Advice on Timing with 355 with MP122 supercharger
09-12-2009, 01:34 PM
#1
TECH Enthusiast
Thread Starter
Join Date: Nov 2007
Location: Evans, Colorado
Posts: 712
Likes: 0
Received 0 Likes
on
0 Posts
Advice on Timing with 355 with MP122 supercharger Hello i am making some progress here with my 355. I am looking for timing recommendations for my (carbed) 355 to run on 91 octane with my Magnacharger. Okay this distributor is the MSD E-Curve and has timing adjustments 1 and 2 (?). i am totally clueless so far as a ballpark of where the timing should be as far as start timing and total timing. I am at 5000 feet elevation (not sure if this would hinder any ideas of where the timing should be). Any help would be totally appreciated. I am planning on dropping the distributor in very soon.
Last edited by T/AWS6969; 09-13-2009 at 01:33 PM.
09-13-2009, 03:36 AM
#4
TECH Enthusiast
Thread Starter
Join Date: Nov 2007
Location: Evans, Colorado
Posts: 712
Likes: 0
Received 0 Likes
on
0 Posts
Sorry i did not be more specific i am at 9.3 compression, I am running trick flow 195 cc heads CNC ported, and the cam is http://www.compcams.com/Cam_Specs/Ca...?csid=202&sb=2
09-13-2009, 03:40 AM
#5
TECH Enthusiast
Thread Starter
Join Date: Nov 2007
Location: Evans, Colorado
Posts: 712
Likes: 0
Received 0 Likes
on
0 Posts
Also forgot to add that at my elevation with the stock pulley on the Maggie i will prolly only be at about 2 to 3 lbs of boost, but after the new motor breaks in i will then up it to 8 to 10 lbs. thanks again guys
09-14-2009, 09:19 PM
#7
I would hit up the forced induction forum,
I've read recommendations of 1 to 2 deg retard per lb of boost,
so with standard normally aspirated timing being 10 dBTDC at idle, and 24 deg of advance for a total of 34 dBTDC at rpm, set the distr. up so you see a max of 28 dBTDC total timing. I know you will need in the range of 8-14 dBTDC of timing just to get the engine started so you'd be setting base timing there.
are these the instructions to your distr. ?
http://www.msdignition.com/uploadedF...structions.pdf
With the supercharger, and any timing retard should be based on boost pressure. now how fast the timing advances depends on what the motor likes which is trial and error.
maybe choose the more conservative timing curve on the distributor to start off with, one that only gives 15 of advance and has the least angle, so curve I on the 15deg chart. You're far less likely to kill a piston or rings with having not enough timing vs having too much timing. Then dial the distr. to J, then K, and L so see if it prefers more advance sooner. I suppose you could get away with using this method if you know the boost is always there, otherwise you might want to look into a boost controller like this
http://www.msdignition.com/product.a...49&terms=boost
and being at altitude you should only compensate the jetting in the carb for the altitude so the carb maintains the correct A/F ratio of 12.5-13 (without forced induction). And then I assume you have a carb that's set up for forced induction so from there it takes care of itself.
I've read recommendations of 1 to 2 deg retard per lb of boost,
so with standard normally aspirated timing being 10 dBTDC at idle, and 24 deg of advance for a total of 34 dBTDC at rpm, set the distr. up so you see a max of 28 dBTDC total timing. I know you will need in the range of 8-14 dBTDC of timing just to get the engine started so you'd be setting base timing there.
are these the instructions to your distr. ?
http://www.msdignition.com/uploadedF...structions.pdf
With the supercharger, and any timing retard should be based on boost pressure. now how fast the timing advances depends on what the motor likes which is trial and error.
maybe choose the more conservative timing curve on the distributor to start off with, one that only gives 15 of advance and has the least angle, so curve I on the 15deg chart. You're far less likely to kill a piston or rings with having not enough timing vs having too much timing. Then dial the distr. to J, then K, and L so see if it prefers more advance sooner. I suppose you could get away with using this method if you know the boost is always there, otherwise you might want to look into a boost controller like this
http://www.msdignition.com/product.a...49&terms=boost
and being at altitude you should only compensate the jetting in the carb for the altitude so the carb maintains the correct A/F ratio of 12.5-13 (without forced induction). And then I assume you have a carb that's set up for forced induction so from there it takes care of itself.
Trending Topics
09-14-2009, 09:36 PM
#8
TECH Enthusiast
Thread Starter
Join Date: Nov 2007
Location: Evans, Colorado
Posts: 712
Likes: 0
Received 0 Likes
on
0 Posts
Yes that is the correct distributor that i have. the instructions are still kinda vague for me. It sounds (i was planning on not even messing with the vacuum advance) like i lock out the distributor before i start the engine, then at idle i set the final (total) timing on the balancer (28 deg etc) with a timing light. then i turn the engine off and then set the switches. does this sound right? it think their instructions kinda suck.
09-16-2009, 12:17 PM
#9
no, that sounds messed up 
it looks like all you have to do is pull the cap and you can get at the adjustment switches, so you can do that once the distr. is installed.
Going from their instructions, there's a matrix of timing curves that correspond to switch combinations. Either before you install it or now with it installed, pull the cap and set the switches to whatever curve you like.
Like I said above, I would choose curve I, which gives 15 deg of advance.
Now without using vacuum advance you will just not hook it up to the distributor, so look on that "Electronic Mechanical Advance Curve" chart and look down the I column. Going down that column it tells you for switch 1 and switch 2 the combinations you can use which are 0/9, 2/9, 4/9, 6/9, 8/9. Switch 2 is always on 9, giving you the 15 deg advance curve. Switch 1 is the vacuum advance curve, which since you won't be hooking it up won't matter, but if it did then those curves are shown on the "vacuum advance curves 1-5" chart. Vac adv #1 gives 10 deg advance at 10 in-HG vacuum, vac adv #2 gives 15 deg adv at 10 in-HG vacuum, and so on.
Only after you get the max timing figured out and how quickly the engine likes timing, then start playing with the vacuum advance. Don't try and do it now because you'll be juggling another unknown variable.
So put switch #1 on 9, switch #2 on 1 which is least amount of vacuum advance,
disconnect vacuum advance from distributor and plug the port on the carb,
idle engine and rotate the distributor to get 10 dBTDC on the balancer, this is your base timing.
it looks like all you have to do is pull the cap and you can get at the adjustment switches, so you can do that once the distr. is installed.
Going from their instructions, there's a matrix of timing curves that correspond to switch combinations. Either before you install it or now with it installed, pull the cap and set the switches to whatever curve you like.
Like I said above, I would choose curve I, which gives 15 deg of advance.
Now without using vacuum advance you will just not hook it up to the distributor, so look on that "Electronic Mechanical Advance Curve" chart and look down the I column. Going down that column it tells you for switch 1 and switch 2 the combinations you can use which are 0/9, 2/9, 4/9, 6/9, 8/9. Switch 2 is always on 9, giving you the 15 deg advance curve. Switch 1 is the vacuum advance curve, which since you won't be hooking it up won't matter, but if it did then those curves are shown on the "vacuum advance curves 1-5" chart. Vac adv #1 gives 10 deg advance at 10 in-HG vacuum, vac adv #2 gives 15 deg adv at 10 in-HG vacuum, and so on.
Only after you get the max timing figured out and how quickly the engine likes timing, then start playing with the vacuum advance. Don't try and do it now because you'll be juggling another unknown variable.
So put switch #1 on 9, switch #2 on 1 which is least amount of vacuum advance,
disconnect vacuum advance from distributor and plug the port on the carb,
idle engine and rotate the distributor to get 10 dBTDC on the balancer, this is your base timing.
09-16-2009, 03:10 PM
#10
Teching In
Join Date: Apr 2006
Posts: 16
Likes: 0
Received 0 Likes
on
0 Posts
Hello i am making some progress here with my 355. I am looking for timing recommendations for my (carbed) 355 to run on 91 octane with my Magnacharger. Okay this distributor is the MSD E-Curve and has timing adjustments 1 and 2 (?). i am totally clueless so far as a ballpark of where the timing should be as far as start timing and total timing. I am at 5000 feet elevation (not sure if this would hinder any ideas of where the timing should be). Any help would be totally appreciated. I am planning on dropping the distributor in very soon.
Ok, here is how I run my 355 with a 144 blower, Holley 950hp carb.
7lbs boost.
Mallory Unilite with NO curve - distributor is locked at 30 degrees.
Mallory Hyfire 6 digital box. 15 degrees start retard - all in after running.
50 passes, pulled the heads. Piston tops are light brown, plugs look great. I run 93 octane pump gas with ethanol blend (unfortunately).
Someone chime in here!
09-22-2009, 08:33 PM
#12
TECH Enthusiast
Thread Starter
Join Date: Nov 2007
Location: Evans, Colorado
Posts: 712
Likes: 0
Received 0 Likes
on
0 Posts
Ok this is what the tech told me on the MSD forum TECH---yes, (referring to locking out distributor and getting total timing at idle) your on the right track..but, i would run a total of 32 degrees for a starting point... and use a 15 degree adance curve.. at 2000 rpm
so, set your total at 32 ..with the dials on zero ..then select curve "L"
selector one ( turn dial to one) and selector two( turn dial to two)
this will give you17 degrees idle timing and the total o 32 will be in at 2000 rpm's/
ME---sorry about the late reply, thanks for your responses. Hopefully this sounds about right (a ballpark timing) with you guys that have experience with this. Here is a pic
so, set your total at 32 ..with the dials on zero ..then select curve "L"
selector one ( turn dial to one) and selector two( turn dial to two)
this will give you17 degrees idle timing and the total o 32 will be in at 2000 rpm's/
ME---sorry about the late reply, thanks for your responses. Hopefully this sounds about right (a ballpark timing) with you guys that have experience with this. Here is a pic
10-06-2009, 08:23 PM
#13
Staging Lane
iTrader: (1)
Join Date: Sep 2006
Location: rochdale,ma
Posts: 63
Likes: 0
Received 0 Likes
on
0 Posts
Ok, here is how I run my 355 with a 144 blower, Holley 950hp carb.
7lbs boost.
Mallory Unilite with NO curve - distributor is locked at 30 degrees.
Mallory Hyfire 6 digital box. 15 degrees start retard - all in after running.
50 passes, pulled the heads. Piston tops are light brown, plugs look great. I run 93 octane pump gas with ethanol blend (unfortunately).
7lbs boost.
Mallory Unilite with NO curve - distributor is locked at 30 degrees.
Mallory Hyfire 6 digital box. 15 degrees start retard - all in after running.
50 passes, pulled the heads. Piston tops are light brown, plugs look great. I run 93 octane pump gas with ethanol blend (unfortunately).
im runnin a 355 with tfs twisted wedge heads,700 holley supercharger carb, 8-10 lbs boost and i dont think my carb is enuff........im runnin a total of 31 * timing with a boost controller set up to take 15* out at full boost... i think my carb is too small since i have noticed i have to take yet more timing out and my headers and intermediate pipe are almost blue from heat..... also what are you runnin for 1/4 mile times with ur setup?
