Hi folks.

My Seven runs with the usual 2 litre 105 hp ford OHC engine with a Weber DGV carp on it. When I bought the car, it had 48IDF carbs and a quite extreme cam shaft. I got that changed to a mild 262 degrees cam shaft and a Weber DGV carb. The engine now runs alright, but the garage that did that change did not connect the vacuum hose for some reason (my guess: they were too lazy). Therefore I drove the engine without vacuum hose until now.

After changing the timing belt I verified the timing and considered connecting the hose as it normally should be. But in order to not break anything, I first wanted to find out how much pre-timing including vacuum adjustment the ignition should have with different throttle conditions and rpm. But the web search does not find any good data sources for that. :-( Google AI however gives me the folling values:

Idle/throttle closed (900rpm): 6 to 12 degrees before TDC
Throttle partially open: 35 to 45 degrees before TDC
Full throttle low rpm: 12 to 18 degrees before TDC
Full throttle high rpm: 32 to 36 degrees before TDC

I am just an amateur but especially the quoted 45 degrees before TDC for partial throttle give me a real shiver! And the sources provided for the Google answer by majority do not specifically point to the Ford Pinto engine. Therefore I am looking for a verification or for reallistic values that work safely for the Ford OHC.

When the timing is set to 10 degrees at idle as specified in the manual, centrifugal adjustment reaches about 30-32 degrees at 4,000 rpm. Using my strobo light with the vacuum adjustment attached, I can see that the pre-timing reaches about 30 degrees a lot faster than without the vacuum hose attached. But my timing never even gets close to the 45 degrees quoted above. The max I can see is somewhere around 32 degrees. Can I use that setup without harming the engine? A carefull test drive showed me that the engine seems to run a little smoother, especially during acceleration, when the vacuum adjustment kicks in the most.

Edited September 10Sep 10 by Amateur

With your set up I'd say you were pretty close and if it runs nicely with no pinking I'd leave it "as is".

Timing wise for the pinto, 10-12 degrees at idle and 32-35 at full advance (normally3500-4000rpm) is a good starting figure. Your vacuum advance can add up to 10 degrees on top of that, but you'll only get that much with the throttle almost closed and the pinto should be quite happy with that. With the throttle fully open you will have little or no manifold vacuum, and so no extra advance.

If the vac. hose was left off you might want to check the mixture. You may find you're now running a bit rich now as the carb. would have been sucking extra air, particularly having an effect at small throttle openings.

Thanks, Foz, for your answer.
But when I said, "the hose left off" I just meant that the hose was not connected to the vacuum box on the distributor. Instead, the nozzle on the carb was closed off with a plug, made from a piece of hose and a screw it it.

But that said, I do have an issue with the mixture running rich, but only at accelleration (attaching the vacuum adjustment has not made this any better or worse though). I have a lambda dail in my car and can see mixture composition in real time. In cruise mode (just holding speed) the mixture is perfect at about AFR 14. But when I push the paddle down to accellerate, mixture drops to about AFR 12. In my option this is too rich (although it's better than being too lean). But when the accelleriation ends, the mixture jumps back to AFR 14 within 2-3 seconds. I tried to fix that for the last years but have not found a way. The accelleration jump is already more or less deactivated. But smaller jets would also directly affect the cruise mixture and that must not become any leaner. So I learned to just accept that behavior. But if you know a way to affect that to the better, I surely would be interested.

TBH buy a ford Cortina ,sierra manual it will inform you about the pinto engine also you can Google about setting up your carb but the manual will tell you about the carb Also you need to put advance and retard pipe/pipes from dizzy to carb as the dizzy advances and retards the timing and also allows more fuel/air mixture as you need it when accelerating then retards when decelerating cutting the air/fuel mixture to what the engine needs at that moment in time. then it needs carb retuning and mixture will be set.

Ah, that makes more sense if the vac. was blanked off.

If your mixture is correct at steady running I'd be happy. Weber carbs such as the DGV are designed to richen the mixture on acceleration, so what you are seeing on the AFR is correct - it should go rich when accelerating.

The thing to remember is that the vacuum advance is there as an economy measure whilst at low throttle settings.

At low throttle the pressure in the cylinder is low before ignition and in the burn time is therefore longer so to get max economy the ignition needs to be advanced.