return tubes, rocker arms, valve covers, chain boxes, chain covers, pressure fed tensioner lines and o-rings, oil cooler gaskets, replace oil cooler, thermostat, oil pressure sender, oil pressure switch, breather lines. I’m sure there’s others I’ve missed.

You could even remove the cam carriers and reseal where they attach to the heads. That would be a lot of work though.

-Andy.

[tdskip]

Thanks Andy.

So anything like valve guides are still heads off, and thus a full rebuild.

If it is those items leave the heads be and maybe I got lucky?

That pretty much it?

[Eagledriver]

Valve guide wear can be evaluated by oil consumption and the appearance of oil in the exhaust port. You’ll also see oil smoke from the exhaust when the engine is on overrun. I would say if the oil consumption exceeds 1 qt. Per 1000 miles you should plan on a valve job in the near future. A compression test can tell you the condition of the rings and how well the valves are sealing in the seats.

Buy yourself a copy of Bruce Andersons 911 performance handbook. It makes a great read and will make you a very informed 911 owner.

-Andy