I'm looking for advice on what I should set my timing curve for... so far I have a duraspark distributor, and I picked up the Mr. Gasket recurve kit, with both springs from the kit and not bending the tabs at all the timing came all in at 2300 RPM, the other day I changed one of the new springs with the lighter of the two stock springs and it's currently in it's origenal location, and now the timing comes all in at 2600 or so but there is no advancement from idle to 1200... Some of my specs of note; around 9.5 compression, and my cam is 280 duration. My end objective is pretty much optimum timing... most effecient burn gaining the most hp and throttle response, think road racing instead of drag.
it didn't rattle any on that setting but I also didn't have my vacuum advance hooked up either for my test run.
just ran to the store with the vacuum hooked up (timed port) and it didn't rattle. also didn't feel any more power either... I think I set the total to 38.
You don't say but I'm assuming you have a 302? A true road racer is almost all open throttle and will often run a locked out distributor. That isn't always best for street driving, though. For street I like to give the engine as much initial timing as it will tolerate, the engine runs cooler and has better response. Every engine combination is different. With the engine at operating temperature I increase the initial timing two degrees, shut down and allow to heat soak for a minute, then restart. If it doesn't spit back through the carb or lug the the starter I advance another two degrees, shut down, heat soak, etc. Keep repeating until you encounter a problem then back off two degrees. This is where the engine likes the initial timing. The only time this didn't work for me I was running a 300* duration cam and had 24* initial and it wanted more! LOL Total timing is also combination and vehicle dependent. Light car, manual trans, stiff gears, you can get away with quicker timing. The car in my sig runs at 16* initial, 36* all in by 2800 rpm, and vacuum advance adds 16* when cruising. Too much advance will hurt power and I've never seen a small block Ford benefit from more than 36* total.
it's a 289 bored .030" over... if I increase base timing than I need a way to limit the swing plate so I don't get 40 total... right now I'm at 38 total which gives me a base of 10 with my 13's (= 26 degrees) slot... the only option I see to limit swing would be to try and pull the swing plate and weld a spacer on it... or find a way to slide something over the tang in the middle to increase it's size there fore decreasing swing, but there is a little tab at the top that prevents me from sliding something on it.
The easy way to limit mechanical advance on a stock Ford distributor is to put a piece of vacuum tubing over the post inside the advance slot. I used to know how many .001" of tubing wall thickness equaled one degree of advance but that was a long time ago. It's easy to calculate, measure the length of the slot minus the post and divide that by the number stamped next to the slot to get camshaft degrees. The slots on the distributor are numbered as to how many camshaft degrees the slot will allow. Double that number to find crankshaft degrees. On my own distributor I have a piece of vacuum tubing and a piece of heat shrink tubing to limit my mechanical to 18*-20*, down from 26*. Remember that a piece of tubing on the post will have wall on the front and back of the post so travel will be limited in both directions. Hope all that made sense...
ok, I did'nt have any vacuum hose laying around so I used one of those silicone vacuum caps and abit of heat shrink and I have it currently set to 14 base / 34 total and it seems to be doing pretty good... Now I'm temped to take it up a degree or two which I know is'nt that big a deal but according to the referance guides I've been pointed to in the past will bring my base above the recomended range for my compression, but would bring my total into the bottom of the "ideal" range for my cam... man it's much easier to do some of this stuff when I'm buzzed abit... I'm normally to high strung and stressed to get much done when I'm not.
