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TR3 engine & box re-build


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Hi Bob,

My view only but if you are spending a few bob on the rebuild and you are only planning to do it once, you need to do it right. The cost of a new set of springs is small beer in the overall scheme of things. 

I have TR4a springs running in a TR3a head and with 3/8” dia exhaust valves. I have a Newman PH1 cam with their followers and it all seems to work together. 

Rgds Ian

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Agreed, but unsure where to find the right springs. I have left a message with Moss to try to find out what "Uprated" means.  My Exhaust valves are 5/16", so I have not been using the 3rd spring anyway.

Bob

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Just now, Lebro said:

Agreed, but unsure where to find the right springs. I have left a message with Moss to try to find out what "Uprated" means.  My Exhaust valves are 5/16", so I have not been using the 3rd spring anyway.

Bob

FWIW Having killed the springs in my 4a I have a set of Racetorations progressive springs and they work very well.

Stuart.

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26 minutes ago, Lebro said:

Revingtons do TR4A standard springs (up to 6000 RPM) for a price similar to Moss, so that may well be the way to go.

Bob.

That's where mine came from.  I was guided that way by Carl who is one of their mechanics and has rebuilt loads of TR engines in his time.

Rgds Ian

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2 hours ago, Lebro said:

Agreed, but unsure where to find the right springs. I have left a message with Moss to try to find out what "Uprated" means.  My Exhaust valves are 5/16", so I have not been using the 3rd spring anyway.

Bob

Newman supply valve spring sets I think.

Page 52 here http://www.erstellen.co.uk/newman-cams/PRICELIST-BROCHURE_2020_WEB.pdf

Be aware that with the triple spring set up the inner spring auxiliary spring may go coil bound with the PH1 cam.

Cheers

Peter W

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I’m sure Revington’s suggest std springs ie light as possible with performance cams until you get to extreme cams and 7k revs when you need to uprated springs. 
I just can’t find the link at the moment. 
 

if you go with Stuart’s advice Racetorations are having a Black Friday sale so maybe worth checking for springs there ?

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11 hours ago, Lebro said:

No valve springs appear on their web site, but I will go with the Revington standard 4A ones tomorrow.

Bob.

You need to give Racetorations a ring for them as theyre not in their catalogue but they come recommended here.

Stuart.

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On 11/26/2020 at 10:14 PM, Lebro said:

No valve springs appear on their web site, but I will go with the Revington standard 4A ones tomorrow.

Bob.

What is wrong with Newman's springs  pt no DNS9974K?  You have a leg to stand on then if they eat their cam shaft or their followers.

Peter W

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They are described as competition springs suitable for up to PH4 cams, so they are probably heavy poundage.  The Revington's standard 4A springs are on their way, together with some 2nd hand caps.

Heard from M & C yesterday, they should be finishing my block today, fingers crossed. Sounds like I may have to "deck" the pistons, I presume this means skim the top surface till it is level with liner top. Will measure thickness of top of piston to make sure there is plenty of metal there.

Bob.

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My pistons had to be decked as well Bob, but I got the machine shop to do it.  After all, they had the block, liners and crankshaft, I just provided a new set of FO8 seals and the pistons and conrods. They sourced new shells for the bearings and checked and skimmed the pistons.

Rgds Ian

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3 hours ago, Lebro said:

They are described as competition springs suitable for up to PH4 cams, so they are probably heavy poundage.  The Revington's standard 4A springs are on their way, together with some 2nd hand caps.

Heard from M & C yesterday, they should be finishing my block today, fingers crossed. Sounds like I may have to "deck" the pistons, I presume this means skim the top surface till it is level with liner top. Will measure thickness of top of piston to make sure there is plenty of metal there.

Bob.

The last engine I did using County 86mm pistons needed 0.032” to come off the piston crowns as that is how much the liner seats had been deepened by.  I have a tool for holding the piston on the Boxford lathe.  It is an old TR Conrod with a length of studding attached to draw the assembly into the headstock against the Chuck face.     The piston to deck height will affect your cr like head gasket thickness does.  You need to check all your pistons and conrods assembled to equal up any deck height differences.  Adjust each piston as required.   Now you need a set of slave conrod bolts so as not to reuse stretched ARP2000 bolts.
Cheers

Peter W

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1 minute ago, BlueTR3A-5EKT said:

The last engine I did using County 86mm pistons needed 0.032” to come off the piston crowns as that is how much the liner seats had been deepened by.  I have a tool for holding the piston on the Boxford lathe.  It is an old TR Conrod with a length of studding attached to draw the assembly into the headstock against the Chuck face.     The piston to deck height will affect your cr like head gasket thickness does.  You need to check all your pistons and conrods assembled to equal up any deck height differences.  Adjust each piston as required.   Now you need a set of slave conrod bolts so as not to reuse stretched ARP2000 bolts.
Cheers

Peter W

PS. Deck height is to the edge/top of the clamped liner.

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39 minutes ago, BlueTR3A-5EKT said:

PS. Deck height is to the edge/top of the clamped liner.

Looks like we have different answers here....

I have checked with the engineering co that did my engine ( Hamlins), both are correct, however, they always go for piston height the same as block decked height.

Iain

Edited by iain
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9 minutes ago, iain said:

Looks like we have different answers here....

I have checked with the engineering co that did my engine ( Hamlins), both are correct, however, they always go for piston height the same as block decked height.

Iain

Then sometimes...they'll be wrong.

Mick Richards

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10 minutes ago, Lebro said:

So the correct answer is ?

Dependant upon the use of the car, the components used, the head gasket used and the compression ratio to be achieved.

Mick Richards

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Does it matter for a road car?  If the pistons are decked to the block then they will be a maximum of 5 thou down which increases the swept volume by less than 0.5% and the combustion volume by approximately 1.2%. Is that material?

Rgds Ian

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14 minutes ago, Ian Vincent said:

Does it matter for a road car?  If the pistons are decked to the block then they will be a maximum of 5 thou down which increases the swept volume by less than 0.5% and the combustion volume by approximately 1.2%. Is that material?

Rgds Ian

Swept volume remains constant. Combustion volume goes up a bit, compression comes down a bit. 

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