TR3 engine & box re-build

[Ian Vincent]

Bob,  I have a Newman cam and the low down torque is impressive.  My rear axle ratio is 3.45 and last year on the LBL rally I had no problems on any of the passes. The car was quite happy climbing steadily in the 2000 - 2500 rpm Rev range. 

Rgds Ian

PS. I’m with Hamish on the valve springs. If you go for a Newman cam you will get coil binding with the exhaust valve if you use the triple springs. I have standard TR4a springs which are quite soft and don’t bind. 

Edited November 6, 2020 by Ian Vincent

[AndyR100]

43 minutes ago, Lebro said:

 

I think I need to create a table showing timings & lifts for all the options, then make a decision, unless anyone can recommend a cam for improved power, without loosing too much low down torque.

Bob

The Tilden Technologies link provided by Iain has most of the comparative info that you need.

you may wish to chat to TRE or TRGB regarding their ‘Yellow’ high-torque profile as an alternative (I believe they are the only supplies of this particular profile).

....... Andy 

[Hamish]

39 minutes ago, iain said:

Morning  Bob, this might save you some work or at least give you a very good start.

http://tildentechnologies.com/Cams/TriumphCams.html
 

Iain

Well done iain I’d forgotten about this website. 
 

one still needs the technical ability ( that I don’t have) to translate the numbers into driving characteristics and likely power band. Unless someone know a rule of thumb ?

I'm sure you know Bob but this thread will be great for those of us that follow .

[Lebro]

48 minutes ago, iain said:

Morning  Bob, this might save you some work or at least give you a very good start.

http://tildentechnologies.com/Cams/TriumphCams.html
 

Iain

Cripes ! my brain hurts now !

[Lebro]

32 minutes ago, Ian Vincent said:

Bob,  I have a Newman cam and the low down torque is impressive.  My rear axle ratio is 3.45 and last year on the LBL rally I had no problems on any of the passes. The car was quite happy climbing steadily in the 2000 - 2500 rpm Rev range. 

Rgds Ian

PS. I’m with Hamish on the valve springs. If you go for a Newman cam you will get coil binding with the exhaust valve if you use the triple springs. I have standard TR4a springs which are quite soft and don’t bind. 

Ok so good low down torque, but did it give a noticable improvement at higher revs, if not may as well stick with standard (whatever that is according to the above chart !)

Bob.

[Ian Vincent]

56 minutes ago, Lebro said:

Ok so good low down torque, but did it give a noticable improvement at higher revs, if not may as well stick with standard (whatever that is according to the above chart !)

Bob.

To be honest Bob, I don't drive my car very  hard.  70'sh or maybe just over on the motorway and with overdrive and my axle ratio that is only about 3000 rpm.  I bought the Newman cam on the basis of good reports from Roger H and a competitive price.

Rgds Ian

[RogerH]

2 hours ago, Lebro said:

a cam for improved power, without loosing too much low down torque.

Bob

My impression is that the PH1 does give both power and low down torque.

 

Roger

[Lebro]

Here is a list of possible candidates in order of sillyness.  Newman looks like a good choice, as similar to Moss road, but less lift, but still much more duration than either TR3 or TR4A standard.

Bob.

Edited November 6, 2020 by Lebro

[BlueTR3A-5EKT]

3 hours ago, Ian Vincent said:

You are right Peter. My mistake. 

Rgds Ian

I feared you might be pulling the front cover off to retime the cam.

 

Cheers

Peter W

[Ian Vincent]

Nope,  it was just a momentary brain fade, (something which seems to happen with increasing regularity).

Rgds Ian

[stuart]

With regards to the cam, a lot of the US Triumph tuners say that the standard 4a one is the best all round one. Mine is still running its original cam and followers at more than 150000 miles and two rebuilds and it performs very well all round and I dont hang about.

Stuart.

[Lebro]

Thanks Stuart I only realised yesterday that the 4A was different to the earlier cams.

Bob.

[Lebro]

Apart from spending the morning worrying about cam choice !

I managed to bolt the stand plate onto the engine, after making up some bushes to locate the 5/16" bolts inside the ½" holes in the arms.

  

Ready to lift onto stand tomorrow.

Bob.

Edited January 16, 2021 by Lebro

[Andy303]

Perhaps another option regarding the cam is to have the old reground? Then you know that you have one made from high quality materials. I had a good TR3 cam reground to the Isky TR-555 spec by Isky Cams. My old TR4A cam was shot after 100K miles - I blame the PO!

The TR-555 spec falls somewhere between the PH1 and the Std TR4A  cam I guess, with excellent torque and a good idle. Its been around a long time and was recommended by an old hand in my local club. No doubt the specialists in the UK can recommend something that suits.

Andy

[Lebro]

Thanks Andy, I have pretty much decided on the Newman PH1.

 

Bob.

[iain]

Something else that will significantly changes the cam characteristics is compression ratio. At 10.75 :1 my High torque cam was happier from 2500rpm up to 6000 very easily. Reducing the compression to 10 :1 brought the torque back. Easily achieved with solid copper gaskets. 

Worth checking from the cam manufacturer at what compression ratio they describe the cam?

Iain

[Lebro]

Having worked on the head earlier this year, with 87mm pistons I am expecting 10:1

Bob

[Ian Vincent]

5 hours ago, Lebro said:

Apart from spending the morning worrying about cam choice !

I managed to bolt the stand plate onto the engine, after making up some bushes to locate the 5/16" bolts inside the ½" holes in the arms.

  

Ready to lift onto stand tomorrow.

Bob.

Now that’s being fussy Bob. I just used large washers. Nice job though. 

Rgds Ian

[Lebro]

    

Transfering to engine stand, &  Measuring end float - 9 thou.  Shells slightly worn will measure crank once cleaned up.

Next job get the liners out

Bob

Edited January 16, 2021 by Lebro

[AndyR100]

Nice progress Bob

....... Andy 

[david ferry]

If you need any new liners, I have an unused high quality set (87mm) that we’re going to go into a race engine. In the end it was built with 83mm pistons and liners.  Let me know if they are of interest - we can discuss a sensible price!

David

[Hamish]

Well done Bob. 
great progress. Keep the pictures coming.

[Lebro]

3 hours ago, david ferry said:

If you need any new liners, I have an unused high quality set (87mm) that we’re going to go into a race engine. In the end it was built with 83mm pistons and liners.  Let me know if they are of interest - we can discuss a sensible price!

David

Thank you David, but I already have the liners & new pistons at 87mm, they came from the TR shop.

I am also fitting some Maxspeedrods conrods.

Note. Today I got round to measuring the big end width of these rods, they come out at around 84 mm across, which means To fit the pistons in to a 83mm liner would be impossible from the top.

Should be ok with 87mm, but will be protecting the liners by putting some insulation tape down the edges of the conrod.

[Lebro]

This afternoons efforts:

  

Liners came out fairly easily, just drifted them out using some aluminium bar.

Crowbar was only used to shift the crank when measuring the end float !

The figure of 8 gaskets were amazing - good as new. Copper of course.

    

Liner seats were also devoid of any corrosion, so should not need any machining

Block ready to go for chemical cleaning.

There was not too much build up of rust inside, none around the front two pots.

Cleaned up the crank, & measured the journals, all just about within tolerance.

Bob.

Edited January 16, 2021 by Lebro

[iain]

Looks like it was in pretty good nick, with the exception of the pistons and rings.
Have you checked the block for the crack that tends to happen next to the NSR  head stud? Increasingly common I’m told. 
Iain