I guess i would call this post a " use what ya got" post. Many times for some reason us hot rodders throw away a factory part and use a ( race ready) piece that is worse than what we took off the car. I personally have done that many times over the years. I see posts on the hamb all the time with buy this , use this etc regarding distributors etc. In most cases its pretty damn hard to out engineer the factory part, this post is one of those time. The factory advance curve is usually perfect for the application, the quality of the part , in this case cast iron and very quality steel parts machine to last the life of the car and even longer. The picture showing the unit as recieved would make most look the other way. Pretty rusty and gummed up inside. We tear it down, bead blast , ultrasonic clean, polish and paint . Then install the best quallity parts we can find. Check the factory specs and adjust on the test machine. You now have the best unit out there with the correct advance and for sure the old school look needed for a early Oldsmobile.!!!!! USE what you got . The total for this ticket was $ 113.95 !!!!!!! Wally is working the bench today.............
agreed! especially on the early olds motors. I've watched my uncle throw three different distributors into his warmed over 371. a mallory dual coil, a magneto and another mallory dual point. the motor would never start or run right. I gave him the stock dizzy out of the motor I pulled out of the woods to use. cleaned the points that were in it and it never ran better!
Very cool, plan on sending you the distributor out of my 472 Caddy this winter for blueprinting/recurving (unless I can find a good core to send before then). Seems like the 'test & tune' is a lost art, I used to spend hours at the strip changing carb jets and metering rods, distributor advance springs and weights, timing changes, etc. then making a p*** or two down the track, then do it all again....
Bubba, what are your thoughts and opinions on ported vacuum advance vs manifold vacuum advance? Talking about hot street, some strip, with cam around 235" dur.@.050, 110* lobe sep. angle .500" lift with 9.7:1 comp. SBC. In a 2200# car, man. 4 speed. 3.70:1 rear, driven "enthusiastically". Dave
I had Bubba do my old delco for my Pontiac flatty, I must say it works beautifully. eliminated the va*** advance on his advice and have had no problems.
To adjust and non factory engine application ( especially with big camshaft, dual carbs etc) is especially difficult either way. Vacuum and mechanical must overlap and actually aide each other.. I just happen to have at this moment a Ford factory spec card from sun electric laying on my desk, lets look at it a bit. 1968 Ford 428 engine with 340 hp. Mechanical advance is 28 degrees engine at 4600 rpm, vacuum is 24 degrees at 25 inchs of vacuum. Intial timing ( balancer ) is 6 degrees at idle. Now we got to think for a minute , first of all we cant ever have 25 inches of vac at 4300 rpm so both would never happen at the same time. Lets pick some numbers saying we are running 1000 rpm with a spec of 20 degrees of mechanical advance with a vacuum reading of 15 inches which would equal another 20 degrees for a total of 40 degrees plus the intial 6= 46 degrees We will ***ume this is perfect for the application driving down the road..... Now punch the throttle to 4000 rpm for a mechanical spec of 24 degrees and a vac spec of 5 inches at 10 degrees of vac advance . Using the intial 6 plus the 34 would still have 40 degrees of advance. When one goes up the other goes down etc making the available close to 40 degrees all the time when driving don the road . They must overlap each other. Now to answer your question in regards to using manifold vacuum or venturi vac it would depend on what my needs from the vac advance actually is. Cars have come from the factory with both for many years and either or????
Ford even used a dual vacuum line advance where manifold and ported vacuum worked against each other depending on engine temperature.
Bubba, the pics reminded me to ask a question about a 37 Buick distributor I've got torn apart. At the tip of the red arrow in the picture below, (using your Olds distributor as an example) my Buick had a lump of dry grease and a spring behind the screw. I can understand the grease, but couldn't figure out why the spring was there? Any light you can shed would be appreciated. Thanks!
Bubba Tech. Yeah! My son is building a little 69 Austin Healy Sprite SCCA style car. It has the stock 1275 4 cylinder with a few little tweaks (a Weber and aluminum intake for one). He has been thinking of buying an aftermarket breakerless conversion or electronic distributor. Anything you can do with his original?
Just done one yesterday. The spring is there to divide up the grease and prevent clogging up. If it was just a orfice the grease would gum up and restrict the flow , the spring makes it spread out all over before going in. Every so many miles the teh would turn the grease cup resupplying the fresh grease. On a oil change the cup was refilled with clean fresh grease...... A model A or a Model T used tons of these all over the car ......
Looks like pertronixs makes a conversion for that car, i would clean it up, freshen up a bit and add the petronix module .....
Hey Jim, a while back you answered my question about using vacuum advance on my Megasquirted daily driver 250 Chevy six. You said better with no vac advance, which surprised me. I'd like to increase fuel mileage somewhat. The Mallory Unilite works fine but always nervous of it dying. My specs: 250 mild cam, 700R4 trans. Fuel injected. I'm just wondering the technical details of your advice and also what core distributor is best to send to you. Thanks! John
Jim. Too good an opportunity, having you here answering questions, not to ask one. I have a stock 401 Buick with 3 x Stromberg 48s. It had the vac advance connected to manifold vacuum and it died badly when the secondary carbs opened. I went to an all at once linkage and some friends told me to run without any vacuum advance to see how it goes. It's a lot better but still not quite right. Same friends suggest getting the distributor modified for mechanical only advance. Would you recommend that move? Thanks, Pete
Dudes , You are wearing this vacuum issue out for sure !!!! Let me help just a bit ...... Ok, no matter what ya do its all about the set up and tuning of the engine. MOST hot rods never get that part of the project done...... So the vacuum issue is a good discussion, properly tuned its a good addition to the basic tune of the engine. Improperly done it does more harm than good. The real issue the difficulity of tuning a vacuum advance with a million changes like camshaft, carbs etc. SO with that thought in mind i usually tell everyone a full mechanical advance properly set up for the application is the EASIEST thing to do. I have customers that have taken the time to do the vacuum tuning and they have for sure benifited from it. Its all about the "tune" and the need to get er done.....
I was at a swap meet this past weekend & couldn't believe all the GM style dist. for just about any make of car for 69 bucks. Are they some Chineese junk ?
YEP , BUT IN REALITY THEY ARE THE SAME UNIT SOME OF THE BIG BOYS SELL !!!! a FEW COMPANYS HAD THEM MADE OVER SEAS AND THE PRINTS GOT OUT AND NOW EVERYONE HAS ONE.......
Holy ****, that's my distributor getting a feature on the HAMB! Thanks again Jim, for your work. I didn't recognize it when I got it back. Very happy customer here.
What can you do for pre-49 Ford flatheads? 42 Crab cap & 46-48 2-pc. cap. And how about the 37-41 Bell distributors?
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