Looking for info on where to buy prestolite advance springs for 318. Couldn't find in the search.
Thanks, Wayne
advance springs
advance springs
1973 32 express fly bridge
Chattanooga
"Southern Lady"
Chattanooga
"Southern Lady"
Re: advance springs
This is an early draft of an article I posted on the old forum
Assume the word “about” in front of each measurement given.
NEW PLUG AND PLAY SPRINGS
The replacement Prestolite springs that I ordered arrived and looked good.. The flyweights had a .025 wire diameter., outside diameter of .250 and were .725 long. We put them on and we were able to get the idle down nicely. They made a smooth but a very shallow advance curve. About 13 degrees at 2500 rpm instead of 23 degrees. An old school mechanic with a Sun machine would work the curve up. He would use heat to soften the spring, stretch it a little even bend the outside posts. I just got some pliers and stretched mine out till it was too long. OOPS. I wish I had it back for another try.
THE FISH SCALE
I got a fish scale, fixed it to a board and marked some lines. The length between the advance spring mounting posts at base is 7/8” (.875“). Extended is 1 ¼”( 1.25“) and is the total working area for the spring. Now I can test the pull in pounds at each of these points.
THE OLD SPRINGS
The Prestolite uses a two stage systems with a heavy and a flyweight spring. The heavy springs are fine. They were .047” wire diameter and worked fine. The wire diameter of the rusty flyweight spring I took out of my boat was .023“. Outside spring diameter was .250. The barrel had 5 loops. They squeezed down to .130”. Add two end loops = .630” a total length well within the .875” of the base mounting posts. But it was stretched out to .812” and applied only ¼ lb to the posts at base. Not enough to snug the weights back and allow the boat to be tuned for idle. For the rest of the working length it applied a maximum of 1 lb of pull. In other words it was shot. The spring on the other side was broken. That engine idled better. Probably because the weights were thrown out to a consistent place.
NEW SPRINGS
You can make flyweight springs from longer spring stock. Attach the length of spring to the fish scale insert a knife between the spring rings and pull it out to the length of the mounting posts at rest make a note of the lbs then pull it down to the extended length make note of lbs again. To vary the pull weight you move a few rings in either direction. You cut and use some needle nose pliers to cold form end loops. .020” wire didn’t work out. The hardware store had 6“ of high quality .025” spring for $4 made by the same firm that wants $7.00 to mail me one .63” long. That’s a lifetime supply. Before I moved on to this stock.,. I found some no name ready made flyweight springs at Menards hardware store ($1.19). .028” wire diameter, .25” outside diameter and .775” long. The fish scale said they apply 1 ½ lbs at the posts and 3 lbs at the end of the working length. I tried them and got a nice smooth 23 degree distributor advance. I put them in both engines and buttoned it up for this year.
WHAT NOW
The flyweight springs are a definite weak spot in the Prestolite distributors. How many ignition systems have been replaced because a bucks worth of spring is stretched or rusted out? I don’t know how long mine will last .The metal used can make all the difference and there is a bunch of different spring metal all going under the label “spring steel”. I do know that a timing light will tell me when they go bad and I can make them if I can’t find them.
Assume the word “about” in front of each measurement given.
NEW PLUG AND PLAY SPRINGS
The replacement Prestolite springs that I ordered arrived and looked good.. The flyweights had a .025 wire diameter., outside diameter of .250 and were .725 long. We put them on and we were able to get the idle down nicely. They made a smooth but a very shallow advance curve. About 13 degrees at 2500 rpm instead of 23 degrees. An old school mechanic with a Sun machine would work the curve up. He would use heat to soften the spring, stretch it a little even bend the outside posts. I just got some pliers and stretched mine out till it was too long. OOPS. I wish I had it back for another try.
THE FISH SCALE
I got a fish scale, fixed it to a board and marked some lines. The length between the advance spring mounting posts at base is 7/8” (.875“). Extended is 1 ¼”( 1.25“) and is the total working area for the spring. Now I can test the pull in pounds at each of these points.
THE OLD SPRINGS
The Prestolite uses a two stage systems with a heavy and a flyweight spring. The heavy springs are fine. They were .047” wire diameter and worked fine. The wire diameter of the rusty flyweight spring I took out of my boat was .023“. Outside spring diameter was .250. The barrel had 5 loops. They squeezed down to .130”. Add two end loops = .630” a total length well within the .875” of the base mounting posts. But it was stretched out to .812” and applied only ¼ lb to the posts at base. Not enough to snug the weights back and allow the boat to be tuned for idle. For the rest of the working length it applied a maximum of 1 lb of pull. In other words it was shot. The spring on the other side was broken. That engine idled better. Probably because the weights were thrown out to a consistent place.
NEW SPRINGS
You can make flyweight springs from longer spring stock. Attach the length of spring to the fish scale insert a knife between the spring rings and pull it out to the length of the mounting posts at rest make a note of the lbs then pull it down to the extended length make note of lbs again. To vary the pull weight you move a few rings in either direction. You cut and use some needle nose pliers to cold form end loops. .020” wire didn’t work out. The hardware store had 6“ of high quality .025” spring for $4 made by the same firm that wants $7.00 to mail me one .63” long. That’s a lifetime supply. Before I moved on to this stock.,. I found some no name ready made flyweight springs at Menards hardware store ($1.19). .028” wire diameter, .25” outside diameter and .775” long. The fish scale said they apply 1 ½ lbs at the posts and 3 lbs at the end of the working length. I tried them and got a nice smooth 23 degree distributor advance. I put them in both engines and buttoned it up for this year.
WHAT NOW
The flyweight springs are a definite weak spot in the Prestolite distributors. How many ignition systems have been replaced because a bucks worth of spring is stretched or rusted out? I don’t know how long mine will last .The metal used can make all the difference and there is a bunch of different spring metal all going under the label “spring steel”. I do know that a timing light will tell me when they go bad and I can make them if I can’t find them.
Re: advance springs
ddependo wrote:Looking for info on where to buy prestolite advance springs for 318. Couldn't find in the search.
Thanks, Wayne
look at http://www.hurrikain.com
A bit pricey at $75.00 a package. 
I sent mine to Lake-land Automotive in Port Clinton OH and had Bruce rebuild mine. He went over them and replaced all the worn parts and springs and used a Sun Machine to set up the advances.
I believe they were around $80 a distributor plus shipping. 
bill
Former owner of
ALUMINATION
Grosse Ile MI
Located on LakeErie
37' F/B Sedan
1975
Twin 360 Chrysler Marine
Raw water cooled
Hydraulic steering both helms
USCG Master Lic. Retired[/color]
Third Owner bill
ALUMINATION
Grosse Ile MI
Located on LakeErie
37' F/B Sedan
1975
Twin 360 Chrysler Marine
Raw water cooled
Hydraulic steering both helms
USCG Master Lic. Retired[/color]
Third Owner bill