HICKL Posted February 6, 2008 Share Posted February 6, 2008 Here it goes, I have a pretty good basic understanding of my HEI distributor as far as how the vacuum advance works as well has the mechanical. I think I understand how they work together. For my tunnel ram, I have to use a points style small dist. A guy has a Mallory Unilite for sale but says it is vacuum advance only (no mechanical advance). I can understand how mechanical advance only would work fine, but how would vacuum only work? Wouldn't it retard the timing under WOT when Vacuum went to zero? Please help the ignorant.. Thanks Jeff Quote Link to comment Share on other sites More sharing options...
1 QUICK Z Posted February 6, 2008 Share Posted February 6, 2008 Hickl, If your distributor is a mallory unlite, the mechanical advance is under the plate under the rotor and can be adjusted by bending the tab and or heaver or lighter springs to get the advance you want for your motor. You can still use the vacuum advance with the mechanical to fine tune your motor. I hope this helps. Quote Link to comment Share on other sites More sharing options...
HICKL Posted February 6, 2008 Author Share Posted February 6, 2008 It is not in my possession, but is is supposed to be pn 4748201. They guy is telling me that it is vacuum advance only and no mechanical advance. Could this be true or does he just not know what he is talking about. Quote Link to comment Share on other sites More sharing options...
1 QUICK Z Posted February 6, 2008 Share Posted February 6, 2008 Hickl, The # 4748201 is a Unilite Electronic - 47 series Distributor with a self-contained optical pickup and module with adjustable mechanical and vacuum advance. They sell new for $ 246.00 If you use it just make sure that you use a # 700 ballast resistor to bring down the voltage or you will burn out the optical eye in the dist. Quote Link to comment Share on other sites More sharing options...
Corzette Posted February 6, 2008 Share Posted February 6, 2008 Hickl, The # 4748201 is a Unilite Electronic - 47 series Distributor with a self-contained optical pickup and module with adjustable mechanical and vacuum advance. They sell new for $ 246.00 If you use it just make sure that you use a # 700 ballast resistor to bring down the voltage or you will burn out the optical eye in the dist. John, question, when installing the Mallory I set the engine to top dead center and the rotor on the old dist points to the number one plug wire on the cap. I take out the dist and put in the Mallory. No way to put in wrong so in it goes. The problem is the rotor on the Mallory points a totally different direction. Do I put the number one plug wire on the cap where the rotor is pointing now? I am confused. Since there is no gear drive its different than doing on a V8. PLease advise... Terry Quote Link to comment Share on other sites More sharing options...
1 QUICK Z Posted February 6, 2008 Share Posted February 6, 2008 Corzette, If your are dealing with a V-8 Take your distributor with the cap on it and mark #1 ( looking straight down on top of it # 1 will be at 5 o'clock position and the vacuum advance will point between the 8 and 9 o'clock ) Mark the cap and the distributor, now bring your motor to 12 to 15 degrees before top dead center on# 1 cyl compression stroke and then install the distributor in the motor with the rotor pointing at the 5 o'clock position matching the mark on the distributor. ( you might need to take a long screwdriver and turn the oil pump shaft to get it to line up ) run your wires and tighten up your dist clamp and it should start right up. If your dealing with a straight 6 with a distributor without a gear ( it will only go in 2 ways ) Bring your motor to 10 degrees before top dead center on # 1 cyl compression stroke. Install your dist and wire your cap from where the rotor is pointing. ( it should be close to where your old dist rotor was pointing.) Quote Link to comment Share on other sites More sharing options...
HICKL Posted February 6, 2008 Author Share Posted February 6, 2008 Corzette, If your are dealing with a V-8 Take your distributor with the cap on it and mark #1 ( looking straight down on top of it # 1 will be at 5 o'clock position and the vacuum advance will point between the 8 and 9 o'clock ) Mark the cap and the distributor, now bring your motor to 12 to 15 degrees before top dead center and then install the distributor in the motor with the rotor pointing at the 5 o'clock position matching the mark on the distributor. ( you might need to take a long screwdriver and turn the oil pump shaft to get it to line up ) run your wires and tighten up your dist clamp and it should start right up. As long as your not 180 degrees out! Quote Link to comment Share on other sites More sharing options...
1 QUICK Z Posted February 6, 2008 Share Posted February 6, 2008 (Quote!) As long as your not 180 degrees out! Sorry, I mean 12 to 15 degrees before top dead center on the compression stroke on # 1 cyl. Quote Link to comment Share on other sites More sharing options...
grumpyvette Posted February 6, 2008 Share Posted February 6, 2008 http://www.digitalcorvettes.com/forums/showthread.php?t=89586 might help Quote Link to comment Share on other sites More sharing options...
HICKL Posted February 7, 2008 Author Share Posted February 7, 2008 (Quote!) As long as your not 180 degrees out! Sorry, I mean 12 to 15 degrees before top dead center on the compression stroke on # 1 cyl. Jon, I think that was implied in your post, I was mainly poking fun at myself for how often I make that mistake. Jeff Quote Link to comment Share on other sites More sharing options...
Corzette Posted February 7, 2008 Share Posted February 7, 2008 Thanks 1QZ. I have the L20 in my Hakosuka so the distributor will only fall into place one way and doesnt seem to be close to where the old rotor was pointing. As long as its TDC (assuming the damper has the little half moon cutouts pointing down at 6PM) I would just start plug #1 where the rotor is pointing. I probably confused everyone but CHEVY is so much easier.... Terry Quote Link to comment Share on other sites More sharing options...
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