Troubleshooting my FE

[CompFi]

Originally Posted by eschaider

I'm sorry, but I'm not surprised to hear that, Brian.

Appreciate the insights here, Ed. And certainly seen many helpful recommendations from Brett here on the forum. And lots of happy customers too. In fact, I watched Brett's video on setting the curve for the distributor. Tremendously informative for someone like me. Sure do wish I could poke my head into his shop, I just might do that some day.

But, as Patrick points out, I need to tune my carb on my engine. And I will probably make some mistakes on my initial attempts. But good to know that I can rely on plenty of expertise here on the forum from folks willing to help. Again, greatly appreciated.

[DanEC]

Backfiring through the carb can also be a lean fuel mixture. But from what’s been posted, I don’t know why the carb would suddenly go lean unless the rebuilder changed the jetting or you do somehow have a vacuum leak. Also FEs are known to occasionally develop an intake gasket leak by sucking part of the lower gasket area into the runner and then it’s sucking air from the crankcase. Those are hard to diagnose other than just pulling the intake to inspect. You might be able to snake an inspection camera down the intake runners to look for any gasket protrusions into the port. You may get an oily combustion chamber too if it’s sucking oil in.

I’m still suspicious of timing though. If you can find someone with a dial back timing light and have them power time it at high enough rpm so that all the centrifugal advance is spun in. Did you receive any tuning instructions with it? I would guess you are looking for around 35/36 total advance (base timing and centrifugal).

I would also see if the accelerator pumps are responding immediately when you yank the throttle and there is a strong jet of gas in both primaries and secondaries. But be careful as you don’t want to be looking directly down a carbs throat when it backfires out the carb.

Good luck.

[patrickt]

Originally Posted by DanEC

I’m still suspicious of timing though.

Well, I dunno... maybe. But his distributor pic looks fine. Better than mine, in fact. And my timing hasn't changed a single degree since it was set on the break-in dyno 20 years ago. In fact, I've never even cracked the hold-down nut on the distributor. For it to have changed in a few hundred miles, and the hold down bolt not being loose, is a long shot. But it wouldn't hurt to put a gun and check the initial timing and the all-in timing at 3500RPM.

[rustyrims]

looks like MSD 5520 street fire ,CDI multi spark ignition box.
I was trying to post a picture. it took me so long sunman had already answered

[CompFi]

Originally Posted by sunman

Street Fire, a MSD product

Originally Posted by rustyrims

looks like MSD 5520 street fire ,CDI multi spark ignition box.
I was trying to post a picture. it took me so long sunman had already answered

Thank you, both. This forum is the best. I post a picture of exactly what, I dont quite know. And within 20 minutes, multiple members respond to assist. Truly appreciated.

[rustyrims]

if the gas in the tank is more than a year old I would drain that and start with fresh. reading your first post the gas might be from 2022. We have had race gas go bad in less than a year.

[CompFi]

Originally Posted by rustyrims

if the gas in the tank is more than a year old I would drain that and start with fresh. reading your first post the gas might be from 2022. We have had race gas go bad in less than a year.

Great point. Not from 2022. But some of that gas in the tank could be approaching a year old.

Should be easy enough to drain that even I could do that...

[rustyrims]

I hope it does not happen to you again but if it does backfire the best thing to do is to cover it with a blanket. A fire extinguisher makes a Hugh mess. I am confident you will get this sorted out. take your time

[Unique427]

Originally Posted by rustyrims

I hope it does not happen to you again but if it does backfire the best thing to do is to cover it with a blanket. A fire extinguisher makes a Hugh mess. I am confident you will get this sorted out. take your time

Dry chemical extinguisher will make a mess of whatever it touches.

Halotron fire bottles are ABC, non-conductive and leave no residue.

https://www.h3rperformance.com/colle...-extinguishers

[DanEC]

Going back to your original post, I would go ahead and put the new plugs in. I’m kind of negligent in changing plugs regularly and last year my old 427 Corvette with a bunch of compression, cam duration, etc started running a little off. Finally put some new plugs in it and it was back to its usual self. Friend with a Hemi Roadrunner just had the same experience and his plugs weren’t real old.

[55312]

Quinton Brothers. Williston. Pete Quinton made my 484 Keith Craft sing. He knows MSD and Holley's (Quikfuel). Once he set it up I never touched the Carb in all the years I owned it.(18) They also have a Dyno.

My E-M Cobra now sleeps in Paris, France

[CompFi]

Originally Posted by 55312

Quinton Brothers. Williston.

PM sent

[sunman]

Street Fire is a cheap non USA product sold by or at best assembled in USA by MSD

The whale oil or whatever was used in the caps in the power supply section of the pcb has dried out

It’s the easiest part to change and I suggest a different brand no matter what due to past history of failure

I’m not saying this is your real problem just something I’d change first

[CompFi]

Originally Posted by sunman

Street Fire is a cheap non USA product sold by or at best assembled in USA by MSD

The whale oil or whatever was used in the caps in the power supply section of the pcb has dried out

It’s the easiest part to change and I suggest a different brand no matter what due to past history of failure

I’m not saying this is your real problem just something I’d change first

Should I confirm proper functionality? Or maybe you are suggesting replace it proactively even if functioning properly now? As in, if not failing yet, it will.

If that is the recommendation, what is the preferred replacement here?

[patrickt]

Originally Posted by CompFi

Should I confirm proper functionality? Or maybe you are suggesting replace it proactively even if functioning properly now? As in, if not failing yet, it will.

If you were in the local Cobra club we would slap on an extra MSD 6AL if our first slapping of the Holley 750 Vac Secondary didn't cure the problem. Remember, there are two clues to your problem: 1) Your car originally ran great, but now is running like crap; and 2) An abundance of heat accompanied that change in performance.

Now, you could have more than one thing wrong with your car, but probably not. But maybe. Not everything that could go bad on your engine is going to cause both symptoms. But if you think really generally, the problem is likely to be 1) Too much air in your fuel air mixture; or 2) The spark is firing at the wrong time. Possible problem #1 could have the air coming in through the carb, or from somewhere else; and problem #2 could have a couple of different causes. Now, it could also be a bizarre combination of something else, but those are two most likely scenarios.

Remember everyone on here is a diagnostic genius, so we'll eventually stumble on the solution.

[sunman]

I think it’s the box
Early firing causes backfiring and late causes overheating
The multi spark is out of control
Dave said the carb is good
Just a guess

[CompFi]

Originally Posted by sunman

I think it’s the box
Early firing causes backfiring and late causes overheating
The multi spark is out of control
Dave said the carb is good
Just a guess

Sunman - appreciate the guidance here. Definitely got my attention that I need to focus on the box.

One thing i should clarify about the backfire thru the carb. That is NEW. As in, happened once this past weekend right after I re-installed the carb following Dave's re-build and I gave it gas to check the throttle linkage etc. Definitely got my attention Could be that the one backfire resulted from me not yet completing the Holley tuning instructions. Then again, could be the box. Just wanted to clarify that the backfire was new in case I was unclear about that.

[eschaider]

I'm glad to be able to help, Brian.

This item I am about to show you is not a go-out-and-buy-one-right-now sort of thing, but it is an in case something goes wrong with your current distributor sort of thing.

This unit is the definitive distributor/ignition tuning solution for carbureted engines. It gives you a fully programmable advance curve capability that mimics the ignition maps used by EFI systems — but is for carbs. It also has a digital engine kill switch/theft preventioin capability that cannot be defeated without replacing the distributor. You control it with a Bluetooth app on your phone.

Here is the link =>https://progressionignition.com

[767Jockey]

MSD boxes work well when they're working, but they're notoriously unreliable. I carry a spare in the trunk of my car. Whether yours is bad or not, I'd recommend you pick up another to carry with you. I put quality plugs (I used this kit with heavier duty plugs on the power and ground lines - https://www.amazon.com/Weather-Pack-...=A39ZZJ3OT79TI ) on each lead so that if I have to swap it out it's a 5 minute procedure rather than running new wires each time I need to swap it. It also makes troubleshooting in cases like this easy - I can very easily just swap the MSD box over to the other MSD box to confirm or eliminate the box as the source of any issue I may be having. Not only are the MSD boxes unreliable, but their failure can drive you nuts when trying to diagnose because the failures manifest themselves in many different ways.

I guess that's all a long winded way to say buy another box and swap it in to see if it helps. It won't cost much and I'd highly recommend that you carry a spare anyway so the money will need to be spent either way. It's also not a bad idea to pick up a spare magnetic pickup for the distributor to carry with you, as they're equally prone to failure as well. MSD stuff works really well but their products are sadly not very reliable.

[CompFi]

Thanks Jockey.

I have already learned plenty from this experience and feedback like yours.

Top of that list is the reliability of the box, or lack thereof. After I complete the Holley's instructions for tuning the carb, I will turn my attention to the box.

And good advice to carry the spare box, so I will incur the expense either way. Pretty sure that Sunman would agree.

P.S. Truly appreciate all the feedback from everyone. Currently working thru the initial tune of the carb. Painstakingly slowly, both due to my inexperience and some work conflicts. So, it might be a while before I update the thread with any progress. But either way, I will continue to update the thread.