Thread: 3.9V8 Timing Cover on a 4.6V8

I have a 4.6V8 fitted to a vehicle that was originally fitted with a 3.5. It has the 3.5 carbs and inlet fitted but still has the 4.6 timing cover - is currently running an EDIS 8 module on the 10 BTDC default mode and actually runs well. I was intending to but MegaJolt in it to control the ignition but am thinking about just putting a dizzy on it.

I have a serpentine 3.9 engine and I understand it will just bolt up to the 4.6 block. I will used the old dizzy from the 3.5 which was a converted electronic Holden Bosch unit with amplyfier etc. Worked well.

So does a 3.9 timing cover just bolt up to the 4.6 and where is oil pump on a 3.9 V8 - the 4.6 is in the timing cover running off the crankshaft where the old 3.5 it runs off the cam shaft with the dizzy drive - what is it on a late 3.9 (about 97).

Also I have heard in doing this conversion a spacer is needed on the end of the 4.6 crankshaft to fit the 3.9 timing cover - is this so and where would I get this?

Also for the moment I am staying with the 3.5 175CD carbs which are currently set up for the 3.5 and actually run the 4.6 pretty well - what changes are needed to the carbs for the bigger engine. Can I just get these bits and put them in or do I need a carb expert to do it.

I may change to injection etc at a later date but for the moment just wanting to keep it simple.

Thanks

Garry

G`day ,

the 4.6 crank nose is longer than the 3.9 but the keys and keyways are the same just the extra length of shaft for the 4.6 .

If you use all the 4.6 pulleys there won`t be the need for a spacer but i remember something about the 4.6 cover being thinner in places so may be no spacer but pulleys may not line up .

If you use all the 3.9 pulleys you will need the spacer because of the extra length of the 4.6 crank but they will line up without drama .

The spacer is the thickness of the crank driven pump which as it happens is the same thickness as the distributor drive gear 3.5 and 3.9 that fits on the cam shaft .

I have used one of these cam drive gears by removing the teeth .

This is all along time ago but 22.5 for the thickness 60 dia with teeth is what i recall .

The 3.9 cover the one you mention will have the crank driven pump like the 4.6 and will bolt on .