HEI (4-pin) and rpm spikes (was "Recommend an HEI coil and module")

[pparaska]

I have some strange rough running conditions that changing the fuel map won't seem to fix. I'm beginning to think I need to make sure the ignition is very reliable before continuing on tuning the fuel map.

 

I have a blue streak module and one of the Brute Thunder coils in the HEI cap (old style, red/yellow wires on coil, 4 pin HEI). I'm thinking of just getting some decent OE type replacements to take the parts I have in there out of the equation.

 

Anyone have a module and coil they like, that's good to 6500 rpm, but doesn't have so much voltage that it constantly burns through the rotor (read on)?

 

My rotors last a very short time before they will burn through under the center post. I believe that the coil just puts out too much voltage (like 50K+), and the dielectric strength of even the best rotors (Accel, etc.) can't hold the voltage back from grounding out on the mechanical advance mechanism below it.

 

The plug wires while not new are the 8.5 msd stuff, and they ohm out o.k. and don't arc over to anything while the engine is running in a dark garage. Plugs are Accel 0414S, with a .050" gap. I'll try closing that gap, but when I've run .035", the burning rotor caps happened just as much.

The cap is an Accel unit, looks great, no carbon traces, etc.

 

I have the ground on the distributor harness that goes to the coil (3 prong connector in cap) running to a ground, so it doesn't depend on the distributor housing for the ground path only. 12 gage wire powering the coil from a relay right next to the distributor, that has a short run to my main positive tap on the ford solenoid over where the battery usually is. Power and ground should be better than a stock GM car that HEIs were put in.

[Mike C]

The first thing I would do is ditch the Accel cap and rotor. I had nothing but troubles with their plastics including broken rotor tips because of either a mis-aligned pin or low spring rate hold down internal to the cap. I was very pleased with the MSD cap and rotor.

 

Most of the aftermarkt OEM's make an increased dwell and higher RPM range module. My only experiece with HEI's is on lower RPM engines, so I cannot attest to the best OEM one. I would seriously consider ditching the under-the-cap module and using just the mag pickup to trigger an ignition box such as a 6A. It is possible to trigger with the module, but why not bypass that animal completely? MSD products are expensive, but almost always deliver as promised. I like the looks of their module, but I am not sure if it is as reliable as the OEM style. Another option to consider from MSD is the external coil/6a HEI conversion.

 

$160 bucks will get you a complete ProForm HEI distributor with a high perf coil and a low-saturation increased dwell module. I did this in my 2x4 truck, but the reduced firewall clearance in my Jimmy sent me to the MSD ready-to-run distributor. Purchased at the same time, the OEM type module in the ProForm has been replaced, while I have had no issue using the MSD. I think Mallory makes an HEI module with a rev limiter?

 

One nice thing about OEM is if (when) the module dies you can get a replacement at any parts store.

[Brad-ManQ45]

Pete:

 

You're running MegaSquirt, right?

 

If so, think about distributorless....I am thinking EDIS (heaven forbid using a Ford product on a GM Engine, but it IS proven and supported by MSnS_EDIS, and you already have a hybrid - right?).

 

Seems like a good way to avoid all problems associated with distributors and high energy ignitions.

 

I will second Mike C's comments about Accel caps, rotors, and even condensers (once had one of their brand new ones go out on me, stranding me for a while).

[pparaska]

Mike - I did some googling on HEI, and man, there are alot of people that don't like it for performance! Issues seem to be the module not handling enough current to be able to run the coil, and those that do may not have good dwell properties. Module can get very hot and intermittent. Coil in cap gets hot and can loose energy and increase saturation time. Coil in cap is not a good design generally, as far as E-core, etc.

 

I'm just about ready to call in an MSD replacement, but not HEI. Even thinking about going to the E-curve job, and getting a Blaster SS coil (good reviews on energy capability and short saturation time). But the dizzy is $350 (after rebate) and the coil probably another $50....

 

Brad - I even have the EDIS-8 stuff in a box! "All" I need to do is mount and wire it, and see if the 50 series 36 tooth chain sprocket will give a decent signal to the VR sensor. But I really wanted to tune the fuel only first. Chicken and egg problem!

[Mike C]

As far as distributor ignition goes, I like MSD's least expensive dist. w/out any electonics using mag p/u. Add a 6A and Blaster II. $175 for dist, $150 for 6A, and $30 for a coil, but still $350. Take a look at MSD replacement module.

 

Significantly different than any body elses around $80. http://www.msdignition.com/pdf_catalog/53_56_hei%20components.pdf

Add the external blaster II and you should get out for $150 w/cap & rotor.

 

Actually Google'd this and Summit has the ultimate HEI kit from MSD, probably best bang 4 buck in hindsight. $149 with module, coil, cap & rotor, dust cover, adjustable rev limiter, Here is the link:

 

http://store.summitracing.com/default.asp?target=partdetail.asp&part=MSD-8501&N=400122&Nao=10&autoview=sku

 

My ready to run MSD for my Jimmy was $240 plus the $30 blaster II. Looks like it is $268 now plus coil. You would have to get cap with HEI terminals to keep your wires however.

[Brad-ManQ45]

Pete:

 

THOUGHT I had seen posts by you on MSEFI forums...

 

Can't fault you for wanting to do fuel first, but if ignition is a problem, I probably would just bite the bullet and just ahead with EDIS instead of spending another $150 or more on getting it going with a distributor.

 

I'm sure there are plenty of people out there that you could get decent maps from as a good starting point for the ignition.

 

From what I can see, it will be a little back and forth between fuel and ignition for the fine tuning anyway. The LC-1 will really help here.

[DavyZ]

Pete,

 

I have an Accel HEI module I can send you for testing if you want me too; it's brand new and I ASSuME it works perfectly. For that matter, I have an Accel HEI Supercoil (new) that's mounted on top of the HEI...I can send that to you too. I'll gladly loan them out to you since my project is far from done *sigh*. Just email me or PM me.

 

Davy

[pparaska]

Thanks, Davy, but I replaced that stuff with a no-name boxed version of the ProForm coil and also a new Standard brand module. New rotor, cap looks fine. I went over the mechanical advance mechanism very thoroughly, and the distributor shaft play is not even perceptible.

 

Using a timing light, there is a good bit of jumping around when the engine is held at 3000 rpm or so in the garage. I'm going to lock out the mechanical advance and see if that's the problem. Otherwise, it might be the wires, but I doubt it. It's not visibly cross sparking, but I need to rule that out.

 

At about 4000 rpm at cruise (TPS and MAP are constant), the rpm is jumping around about 1000rpm, very quickly. No wonder I can't tune in this region.

 

I've done all of the known fixes to the tach input on the Megasquirt V2.2 board (Dave cap, etc.) The one thing I haven't done is a shielded tach wire. I have a microphone cable I'll use to do that mod with soon if the locked out mechanical advance takes this rpm jumping around away in the logs.

 

The EDIS just may go on soon if the distributor is shown to be the problem.

[Guest tony78_280z]

What I got it...

 

Proform HEI Upgrade Kit Kit includes: hi-power 50,000 volt coil, ''no arc'' rotor, premium "no arc" cap, module, coil dust covered, hi-performance vacuum advance unit, HEI bushing, wire harness and capacitor, hi-performance advance spring, weight set, and mounting hardware.

 

I got it through JEGS for $80.00. It came with no instructions so, being my first time inside a distributor it was a bit confusing. Purchasing a High power coil and module was my goal at the time. But the advertised "No Arc" Cap and Rotor was the selling point for this kit. I don't know what makes it "No Arc", or how to test if it is "No Arcing" But with a big powerful spark, you want to be sure it is directed at the right spot. And that sounds like what your timing problem might be. If your dizzy is mechanicaly (bearinsg and all that) sound then this kit will upgrade and refresh all the electrical stuff. Of course there is also the adjustable curve components that sweetens the deal.

 

Definatly get your spark under control before tuning fuel. I tuned my carb to a real weak spark (Piss poor wires that looked good.) Now I think I'm running lean.

 

If you are wondering I'm using: Accel 8.0 mm Super Stock Spiral core Wires, and And Bosch Platinum Plugs.

[pparaska]

Well - after replacing ALL of the electrical parts in the distributor, and going through the mechanical advance, and indexing the rotor to the cap, there were still problems. The ignition is fine, the rotor seems to last longer now, but I still had tuning issues.

 

But these issues were related to the tach signal filtering that was going on inside the Megasquirt ECU. I tried all of the fixes I could on msefi.com find but nothing worked. I cried for help on msefi and someone came to the rescue with a better tach signal filtering circuit that works with points and the 4-pin HEI distributor TACH output and the MS ignition input. My rpm in the datalogs are now smooth, no more spiking at constant throttle position and load.

 

Here are the threads there that cover what I did, etc.:

http://www.msefi.com/viewtopic.php?t=11891

http://www.msefi.com/viewtopic.php?t=7861&postdays=0&postorder=asc&start=17

 

Now it's time to get the fuel map straightened out. I was having a horrible time tuning the MegaSquirt - and no wonder the ECU was pulling VE values from several RPM bins of the same MAP value rows in the VE table every run through the fueling calculation loop (think many times a second). Imagine what the engine was getting for fuel - a sometimes vastly different amount of fuel each pair of revolutions. No wonder it ran like crap and was almost unresponsive to tuning the apparent VE map value at a constant load / rpm pair.

 

This started out as a Chevy V8 topic since I was asking about HEI parts - and you guys came through! But it turned into a problem with 4-pin HEI and the Megasquirt ECU, so I'm going to move it to the HybridZ MegaSquirt but keep a placeholder in the Chevy V8 forum.

[dr_hunt]

GM has a tach filter on the "85 Monte Carlo SS's, and probably other cars as well, seems your problem isn't as "new" as you might think. Actually my '84 had the same filter.

 

If it's burning through the rotor, then the rotor is "junk" to start with or you have too much resistance between the coil and the plug, which includes the plug. Don't rule out the plugs. There is no such think as too hot of a coil since the spark follows the path of least resistance, which in your case is through the rotor. A hotter coil only exacerbates the problem, but the problem is still in it's original form of too much resistance in the path from the distributor cap to the plug itself. With the HEI you want to run brass or copper contact caps, not the cheapo aluminum contacts. I'd change plugs to a different brand/type and try that first, before ditching the system entirely. If you have mega bucks lying around, then go MSD or other system, they're not cheap, but in the end you'll know what you were missing.

 

The HEI will work, however IMO isn't as good as MSD, which seems to be the industry leader and what all the top fuel guys run. I haven't tried the others but I have two MSD 7AL2's and love them both, although I think I'm going to upgrade for more spark energy with my exotic fuel.

[pparaska]

dr_hunt, I concur with your thoughts on the HEI cap burn through, and the probability that I have a secondary ignition system issue.

 

I think I've fixed it though - the extra resistance past the rotor was right there all the time - in the form of too large of an air gap at the rotor/plugwire terminal interface - the rotor phasing was strangely out of whack. I moved the vacuum advance cannister a good bit (slotted the mounting holes) so that it sparks across the terminal now as the vac advance moves through it's range. Before I only had a spark trace mark near one edge of the plug terminals, but now it goes from near the middle to near the edge. I'm not sure how it could have been so bad before. Possibly the wrong aftermarket (Crane) vac advance cannister was installed by the shop that initially set the distributor up, installed the vac advance cannister from their stock, and put the timing curve on it. I'm going to order an MSD rotor though, as the stock (STANDARD brand) replacement one is pretty thin and the nylon material it's made out of is not as good dielectrically as the MSD's Rynite material. I've always run non-resistor plugs in the 327 and now the 406, and always used good (tested) MSD 8.5 wires. The Accel cap is actually pretty decent - brass terminals. I've had blue streak parts on there as well.

 

I'd probably go with an MSD (non-HEI) distributor and 6AL if I were to stay with a distributor. But I'm going distributorless, with a crank trigger, etc. (Ford EDIS) and programmable "mechanical" and "vacuum" advance curves through the MegaSquirt-n-Spark-Extra setup. I need to go away from the large cap HEI in the near future anyway, as the two induction systems I'm moving to won't allow it (Offy Z/28-type crossram with 2 670cfm TBIs, or the Hilborn injector converted to EFI).

[mobythevan]

I wanted to add one thing to this post. I really didn't read through the entire thing, but one problem that me and my buddy had with the two SBC MS setups we have done is with making sure that we had condensers in the system to filter out noise. We basically settled on making sure that we put two condensers in like most factory setups. One at positive coil and one at postive alternator. That helped greatly with noise spikes and false triggering, etc. However both of these setups were TPI so the distributor setup and coil was different (small cap TPI dizzies).

[dr_hunt]

alot of people don't even know how to phase a rotor in the first place. It can be a huge difference in performance. It's all part of tuning an engine and the difference between winners and losers. Some MSD distributors have adjustable phasing, most distributors regardless of manufacture don't. Just because it isn't adjustable, doesn't mean it's correct from the manufacturer. People must check it if your going to properly tune your motor.

 

Drill a hole between the #1 terminal in the cap and the center coil terminal, attach a timing light as usual to time the engine and shine it through the hole, you should be albe to see the brass contact of the rotor exactly in line with the contact through the whole advance curve, if not your going to get misfires whether you can hear it, detect it or not, it's a fact, and you'll realize a performance gain if it was off and a smoother running engine.

[pparaska]

Mobythevan - thanks for that tip - I'll look into the condensor at the alternator. However, this is a CSI alternator, which ought to have a pretty nice flat 14V coming out of it. I did replace the condensor/wiring harness in the HEI housing. All seems to be well now, with Peter Florance's tach filter circuit.

 

dr_hunt - I admit - this is one thing I never really paid attention to before - rotor/cap phasing. I have plenty of caps around and I'll try that trick. However, my timing light is really suspect right now (doing strange stuff), so I need to get a new one. Anyone have any recommendations?