My 4.6 V8 Rebuild Thread

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Originally Posted by davidsonsm

Totally agree with the aim being mild enhancement rather than hot rodding.

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The only hotting up is putting in the 4.0 pistons and putting a Crow 4.6 Touring Cam which gives a bit better torque but a little higher in the rev range to assist highway driving. In the 101, even the old 3.5 has enough grunt offroad at lower revs and just going to a 4.6 will make that better. Where the 3.5 in the 101 runs out of grunt is at 100kph and around 3,000rpm and this is where I am wanting an increase in power and torque so it will hold this sort of speed and not die on hills.

Cheers

Garry

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Originally Posted by garrycol

No you make some good points. The 4.0 pistons are out of a low compression engine so should give a compression ratio of about 9.1:1 in a 4.6 - were there any 4.0 high comps sold in Aussie vehicles? Now I have not actually ccd the pistons to make sure so I might just do that.

Thanks

Garry

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IIRC the last of the D2s prior to the release of the D3 were imported by LRA with the HC 4.0 V8 engine. I'm not sure if they also didn't have the HC version of the 4.6. There was certainly a NAS HC 4.6 version of the D2. Am sure some of the D2 afficianados will be able to enlighten us!:D

I think all 4.0s and 4.6s in the US were Hi Comps.

Work has started again.

Over the past two weeks I have had the 4.0 conrod/piston units and the 4.6 conrod/piston units disassembled and due to my inconsistent readings in trying to weight the 4.6 conrods I put the 4.6 conrod/gudgeon/4.0 pistons into the rebuilding for balancing and reassembly - and installing the new piston rings. After carefully measuring the volume of the bowl in the 4.0 LC pistons I have calculated that they will give me a comp ratio of about 9.0:1. A handy increase over the standard LC 4.6 pistons.

I also had the heads refurbished - no major issues with the heads and just needed a light shave, relap and new seals.

So I am now ready to start assembly which I will do after Christmas.

The next decisions are what to do with a timing chain and gears - the old ones have had minimal use and the engine will not be a high mileage unit in the 101 covering only about 4000km a year however new may be better. The other aspect is getting alignment correct given comments that the marks are not accurate.

The other consideration is lifters and pushrods - again the current ones have had minimal use do subject to detailed inspection will most likely use them. I will use the standard rockers. I have been reading the recent threads on setting the clearances which is good information as I thought being hydraulic they would look after themselves.

Costs are starting to build up - noting I started with free components

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Originally Posted by garrycol

Cost so far - shipping included.

• 4.6 block, crank, pistons and rods - Free courtesy of a generous AULRO member
• Top Hatted 4.0 engine - a couple bottles of Bundy from a generous friend and AULRO member
• Block welding - $110
• Block helicoil - $55
• Block work and crank machining - $593
• ARP Head studs and main studs - $439.34
• Gaskets and bearings - $495.11
• Rings - $228
• Crow Cam - $360.80

So without actually putting anything together costs so far are around $2300. So the costs do mount up.

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To those costs we add:

• Disassemble 16 rods/pistons, reassemble 8 rods and pistons - $266
• Balance rods and pistons - $96
• Refurbish two heads - $502
• Valve seals - $35

So costs so far is about $3200 so a good used 4.6 would be a cost effective option to a full rebuild.

New cam = new lifters. It's cheap insurance from causing premature wear on it.

About to start the actual build now that Christmas is over - just waiting for the weather to get better and I have to clean up the garage.

I need to buy new lifters and push rods but planning to use the old rockers. I also need to buy a timing chain kit so will be asking questions at the time on how best to to the valve timing in view of the issue of the timing marks not being correct in some cases.

I am also wondering if i made the right decision in going dizzy less but I have the cam so am now locked in - ultimately it will be best but having a dizzy means I would not need computer control to get the engine going. Other than megajolt/squirt does anyone know of a cheap electronic ignition system that does not use a dizzy. But then I might as well just splurge now and get the full on megasquirt system now.

The question of the day is - I do not have a front crankshaft pulley for the 4.6 but I do have a serpentine pulley off a 3.9 and the V belt pulley from the 3.5. (both are still on their engines).

Will either of these fit the front of the 4.6 crankshaft?

I have not yet decided whether to go serpentine or V belt as there are issues with both. I have all the V belt gear such as tensioners and the alternator is twin V belt. If I go serpentine I will have to get a tensioner, which I can get but would have to convert the alternator to a serpentine pulley. I am leaning towards V belt if the V belt crank pulley will go, so advice would be appreciated.

Thanks

Garry

G`day Gary ,

as i read it ,

with the cover your using being a 4.6 type you have to use the serpentine water pump which rotates in the opposite direction to the V belt type unless you intend changing the impella on the serp type .

We have 2 using the crossbolt type engine lump 84/5 and 94/5 classic type RRs , the 85 using V belts and the 95 using serpentine belt .

Both use distributors with their respective covers , 3.5 and 3.9 and both use thier respective crank balancer/pulley .

So yes , either balancer/pulley set up will physically fit on the 4.6 nose but in your application a bit more thought will be needed .

The 3.5 and 3.9 front pulleys both bolt on , the 4.6 front pulley is actually grooves machined into the balancer .

The 3.5 (any) and (3.9) any timing covers are thicker than 4.0/4.6 covers .

This is a reason why rollmaster timing sets can be used in any 3.5 or 3.9 timing cover and not in 4.0 or 4.6 timing cover .

The distributor or lack of is the reason for the 2 thicknesses .

The waterpump is set back more on the 4.0/4.6 because of this difference and so will the pump pulley be so as said a bit more thought for your application .

Peter

Edit !! So it dawned , you have a 3.5 and 3.9 cover which you will use and blank the diss hole so all the respective to each will bolt up and you can then also use rollmaster if you want and sorry post above edit is mostly a waste of space .

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Originally Posted by PLR

So yes , either balancer/pulley set up will physically fit on the 4.6 nose but in your application a bit more thought will be needed.

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Thanks for all the information - yes you are correct that more thought is required - hence the question so I can work out exactly what I can do and cannot do. I was not aware the 4.0, 4.6 water pump turned the opposite direction - I assume it is an impellor thing rather than the water flow around the engine being opposite to earlier engines. I will have to have a good look at this aspect if I go V belts.

Quote:

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Originally Posted by PLR

Edit !! So it dawned , you have a 3.5 and 3.9 cover which you will use and blank the diss hole so all the respective to each will bolt up and you can then also use rollmaster if you want and sorry post above edit is mostly a waste of space .

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No your initial thoughts were correct. I am intending to use the 4.0/4.6 timing cover and have a new Crow camshaft that suits. I have the old 3.5 engine that I want to leave intact and an old complete 3.9 that I can take bits off but was not intending to use their timing covers as the new camshaft will not suit their use.

Cheers

Garry

I found I had to grind away quite a bit of the Distributor shaft casting in the front cover of my 3.9 to be sure of clearance for a Rollmaster chain and gear.

Regards Philip A

The cover won`t effect which cam you use , the difference is your new cam can`t drive a distributor because there`s nowhere for the gear to go .

A 3.9 cover will have the later pump type and all the serpy bits can bolt on .

Some V belt water pumps have straight vanes some have angled all serpy type i`ve seen have angled vanes .

Edit ...

Just had a look in the shed .

Serpy impeller vanes are angled anticlockwise and V belt impeller vanes are angled clockwise .


The 2 V belt pumps i have have cast impellers but the serpy type i have and any i`ve seen are pressed tin .

The serpy type would not mirror or go on upside down/backwards because each vane has a flat on it and i would likely be destroyed removing it .

The V belt impeller is about 3 times the diameter of the serpy impeller so they can`t be interchanged .