• Hey Guest!
    British Car Forum has been supporting enthusiasts for over 25 years by providing a great place to share our love for British cars. You can support our efforts by upgrading your membership for less than the dues of most car clubs. There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Upgraded members don't see this banner, nor will you see the Google ads that appear on the site.)
Tips
Tips

TR2/3/3A What Distributer?

Share this page

Q

Quelch

Member
Offline
Hi Everyone,
I'm running a TR4A engine with SU HS6 carbs in my 1959 TR3A. When I rebuilt the engine a couple of years ago I found that the camshaft was damaged (lobe wear due to incorrect oil) anyway I replaced the cam but used a servicable one from a TR3 engine not realizing that they were a different "grind." Since the rebuild I have noticed that I have to set the ignition timing closer to TDC rather than the prescribed 4 degrees BTDC to stop the engine pinking even when using premium fuel.
My question is, should I be using a TR3 Distributer to match the TR3 Cam?

Regards,

Quelch
 
With TR4A pistons and a TR3 cam it is not simple to know which distributor is best -- quite possibly the ideal advance curve is one offered by neither the stock TR4A nor TR3 dizzy.

I think the most important difference in those distributors is the total advance you see at speed (determined by the stop built into the weights) and the second most important the curve of that advance (determined by the springs used).

A distributor specialist might be able to help but you might at least put a timing light on the pulley marks and see what advance is at, say, 3500 RPM.

Personally, if an engine runs well once you've eliminated all pinging I wouldn't stress over whether or not the static advance is per the book.
 
To follow on - the distributor will be the same but how it is tuned (timing / advance) will be what you are tweaking. I'd also agree that once everything is known to be working properly just tune to the point of pining and dial back some. I doubt you'll be much of optimal at that point.
 
Back
Top