Head off for valve guides

[Deacon Blue]

I have an oil leak down cylinder 2 inlet valve so it's time for the head to come off and get new guides fitted. Is there anything that's worth doing to the head while it's off? I believe it's a TR3A head on a 4A engine. Standard inlet and exhaust manifolds.

Steve

[Chris Hubball]

 Take it to Pete Burgess for gas flowing , porting and bigger inlet valves plus converting to unleaded if not already done.

Cheers Chris

[Lebro]

I would check for flatness of the head surface, look for corrosion especialy in the very center in the gap between two water holes. a light skim may be advantagous.
If not already done (as said above) get unleaded exhaust valves & seats done. 
Lots more could be done if you are looking to increase power.

Bob

[Deacon Blue]

2 hours ago, Lebro said:

Lots more could be done if you are looking to increase power.

Bob, a bit more power is always welcome!

Steve

[Lebro]

Open up the area around inlet valve  but keep within the bore / gasket outline,  smooth out the inlet tract, after mods, measure capacity of combustion chamber, & calculate how much to take off the head surface to resore original CR, or new higher CR.

Check cam followers for wear / pitting etc  think about a different cam.

Problem is knowing when to stop !

Bob

[Chilliman]

34 minutes ago, Lebro said:

Problem is knowing when to stop !

Exactly! Just don't fall down the rabbit hole, there is so much that can be done (much of which cannot be undone)  but for a reliable economical club car - keep it as stock as possible & enjoy it.

 

[Malbaby]

Plus one on Bob's comments.

Apart from the initial valves and guides replacement, I would then measure the current compression ratio.

[Ian Vincent]

The TR4a head has a different shape combustion chamber to the TR3a. It has a chamfer along the side opposite the spark plug hole. I would be inclined to introduce this chamfer even if you don’t go the whole hog of sending it to someone like Pete Burgess for gas flowing. 

Rgds Ian

Edited November 25, 2025 by Ian Vincent

[BlueTR3A-5EKT]

The chamfer is also there I think to reduce the compression ratio when the engines went from 83 mm bore to 86.  So adding that chamfer on its own will drop the CR. As Bob remarks test the chamber size/capacity and do some calculations to find out where the CR is now and get an idea of where you want it to be.  You will also need to know the compressed thickness of the head gasket and the piston crown height clearance, compared to the top of the liner.   My aim for CR is over 9 but under 10.  9.5 being a nice middle point.

[Lebro]

I ended up with this shape, I did not go for the TR4 chamfer as that would have required too much to be taken off the head surface to restore CR,
as it is I took 60 thou off, aiming for 9.5:1.  Head is a TR3A head, capacity 2187CC.  I did have to relieve the underside of the thermostat bulge, & also the top of the water pump in order for the reduced height head to sit low enough.

Bob

[Hamish]

How much can come off a head ?

for the first time ever I saw the result of a tr4 head failure where the flat surface opposite the valves collapsed under combustion pressure 

it looked quite rusty inside the collapsed area 

sorry I don’t have a picture  I saw a photo from a fellow competitor and he didn’t run a high compression ratio either. 
 

borrowed you pic Bob hope you don’t mind. 

[Motorsport Mickey]

Back in the day using 87 mm pistons I used to take .130 thou off and run at 11.3 :1 comp ratio.

Basic problem with TR heads in those days ( and even worse these days) was not what you were taking off the deck surface, but what age and rust had eroded from inside the water jacket the other side of the squish area. 
The ages old “ stake support system” was employed then, and will still work to preserve the Squish areas.

Mick Richards

[Andy Moltu]

When modifying the 4 pot head, be careful about removing too much from around the inlet valve to avoid unsupported/untrapped head gasket protruding into the combustion chamber.

The inlet valve is somewhat shrouded on the 4 pots which isn’t ideal for performance but not as much as you might wish can be safely removed for reliable longevity in a road car. 

[Lebro]

Yes, I used the gasket as a mask to show how far to take it.

Bob

[Deacon Blue]

Well, the head is off and I've just discovered this. A small crack between the central water jacket and a head bolt hole. Doesn't appear to have migrated into the bolt hole as no evidence there and no rust on the bolt. Is this fixable?

Steve

 

 

[Lebro]

No need to fix realy, both holes are for water transfer. a light skim would improve it.

Bob

[Ralph Whitaker]

They all seem to crack between those water jacket holes, and the fact that it has extended into the stud hole is no surprise. I think it is because of over zealous tightening of the centre bolts when re fitting the head. I know all the books say to work from the inside bolts out, but with our cars having raised liners, coupled with the reinforcing ring on the head gasket,  there must initially be a gap between the block and the head until the gasket is properly squashed, and too much tightening on the centre bolts before the rest have been tensioned must bend the head and cause the crack.  I think tightening the bolts needs to be done in a lot of small stages, even one flat of the nut at a time to avoid over stressing the head.

The crack could be repaired, but as it has not given a problem up to now I think I would be inclined to grease that stud well in case water does manage to get through and keep an eye on it, see how it goes. 

Ralph

[Ralph Whitaker]

11 minutes ago, Lebro said:

No need to fix realy, both holes are for water transfer. a light skim would improve it.

Bob

If you look closely Bob, the crack extends into the stud hole and that is what Steve is concerned about

Ralph

[Hamish]

I think Steve is referring to this crack

Edited December 17, 2025 by Hamish

[BlueTR3A-5EKT]

I’ve seen this before.  The repairs was to bore out the stud hole, and freeze fit a sleeve.  No idea how long it lasted. 

[RogerH]

That crack will extend, in time, and stop at the bolt hole.   
So as mentioned above you pack the hole with grease to protect the stud and reduce water escaping. 

Or  drill a shallow counter bore and sleeve as suggested by PeteW.  The sleeve would need to be a good tight fit.

Or gently Dremmel out the crack and fill with JBweld (rather dramatic)

The large crack in the middle is going nowhere.

It could all be cleaned and welded £££££££

What is the block like in the same place - they can crack.

 

Roger

[Deacon Blue]

Thanks all for the comments. I haven't checked the block yet. I don't need any more surprises!

Steve

[Lebro]

If the crack (I see it now ) is shallow then a head skim should make it dissapear. ( if you are planning chamber modifications then an ammount would need to be taken off the surface to restor CR)
If it goes deeper then welding or filling won't really help as water could still creep through under the repair. I go with the above advice of greasing the stud, & hole on assembly (not the stud threads of course) & carry on.

Bob

[Deacon Blue]

Having had a look at the block , that seems ok. I have disassembled the valve train and want to check for wear. Are there wear limits for inlet and exhaust? And how is this measured? I've wiggled the inlet valves and all seem to have some degree of "slop". Just how much I have yet to determine.

Thanks for the hint about greasing the head stud. I like simple solutions!

Steve

[Deacon Blue]

Is this sufficient hold downs for the liners or do I need another across the central studs. I couldn't find washers wide enough for those.