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reverse engine timing

H

Haj

New member
I have a Crusader 350 engine around 1976 reverse in a Riva power boat having problems timing it. To start with what are the ignition advance settings and what is the firing order. I have the firing order for the reverse engine as 18436572 distributor runs clockwise but if I do this firing order in a clockwise manner will not start. As it came the cables are set correct but in a anti clock wise manner engine starts and runs ok but quite a rough tickover. Have fitted electronic ignition and when I went to set with strobe light found markings on block to be other direction ie clock wise. Also other prob is will not start when hot. I think this is probably carb but need to get ignition correct before looking at this.

Also cannot find any engine numbers so not to sure as and what I have.
 
Timing details will vary with the specific year....if the engine is stock, you are usually safe with the initial at 8 deg BTDC and having a total advance between 30 & 32 deg BTDC @ 4000 RPM.

The RH firing order is NOT what you listed on a factory engine...it is 1-2-7-5-6-3-4-8 and yes, distributor spins "clockwise" when viewed from above...
 
I agree with Mark.

Let's start with the differences between a Std LH rotation SBC engine and a REV RH rotation SBC engine.

The wrist pin offset will be oposite (very important).
The camshaft profile will be correct for the reverse rotation.... it may be chain driven, or it may be twin gear driven.
If chain driven, the cam will follow crankshaft rotation.
If twin gear drven, the cam will remain rotating in the Std rotation... although the profile will be for a RH rotation.

If chain driven, the helical cut on the both the cam drive gear and the distributor driven gear will be special for this rotation.
When all is said and done..... the oil pump and distributor will rotate in the same direction as the Std LH engine.

The front and rear seals will be unique for REV RH rotation.

And of course the starter motor will need to be correct for this rotation.


#1 cylinder will always be the Forward-most cylinder...... doesn't matter which engine.
Firing order always begins with #1 cylinder.
As Mark said.... the SBC firing order now changes from the Std LH of 1-8-4-3-6-5-7-2 to the REV RH of 1-2-7-5-6-3-4-8.

When you place the spark plug wires into the distributor cap, you'll still begin with #1, but #1 will now be followed by #2, and so on.... and in a CW direction from #1..... same CW direction as the Std LH rotation engine.

TDC markings will be the same, since #1 TDC is #1 TDC all day long.... (but it gets tricky here)



While strobing the timing marks, instead of seeing your ignition advance lead away to the Stdb side of TDC, it will now lead away to the Port side of TDC.
IOW.... just oposite!

Since the Std LH engine timing tab does not offer but a few degrees in this direction, your best bet will be to mark off the balancer up to approx 35* in the oposite direction.
IOW, just oposite of this Std LH rotation balancer.

Now you'll use the tab's ZERO notch only for any and all timing.


Your BASE advance should be the same as is with the LH engine.
Your progressive advance and your total advance should also be the same.

Basically, this REV RH rotation engine won't know that it's turning oposite from standard unless you tell it. :D


Just to be clear.... engine rotation is determined as though viewing from behind the flywheel end of the engine.



.
 
Last edited:
RicardoMarine said:
I agree with Mark.

Let's start with the differences between a Std LH rotation SBC engine and a REV RH rotation SBC engine.

The wrist pin offset will be oposite (very important).
The camshaft profile will be correct for the reverse rotation.... it may be chain driven, or it may be twin gear driven.
If chain driven, the cam will follow crankshaft rotation.
If twin gear drven, the cam will remain rotating in the Std rotation... although the profile will be for a RH rotation.

If chain driven, the helical cut on the both the cam drive gear and the distributor driven gear will be special for this rotation.
When all is said and done..... the oil pump and distributor will rotate in the same direction as the Std LH engine.

The front and rear seals will be unique for REV RH rotation.

And of course the starter motor will need to be correct for this rotation.


#1 cylinder will always be the Forward-most cylinder...... doesn't matter which engine.
Firing order always begins with #1 cylinder.
As Mark said.... the SBC firing order now changes from the Std LH of 1-8-4-3-6-5-7-2 to the REV RH of 1-2-7-5-6-3-4-8.

When you place the spark plug wires into the distributor cap, you'll still begin with #1, but #1 will now be followed by #2, and so on.... and in a CW direction from #1..... same CW direction as the Std LH rotation engine.

TDC markings will be the same, since #1 TDC is #1 TDC all day long.... (but it gets tricky here)



While strobing the timing marks, instead of seeing your ignition advance lead away to the Stdb side of TDC, it will now lead away to the Port side of TDC.
IOW.... just oposite!

Since the Std LH engine timing tab does not offer but a few degrees in this direction, your best bet will be to mark off the balancer up to approx 35* in the oposite direction.
IOW, just oposite of this Std LH rotation balancer.

Now you'll use the tab's ZERO notch only for any and all timing.


Your BASE advance should be the same as is with the LH engine.
Your progressive advance and your total advance should also be the same.

Basically, this REV RH rotation engine won't know that it's turning oposite from standard unless you tell it. :D


Just to be clear.... engine rotation is determined as though viewing from behind the flywheel end of the engine.



.
Click to expand...
Thanks this is what I was thinking and wondered why no timing marks. Other problem having is getting correct rotor arm. I have mallory distributor with a flat top cap. The only rotor I seem to be able to find is a small spindle type and need the larger spindle type. I have been sent the small spindle type part no 9-29210 I have fitted a different one part no 9-29211 of which I have had to bastardize to make it work ie diameter needs to be greater. Not sure of distributor as numbers scratched off. Think engine number could be 93502 but have been told this is incorrect

Many Thank Haj
 
Haj said:
Other problem having is getting correct rotor arm. I have mallory distributor with a flat top cap.
Click to expand...
Do your engine a favor, and get rid of the old flat cap YL distributor.
You'll pay dearly for a new cap, and still end up with a very outdated ignition system.
 
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