asking all the fellow Pre-HE V12 owners.

I need to check the timing on our coupe and I was curious on what kind of advance everybody's running, per spec it says 10° at 750 can we go a little bit further than that?

and would a retarded timing curve give a bit warm running at freeway speeds?

 

When I had my XJ12C we used to advance the timing to almost 20 BTDC & only back it off if the car started to surge. You have 7.8/1 compression so detonation will not be an issue.

 

Same here.

I set ours at 10 Static, then kept advancing by "drive timing", until it got the surges, then backed it off a tad.

Ours was Fuel Infected, and 9:1 Comp ratio.

Some of these had Vac Retard capsules, and ours did, but I swapped it for a Vac Advance capsule, and just fiddled the timing to suit "her" driving style, Usually flat out 6500 change points being normal.

Retarded running WILL run hotter at highway speeds.

 

Yes, engine timing was a compromise of the times. But, times change.
Fuels differ, climes differ, driving habits differ.


When I had cars that I could mess with timing, I did the "power time" thing. Even to accepting just a touch of ping under heavy throttle.


Retarded timing was/is an emsion ruse to get more heat, thought to reduce emsions???


The emision "fix" for my 69 Toyota FJ40, was a plug on the vacuum advance line. Limited advance???? It was a hard line. So, a bit of tubing restored the advance. It ran much better...


MY LT1 has a "knock" detector. So, the PCM can dial in a lot of advance and only back down on a knock signal. Good for emisons and power.


I just see and engine running ad it's best as the way to reduce emsions.


Carl

 

checked the timing last night. and it was 4* btdc at idle.

needed to move the distributor a little bit. I kept the retard screw all the way at zero just in case I overly advanced it.

ended up setting it at 12* we definitely noticed a quicker pick up immediately after we put it all back together. and the temps are about 195 and then go up to about 210 after freeway run then the fans brings it down.

i'm thinking I should bring it up a little bit more. we also tested the vacuum advance unit and that is working.

 

@Grant

I've heard of pinging and pinking, but I've not heard the term "surging" before, when talking about timing. Can you explain what surging means/feels like?

Thanks

Scott

 

Scott,

Surging is when there is too much advance.

The engine will NOT sit at a steady idle, it wanders.

Driving it is usually worse at the cruise position, when the engine again, surges.

Putting my "made in the USA hat" on, I THINK you guys call it "hunting", but not sure.

Pretty hard to get a PreHE to ping, unless it has some serious other issues.

The HE is simple to get pinging.

 

@Grant

Got it, thanks. The car is in an old skool custom muffler shop having a new system built, so once I get it back from there we will experiment with a bit more advance. Certainly the 8° we adjusted it already makes a huge difference in performance and also running temps.

 

i run 25/28* BTDC at 950rpm,(any more has startup kick back), 48/50* all in at 3000rpm!

runs great no hunting/surging, custom curve,(just finding what works for Pre-HE combustion chamber).

93 oct, USA fuel, and Grant's right almost impossible to make pre ping, 9.2 pistons.

i use stanalone ECU ,SDSefi.

 

I think we can definitely go a bit further, yay !

 

Ron:


Remember the old school "stock" car racing system. Out with vacuum advance and in some cases, even the centrifugal weight thins. Locked, simple. Time to all in advance for WOT!!!
Idle quality, not an issue. WOT for racing.


Oh, oh, kicks back on cranking??? Fix. Two switches. Crank with ignition switch off. When spin is up, quickly flip on ignition and off cranking switch. fires up nicely, ready to run the oval, dirt or black top.


Old Fords already so wired....


Carl