I'm confused on timing my new rebuilt 312.  Trying to time it by the vacuum method along with a timing light. As I advance the distributor to increase vacuum reading it does run much better but the vacuum advance can hits the intake manifold when I reach 17" hg @20 degrees advance. I'm sure I could get a higher vacuum reading yet if I pull the distributor and rotate it a notch but I'm concerned about the initial advance climbing over 20 degrees. The engine does have an Isky E4 cam advanced 2 degrees, the Mr. Gasket lighter advance springs along with a rebuilt distributor modified per a post here to give 26 degrees centrifugal advance. Is it possible the springs are too light allowing extra advance @ idle or?    Dave v

SE Wis

That's one reason I don't time with vacuum.  You may find that the engine is hard to start and you will have far more total advance than you need.  It's not likely that the springs are too light.  You can test it by reving the engine slowly with the vacuum advanced disconnected and watching the timing marks.  If it advances immediately, then they are too light.It also seems like an E-4 should have more vacuum than 17 with a more normal initial advance setting.  What is your idle rpm?



Lawrenceville, GA

Dave, what is the condition of your damper? Did you verify TDC? If not it could have spun and your timing marks are NFG. I time my 312" with a vac gauge and find it runs best at 18" hg which equates to 16° advance.Here's a link to a thread where I had a similar question as yours. http://forums.y-blocksforever.com/Topic88289.aspx



"The Master Cylinder"

Enjoying life at the beach in SOCAL

DaveYour first question was what to do about the distributor vacuum advance can hitting the intake and limiting the amount of advance you could set. Either pull the distributor and jump one tooth or pull and replace the ignition sparkplug leads on the distributor cap as needed.The weight or strength of the advance springs is what controls the rate of mechanical distributor timing as the engine RPM is increased. The total is controlled by stops on the distributor plate and is a function of RPM until the limit is reached.The distributor vacuum advance should be disconnected and plugged while timing the engine. Go for highest manifold vacuum and as the timing is advanced the RPM will increase and the manifold vacuum will increase too. Then back off 1 or 2 inches of manifold vacuum. Road test and listen for pinging and hard starting while hot. As many others have said limit total mechanical advance to 34/36 %. Pete

Thanks for the replies. I was gone yesterday and did not work on the car. To answer your questions, I did have the vacuum line disconnected from the advance can and plugged at the carb, idle 550 RPM, degreed the cam when assembled & found TDC, checked the damper for accuracy and even put a scribe mark on it @ 38 degrees. Master Cylinder:  I really appreciated your article pertaining to the same problem. Is it still running ok?  I will be working on the engine again today and check the rate of advance on the lighter springs. I forgot to mention that I do have a Pertronix II in this distributor and the coil to match. I'll reply to all later.  Thanks again  Dave V

SE Wis

Moving the wires one notch is a quick and simple solution. Of course the "correct" way would be to move the distributor but either way will accomplish the same thing. Chuck


Y's guys rule!
Looking for McCullouch VS57 brackets and parts. Also looking for 28 Chrysler series 72 parts. And early Hemi parts.

MoonShadow, 292 w/McCulloch, 28 Chrysler Roadster, 354 Hemi)
Manchester, New Hampshire

Dave, still running good, starts easy.



"The Master Cylinder"

Enjoying life at the beach in SOCAL

I did get back to the engine today. I rotated the distributor 1 tooth so that the #1 on the cap is correct. Started to set timing again and found the light Mr. Gasket springs started advancing timing @ 900 RPMs and stopped advancing @ 1850 RPMs. I was getting a fluctuating needle on the vacuum gauge which I realized was coming from the 600 Holley leaking fuel thru @ idle. Installed a pressure gauge and found 8 psi fuel pressure coming from my FE fuel pump. Made a makeshift bleedoff in the fuel line to hold the pressure @ 6 psi and the engine ran very well. I will pick up a fuel pressure regulator and start over. I'll keep you posted.  Also, is there a way to remove the temp sending unit bushing in the cylinder head. The old sending unit for my 56 is 3/8" pipe but the bushing in the 57 G head is 1/4"?  Dave

SE Wis

Dave there is a puller available for the sending unit bushing, from the normal repro parts places. I got mine from my go to place, Tee-birds Products. http://www.tee-bird.com/catalog_search.cfm

"The Master Cylinder"

Enjoying life at the beach in SOCAL

So this is just a press in bushing?  I should be able to pull it out with a slide hammer screwed in to it?  Dave

SE Wis