When does a vernier timing gear become viable

[StevecTR4]

Hi,

Just starting a TR4 engine rebuild and will possibly go down the route of a Newman PH1 camshaft or similar.

Would this benefit from a sparkly vernier cam gear, or am I being blinded  by the sparkle.

Many thanks

Steve

[Chilliman]

I use the vernier on a couple of mine Steve, nice & easy to set up but you absolutely don't need it to get the timing right & having seen the cost of them recently I wouldn't bother.  It's not going to go any quicker & no-one will see it.

[trchris]

Hi Steve as John says l wouldn’t bother either save your money 

Chris

[Z320]

Hi Steve,

with the standard cam gear you have already 4 options to adjust:

- standard is 0 or +/- 1 full tooth

- spin it 90° you have a 1/2 tooth

- turn it you have a 1/4 tooth

- spin it 90° you have a 3/4 tooth

- + the play of the gear on the bolts

On my TR4A the original position was good enough

Ciao, Marco

[Andy Moltu]

The vernier cam gear just makes it easier to get the timing accurate.

Easier but ultimately not better.

[Lebro]

Agree, don't bother.

Bob

[StevecTR4]

Thank you for your advice. £100+ now available to spend elsewhere on the build.

Regards

Steve

[BlueTR3A-5EKT]

My simple purchase guidance question for non standard items.

“Does it enhance performance or economy?”

 

You make the decision after asking that question.

 

 

[Andy Moltu]

If your existing cam gear is worn then the equation to consider is the price differential between a standard one, a vernier one and the potential time saved timing the cam.

[Z320]

In my opinion with a chain in a oil bath

both sprockets are good for the use of 2-3 chains

Edited October 4, 2025 by Z320

[BlueTR3A-5EKT]

My thoughts too that it speeds up installation.   Think A series cam here that has no adjustment as it is keyed.   You have to buy offset keys to change the cam timing.    Very fiddly!     It also gives a possibility to advance or retard the cam timing quickly whilst completing power runs on a dyno.    Dennis Welch of Healey Spares supply I think offer a  special timing chain cover for the 100/4 models with a detachable ‘window’ that allows you to adjust the cam timing without removing the entire cover, assuming you have a vernier type cam chain wheel installed.    
 

 

[RogerH]

.........so you do not have a very small mechanic inside the timing chain case that adjusts it between runs  

[BlueTR3A-5EKT]

13 hours ago, RogerH said:

.........so you do not have a very small mechanic inside the timing chain case that adjusts it between runs  

As ex BEA Roger I would have expected that you had worked in their engine test cells and known there were mice to do those fine engine control rod settings and adjustments. That's what the cell staff told us when they certified (or not) our Dart engine overhauls.

Edited October 4, 2025 by BlueTR3A-5EKT

[RogerH]

I didn't get on well with the BEA engine test beds. 

A bunch of weirdo's. Or perhaps I did not get out much.

 

Roger 

[tim hunt]

On 10/1/2025 at 8:52 AM, BlueTR3A-5EKT said:

My simple purchase guidance question for non standard items.

“Does it enhance performance or economy?”

 

You make the decision after asking that question.

 

 

or safety?  e.g. high level brake light in rear screen of surrey car, hazard flasher kit, air horn, E10 resistant fuel hoses and other rubber components of fuel system.

Tim

[BlueTR3A-5EKT]

10 hours ago, tim hunt said:

or safety?  e.g. high level brake light in rear screen of surrey car, hazard flasher kit, air horn, E10 resistant fuel hoses and other rubber components of fuel system.

Tim

I fully accept that errata and will add it to my adage 

“Does it enhance safety, economy or performance”

[Drewmotty]

….or reliability?

[Chilliman]

......What did the Romans do for us...........?😁