TR2/3/3A TR3 Head Work

[CaptRoy]

I have my spare engine block at TSI and Ted is doing a complete rebuild with 87mm, 284 cam, etc.

I need to get the TR4A head work done and send it to him. I have oversize valves, bronze guides on hand. We are going to
install headers, roller rockers, along with a TR4A manifold and HS6 carbs.

Any recommendations as to where to send the head to get the valves, stems, guides, along with some minor porting and polishing done.

Also, there were some discussions about the clearance for the bronze guides. Something like to tight and there will be problems.. any thoughts...

Thanks,

 

[JFS]

I found a local shop that does a lot of head work for race cars. I bought the ss valves and bronze guides from Moss. The shop called a number of times for me to come over while they explained options during the work. For example, they asked about the total lift at the valves and showed me that my current valves springs would bind before the .427 lift I required; I purchased the springs to accomodate this lift from British Frame & Engine. They also showed me the areas to be removed with porting and polishing. My point is that the local shop was able to contact me and show me what could be done, how they could do it, and explain my options. I am extremely pleased with the performance of my TR3. Do you have any local shops with good reputations that specialize in building race/modified engines?

 

[Alan_Myers]

Hi,

JFS is making a good point, try to work with someone locally. There is a lot that can be done with the head. It would be most useful if you can talk with them and work out the details, as they go along.

You'll need to decide on the compression ratio you want to use, then have the head milled for that. But first, it's best to rework the combustion chamber shapes and cc them (measure them for volume) so that you know what you are working with.

Get a copy of Kas Kastner's manuals from his website (www.kaskastner.com). There are combustion chamber tricks, as well as lots of porting that can be done, all shown in his books. For example, look at the illustrations regarding welding up and reshaping the exhaust port right above the valve. It starts out as a sort of a 90 degree turn, works much better if it makes a nice radius.

With oversize valves, you need to talk with the builder. There is very limited room in there for larger valves.

Personally, I think the exhaust valves need more enlargement than the intake, on the 4-cyl TR motor.

Problem is, it's a good idea to install hardened seats for unleaded fuel, especially on the exahust side. These take up some of the room, too. Another option might be induction hardening of the seat, rather than installing an insert.

Yes, in Kas' second book there is some discussion of the problem with using bronze valve guides (necessary for unleaded fuel) and following the specs found in the service manual, which are for the cast iron guides that were originally used. The different rate of expansion can cause siezed valves, if the old specs are used. On the inlet side, add .001 to .0015" to the specification. The exhaust side needs a little more, since it runs hotter: .002 to .0025".

Since you are going to the work of improving the head, take the header and intake manifild to the head builder too, so that they can insure the ports in each are matched. Might want them to look at the carbs mounted on the intake manifold, too.

Hope this helps!