Distributor setups for L78 or L72 engines?

Chevy454 · #1 10-14-2006, 12:59 AM

What are your plans for the car? Is it the GM hei setup??

Jeff H · #2 10-14-2006, 03:04 AM

The car is just going to be a fun driver and it has a GM HEI distributor in it now. It starts right up and the plugs look great so I plan on keeping the HEI. I checked timing after work tonight and with the vacuum advance disconnected I had about 10-12 initial and 36-38 total timing. It seems to like these settings and idles around 625 to 650 rpms. My factory tach is reading high around 1050-1100 rpms but the multi-meter is reading the 625-650. It felt pretty good tonight doing a quick test drive so I'll probably leave it as is.

**WILMASBOYL78** · #3 10-14-2006, 03:25 AM

625-650 rpm for an L78 motor seems a little low...??? what kind of vacuum reading do you have at idle?

wilam

Jeff H · #4 10-14-2006, 03:36 AM

The vacuum reading is around 14-15 at idle. It's definitely a low idle but the car has no problem at this idle speed. If I advance the timing a little I will get some pinging. If I turn up the carb idle speed it tends to get hung up a little so I like it where it's at right now. The carb is a tweaked Holley 750 that I don't really like with the modifications to it so I'm trying to get an original 4557 rebuilt. The engine has some 71 oval port heads so the compression is probably lower than a stock L78.

**WILMASBOYL78** · #5 10-14-2006, 04:20 AM

14-15" of vacuum for an L78 cam motor is good...maybe the lower compression of the oval ports helps. I only get 11-12" on any of the original cars. Eric (vintage musclecar) is a good source for a rebuild of that 4557.What intake you running on those oval port heads?? Does the motor ahve the L78 cam??

wilma

Chevy454 · #6 10-14-2006, 05:55 AM

[ QUOTE ]
The car is just going to be a fun driver and it has a GM HEI distributor in it now. It starts right up and the plugs look great so I plan on keeping the HEI. I checked timing after work tonight and with the vacuum advance disconnected I had about 10-12 initial and 36-38 total timing. It seems to like these settings and idles around 625 to 650 rpms. My factory tach is reading high around 1050-1100 rpms but the multi-meter is reading the 625-650. It felt pretty good tonight doing a quick test drive so I'll probably leave it as is.

[/ QUOTE ]
I'm not a fan of the GM hei pieces...while they will work, *IMO* they look out of place, and believe it or not a good points system can work just as well. Anyway, when is your total timing in? And what compression & pistons you running?

**Salvatore** · #7 10-14-2006, 07:43 AM

"A good points system can work just as well".....We agree on something! WOW. I totally agree on a good distributor set up with a set of points.

mbxlesney · #8 10-14-2006, 04:06 PM

On my L78 Nova Iam going with a restored stock 1112000 distributor with a Crane pointless ignition with the built in rev limiter. so I can retain the stock appearance and not having the hassles of points. The GM HEI units in the mid 70s are great units but seem to remember a firewall clearance issues on 1969 Camaros and same period Novas.

Chevy454 · #9 10-14-2006, 06:19 PM

[ QUOTE ]
On my L78 Nova Iam going with a restored stock 1112000 distributor with a Crane pointless ignition with the built in rev limiter.

[/ QUOTE ]
Not to discrourage you, but I heard in Stanton this year of some folks having some problems with the Crane unit...I'm not sure if Casey Marks tried one of the Crane units or not, but I do know he found that a set of points whooped the snot out of the Pertronix on the dyno...

VintageMusclecar · #10 10-14-2006, 06:59 PM

[ QUOTE ]
...I'm not sure if Casey Marks tried one of the Crane units or not, but I do know he found that a set of points whooped the snot out of the Pertronix on the dyno...

[/ QUOTE ]

Rob;

That's the 3rd or 4th time I've heard someone say that (re: Pertronix). Can you give some details?

Eric

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