Engine LOSS OF POWER AT 4,000 RPM.

[AeroCoupe]

I will say that it would not surprise me if it was the MSD 6AL or the coil. I have seen a few of both fail and had a coil fail on me. In 2007 the coil literally came apart when I was headed to Dallas from Houston. This was a brand new coil I got from Summit Racing and it stranded me on the side of the road. I have not had a 6AL take a dump on me but all three of mine (one is a spare) are 20+ years old so hopefully they will just keep on keeping on.

 

[Noobz347]

Once it's back together it wouldn't hurt to crank it up and in the dark and look for lightning leaks.

 

[Jarhead67]

It doesn’t act like it’s a mechanical issue. I also suspect the MSD box. Those misfires at load, could you hear it out of the exhaust or intake; was it a set of big bangs, or just muted sounds, like a rev limiter would sound? Good luck.

It’s like a rev limiter, just stops making power at 4,000. No backfiring or any other noises.

 

[General karthief]

Let's make a clarification, it will physically not rev past 4k RPMs?
Observe the timing changes at the balancer while raising the RPMs.
I'm wondering if maybe the distributor is a tooth or two off.

 

[Jarhead67]

If these are gt40 iron heads, i agree with this. A 331 with those heads is a total waste.
Now should they float that at that low of an rpm? I'm not sure, someone more versed with cams and springs will have to answer that.
I had an engine way back that floated stock head springs with an E cam, it's an unpleasant feeling and sound, much like the rev limiter sound you are speaking of. I should have never done it in the first place.

Let's make a clarification, it will physically not rev past 4k RPMs?
Observe the timing changes at the balancer while raising the RPMs.
I'm wondering if maybe the distributor is a tooth or two off.

Will not rev above 4,000 rpm. Timing is right, car has excellent power up to 4,000

 

[Noobz347]

Will not rev above 4,000 rpm. Timing is right, car has excellent power up to 4,000

I've had this happen to me before but the difference is that mine occurred in a blown application.

It sounds like you got your hands full so, I'm waiting until you get a chance to rule out what you got going on before adding 'stuff' to the pile.

I am fairly convinced that this is an ignition issue. Valve float doesn't (in my experience) pick an RPM wall. It comes on more gradually. Others may have a different take on this part.

 

[Jarhead67]

Yea, but there’s no problem and then one day, 4k limit because the valve springs woke up and decided they no longer like that specific RPM. I doubt that is more likely than an ignition issue. Occam's razor people.

It didn’t happen overnight. That’s a ridiculous assumption.

 

[Mustang5L5]

I remember when my car suddenly decided it didn’t like to go past 3500 I chased fuel and other potentials for almost a year….


Ended up being the junk Accel coil, which was relatively new. Do you have another coil handy just to check that box off?

 

[Jarhead67]

I remember when my car suddenly decided it didn’t like to go past 3500 I chased fuel and other potentials for almost a year….


Ended up being the junk Accel coil, which was relatively new. Do you have another coil handy just to check that box off?

I can borrow one after I get the heads back on and it’s running if it’s still giving me trouble.

 

[89notchDude]

Speaking of coils, are the screamin demons pretty reliable? I just installed one a few months ago. No issues so far.

 

[89ripper]

Ive had one fail on me, in less than a year. I have the original coil from 1989 on my car....

 

[Jarhead67]

Ive had one fail on me, in less than a year. I have the original coil from 1989 on my car....

I know guys that have had good experiences with them.

 

[89ripper]

I know guys that have had good experiences with them.

Im happy for those that do. Maybe it was my fault? Either way, no reason for 89notchdude to take it off his car if its working for him.

 

[Noobz347]

Waaaaaaaaaay back the day, I tried several [coooooooooool] looking/sounding coils off the magazine pages to get that little [extra] HORZEPOWERZZZZZZZ and chasing down an intermittent stumble after a SC install.

Meh...

Meh...

Meh...

...and after [all] of that, I ended up with this:

I have often said that there is nothing [short] about the OEM ignition systems on FI Windsors. Unless you're over 500 HP, you really don't need to screw with it.

They came right off the factory assembly line [HOT!]. It's the [rest] of our electrical system that sucks. LoL

 

[Trogdor]

Whither the SPOUT connector plugged in, what does your timing do when you rev the engine?

 

[Jarhead67]

Whither the SPOUT connector plugged in, what does your timing do when you rev the engine?

Are you replying to me about my original post or to the posts about the coil?

 

[General karthief]

Coils,
The SHOCKING Truth!!
In theaters soon......
But seriously folks, I think it comes.down to quality control. Them big, ugly yellow Accel coils were about the only thing you could get and they worked great on points ignition and even the early CD ignition but the build quality suffered after getting scooped up by one then another big corporation.
And we all knows what happens when 'investors' get control of companies

 

[Trogdor]

Are you replying to me about my original post or to the posts about the coil?

With the engine running and the SPOUT connector plugged in check your timing. It will probably be bouncing around 10 to 20 degrees. When you Rev the engine it should slightly increase. Does the timing in your engine increase when you Rev the engine higher, or does it stay the same or decrease?

 

[Jarhead67]

With the engine running and the SPOUT connector plugged in check your timing. It will probably be bouncing around 10 to 20 degrees. When you Rev the engine it should slightly increase. Does the timing in your engine increase when you Rev the engine higher, or does it stay the same or decrease?

Don’t have a spout anymore, it’s got a Terminator X and Holly Dual Sync Distributor