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Username Post: Ramjet 350 spark advance        (Topic#229710)
Stephen S 
Newbie
Posts: 36

Reg: 09-22-07
11-14-09 10:18 PM - Post#1805966    

A shop recently installed a Ramjet 350 with MEFI 4 in my 65 Impala. Seems to run OK. I checked the spark advance according to the GM instructions and my Craftsman timing light reads 12 degrees instead of the 10 that's required.

Does this cause any problems or should I just leave it alone? I'm wondering if the extra advance might be causing unheard pinging that the antiknock sensor is correcting by retarding the total advance which might reduce power & mileage.



 




Scotts 
Frequent Contributor
Posts: 1045
Scotts
Loc: McDonald, TN
Reg: 07-20-08
11-14-09 10:23 PM - Post#1805967    
    In response to Stephen S

In my opinion - I would leave it alone unless you can hear it ping? Two degree's shouldn't make or break your pinging threshold. But then again, brining it back won't make a great amount of difference in running. Timing lights vary, inductive with arrow towards plug, angle of beam, etc... I wouldn't get excited but your point IS valid (good call)! Most OEM settings are conservative and engines love advance, to a point. Make sure your cooling system is up to speed and engine temps. Also it wouldn't hurt to call the shop - communicate your concerns and give them a chance to explain and/or correct...

NO WARRANTY EXPRESSED OR IMPLIED! I may be wrong, have in the past and will be in the future!


 
puzzley 
DECEASED "12th Year" Platinum Supporting Member
Posts: 2538
puzzley
Loc: Lexington, Ky
Reg: 02-21-04
11-17-09 06:11 PM - Post#1807700    
    In response to Stephen S

The electronic control module on a Ramjet has to be entered into the "service mode" using the diagnostic trouble code tool before the timing is set. When in this mode, the timing is set to 10 degrees. After the timing is set, and the ECM is back in it's normal mode, it may be that the ECM has changed the base timing. I think you would have to use the tool to put the ECM back into service mode to be sure the timing you're seeing is incorrect. did you have it in service mode when you checked it?

John
Carpe Diem, Vita Brevis - "Seize the day, life is short"


 
Scotts 
Frequent Contributor
Posts: 1045
Scotts
Loc: McDonald, TN
Reg: 07-20-08
11-17-09 10:20 PM - Post#1807828    
    In response to puzzley

Plug in your supplied code reader with the engine off / code reader switch off. Start the engine, then switch your code reader to on, you'll be in set timing mode - I read it in Google cache - I don't own one or have docs... The only experience I can remember was - (marine unit) at idle, the timing advanced 2-4 degrees after the ecm took control.

NO WARRANTY EXPRESSED OR IMPLIED! I may be wrong, have in the past and will be in the future!


 
Stephen S 
Newbie
Posts: 36

Reg: 09-22-07
11-18-09 11:13 AM - Post#1808046    
    In response to Scotts

I did use the diagnostic trouble code tool and followed the GM instructions. The 12 degree advance appeared during the service mode. When I turned off the tool it advanced a few degrees.



 
Scotts 
Frequent Contributor
Posts: 1045
Scotts
Loc: McDonald, TN
Reg: 07-20-08
11-18-09 11:26 AM - Post#1808053    
    In response to Stephen S

That's been my experience - it usually jumped a few degree's up at idle when ecm took control. Back to my original thought, I don't think 2 degree's would do it BUT if you back it off with your timing light, you can always reset to their specs. Is the cooling system up to speed - new mills get warm and contribute to detonation... Did you communicate with the installation shop? I would be hesitant to mess with it IF you suspect major problems. You know story - "you voided the warranty when", blah blah...

NO WARRANTY EXPRESSED OR IMPLIED! I may be wrong, have in the past and will be in the future!


 
Scotts 
Frequent Contributor
Posts: 1045
Scotts
Loc: McDonald, TN
Reg: 07-20-08
11-18-09 12:05 PM - Post#1808067    
    In response to Scotts

Offers an affordable datalog / scantool among others... Would be sure fire way to know what's going on with your timing / knock sensor, with a suggested contact number to make sure!

http://www.obd2allinone.com/sc/details.asp?item=me...



NO WARRANTY EXPRESSED OR IMPLIED! I may be wrong, have in the past and will be in the future!


 
Stephen S 
Newbie
Posts: 36

Reg: 09-22-07
11-18-09 10:30 PM - Post#1808400    
    In response to Scotts

Scotts Auto, I guess my engine is no longer "recently installed" as I stated. It's been broken in according to the GM instructions and has about 600 miles. Never exceeded 190 degrees during the past summer and seems to run OK.

Thanks for the lead to OBD Diagnostics for the scantool. I'm considering the DIACOM by Rinda Technologies since they make the Diagnostic Trouble Code Tool that GM included with the engine. Any opinion?



 
Scotts 
Frequent Contributor
Posts: 1045
Scotts
Loc: McDonald, TN
Reg: 07-20-08
11-18-09 10:38 PM - Post#1808402    
    In response to Stephen S

Gotcha on the time factor. As for Rinda, I think they are much more expensive, around 600 bucks or so for the PC scan/data software and adapter?

http://www.rinda.com/acro/prodlist.pdf

I did check them out but the price sent me scampering. Some handhelds looked cheaper, but not sure of the options. Otherwise, I have no opinion on the hardware, as I haven't read much on it, only a glance. They do have a large following with good feedback, I wouldn't be afraid of them. My thoughts were, if I were only looking for diagnostics and datalog, I'd get in as cheap as possible... I own several hand held scantools but find myself utilizing one of cheapest PC solutions around (depending on needs). I plug in a bluetooth and I'm rocking on a notebook 30' away.

NO WARRANTY EXPRESSED OR IMPLIED! I may be wrong, have in the past and will be in the future!


 
cbernhardt 
Senior Member
Posts: 581
cbernhardt
Loc: Lexington,NC
Reg: 08-28-00
11-19-09 06:02 AM - Post#1808470    
    In response to Scotts

I borrowed one of the Rhinda Ram Jet scan tools about 4 years ago to help diagnose a problem with my Ram Jet 350. The unit was setup for the MEFI3 and I had an MEFI4 system so I had to purchase a $90 prom upgrade in order to make it function properly. Since that time I have purchased the full OBD Diagnostic scan/tune package and it was much easier to use and had greater functionality. Of course you will need a laptop computer with the OBD software.

Charles



 
area53grunt 
Newbie
Posts: 1

Reg: 06-17-16
05-22-24 12:00 PM - Post#2870108    
    In response to Stephen S

The mark on the balancer when aligned with the center of the "V" timing pointer will get you to TDC. Get yourself a timing light with variable advance and set it to the Initial Timing: 12 Before Top Dead Center.

Setting Initial Timing: In order to change base timing on the system, the ECM has to be entered into the "service mode" using the diagnostic trouble code (DTC) tool, part number 12489400 or CodeMate Tester - MEFI Code Reader - 3851088.

This can be accomplished by attaching the DTC tool to the data link connector on the wiring harness.

1. Turn the engine's ignition switch to the off position (Engine not running)

2. Place the DTC tool's test switch in the off position and plug the tool into the data link connector on the wiring harness.

3. Start the engine, and place the DTC tool test switch in the on position. The Ignition Control (IC) module will then go to base ignition timing. At this time, the base timing can be adjusted by turning the distributor. Using a variable advance timing light, set base timing at 12 Before Top Dead Center (BTDC)."




 
acardon 
Ultra Senior Member
Posts: 11492

Loc: DFW TEXAS
Reg: 03-25-05
07-04-24 06:25 AM - Post#2871443    
    In response to area53grunt

My Ramjet 350 manual suggests 10 degrees. It's been running that way for 13 years. Is 12 degrees better? Will that allow more total timing with stock tune?

Don
66 Corvair (driving)
57 2dr HT (driving)
56 2dr HT (waiting to be restored)


 
65_Impala 
Very Senior Member
Posts: 5022

Reg: 12-29-02
07-06-24 08:02 AM - Post#2871509    
    In response to acardon

The base timing will be used during cranking and the initial ignition of the engine then as it starts running the ECU will take over controlling the timing. So, 10 or 12 degrees really makes little difference here.



 




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