Posted By: Dr V
69 Hemi is breaking up at 3200 rpm. Its Fixed!!!! - 05/29/12 02:59 PM
Well, I have the hemi back in my 69 black RR. Custom 3000 stall, motor is 40 over with orig manifolds, mild cam, brand new restored orig carbs, new firecore wires, mopar electronic ign, electric and mech fuel pump with 10 psi at idle and 6 psi under full throttle. Car idles wonderful and rips the tires off from the line but it seems to break up (seems electrical) at about 3200 rpms when the pedal is to the floor. Seems to choke and it wont pull hard all the way. Im at my wits end.
Posted By: Challenger 1
Re: 69 Hemi is breaking up at 3200 rpm. Help! - 05/29/12 03:06 PM
My
I have installed 3 brand new MP distributers right out of the box.
All 3 would breakup under load, I ohmed the pickups and all three were different than stock pickups that I had laying around. So I installed used pick ups in all 3 distributers and the breaking up went away.
3 times I experienced this with MP distributers and all 3 times replacement pickup fixed the problem.
Posted By: Dr V
Re: 69 Hemi is breaking up at 3200 rpm. Help! - 05/29/12 03:10 PM
Ya know, I am leaning towrds the distributor too, Its the only thing that I havent replaced. Literally!! I changed the box from orange to chrome, no change. Do I just order a new one from mancini or summit? Whats best??
Posted By: Challenger 1
Re: 69 Hemi is breaking up at 3200 rpm. Help! - 05/29/12 03:22 PM
Got any old distributers laying around that you could borrow a pickup from to see if it's the problem?
Posted By: RapidRobert
Re: 69 Hemi is breaking up at 3200 rpm. Help! - 05/29/12 03:29 PM
try disconnecting the vac advance & see if that makes it better or worse. rotor phasing.
Posted By: Dr V
Re: 69 Hemi is breaking up at 3200 rpm. Help! - 05/29/12 03:48 PM
All I have at home is an original points dist that came out of my 68 charger 383.
Posted By: Dr V
Re: 69 Hemi is breaking up at 3200 rpm. Help! - 05/29/12 04:00 PM
RapidRobert, I run the car with it plugged.
Posted By: Silverbullet2
Re: 69 Hemi is breaking up at 3200 rpm. Help! - 05/29/12 04:58 PM
Not champion spark plugs is it?
Posted By: Dave Watt
Re: 69 Hemi is breaking up at 3200 rpm. Help! - 05/29/12 05:58 PM
I agree to change out the distributor pickup first.
How old are the valve springs? What brand are they?
My buddy's Hemi had Mopar Performance "Hemi" valve springs in it, wouldn't rev up anymore. We went through the carb and distributor, then fuel pump before finally checking the springs. They were shot.
Posted By: 67Satty
Re: 69 Hemi is breaking up at 3200 rpm. Help! - 05/29/12 05:59 PM
maybe try setting the reluctor gap? My 440 with a brand-new distributor was doing the same thing. I checked and found the reluctor gap was set a mile wide. I reset it to .008 and all was fine.
Posted By: 67Satty
Re: 69 Hemi is breaking up at 3200 rpm. Help! - 05/29/12 06:12 PM
Yeah, that one. You're supposed to use a brass feeler gauge. The spec is .008 for 440s. I don't know if it's the same for Hemis.
It's best to have the distributor out to set it, that way you can spin it through some revolutions because there are going to be tight and loose spots since it's not going to spin perfectly with no runout. For example, I set mine with the distributor in the car just in one spot. Then fired up the motor and ended up with some little plastic shavings where it found a tight spot in the rotation.
Posted By: Dr V
Re: 69 Hemi is breaking up at 3200 rpm. Help! - 05/29/12 06:29 PM
So the gap for each fin should be .008???? Thanks, I will look at that tonight after golf league, If im not seeing straight then tmrw afternoon it is!! Thanks..
Posted By: 67Satty
Re: 69 Hemi is breaking up at 3200 rpm. Help! - 05/29/12 07:38 PM
Yeah, .008. But it's not super critical. It will run fine if it's anywhere close to that. But if it's too wide a gap, like really wide, you will sputter at higher RPMS under load. But set it at it's tightest point. That way you won't be shaving plastic because the distributors, even the new ones don't have perfect runout.
Here's a good thread:
https://board.moparts.org/ubbthreads/showflat.php?Number=5393292
Posted By: Dr V
Re: 69 Hemi is breaking up at 3200 rpm. Help! - 05/29/12 08:25 PM
I will check that gap for sure. What would make it go out of wack? Bad bushing in the shaft or something?
Posted By: RapidRobert
Re: 69 Hemi is breaking up at 3200 rpm. Help! - 05/29/12 08:52 PM
locking screw loose or gap set incorrectly in the beginning
Posted By: Exit1965
Re: 69 Hemi is breaking up at 3200 rpm. Help! - 05/30/12 12:51 AM
Someone checked the piston/valve clearance? Hopefully it's a long shot but I had a 383 which similarly hit a wall around 3000 rpm, which was valves smacking pistons.
Posted By: Dr V
Re: 69 Hemi is breaking up at 3200 rpm. Its fixed!!! - 05/30/12 10:33 PM
Thanks to all for the advice, I set the gap on my new distributor today, installed it, set my final at 36.5 degrees. Took her down the road and the car runs like a raped date!!!!! The plate that the pickup sits on in the old dist was flopping all over. Something broke inside or the bushing let loose because the pickup was mobile . Im thrilled. Thanks Gang!!!