Logo
FULL SITE MENU

Distributor question

S

srfdude

Member
Brand new MK IV 454s, new cooling top to bottom, new edelbrock manifolds/carbs. Finally the last thing is distributors. Any suggestions which would be best?
 
Im not a fan of EST (electronic spark timing), but the industry has gone with these.
With EST the system is initially set as to see full spark lead (advance). Via the electronic controller, the spark event is then delayed. The delay is then altered as per engine speed as per OEM ignition specs!

The other option is the ole tried/proven mechanical advance. Many of the mechanical advancing systems are adjustable.


I prefer VR (variable reluctor) over photo-eye triggering.


Ignition distributor style “Hall Effect” triggering would be my least desired. (Pertronix for example)


Which ever system you decide to go with, make certain that you find your OEM ignition advance curve.
Make sure that your new system is delivering this exact correct advance curve throughout the RPM range.


I would strongly suggest that you properly mark off your harmonic balancer up to approximately 35° BTDC. These marks will assist in verifying that the correct curve has been established. This also allows the use of a standard style strobe light so that we see Real Degrees in Real Time.
In other words, it reduces the risk of user-error or equipment-error as with a digitally advancing timing light.


.
 
Last edited:
The manual shows entirely different curves, dependent on the distributor module. That is somewhat puzzling as the curves should be the same for proper engine operation. At any rate the distributors shown are old and not current. One side had had an old truck carb with vacuum which was hooked up to a distributor which was so green inside as to make identification nearly impossible. Don't know how it ran, although it obviously had no advance. Which distributor would be an example of VR operation?
 
srfdude said:
1) The manual shows entirely different curves, dependent on the distributor module. That is somewhat puzzling as the curves should be the same for proper engine operation.

2) Which distributor would be an example of VR operation?
Click to expand...

1) yes, the engine design and intended usage should dictate the ignition advance curve.

2) Mallory YLM would be VR.
With exception to the tall block, the YLM 624 AV is for the STD LH Rotation GM V-8.



.
 
srfdude said:
The manual shows entirely different curves, dependent on the distributor module.
Click to expand...

A more detailed description here would help clarify what you are getting at.

As far as the distributor goes, a lot depends on how you define 'best'.....some prefer the simplicity of the EST concept and some of us prefer to tune the advance curve in the distributor to the engine it's installed in.

Several members hear have used the Davis Unified (D.U.I.) system and report being happy with the results....
 
[h=1]This is what I replaced my distributer with and It was a very easy switch to do. My small block chevy starts and run's much better with it.

Distributor, Chevrolet GM V8, Electronic Ignition - 18-5494-1[/h]

​
83477F-p.jpg


[h=3]Mfr. Sierra[/h]
See Products
$639.34 ​
Distributor, Chevrolet V8, Electronic Ignition - 18-5494-1 is for use on a Pleasurecraft Inboards, Mercruiser Inboard/Outboards and Crusader Inboards - Regular and Counter Rotation.
  • For use on Pleasurecraft Inboards, Mercruiser Inboard/Outboards and Crusader Inboards
  • Replacement for Mallory and Sterndrive/Cobra Inboard/Outboard #YLM624AV
  • Conventional Rotation
  • For all Chevrolet V-8's including 482, 502, 540 CID, except 348, 409 & Tall Deck Big Block




​
Part No.Mfr No. Unit Leaves Warehouse* List Price Your Price
 Qty.
Electronic Ignition Distributor - 18-5498-1
92665 18-5498-1 Each In-Stock: 1 Day

$692.41 $639.34



* Leaves Warehouse: Does not include Weekends and Holidays.
When will my order arrive? Add the Estimated Leaves Warehouse Time + Estimated ShippingTime.

 
Use caution.
The Sierra info suggests that this unit is a “replacement” for the YLM624AV.
I have seen Sierra substitute the VR with a Hall Effect unit and with a Photo-eye unit.

If you want VR, you may need to ask questions and/or specify!

.
 
Last edited:
makomark said:
A more detailed description here would help clarify what you are getting at.

As far as the distributor goes, a lot depends on how you define 'best'.....some prefer the simplicity of the EST concept and some of us prefer to tune the advance curve in the distributor to the engine it's installed in.

Several members hear have used the Davis Unified (D.U.I.) system and report being happy with the results....
Click to expand...


I installed DUI distributers on my 454s 3 years ago with no issues.
 
I'm running a pair of pertonix marine complete distributors on mine. Dropped in, set timing, been running great for 2 seasons. think they were on sale for around $250 each at summit or jegs
 
Back
Top