RB Block with Eddy Heads......Distributor clearance issue's

[Propwash]

Hey Fella's.....

Engine guy did a mock up on the upper end of my 512. While trying to install the Billet Petronix Distributor (w/ Vacuum advance) the distributor body and cap hit the front inner corner of the Eddy head. I know some guys have run into the same issue with some of the MSD distributors. A little work with the die grinder and they can get them to slide in. Questions are: Anyone here running or tried to run the Petronix Billet Distributor with aftermarket heads? Is it even possible and if so, how much shaving is needed on the corner of the head? I don't want to go on a big excavating mission and end up screwing up a perfectly good set of eddy heads I poured a bunch of money into to accommodate a distributor that cost lest than 10% of the eddy's and the port/bowl/valve work done on them.

Also, what other distributors fit with no/minimal clearance work? I really wanted to stick with the Petronix, but if worse comes to worse I have no issue posting a For Sale ad here on FBBO. I do want to stick with Vacuum Advance though.

Thanks for your time

 

[RustyRatRod]

Jim (IQ52) would probably be a good one to know. I bet they've had that combination or one similar. If he doesn't see this, maybe shoot him a PM.

 

[64 Post]

Same heads and distributor on a low deck and yes had to grind the shiite out of the head. Like the distributor and the ease of adjusting the curve.

 

[Mopars & Missiles]

I just finished up my 499 with the Eddy heads. Using a MP electronic distributor with no clearance issues at all.

 

[Propwash]

Thanks guys!!! Appreciate the input.


Here's another one for ya......bouncing around the net, i'm reading the petronix V.A. isn't going to like a lower vacuum signal anyway. Cam in the car has a CL 110* 250/252@ 50 and advertised 289 duration, lift 570-580. My guess is i'll be at 8-10# of vacuum at idle anyways. I'm guessing the vacuum advance will have an issue with that and i'll end up with a jumpy/sporadic idle or usless V.A. . Honestly would it be better to ditch this distributor and just go with a decent mechanical advance (that fits!)....BTW, this is a street/strip car with a majority on the street. Got this distributor on money owed for sheetmetal work so i'm not going to start bawling or anything if I have to replace it..


Thanks again for your time/thoughts guys

 

[RustyRatRod]

Vacuum advance has no effect at idle. You'll be much better off with a vacuum advance on the street. Trust me.

 

[64 Post]

I went with the mechanical distributor, solid MM lobe Comp cam. Cam is 260/266 in at 109º .570" net lift. I never saw more than 7" vacuum from 20º-24º initial.

I think 8"-10" at idle is going to be pretty close.

 

[Mopars & Missiles]

You want a "ported" vacuum source for your distributor vacuum advance. No vacuum to the canister at idle, your only advance at idle should be your "Initial" that is set by rotating the distributor. Mechanical starts coming in around 1200 rpm. Vacuum is added on top of mechanical when you are at a steady state cruise speed. So, 3 distinct and separate types of ignition advance.

RRR is correct in his statements above, and yes you do want vacuum advance on a street car.

 

[Propwash]

Thanks for clearing that up M&M....Reading countless threads on the net, one guy says use Manifold vacuum, next says use ported an on and on and on...

If/When I do in fact find/pick a Vacuum Advance distributor that fits, will my low vacuum signal engine even be enough to make it count? Can the pot be changed out to another that will pick up on a lower signal?

 

[benno440]

i had same problem with the standard msd dizzy, then i found they make an extended shaft one so i bought that and it fits good.
not sure if petronix do same, some guys have used offset distributors, or maybe you could grind soem out of the head?
heres mine with the longer shaft dizzy

 

[Propwash]

Thanks Benno......Is that the MSD P/N 8546?

 

[Meep-Meep]

Count me in as another one who will always run a vac advance on a street car, and I always run off the the ported port.

 

[Propwash]

Thanks Meep! I'm heavily leaning towards the vacuum advance, like initially mentioned. Just need to know if I can get away with it, having low vacuum. Going off M&M's set up I can run the MP without clearance issues. I see 4secondsflat will custom curve and phase a MP for a guy. Wonder if that would be the route to go.

 

[RustyRatRod]

Yes. It will be fine. Your vacuum signal at part throttle where the vacuum advance works will be much higher than at idle. I would use one regardless of camshaft size if the car was street driven.

 

[eric383]

Prop, have you considered using an old style points type dist. Removing the points and converting to a Pertronix module? I've bought springs for these to recurve them also.

 

[Mopars & Missiles]

....I see 4secondsflat will custom curve and phase a MP for a guy. Wonder if that would be the route to go.

Yes, it makes a world of difference in engine performance. It isn't that difficult to do, you can do it yourself with a little patience.

 

[Propwash]

Thanks again fella's........Spent a good half hour on the phone with Don at 4 Seconds flat today. Super nice guy and really knows his stuff. Sent me his 20 or so page book as well via email. Going over all the variables of the roadrunner (cam, heads, gearing, weight ect...ect..), sounds like my best bet will be a mechanical with the springs recurved for a slip/loose spring at idle and just above and a higher tension spring for the top end. To keep the motor cool at low RPM I need to have a lot of of advance off the bat to toss in the spark a bit earlier in the lean burn scenario, but want that backed off for the more heavy throttle/rich conditions. Being the mechanical works off of RPM and not load, it sounds like the curving he recommends seems to be the best fit for basically running a borderline race engine in a street car. He said a vacuum advance would be a waste of time being it's gonna need at least 10" for the can to be effective. He stated my cam will run 6-8" and that's pretty much what comp cams had to say as well. I've read somewhere the Mopar Performance Dizzy's Vacuum advance can could be possibly swapped out with one that's triggered with a much lighter vacuum signal, but for the life of me I cannot find that part or article.