project with 302 needs exhaust....and future part list.

That certainly is different. Very nice!

 

It sounds pretty good.

 

No time slip yet, but mostly dialed in, and can say that with whatever cam is in there, the power doesnt happen until 4K, but pulls fairly hard up to God only knows because I am chicken to rev it over 5500. I love the way it sounds at WOT and all places inbetween. I am certain with the 3.25 in there, it will run a 1/4 in mid 14s at 90+. My P&P C4 will bark the tires good into second, and the shift to D is also very firm. Car is a bit sluggish off the line....and I want to blame the mystery cam that I suspect has too much overlap, but hey, how is a guy who has trouble going over 5500 rpm really gonna know?

 

Sounds good. If your bottom end is that sluggish then you probably need to add much more initial timing. Quick n dirty test to show what the motor wants is to twist distributor housing with a vac gauge hooked up. Adjust mixture screws to compensate for lean out and do some quick bunny hops to feel all that extra torque. Just don't run it past 2,500 rpm or so because the total timing will be sky high.

Single planes with bigger cams have piss poor mixture motion and crappy combustion dynamics.. which is why they LOVE really fat and short timing curves. Could also lock timing at 36 and run an ignition cut switch or timing retard box to keep the starter happier during initial cranking. Timing and fuel enrichment in the lower rpm range will wake that motor right up. Also allow it to come up on the carbs booster and cam quicker to make it feel more violent.

 

I think I am BEGINNING to understand the whole manifold vacuum thing. I currently have initial set at about 16 degrees with the vac advance disconnected. The vac advance wanted to add about 18 degrees at idle, and when I throttled up to 3000 rpm, I was in the high 50s, so I left it disconnected to get around 36 total degrees by 3-3500 rpm. If I adjust the vac advance to allow only 10 degrees, and all 10 fall away at wot, then I would have about 26 degrees at idle and still have a max of 36? when does the manifold vacuum give zero advance to the distributor? I seem to be getting about 20 degrees from the centrifical advance.

BTW, do you know off the top of your head if the stock resistor wire is a substitute for a ballast resistor? I assumed it is....but assumption gets your foot shot off in some cases. Also, is this vac advance a reasonable one to use? I am still using points, but I am getting 28 degrees of dwell and the ignition system seems to be performing very well at the moment.....so I dont want to mess with it. I need to find my vacuum gauge before I take another run at tuning, it IS around somewhere........

 

Well you really want full mechanical advance before 3K RPM, and then use vacuum advance to give another 10* or so at cruise... This'll start discussions but Ford always used ported vacuum for advance and I generally still do... That way at WOT the 46* of advance will fall back to 36* so won't be excessive...

 

Well, I have done a bit of reading, which is my substitute for experience, and what I gather is that idle and cruise fuel mixtures tend to be lean and take longer to burn, so getting the spark there sooner gives that mixture more time to burn. In both of these cases, manifold vacuum is high and will give advance until the throttle plates open. At that point, fuel mixtures richen and need less time....less advance needed....and manifold vacuum drops, enabling the distributor to cooperate with what the engine needs if it is using manifold vacuum. Theoretically, this also enables the engine to run cooler at idle and cruise. Good for performance, bad for tailpipe emissions. I really want to get two vacuum gauges with hoses long enough to put them on top of my dash, hook one up to manifold and the other up to port (timed port?) and see how they compare under various driving conditions. I will have some info on MY engine at that point that should be useful, or at least interesting.

 

The ported vacuum will start at zero & increase as throttle opens, to maybe quarter open(lots of variables, carb size, cam/ign timing etc)... At approx that point manifold vac begins to fall and ported vac will follow along... Usually ported vac will not be more than manifold vac, same variables already mentioned apply...

 

With todays internet knowledge the need for major trial and error is greatly reduced. And your reading comprehension skills are excellent so far. Aside from the lean mixtures you also have to remember piston speed induced mixture motion, not to mention gas velocities in the carbs venturi and induction tract, are relatively slow as well.

The long hose and vacuum gauge trick you mention is exactly how i learned to apply most of what i know about engines spark timing requirements. It was, still is to some extent, far from what many gearheads and magazines of the day were talking about. I also plotted how much a handheld vac pump added to a vac advance pot per psi of vacuum applied to dial in full throttle power as well. Kind of a handheld timing advance tool. Can even preapply timing with it to create a high speed retard function to check if the engine picks up past its power peak on the big end.

As for the ported vs manifold debate.. i prefer to apply as much spark advance as an engine will tolerate from idle to redline. Under ALL conditions. As you rightly pointed out already.. poor combustion dynamics of idle/part throttle/light load requires much larger spark head starts to maximize cylinder pressures. Maximized cylinder pressures equate to improved engine efficiency and are denoted by higher than average manifold vacuum numbers. They run hand in hand as byproducts of one another.

If you've ever seen the efi timing plots of todays engines you will see self learned spark tables exceeding 50 degrees under light load in cooler induction conditions. Guys that tune for a living can approach and even exceed 60 degrees but the tuneup needs to be spot on and well maintained. Conventional distributors with vacuum pots will of course never allow such tuning flexibility but computers give perspective as to what engines actually prefer.

PS. MSD makes a programmable 6 and 7 series box that allows MAP based tuning like the OEMs. Get one of those boxes dialed in and you will never want to go back to those old antique weights and vac pot designs.

 

I finally tracked down my vacuum gauge, and put a tee in my vac adv hose (hooked to manifold vacuum) to run the gauge. Hooked up timing light. My vac adv needed to be taken apart and add washers (3+ the one that was there) to get it to give 9 degrees of advance. set initial at 10. Got 15 in. of vacuum at idle in park....13 was the previous best. Mixture screws stayed at 1 and 1/2 turns from lightly seated which seemed to be the best place. Advance at 2800 RPM was about 40, and 4000 rpm was about 46-48. My balancer does not have markings past 30, so that is a close guess, but it quit climbing at 4000.

I also gave it a rev past 5K and witnessed my lower hose get sucked shut. I also had to crimp the tabs on my radiator cap to make it seal tighter.....it was not sealing but is now. Now I need to get a hose with a coil in it. Then I will clean all the radiator scum off my engine and drive it to see if I collect a new layer of slime! My previous issue with flooding was from excessive heat....re-workinjg my grounds for battery cable, electric fan, and voltage regulator cured intermittent cooling fan issues, and lowering the float in the front bowl to make fuel level slightly below the check hole may or may not have helped. Test drive coming after lower rad hose r&r .

 

I dont have time to eloborate but i will quickly say that your igintion curve is far from optimal. Especially true with a performance cam. Little motors need every bit of extra torque they can get to help come up on the cam quicker. The supplemental 9 degrees from the vac pot is a good number but you need to temporarily set that aside while tuning for strong manifold vacuum under abrupt part throttle transitions. Also, the fact that you still have advance coming in upwards of 4000 shows your mechanical curve is still to long. Should be all in by about 3000-3200.

 

That seems to be the consensus....so I need lighter springs in the mechanical advance? Is it a matter of taking out what is there and swapping them for lighter springs out of some sort of spring assortment package? I will have to dive into that...and look for a part number on my distributor.

 

One of the basic things you need to do is determine just how much mechanical advance there is in dist... For performance tuning you want approx 15*-18* of base timing with the remaining 20* or so in the mechanical curve, again fully in by approx 3000 RPM... Most factory tunes start at maybe 6*-10*, then toss in 26*-30* mechanical... Usually not till well past 4000 RPMs...

There are other factors beside just swapping out springs... For a Ford dist the points cam or reluctor has a pair of slots that limit the amount of mechanical timing... Well limit isn't a good word, for the most part are overly generous... The slots can be anywhere from 10*(20* crank) to 18*(36*)...

Here's one I was experimenting with, did same to one in my Comet... The wire wrapped around the stop pin limits advance to approx the 10* I mentioned(normally 13* other slot in this dist is 18*)... I added heat shrink over the one in Comet and also soldered wire... From factory there was a small piece of rubber tubing on pin to act as stop/bumper... Most have fallen off 35 years ago...

BTW giving credit where it's due, Mr Roberts clued me in on these mods...

 

Lol....I just read about that wire "limiter"....but your picture is worth a thousand words and is way easier to comprehend. I got 24-26 mechanical: 20 of it is there by 2400 and the rest is there at 3000. I hooked Up a tach under the hood, my other instrument is not accurate. So, if I can subtract a few degrees with the wire, I would be all in with what is left by 2400 rpm since the wire stops it at the end and not the beginning? Is that too soon? Or do I need a slightly heavier spring with a limiter to be all in at 3K? I know this is a lot of fiddling, but it cost nothing to fiddle and you dont know what you got till the fiddling is done. Thank you both for your help, as you are Ford experienced and that may mean more than just experienced....I am neither!

 

Increasing pin size reduces travel at minimum and max, so it'll add a bit on bottom end and reduce the total advance... Likely will require a bit of fiddling to get curve in proper range...