Erratic idle

[diesel_lv]

I did my obligatory search and possibly just not searching the correct combination of words. 383 stroked to 496. Comp Cams Extreme Energy 230/236 hydraulic roller cam. 230/236 duration at .050, .541/.537 lift. 10.5:1 compression and 440 Stealth heads. FiTech Fuel injection. Edelbrock RPM manifold. Has idle vacuum at about 12-13" but fluctuates. Trying to set idle, looking at balancer w timing light, it bounces around. I want 14° at idle. 1st engine I've built w any sort of "cam". All engines I've built or worked on, timing is steady. Is this because of the cam, or is it possibly an underlying issue? Thanks in advance. N yes, vacuum disconnected and plugged while setting.

 

[451Mopar]

I have the FiTech PA controlling timing. Sounds like yours is a non-PA unit? or just using a normal distributor.
What is the idle RPM set at? I have seen some distributors with really light advance springs start advancing at a idle.
On the self-learning EFI, I usually just start with about 32-degrees total timing until the EFI learns for about 100 miles.
When you first start driving with the EFI, it won't be all that great until it learns a basic fuel map.
I has some issues with return to idle speed and had to make some manual adjustments, so even though the basic fuel map is self-learning you may have to manually make adjustments to the EFI.
I haven't tried this yet, but I think with the EFI, you could connect the vacuum advance directly to manifold vacuum (vs ported), this should advance the at idle after starting the car to help it idle smoother. Because of the advance the idle will want to speed up, but the EFI will compensate. Just need to adjust the hot idle to get the IAC around single digits values.

 

[diesel_lv]

I have the FiTech PA controlling timing. Sounds like yours is a non-PA unit? or just using a normal distributor.
What is the idle RPM set at? I have seen some distributors with really light advance springs start advancing at a idle.
On the self-learning EFI, I usually just start with about 32-degrees total timing until the EFI learns for about 100 miles.
When you first start driving with the EFI, it won't be all that great until it learns a basic fuel map.
I has some issues with return to idle speed and had to make some manual adjustments, so even though the basic fuel map is self-learning you may have to manually make adjustments to the EFI.
I haven't tried this yet, but I think with the EFI, you could connect the vacuum advance directly to manifold vacuum (vs ported), this should advance the at idle after starting the car to help it idle smoother. Because of the advance the idle will want to speed up, but the EFI will compensate. Just need to adjust the hot idle to get the IAC around single digits values.

I'm using a DUI Tri power HEI ignition. Stock electronic distributor w HEI module mounted on heat sink and 50k coil. Stand alone. They dyno curve the distributor based on cam n engine. Springs give 24° at 2,600 rpm. I guess I should actually want 12° at idle so I'm all in 36° at 2,600. IAC is all over, from 0-9 n back n forth. Again, nothing stays steady. I'm hoping it's just because of the cam. I'm gonna call them Monday about it, but hate wasting a weekend. How difficult is it to convert an electronic distributor to be controlled by the FiTech?

 

[451Mopar]

With the FiTech, I think only the power adder versions control timing. All the Sniper versions have that option.
On my '71 Charger 400 block 499" stroker 12.4:1 compression, and a 272/278@ 0.050" solid roller 0.726"/0.726" lift cam (not much vacuum at all)
Yes, the EFI works with a large cam, just took a bit extra adjustments to the unit.
I am using a factory lean burn distributor with the FiTech Go 8 (1200 PA) unit. It actually works fine. I checked the phasing with an old cap drilled to see the rotor terminal alignment.
The main thing with the EFI controlling timing is the rotor phasing.
With a stock distributor, You lock out all advance in the distributor, and re-phase the rotor by drilling a new reluctor pin hole in-between the reluctor teeth to change the rotor to cap phasing.

 

[diesel_lv]

With the FiTech, I think only the power adder versions control timing. All the Sniper versions have that option.
On my '71 Charger 400 block 499" stroker 12.4:1 compression, and a 272/278@ 0.050" solid roller 0.726"/0.726" lift cam (not much vacuum at all)
Yes, the EFI works with a large cam, just took a bit extra adjustments to the unit.
I am using a factory lean burn distributor with the FiTech Go 8 (1200 PA) unit. It actually works fine. I checked the phasing with an old cap drilled to see the rotor terminal alignment.
The main thing with the EFI controlling timing is the rotor phasing.
With a stock distributor, You lock out all advance in the distributor, and re-phase the rotor by drilling a new reluctor pin hole in-between the reluctor teeth to change the rotor to cap phasing.

You may be right. Mine is a Mean Street 800. I'll have to go through the instructions tomorrow about the timing. If so, I'll have to get the distributor recurved to only advance 18° at 2600 rpm.

 

[diesel_lv]

On the erratic timing, I noticed that the distributor shaft to drive gear has a bit of slop. Could that be causing the erratic timing? If so, is there a fix for that?

 

[Bee1971]

On the erratic timing, I noticed that the distributor shaft to drive gear has a bit of slop. Could that be causing the erratic timing? If so, is there a fix for that?

Yes

Yes , a locking collar on the distributor shaft where it engages the intermediate shaft

 

[Bee1971]

Also on your stock electronic distributor , how are the distributor shaft bushings themselves inside


What year is the distributor

 

[diesel_lv]

Yes

Yes , a locking collar on the distributor shaft where it engages the intermediate shaft

Thanks, I just did a bunch of research on that from your suggestion. Makes sense. But not sure if it will solve it completely. The slot in the "Brand New" bronze drive gear is a bit bigger that the blade on the distributor shaft. This still allows rotational play of the shaft once distributor is locked down.

 

[diesel_lv]

Also on your stock electronic distributor , how are the distributor shaft bushings themselves inside


What year is the distributor

It is a completely refurb, dyno curved distributor from DUI Performance Distributors.

 

[diesel_lv]

During my research, I've seen 3 things listed, shaft collar w .010 distance from drive gear, plastic bushing shimmed to proper distance and peening the blade end of the distributor so is doesn't twist in the gear slot. Does anyone know how the peening is done or have any pics. I've Googled the hell out of it n haven't found anything. Thanks.