So ive always had issues getting my 306 timed correctlym problem is that there are two sets of timing marks on my balancer. I have both marked at 12btdc as a reference. When I put the timing light on the car I'm between the two marks.....try to advance to one and it does before I can get there....retard timing to reach the other and it dies. Right in the middle the idle is at its best. Is the dizzy stabbed wrong? Car runs and drives down the road. Its driving my crazy not knowing for certain I'm where I need to be exactly.
Ford used 3 different sets of timing marks on the 302 over the years. A mismatch of parts will confuse you. Best thing to do is set the engine on TDC of the number one cylinder and identify which set of marks are correct for your setup. From there it will help identify if you are.
Took it to tdc 1 compression and sure enough tdc is bwtween the two sets of marks. Marked and got it close to 8-10btdc.
That's fine for a factory style grocery getter that's "good enough for ma and pa".. but you're still about 10 degrees off of what that motor will like. Try this simple test. Use a vac gauge and adjust initial setting to 18 degrees and readjust the mixture screws to tame the idle and see what the vacuum level looks like. You'll be surprised what the total vac reading will go up to. Now hook up the vac advance running off manifold vacuum and readjust the mixture screws once more. Does the vac reading still go up? Now test drive the car at abrupt/heavy throttle from standstill and make note of the major throttle response and "extra tire spinnage" associated with those higher vac readings. BUT.. DO NOT.. I REPEAT.. DO NOT.. REV THE ENGINE MUCH PAST 2,000 RPM WITHOUT FIRST TAKING AWAY THE SAME AMOUNT OF MECHANICAL ADVANCE AS YOU ADDED INTO THE INITIAL SETTING.. OR THE ENGINE WILL LIKELY DETONATE.. AND POTENTIALLY CAUSE DAMAGE DUE TO EXCESSIVE TIMING LEAD AT HIGHER RPM'S. All that this low rpm abrupt/heavy throttle from standstill testing does is show you that these little motors tolerate MUCH more timing than most accept as "normal". Let the vac gauge tell you what the engine likes and then adjust the fueling to better match the more aggressive initial and centrifugal timing curve. You'll likely need more main jet and more pump shot off the front side too. The basic tuning rule that I use is this. If my engines.. stock or otherwise.. aren't chirping the tires at extremely light throttle levels during gear changes?.. I'm not done tuning yet. And modified engines should be able to lose traction instantly with abrupt throttle changes from at least 10-15 mph rolls.
Just to get this straight. I need to set initial timing to 18 degrees with vac advance unhooked. Then change idle mixture to best vac reading at that setting. Then hook up the vac advance and tweak idle mixture some more until I get best vac reading again. Test drive under 2k to see how much I have gained / lost Then reset timing advance back to ???? Sorry just trying to understand the directions. Thanks.
71 gold..... probably do I pieced all the accesory stuff together. Update..... Started getting 16hg of vac. Made big changes to timing....added another 8-10 degrees. Adjusted air fuel screws quite a bit. Ended up with 20-21hg of vac and still have easy start. Idle sounds healthier and throttle response seems improved. I'm running the holley vac secondary with 2nd to lightest springs and Unknown cam. Just me and my daughter so no test drive until tomorrow after work but I'm certain its way better.
Good for you! ok.. back to the carb adjustments you asked about and adding some clarity. ALWAYS readjust mixture at the least.. and sometimes even main jetting with major timing changes like you're fiddling with here. Make sure you get yourself an adjustable vacuum pot if your disty doesn't already have one installed. Adding a lot of initial timing usually requires tightening up the vac pots contribution to around 8-14 degrees or you'll end up well over 50 degrees under light throttle at highway rpm's when the centrifugal has kicked in. IMO,.. and not to contradict what baddad already mentioned about spring preference because that guy's probably forgotten more about engines than most will ever know.. but your particular heads flow capability cannot take advantage of those lighter springs. He has Canfields that flow substantially more than your heads do and can take advantage of the additional airflow and at an earlier transition point. For your setup.. I wouldn't even consider using anything lighter than the purple spring because it will improve midrange response(torque spread) and keep the motor from going soft on the top end. In fact.. you could probably use the brown spring and barely notice any top end power loss on your combo. Many people.. including myself on occasion.. have been throwing light springs on the secondaries in hopes of more power up top.. but a little motor can only flow so much air with stock heads and small'ish cam to begin with. This is one of those times when more is definitely not better. Testing and playing with various combo's is the only sure way to figure it out for yourself though. BTW, you don;t even need to drive any place to test the cars throttle response and off-idle torque. Just simply jab the throttle and measure the wheel spin on pavement compared to previous settings. Trust me.. the engine will seem much bigger than it really is. Initial timing is really only useful for the first 800-1,200rpm from your idle speed(let's assume 700rpm) when the centrifugal starts coming on strong and contributing to the total number.
You lost me.on the vac pots lol. Ive got a stock distributor with a petronix unit in it so not are if I have adjustable pots or what they are......research on my end is needed. I believe it had the purple in to start with I will go back to that. My next upgrade is to a set of e7 heads I will try and port or a set of gt40 heads when I find a steal. Thanks guys.
vac pot = vacuum advance mechanism hanging off the side of the distributor. It has a diaphragm inside it that pulls on an arm inside which is connected to an advance plate which allows it to add more advance during low load/high vacuum situations when the engine can tolerate it without pinging. Most Fords are adjustable via allen wrench(3/32, IIRC).. or are about 20 bucks for an aftermarket unit. Because mixture motion and lean mixtures need much more advance during light throttle cruising(sometimes slightly more than 50 degrees).. you'll need adjustment there to really dial all this stuff in.
Ok thanks. I will check that out and post up what I found. I'm gonna measure out the degrees on my balancer and make marks for 36 and 38 degrees and see what I'm pulling all in. Thanks again.
I'd shoot for 40 degrees to maintain a tad bit of margin.. but that iron can probably tolerate even slightly more. 36 degrees is for newer fast burn heads and tiny(high CR) chambers being run atop 0 quench setups. That's not where you're at right now.
Where're you getting this from ? My Canfield headed 331 does not have a vacuum sec Holley feeding it. It's got three 2 bbls linked by a mech linkage. And as for the advice I gave about using a lighter spring in a Vac sec Holley, that DID apply to iron headed 302's. The last I had was an E7 headed roller 302 fed by three different Holleys over the time I had it in my 89 Ranger. The first was a modified 1850 600, this carb had the next to the lightest sec spring, and yes, it did use the extra airflow provided by the secondaries. The second carb was a 3310 750. I don't recall which sec spring it had, but it rarely opened the secondaries as the primary side was sufficient to feed it. The third carb was a 570 Street Avenger, it too had the next to the lighest sec spring and as with the 1850 600, it would open the secs nad use the extra airflow. The thing about a vac sec holley is if the engine can open the secondaries, it will use that extra airflow. If it doesn't then the secondary spring is either broken or missing altogether. The spring that Holley puts in these carbs is nearly always too stiff (Every one I've seen had the black spring)to allow the secondaries to open, when they to it's at the upper end of the rpm range. As I recall the purple spring is the next to the lightest sec spring. The difference between it and the white spring (that's the lightest as I recall) is minor at best when it comes to opening the secondaries. The purple would open them a second or two after the go pedal was mashed on that E7 headed roller 302 (with the F4TE Explorer/pickup cam) And you could feel them open when they did in the added acceleration, so yes, they were adding needed airflow.
