Distributor Curving - Page 2

tbm3fan · #16 (**permalink**) 08-09-2007, 07:07 PM

Almost sounds like my big Merc with a 410, C6 and 2.75 gears. Mine is set on 13L for 26 mechanical degrees and then 10 initial degrees for a total of 36 degrees. My 410 is 10.5-1 compression and the rule of thumb is the higher the compression the less total timing the engine can handle before detonation. So Fords from 9.1-9.5:1 run best between 38-42 total, 9.5-10.5:1 run best from 35-38 total and over 11.1:1 not over 35 total. Also too high an initial can make the engine a bit harder to start and too high a total can make a car, with high gears, start to ping early on.

I did a detailed cleaning of my centrifugal advance system so it was free moving and replaced the heavy spring. I have a bunch of springs out of Ford distributors that I rated by checking spring wire diameter. I have no way to measure tension so I did diameter and have springs from .062-.025. Seems heavies are .050 and up, medium around .039-.043 and lights near .025. The 410 had the heavy spring replaced with one medium spring at .039. Didn't want two light springs in the car with a 2.75 rear. One can also bend the tabs in to decrease spring tension. I just experiment from there with the 4 different Fords and their distributors plus another 6 distributors on the bench.

Vacuum advance is definitely trial and error. Got an adjustable kit that can be put into the original small can unit from the 60's and keep the engines OEM. Adjust through the nipple just like the big can units of the 70's. Initially set it a three turns open, out of 6.5 turns, and then drive the car. Go 1/2 turn open until I hear pinging and then back it off the last half turn and another quarter turn to be safe. Again just experiment using those basic rules and the big Merc runs fine. The 360 had the biggest improvement overall in driveability and acceleration. The 302 had the biggest improvement in idle with the cam that it has. The stock 289 ran fine overall but the lighter spring help make it more responsive at WOT with the total in faster. I can't do anything with the 2.3L Focus...

73F100*8Mile · #17 (**permalink**) 09-08-2007, 09:33 PM

Well to update my timing situation a bit, I pulled a ski nautique up the mountain today and boy she started to ping. I had the timing set at 10 initial w/ 13L totalling out at 36 w/o vacuum advance. Then I pulled it back down to the shop to back the timing down w/o my gun so it's prolly around 6-8 or so. Not sure what exactly is killing me so bad at this point. Head gaskets? Hot air to the intake? Lean jets #65's?? Could a better set of spark plugs help me here? I've got autolite 124's right now. I'm tired of listening for pining!! I just wanna drive the snot outa my truck w/o worrying!

mark a. · #18 (**permalink**) 09-09-2007, 01:24 AM

36 is too much. Try to get it down to 32.

tbm3fan · #19 (**permalink**) 09-10-2007, 12:08 AM

Quote:

Originally Posted by 73F100*8Mile

Well to update my timing situation a bit, I pulled a ski nautique up the mountain today and boy she started to ping. I had the timing set at 10 initial w/ 13L totalling out at 36 w/o vacuum advance. Then I pulled it back down to the shop to back the timing down w/o my gun so it's prolly around 6-8 or so. Not sure what exactly is killing me so bad at this point. Head gaskets? Hot air to the intake? Lean jets #65's?? Could a better set of spark plugs help me here? I've got autolite 124's right now. I'm tired of listening for pining!! I just wanna drive the snot outa my truck w/o worrying!

Driving up a mountain with a boat in tow definitely has that engine under load and it pings. What does the engine do when cruising at 65mph on a freeway? Also with this 390 from a 360 what is your compression at now? Thirty six degrees is not too much for a compression under 9.5:1. What is the situation with your vacuum advance unit? Is it the big cannister design which you can adjust with a allen wrench through the snout? If so have you tried adjusting it at all? The only other issue I can see is that a 2.75 rear is not really conducive for towing and if that is what you wil be doing then you might need to keep the initial down if all else checks out.

mark a. · #20 (**permalink**) 09-10-2007, 02:03 AM

Vacuum advance has no effect under a load. The fact of the matter is, if it pings under a load it's got too much, so it has to be backed off. Turning the initial down is not the answer, limiting the total is.

73F100*8Mile · #21 (**permalink**) 09-10-2007, 10:43 AM

Ya I'm not even running the vac advance. Thats last on the list. And ya I'm thinkin about redoing the gearing. I'm in the hunt for a Trans-loc rearend with something a little higher than 3.00. Not sure what all gears were made for the 9" but something around a 3.25 or so. That'd help in the timing dept. The only reason I went with the 2.75's was for more of an experiment more than anything else. I had to go in to replace my carrier bearings and I had the gears so I did it just for kicks-n-giggles. As far as my compression, I can't remember what it figured to. I know it wasn't 10 or anything. Prolly around 9.5:1.

tbm3fan · #22 (**permalink**) 09-10-2007, 08:54 PM

Quote:

Originally Posted by mark a.

Vacuum advance has no effect under a load. The fact of the matter is, if it pings under a load it's got too much, so it has to be backed off. Turning the initial down is not the answer, limiting the total is.

Vacuum advance is adjusted under "moderate load" when driving your car. You are not at WOT and so you are pulling vacuum while making the engine work harder. The standard suggestion is to drive up a slight grade and listen. On the old vacuum units you needed to play around with the thickness of the washers inside the unit besides the unique spring and fiber stop. Increasing washers decreases vacuum advance while the opposite increases. An adjustable unit does away with the washers but the same rule holds... adjust vacuum advance by driving the car under moderate load and listen for pinging. If none then adjust up until heard and then back off a bit. Works just like they say. He'd be far better off getting rid of that highway cruising gear of 2.75, for boats like my Parklane, and getting a 3.25 or more.

HemiEater · #23 (**permalink**) 09-10-2007, 09:08 PM

Have you checked the outer ring of the balancer, it might have slipped.......

73F100*8Mile · #24 (**permalink**) 09-10-2007, 11:41 PM

Ya I've been talked to about the balancer ring before. I don't have a new one to compare it to and well don't want to spend the 70 bucks to find out mine is ok but I'm not positive mine is ok so ya I'm still battling with what to do about that.

HemiEater · #25 (**permalink**) 09-11-2007, 12:19 AM

pull #1 plug and bring the piston up to TDC it don't matter what stroke it's on just get it to TDC. i use a screw driver in the plug hole to help feel the piston move, it's not the best way but it will tell you if the marks are close. after you are sure your at TDC look at the marks on the balancer if they are off mark the balancer and see how far off it is. they also make a tool that screws into the plug hole for getting true TDC........