El Camino Central Forum banner

1 - 19 of 19 Posts

·
Registered
Joined
·
88 Posts
Discussion Starter #1
ok here goes , i'm new in here ,,i have a 70 with a 502,going to change the carb for a MSD EFI,I also want to change the distributor to MSD do i have to stick with HEI?? with vac advance? or can i get a distibutor with out it? I talk with someone from MSD and got very little info out of him he could not answer me,, sounded like he was reading it!!! I have been out of the loop for 42 years and getting started all over again:nanawrench:but i'm having way to much fun:beer: thanks guys
 

·
Registered
Joined
·
2,938 Posts
Very cool, Mark. Their efi unit looks sweet, I would like to do the same. Did you just want to change the distributor, or were you going with the distributor and 6AL unit? If the latter, there is no problem with that. I have the Pro Billet distributor (vacuum advance), 6AL unit and Blaster coil on mine.
Welcome to NECOA by the way.
 

·
Registered
Joined
·
88 Posts
Discussion Starter #3
thanks Jim ,, i'm changing it all to MSD, distributor and the 6AL, can i get rid of the vac advance?:nanawrench:should have it done in about 4wks ,, just ordered the EFI today,, I'm have a 400 with 3200 stall 3:90rears 12 bolt runs ok ,,,my wifes mustang Mach1 428 still pulls me on top ead,,,:beer:
 

·
Registered
Joined
·
555 Posts
Yes, lose the vacum advance. Get the MSD Pro Billet with mechanical advance and get the 6A or 6AL. If you have the cash, get the Digital 6 or the new Power Grid system. Digital ignition is awesome. You can do so much with it, but yes, it is unnecessary and expensive.
 

·
Registered
Joined
·
2,938 Posts
For a race car, I would agree that the vacuum advance is unnecessary. For a street driven car, drivability would suffer somewhat without it, in my opinion. I'm not sure what you would expect to gain without it. It would take a lot of motor to get that two ton El Camino out in front of that Mustang.
 

·
Registered
Joined
·
304 Posts
I would suggest that if you're going to race the car then use the mechanical advance. I read somewhere where they said that mechanical advance was not all that great for a street machine. I am really interested to know how the efi works out for you, I have been thinking about putting it on my 454. Keep building until you beat that mustang, no matter the cost. Back in the sixties I had a fifty eight corvette, and when they came out with the 289 mustang I got beat by one. So, I pulled out my motor and spent everything I could spare and when I finished I went back and found that mustang and gave him the works. I have never been a ford fan, although they ARE made in the USA.
 

·
Registered
Joined
·
88 Posts
Discussion Starter #7
you guys are great:beer:going to keep the vac advance! got this el camion on a trade for one of my Harleys everyone was happy thats all that counts! To make a long story short ,, we were on a sunday ride and stopped for a beer and i saw this El Camion and was checking it out and this guy was looking at my bike and well we did it in the parking lot,,,,, so the feud has begun !!!! ford against chevy:twisted:at 62 life is just starting all over again,,,, again you guys rock, will keep you posted on the MSN EFI:)
 

·
Registered
Joined
·
555 Posts
I don't know where people come up with this "only for racing" stuff. Mechanical advance is called mechanical because the ignition timing increases the moment the engine's rpm-s increase. It is way more efficient than vaccum advance. Vaccum advance would be ok for a completely stock engine that's being driven by our grandmothers. You have a 1970 El Camino with a freakin 502 Big Block, Come on brotha! :rockon:

Here is an article where a guy is asking a MSD tech about mechanical vs vacuum advance:

http://www.msdignition.com/forum/showthread.php?t=6236

msdtech22

MSD Tech
Join Date: Jun 2003
Posts: 4,447



For street driving I would recommend that you DO use the mechanical advance this will give better performance for you. This will allow the timing to be at a more preferable mark when at idle and ramp up as you accelerate. The vacuum advance is usually used during street performance to advance the timing when stopped at a stop light or stop sign. This advance helps the engine smoother during those periods when stopped and actually help with fuel economy.

You won't neccesarily need to run a crank trigger unless you want to. Remember, when running a crank trigger, you will have to run total timing at all times, defeating the purpose of the mechanical/vecuum advance.

The 8582 already has a magnetic pick-up in it.
__________________
MSD Tech Line: 915-855-7123

MSD Tech: "For street driving I would recommend that you DO use the mechanical advance this will give better performance for you. This will allow the timing to be at a more preferable mark when at idle and ramp up as you accelerate. The vacuum advance is usually used during street performance to advance the timing when stopped at a stop light or stop sign. This advance helps the engine smoother during those periods when stopped and actually help with fuel economy."
 

·
Registered
Joined
·
2,039 Posts
The vacuum advance is usually used during street performance to advance the timing when stopped at a stop light or stop sign. This advance helps the engine smoother during those periods when stopped and actually help with fuel economy.
Can someone explain why this is a bad thing on a street car?

Mechanical advance only makes perfect sense on a car that spends most of its time at WOT , rich mixture, full load, and high rpm all the time, so they don't need a system (vacuum advance) to deal with the full range of driving conditions encountered in street operation.

A street operated vehicle without vacuum advance is sacrificing idle cooling, throttle response, engine efficiency at part throttle/cruise, and fuel economy.
 

·
Registered
Joined
·
555 Posts
Can someone explain why this is a bad thing on a street car?

Mechanical advance only makes perfect sense on a car that spends most of its time at WOT , rich mixture, full load, and high rpm all the time, so they don't need a system (vacuum advance) to deal with the full range of driving conditions encountered in street operation.

A street operated vehicle without vacuum advance is sacrificing idle cooling, throttle response, engine efficiency at part throttle/cruise, and fuel economy.
Its not a bad thing. There is nothing wrong with vacuum advanced distributors. Everything has it's purpose.

A properly set up mechanical advanced distributor is going to out perform a vacuum advanced distributor. Mechanical advanced distributors allow you to install different bushings and springs so you can fine tune the timing on your specific engine, which means, easier starting, smoother idle, better acceleration and WOT.
 

·
VINTAGE MOTORHEAD
Joined
·
4,102 Posts
I am running an MSD dist#8361 with vac adv on my slightly tweaked Zz4. I suggest uskng the vac adv after proving to myself that it is very beneficial.
After decades of running MSD ignitions on my race machines their products are my first choice. Their tech service and warrantee attitude set them apart. Just my dos centavos.
 

·
Registered
Joined
·
2,039 Posts
Its not a bad thing. There is nothing wrong with vacuum advanced distributors. Everything has it's purpose.

A properly set up mechanical advanced distributor is going to out perform a vacuum advanced distributor. Mechanical advanced distributors allow you to install different bushings and springs so you can fine tune the timing on your specific engine, which means, easier starting, smoother idle, better acceleration and WOT.
This is possible on every distributor I've ever owned, all of which were equipped with vaccuum advance. Since at WOT there is no vaccuum advance, there should be no difference between a properly setup mechanical only distributor, and an equally properly setup mechanical + vacc distributor, except that in situations other than WOT the vaccum equipped one will be better.
 

·
Registered
Joined
·
2,938 Posts
Some of these posts read like a distributor is advanced by EITHER centrifugal OR vacuum. A distributor with a vacuum advance has both. I would think this to be common knowledge and redundant to mention. That's just how they read to me, I could be wrong.:dontknow:
I would be curious to know what the question was for the MSD tech. He recommends that "you DO use the mechanical advance". Was some chump considering locking up the centrifugal in his distributor and only using vacuum? That would be just "retarded", pun intended.
 

·
Premium Member
Joined
·
12,122 Posts
I've run both ways, with & without vac advance. Early Corvettes had no vac advance, but gas was cheap back then. For cruising, the vac does the job in helping mileage, and the spark timing is up some degrees, and the engine seems happier.:smileyb: Of course if you have your foot in it, there's no vacuum on the distributor anyway until the RPM picks up, depending somewhat on if it's ported or manifold vacuum.
 

·
Registered
Joined
·
12,533 Posts

heres the question he asked Canted.. (its in the link)
What's the advantage of mechanical advance or vacuum advance?
I plan on mostly street driving...with an occasional trip to the track. Thanks,David
Mario i see your point, for your cruck,,no vacuum.. but he's not runnin a blower.
do you have any vacuum runnin 25# or so of boost??:dontknow:
i have a turbo diesel and it never shows more than 1-2 inches vac. at idle,, makes 20# boost tho..


vacuum advance is a good thing on the street,, so is mechanical or centrifugal and so is initial timing,,
but its all gotta work together..

rof lol, me too.:texas: keep us updated on that MSD Atomic efi.
 

·
Registered
Joined
·
2,938 Posts
OK I have read "dodell's" post on the MSD tech forum. I believe the response he got was due to the way he worded the question. " I've been told that unless I plan on racing, mechanical advance is more of a pain than it is worth. Is this true?" Perhaps he should have written "mechanical only"
The "tech" then responds, writing that dodell should use mechanical advance for his engine to perform properly. Well duh! Without it the thing would not get out of it's own way. He then poorly explains how the vacuum will benefit. Sorry MSD, not your best moment.
 

·
Registered
Joined
·
555 Posts
Mechanical or Vacuum, whatever...:smile3:

They both are good and basically serve the same purpose. . I don't want 50 degrees of timing in my motor while I'm cruising around and I want timing to be put in my motor the moment the rpm's increase, not when the vacuum pressure drops in the intake manifold :beer:

Mario
 

·
Premium Member
Joined
·
5,789 Posts
When vacuum drops timing is taken away from your motor.

Just noticed post # 3600! I got to get a life LOL
 
1 - 19 of 19 Posts
Top