What do I need to do to freshen up a set of 351W Lightning GT40 heads?

[GrillMaster]

Out of a '96 Gen 1 lightning with 150k. I don't want to cut corners but also don't want to spend over $4-500 if possible. They are going on a stockish lightning like motor.

I hear a valve job will removing the hardened seats, I was jut going to surface and lap them, new seals and springs,

Thoughts?

 

[Viperwolf1]

A valve job doesn't completely remove the seats unless the guy cutting them falls asleep while doing it.

 

[GrillMaster]

I was told the hardened portion of the metal is very thin and will most likely be removed if material is taken off with a valve job.

 

[Timmy390]

Out of a '96 Gen 1 lightning with 150k. I don't want to cut corners but also don't want to spend over $4-500 if possible. They are going on a stockish lightning like motor.

I hear a valve job will removing the hardened seats, I was jut going to surface and lap them, new seals and springs,

Thoughts?

Depends on how bad they're wear is.

Just went through a set of E7 PA heads off a 96 351W out of a running E350 van. The heads were DIRTY. Not caked at all just a thick layer of hard black carbon. So much so the valve keepers were frozen in place. Had to give them a tap to get them released. I would suggest a bath at the machine shop to clean them up. I did it myself and it took lots of time an effort. That said, the valves just needed cleaning up and lapped. The intakes were not bad but the exhaust vales were nasty. I kept the intake contact point to .060 and the Exhaust contact at .080. Valve guide wear was very minimal. I replaced the valve stem seals as the ones on there were starting to get hard.

Should be installing them on my build soon. That is unless I come across a set of GT40's in the local yard. I need to go look because I think I know were a set is.......

Tim

 

[GrillMaster]

Is it ok to hot tank them then just lap the valves if they is no pitting? Prob mag them and have them resurfaced while they are there.

 

[Timmy390]

Is it ok to hot tank them then just lap the valves if they is no pitting? Prob mag them and have them resurfaced while they are there.

Most places don't "hot tank" any longer. The EPA put so many regulations on it. My guy has a big "dishwasher" if you will. Sets the engine block (or in this case heads) in it, turns it on and walks away. I think it even has an air dry system in it where the parts are blasted with air.

It's always a good idea to have them "magged" but I didn't. The engine I got was a runner and didn't have any issues. If they're square (mine were) no need to resurface unless your trying to get the compression up. Just clean the gasket surface well.

Tim

 

[00gyrhed]

I have had two engines that I ran another 50,000 miles and then sold them where all I did was clean and lap the valves. Sometimes it takes quite a while to get them lapped but you can actually overcome a significant amount of damage or even a slightly warped valve, but again it can take a while. As long as its not recessed and/or you don't recess it all you are doing is making the sealing band wider and a little more restrictive. But if you need to save money in the short term and the valves and seats are in pretty good shape it will do. Problem is that usually one or more of the guides are crapped out and you need that work done to get them to seal. I have put in guides myself and then lapped the valves, but had access to the tools.

 

[bronconut73]

Question....
I thought first gen. Lightnings were only '93, '94, '95?
I had a '93 and a '95.
Was there a '96 that I am unaware of. They had trouble selling them....maybe some 95's were rebadged as '96....

 

[jckkys]

The GT40 hardened exhaust valve seats are machined steel parts that are pressed in. Other small block heads heads have the surface of the cast iron seat induction hardened. Just look at the GT40 heads you can see the seat isn't a thin surface hardening used on all other cast iron heads.

 

[hucklburry rev2]

Here in St. Louis, I called the guy all the mustang guys use, and he is all over it. $300 to freshen up a set of used heads. That is what I am doing, will decide on the cam and tell him to ensure the springs will work, or I will get new springs. stlmustangs.com is a good site for me, do some asking on a local place to you, someone near you has done lots of 5.0 heads and the mustang guys know who it is.

You been on socal, eh?

 

[sykanr0ng]

If the heads do not have hardened valve inserts then have them put in while doing a valve job.
That is the least expensive time to do it.
They are cheap protection against valve recession.

 

[toddz69]

Question....
I thought first gen. Lightnings were only '93, '94, '95?
I had a '93 and a '95.
Was there a '96 that I am unaware of. They had trouble selling them....maybe some 95's were rebadged as '96....

Correct - only those three years.

Todd Z.

 

[GrillMaster]

Correct - only those three years.

Todd Z.

Yes, my mistake they are off a '95 Lightning. Got the lower too.

Good to know they have pressed in seats.

How can I tell if the guides are within spec and if the heads are true (not warpped).

There was a small amount of play in the valves when I pulled them out 1" and wiggled them side to side.

Yes, I'm in so-cal if anyone knows a good head guy in the West LA area.

 

[Timmy390]

How can I tell if the guides are within spec and if the heads are true (not warpped).

There was a small amount of play in the valves when I pulled them out 1" and wiggled them side to side.

FLATNESS CHECKS
Place the straight edge on the face of the cylinder head or block and then use a feeler gauge to check any gaps between the straight edge and the surface. If the clearance between the straight edge and surface exceeds the following maximum limits, the head or block is not flat enough to hold a good seal and should be resurfaced:

Out-of-flat lengthwise should not be more than .004 in. (0.102 mm) in a V8 head. The maximum allowable limit for out-of-flat sideways in any head is .002 in. (.05 mm) -- with no sudden irregularities that exceed .001 in in any direction.


For the guides. if the valve wiggles, the guides need replacing.

Tim

 

[ntsqd]

Frequently the seat machining can leave a witness that looks like a pressed-in seat while the valve is in place. I highly doubt that as built by Ford that these heads would have insert seats. It's too inexpensive for them to induction harden the cyl head iron and too expensive (even at their scale of economy) to put in hard seats.

Typically induction hardening doesn't go deeper than .030" Any seat recession plus a grind will very likely go thru. Just not worth the gamble.
As I've said, clean them up, check for flatness, maybe replace the stem seals if dodgy, and run them. Anything more will start to add up fast and better heads (Alum.) then start to be economically viable.

 

[mattt]

if anyone knows a good head guy in the West LA area.

TMI???????......That ought to be easy in the West LA area, I mean No Ho isn't that far if no one turns up in West LA, right? Ha ha

Back to the regularly scheduled programming.....hijack over.
sorry, couldn't resist with how wide open that door was left. ;D

 

[GrillMaster]

saw that one coming (no pun intended)

TMI???????......That ought to be easy in the West LA area, I mean No Ho isn't that far if no one turns up in West LA, right? Ha ha

Back to the regularly scheduled programming.....hijack over.
sorry, couldn't resist with how wide open that door was left. ;D

 

[jckkys]

Apparently ntsqd has never looked at GT40 heads or is unwilling to research the specifications. Either way GT40 heads DO have pressed in steel exhaust valve seats, and have no need to have them installed again.

 

[GrillMaster]

I am going to take a look at them this week. So they only pressed in seats on the exhaust side?

 

[jckkys]

Yes. Heat and wear isn't as much an issue to intake valve seats.