unleaded v4 ignition timing.

[mavis cruet]

hello. ive finally got round to buying a timing light and was going to check the timing on my 1972 v4 camper. its been converted to unleaded and i wondered if the timing should be set as per the haynes manual, or if the unleaded thing would change the settings? cheers in advance....

[walt1984]

I was advised by bacondozen on here that you cant allways go by timing marks with modern fuel and electronic ignition.
I got a vacuum gauge from a auto jumble and connected it to the vacuum pipe that operates the flap in the air filter.
Ran the engine at fast idle the adjusted timing until it reached peak vacuum.
Mine looks something like this.

[1958 harry]

I agree, I set my Pinto to the Haynes settings and it pinked like anything.

So I just played with it until it sounded and ran right. Seems fine now.

Electronic ignition also improved things.

[jonochap]

Agreed...half a tank of petrol, an hour, a quiet road and a spanner

[baconsdozen]

A vacuum gauge works well,the other way is to advance the timing by small increments until the engine starts to pink under heavy load and then retard it slightly so it doesn't. This is pretty much what knock sensors do on modern engines.
A vacuum gauge will also show up other faults like sticking or knackered valves,air leaks and blown gaskets.Basically the higher stady reading the better.

[mavis cruet]

ive never knowingly experienced pinking, but my engine makes a metallic rattly sound through the exhaust under load sometimes. is this pinking? engine runs sweet generally. i dont have any hoses going to the air filter, so not sure what to use as a vacuum take-off. cheers for your help. will dig the old girl out n have a play...

[1958 harry]

Yep that's pinking.

[baconsdozen]

Pinking sounds a bit like small coins being dropped onto a concrete floor but it happens in the cylinders not the exhaust. It happens under heavy load and stops instantly if you lift the accelerator. V4s have a plug on the manifold which can be used for a vacuum gauge,Ill try and get a picture if it helps. Its to the right of the carb looking under the bonnet.
If you retard the ignition to the point that just eliminates pinking under hard acceleration that should be about right.