Yellow Bullet Forums banner

1 - 6 of 6 Posts

·
Registered
Joined
·
1,742 Posts
Discussion Starter #1
I'm running a Crane hi-6 box using a HEI coil in cap distributor as the pick up on a carb 509 BBC.
This has been a solid combo for years, but suddenly, now when the engine hits 5000 rpm, it feels like the rev limiter kicks in, it just drops off and goes flat.
I've changed the coil, double checked all the connections and the voltage is steady at almost 14v.
Valve springs are good, Fuel pressure is good and the AFR seems to go a little rich when it happens... but I only have the gauge and no data logs.

So what is the procedure to test the box? I can't find anything on the web. Any help would be appreciated.
thx
 

·
Registered
Joined
·
1,754 Posts
Can you borrow a ignition box that is known to be good?


I had a similar problem a few years ago. Thinking that my MSD box failed, I switched over to a HEI module at the track and everything seemed better. I sent the box back to MSD but they said it was fine.

Before the box could get back, the car started acting up again. I tried a new pickup coil and plug wires without any luck. The MSD cap was fairly new and looked to be in good condition but I swapped it anyway, problem disappeared. I continued to use the same Wells cap until I pulled the engine earlier this year.
 

·
Registered
Joined
·
1,742 Posts
Discussion Starter #3
No one I know has a crane box and I don't want to rewire for a MSD... but the cap has not been changed. I will give that a try. Thx! and Merry Christmas!
 

·
Registered
Joined
·
1,742 Posts
Discussion Starter #4 (Edited)
I THOUGHT IT WAS FIXED! Thank you JuicedCoupe!!
New cap and rotor and it screams right up to 7K.
Same deal, MSD cap and rotor, everything looked good, no tracking, no marks, no signs of anything unusual what so ever.
 

·
Registered
Joined
·
1,742 Posts
Discussion Starter #5
I cut open the MSD rotor. The spring steel section could move around and maybe lose contact with the brass? I could wiggle it a little, but the brass was solid.
The studs on the cap that the plug wires go onto are also made out of two pieces.
Sensitive content, not recommended for those under 18 Show Content
Screen Shot 2019-12-21 at 5.50.19 PM.png
 

·
Registered
Joined
·
1,742 Posts
Discussion Starter #6
FIXED! Thank you JuicedCoupe!!
New cap and rotor and it screams right up to 7K.
Same deal, MSD cap and rotor, everything looked good, no tracking, no marks, no signs of anything unusual what so ever.
NOW ITS FIXED!!
# I Fuckin Hate Electrical Shit
One thing I forgot was I turned the rev limiter off, set it to 0-0, when I swapped the cap and rotor. So yesterday I remembered and switched it back to 6-7 (for 6,700)
I took the car out for a ride today and it fell on its face at 5,000 again. So I switched the rev limiter back to 0-0 and itls fine.
THE PROBLEM WAS THE REV LIMITER IN THE CRANE BOX

One other thing I did learn was that MSD makes a Heavy Dyty HEI rotor that has the contacts pinned togeter, 84101 is the part number
 
1 - 6 of 6 Posts
Top