View Full Version : Where is advance on Indmar's HEI distributor?

11-07-2004, 12:16 AM
While troubleshooting my boat (as written in earlier post), suddenly I lost all mechanical advance in the distributor. In other words, the engine runs at 10 BTDC at 750 RPM just the same as at 3,000 RPM.

I opened the cap and attempted to diagnose the problem, assuming there was some centrifugal weights or springs (based on what I read on the Internet). However, there doesn't appear to be any sort of advance system implemented.

Am I missing something, or is this done in the module somehow? I can't understand how it could be done by the module because it isn't specified and it certainly doesn't tie out to a computer as with an EFI engine, etc.

Thank you in advance for any ideas!

11-08-2004, 01:20 PM
Is it carb, or fuel injection? It should have an HEI distributor anyway. If Its HEI you'll have two connectors at the base of the distributor. Theres a base timing connector that should be unplugged when checking timing. Not too sure where that connector is. maybe its unplugged. If you go to indmar.com you can purchase a shop manual. It should have that kind of info for you.

11-08-2004, 02:00 PM
Sorry. It's a 350 Vortec, carburated. It has the HEI distributor with the Delco module.

I'm getting the impression that the module is providing the advance, despite there being no EFI computer.

If the module does provide the advance.. Does anyone know -- is it only this unique delco module that creates advance on it's own, or is this common with HEI modules?

Thank you in advance!

11-10-2004, 02:35 PM
I should also mention, I attempted twice in the past to purchase such as shop manual without luck. Indmar doesn't sell to consumers, it appears. Keaton, do you know of a way around this? As I've mentioned in other posts, I don't have a responsive dealer in my area - which is the reason I need such a manual.

Brian Raymond has responded to other people on setting base timing by applying positive current to the black wire on the timing shunt; however, there has never been clarification provided as to whether this is relevant for a carburated engine without an ECU. When I applied current to the shunt, it did nothing.

I'm still without advance and no idea where it's supposed to be coming from. I can only assume the module because I just don't see anything other than the breakleress hall-effect pickup.


11-10-2004, 02:53 PM
There are several types of hei dist. There is the earlier kind with vacuum advace and a module and there is the later kind that uses the knock sensor signal to tell the module to retard. This is called ESC system. (electronic spark control). If its running at 10 degrees BTDC at idle then it doesn't sound like there is anything wrong. The module will pull down the advance based on the signal from the knock sensor. Im a gm tech at a dealership and vehicles use the same system. Sounds like you have another problem.

11-10-2004, 04:06 PM
This is the more modern style, no vacuum and breakerless. I don't think it uses a knock sensor to retard the timing, but I could be wrong about that -- I thought the only wires with missing ends were the ones going to the ingnition, but it's very likely I'm missing something.

I was under the impression this was the 1985-1993 distributor for 350's, although this is a 2000 engine.

From what you're saying, it sounds like the advance is implemented by the module (even without an ECU), is that correct? I'm still not receiving any advance and wondering how it's normally implemented, since there are no springs or weights.

If there is no advance and it's supposed to be provided by that module, I had assumed I would need a new module, is that fair? Do you know about the shunt and whether applying positive is required for setting "base timing" on this model?

Thanks again!

11-11-2004, 03:20 PM
With the kind of dist. your talking about you have to have some type of ecm to tell the module how much to advance or retard timing. The ecm needs inputs like throttle position and engine load. Are you sure you don't have a computer controlled carb.(CCC)
CCC has a throttle position sensor on the side and the ecm uses a MAP sensor to measure engine vacuum to tell the ecm engine load. The distributor you have only works with an ecm to advance. Im not sure about adding power to a shunt. On vehicles we ground or open a pigtail thats usually mounted near the fire wall. This puts the ignition system in base mode to adjust or check timing. If you don't put it in base mode then you'll have a reading that is already been adjusted by the ecm and thats probably why you think its not adjusting when it really is. You wont see much advance with no engine load. On vehicles we set the timing to 0 degress in base timing mode.
I got my manual from indmar but through my dealer.
What kind of symtom do you have? Most lack of power concerns are poor fuel quality or fuel starvation

11-11-2004, 04:06 PM
Hi Keaton,
Thanks a lot for the suggestions. You probably don't want to read the long details of the issue I'm having, although it's an interesting thread ( here: http://www.moomba.com/bb/viewtopic.php?t=1213 ). The short version is that I'm not able to get over 3,500 RPM under load. It's not the fuel, everything has been replaced leading up to the engine, just to be sure (new fuel pump, fuel filter, fuel filter assembly, pickup from gas tank, hose cleaned out, etc). The fuel has been entirely drained and replaced with fuel that was checked prior to using. As far as air goes, I've run it w/o the flame arrestor, etc. I've aligned the shaft, replaced all ignition related components other than the distributor/module, just about anything that's ever been suggested since I'm certainly no expert in this area!

The reason I'm asking about timing separate from the above issue -- is that I know for a fact that it's not performing correctly. I'll explain... I set timing twice during the process of diagnosing/testing this engine. Both times I made sure it was at the recommended timing (8-10 degress BTDC); both times it had 24+ degrees advance at 4,000 w/o being under load. It always ran perfect, was in-time, etc.

Out of nowhere, the engine wouldn't start. After listening to it, my friend told me the timing was way out. I couldn't believe it, but to appease, I twisted it -- it eventually started/ran when it was severely advanced. In addition to being overly advanced, it had also lost any mechanical advance. The timing stays consistent no matter what the RPM.

The ignition module with the Indmar/GM HEI looks like this:
http://www.skidim.com/prodinfo.asp?number=R116014&variation=&aitem=25&mi tem=36

The wire that would typically go to the ECM are *not* connected, as you'll see in the specs for this engine. There is no sort of ECM and the only two wires on the carburator are to engage the choke, from what I've been told. I had once, accidentally, operated it without those wires connected and it still had advance. I simply can't find anything outside the simple ignition module, nothing that would provide advance.

Keep in mind, this is a separate issue from my performance problem. I haven't even put the boat in the water since this started, I'm definitely not going to get into my original problem until I can figure out why I have to run over 50+ advance and no added advance comes into play any longer.

If I could start by determining where the advance is coming from, and whether it indicates I need a new module/this would fix the issue, I would do that prior to continuing.

If there were only a local Indmar mechanic that would return a phone call, I would be set!

old geezer
11-11-2004, 11:42 PM
Its been a long time since i have played with inginition systems so take this with a grain of salt. It seems strange that your base timing changed so much. I once had a bayliner that had a distributor problem and shortly after the dealer fixed the problem it would not run. I found that drive gear that contacts the cam gear was worn down and had sliped which caused the timing to be off. Other mechancal issues that could effect base timing might include slipped timing chain (unlikley if this was the same motor problems i recalled from this summers posts on message board) (however a cam that is out of time with the crank could cause loss of power)

If the control module controls the advance and it not advancing as RPM increases then possibley a knock sensor is picking up an engine noise and limiting the advance. It is almost impossible to efficiently trouble shoot this problem without a manual. With that said one could trace the wires that plug into the module and use logic as for the porpuse of each wire based on where it comes from.

Good luck and keep us posted as this is an interesting problem.

11-12-2004, 04:56 PM
The ignition control module has a built in "logic." This logic references off of the pick up coil and rpm. This "logic" has a built in timing curve of about 21deg. plus the 10deg. gives you a total advance of 31deg. When at 3000rpm, you should have about 28deg. showing at the crank. I have seen cases where the module has gone bad and not delivered the proper timing. This can happen when the shunt wire is hooked up to positive current to long. Hope this helps, keep us posted. Brian Raymond

11-12-2004, 04:58 PM
The ignition control module has a built in "logic." This logic references off of the pick up coil and rpm. This "logic" has a built in timing curve of about 21deg. plus the 10deg. gives you a total advance of 31deg. When at 3000rpm, you should have about 28deg. showing at the crank. I have seen cases where the module has gone bad and not delivered the proper timing. This can happen when the shunt wire is hooked up to positive current to long. Hope this helps, keep us posted. Brian Raymond

11-12-2004, 04:59 PM
The ignition control module has a built in "logic." This logic references off of the pick up coil and rpm. This "logic" has a built in timing curve of about 21deg. plus the 10deg. gives you a total advance of 31deg. When at 3000rpm, you should have about 28deg. showing at the crank. I have seen cases where the module has gone bad and not delivered the proper timing. This can happen when the shunt wire is hooked up to positive current to long. Hope this helps, keep us posted. Brian Raymond

11-12-2004, 05:16 PM
The ignition control module has a built in "logic." It gets its references from the pick up coil and from the rpm signal. The module has a programmed timing curve of up to 21deg. When adding the 10deg. from the motor, you end up with a total of 31deg. of total advance. When at 3000 rpm, with a timing light on the balancer, and the shunt not hooked up, you should show about 28deg. I have seen modules go bad and keep it at 10deg. no matter what rpm. This can be caused by leaving the shunt wire connected to a 12v source for long periods of time. Hope this helps, keep us posted. Brian Raymond

Brian Raymond
11-12-2004, 05:25 PM
The ignition control module has a built in "logic" that gets its references from the pick up coil and a rpm signal. The module has a programmed timing curve of about 21deg. The 10deg. from the motor shoud give you around 31deg. of total advance. When the motor is at 3000rpm, with the shunt wire not hooked up and the timing light on the balancer, you should get about 28deg. I have seen modules default internally and not let the motor advance past base time. This can be caused by leaving the shunt wire connected to a 12v source for long periods. Hope this helps, keep us posted. Brian Raymond

11-16-2004, 02:14 PM
Hi Brian,
Thank you for the information. On a separate note, have you noticed the strange issue on this forum lately where "phantom" style posts are appearing with no author?

Regarding my troubleshooting -- here is the latest after a weekend of testing new suggestions (if only I could find an Indmar mechanic, life would be so much better).

On Geezer's suggestion, I checked the distributor gear -- no problem there. The only strange thing I noticed is that it didn't look like brass -- I was under the impression all distributor gears must be brass when used with roller cams. The original Delco module, no matter what I did, was stuck in base-timing. Brian - it had never been connected to 12v for a long period of time, but it's good to know one can fail without the other -- sounds like it may be the module.

I dissassembled the engine and removed the timing cover to check the cam v. crank location and they were dot-to-dot (8 hours wasted with that disassemble/reassembly).

In short, everything seems to be "degreed" correctly; however, the engine runs far better at 35-40 degrees of advance than it does at 10 degrees, and I'm just talking about idle! I've double checked this with two timing lights (one expensive digital, one conventional) and I've done it by degreeing the harmonic balancer, they all agree.

Despite the ignition not showing advance, this appears to be an entirely separate issue (the spark timing v. balancer position can't lie no matter what is going on to cause problems, right?) And I'm out of ideas again.

Is there any diagnostic book that can give me ideas as to what to check / why my engine would require so much advance timing to run? Someone also mentioned that it could be the pickup in my distributor, could this be at all relevant?

Thank you in advance,

11-16-2004, 07:35 PM
Pickup coils are either good or bad. If they are bad then it wont run at all. With the kind of system then Brian explained it would just about have to be the module but you should double check with Brain as Im not familiar with this style of ignition. A module shouldn't be that expensive. Its worth a shot to put one on and see if it fixed it.

Cars require inputs to know how the engine is running like for example. Engine load via vacuum, rpm, throttle position to control timing if its an ESC system. I think its different because boats don't have to meet EPA regulations that cars do so they can get away with this kind of ignition system. Basically that explains some of your questions about car parts tranfering over to boat applications. The anwer is no. I was reading some of your other post about the engine being from automotive application. I would advise that if you do get this problem resolve try and stay within the boat application parts. I don't have anyway to prove it but I wouldn't be surprised if the cam is different in then the motor that was origanal. I do know that the freeze plugs are going to be different so keep an eye on them or you'll be doing this again. Keep in mind there is two in the back of the engine.

11-16-2004, 08:07 PM
Hi Keaton,
Fortunatley the freeze plugs in the engine are brass. I switched the cam with the original, and although the lobe height was identical, the opening was quite a bit longer. I concur in the cams being significantly different, not to mention the marine application uses a roller cam. This forced me to replace all related components -- push-rods and everything. It hasn't made a performance difference, but you can definitely hear the difference in sound.

But at this point, I have an engine that is 100% marine. Because I utilized all Indmar parts (from the intake manifold, to the balancer -- everything) and because the cam and all related parts have now been switched, this is the marine engine. The distributor and module we're discussing is the original that ships with Indmar as well.

Based on what I've found, you're correct about the emissions being the issue relating to not requiring MAP sensors and so forth; I've read that factually on several ignition websites, etc.

I'm just hoping to determine what could cause the engine to want so much advance. This can't be the module alone, I don't believe, since the timing light proves it.


11-17-2004, 04:00 PM
It occured to me while mentioning the differences relating to Indmar's 350 Vortec marine cam v. standard 350 Vortect, that the cam may also be set advanced in the engine. Perhaps this is why after replacing the cam (going to the Indmar cam instead of the stock Vortec cam) I increased the RPM's a bit, but didn't get the full RPM's.

Have you or anyone else on the forum taken a look at the cam positioning or read a spec that shows whether the Indmar cams are degreed?

Thank you!

11-17-2004, 11:57 PM
Did you put a indmar timing chain and sprockets on when you changed the cam shaft. That would eliminate the posibility of the cam degreeing. I think you on the right track. I think you have a problem with the corrolation between the crank and cam therefore having to advance the timing because the cam is advanced. You can make sure that the cam is degreed right with a degree wheel. That way you can make sure the valve are opening and closing at the right time. You would have to get the specs from Inmar and that could be a task. LOL. Even working for a dealer getting that info could be tough. But like I was saying if you use the Inmar timing set then it should already be degreed and will take out the guess work. If all that checks out then Im stumped. Its starting to be one of those problems where you just have to be there and work on it.

11-19-2004, 04:39 AM
When degreeing a cam set-up with a degree wheel, doesn't one actually change the relative positions of the gear alignment marks?

11-19-2004, 11:42 AM
Hi Keaton, Catdog-
Yes, I did use the Indmar timing gears and chain, which is a roller style chain. I was forced to use them because the Indmar roller cam is a style of a different year than the crate engine had implemented.

I put the two gears "dot to dot" which I had assumed would be propertly aligned. As CatDog mentions, I wonder if aligning to the zero-degree isn't how Indmar typically installs them? Perhaps they install theirs with a slight advance between the two timing marks?

I wonder if I should just mount a two-piece timing cover (easy access) and just test/tweak different degrees to see if I can get more out of it? Sort of a poor man's Dyno :-). Speaking of which, how do they setup Dyno's for boats anyway? I mean, is it possible to create load for a stationary boat?

Since I'm required to add too much advance in the ignition, to compensate, I would assume I would want to retard the timing grear alignment.

Indmar ought to run a support forum.. It could be paid support -- it would be well worth every penny and then some!


11-19-2004, 06:37 PM
Yes. cam degreeing is done but using a adjustable (slotted) cam gear and you can adjust the degree relative to the crank but you don't want to do that. It would be a waste of time because if you used the stock cam and gear set and alighned your marks then you know that not a problem. Dont devert from the factory specs. They spent alot of time developing that cam and its relation to the crank.

Brian Raymond
11-19-2004, 10:47 PM
It sounds like your a tooth off somewhere. I would double check the distributor installation. Indmar is very helpful, you can get great tech support from them at (901)353-9930. Brian Raymond