3.9V8 Timing Cover on a 4.6V8

[garrycol]

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 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).

I know I will need to change the cam shaft but I have also 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.

Thanks

Garry

[SuperV8]

I think there were a couple of 3.9 timing covers. The interim cover adds the dizy drive and the crank driven oil pump.

You would need the correct sump and oil pickup to match the front cover.

This thread might be useful:
viewtopic.php?f=12&t=9729&start=15

[ChrisJC]

The 4.6 crank is about 20mm longer (approx), so you need what is effectively a sleeve to go over the nose of the crankshaft after the pulley to space it out to the crankshaft bolt. I think I got mine from RPi.

Apart from that already stated, the earlier cover will bolt straight on. There might be one crossbolt that interferes, but I can't remember if that's at the starter end or the oil pump end of the block.

The 4.6 engine does not have the drive gear for the distributor, so you will need a different camshaft that is a bit longer so it can have all of the distributor drive / oil pump drive stuff on it. But check the details of this as I forget those too!

Chris.

[GDCobra]

Given that you presumably already have:
A toothed wheel on the crank
An EDIS module
2 coil packs - Mounted and correcct length leads

I'd have though it would be much easier (possibly cheaper) to simply add in an ECU to control the ignition.
This would be much better than a distributor system. Personally I'd try not to use an EDIS as they must be a bit thin on the ground now and old but apparently they're quite reliable.

I will admit to being biased as I just hate distributors, they're like something out of the dark ages.

[Mc Tool]

Given that you presumably already have:
A toothed wheel on the crank
An EDIS module
2 coil packs - Mounted and correcct length leads

I'd have though it would be much easier (possibly cheaper) to simply add in an ECU to control the ignition.
This would be much better than a distributor system. Personally I'd try not to use an EDIS as they must be a bit thin on the ground now and old but apparently they're quite reliable.

I will admit to being biased as I just hate distributors, they're like something out of the dark ages.

Am I missing something here . I thought EDIS was " electronic distributorless ignition system" ( you can buy them new aftermarket) and if you dont use a distributor thats , by definition an EDIS so Im not sure if your for or against

[SuperV8]

Given that you presumably already have:
A toothed wheel on the crank
An EDIS module
2 coil packs - Mounted and correcct length leads

I'd have though it would be much easier (possibly cheaper) to simply add in an ECU to control the ignition.
This would be much better than a distributor system. Personally I'd try not to use an EDIS as they must be a bit thin on the ground now and old but apparently they're quite reliable.

I will admit to being biased as I just hate distributors, they're like something out of the dark ages.

Am I missing something here . I thought EDIS was " electronic distributorless ignition system" ( you can buy them new aftermarket) and if you dont use a distributor thats , by definition an EDIS so Im not sure if your for or against

EDIS would need an input signal (PIP & SAW) from an control module like original car ECU/megasquirt or megajolt for mapable ignition. Without one it runs at 10btdc 'limp home mode' - which is how "Garrycol" is running it.

[GDCobra]

Given that you presumably already have:
A toothed wheel on the crank
An EDIS module
2 coil packs - Mounted and correcct length leads

I'd have though it would be much easier (possibly cheaper) to simply add in an ECU to control the ignition.
This would be much better than a distributor system. Personally I'd try not to use an EDIS as they must be a bit thin on the ground now and old but apparently they're quite reliable.

I will admit to being biased as I just hate distributors, they're like something out of the dark ages.

Am I missing something here . I thought EDIS was " electronic distributorless ignition system" ( you can buy them new aftermarket) and if you dont use a distributor thats , by definition an EDIS so Im not sure if your for or against

EDIS would need an input signal (PIP & SAW) from an control module like original car ECU/megasquirt or megajolt for mapable ignition. Without one it runs at 10btdc 'limp home mode' - which is how "Garrycol" is running it.

That's my understanding of the situation, EDIS is simpley a box of trick used to fire the coils it doesn't decide on the timing value, this is why I'd rather have a single box of tricks to do it all. I'm currently doing it with an MS2 (only the ignition which is a bit a a waste of a large box of tricks), I tried the Nodiz system (which I think is now discontinued) but could not get it to work.

[garrycol]

Hey lets stop the discussion on EDIS and dizzy-less ignition right here - lets stick to questions I have asked and not divert.

I am not interested in going this route at the moment. To those who have tried to provide information on the main topic - thanks. I had not considered that there would be issues with the sump and will look into this.

Thanks

Garry

[GDCobra]

Hey lets stop the discussion on EDIS and dizzy-less ignition right here - lets stick to questions I have asked and not divert.

I am not interested in going this route at the moment. To those who have tried to provide information on the main topic - thanks. I had not considered that there would be issues with the sump and will look into this.

Thanks

Garry

No problem Garry, I've clocked your monica and I'll refrain from contributing to your threads in future. Good luck jumping through hoops to make your car worse than it currently is, I hope it all goes well for you.

[garrycol]

No problem Garry, I've clocked your monica and I'll refrain from contributing to your threads in future. Good luck jumping through hoops to make your car worse than it currently is, I hope it all goes well for you.

Thanks for that.

The reality is of course if I wanted to know about ECU and Injection issues - eg Mega Squirt and/or MegaJolt or any other ECU system I would have asked for that information as I have in the past. As it is I do have a Megajolt kit and a fully built MS3 but due to poor documentation and support in my country I have decided to stay with carbs and a dizzy - I have all the bits to revert back just need to clarify a few things such as camshaft, sump, and oil pump etc.

Thanks for your input.

Garry

[Mc Tool]

Poor documentation and support in your country ? Australia ? is that for everybody ........or just you . I mean Aus ( much as I hate to admit it ) is hardly backward in technology ..... or motorsport.

[Pistonsquirter]

Just buy a megajolt and plug it into your EDIS?

The spark map for a 4.6 on carbs is on the lr4x4 forum.

I’m doing it because it’s easier than a dissy, and also approximately 300 years more modern

HH

[paul c]

The crank spacer is required, I got mine from rimmerbros
https://rimmerbros.com/Item--i-LR012879SPACER
It says for pre 94, but the serpentine 3.9 needs it as well as it was designed for the short snout crank but the 4.6 is long snout. I used a 4.2 camshaft as was common in the US for 4.6 conversions on 3.9 defenders. They were 14cux injection but it seems to be working fine with my HS6 SUs.
The oil pump on the 96 on serpentine covers is crank driven.
I used the SUs and jetted them according to what I could find others using, with a factory spec needle. The cd175s I can't help too much with, but mine ran fine on my 3.9, I checked them with a colortune and seemed satisfactory. A dyno would be better if you can get to one.

[garrycol]

Thanks Paul - great information.

[unstable load]

Is a different camshaft not also required with the gear to drive the distributor?

I may be wrong, but what I think you are looking for is an Interim Cover which was fitted to engines that had the crank driven oil pumps but retained the distributor.
I'm not sure if it was a serpentine or V belt cover, though.