My 4.6 V8 Rebuild Thread

For ease of use I have decided to stay with the 8.25:1 pistons - power and torque a little less but easier to manage when in service.

Went to pick up the block today but they have not given it a hone so that is being done tomorrow for a pick up tomorrow night. I will take the crank, rods and pistons down tomorrow.

That leads me to to next consideration.

Being a 4.6 crank it did not run a dizzy so has a different timing cover to the dissy V8s. I am intending to put the timing cover, oil pump etc off a 3.9 on the 4.6 and not use the cover etc off the old 101 3.5 (is different again from the Rangie 3.5).

I have something in the back of my mind that the front end of the 4.6 crank is too short for the dissy timing cover and will have to be lengthened. I believe a spacer is needed to be made up (can these be bought).

So can someone please clarify what I need to do to the 4.6 crank so that it will run a dissy timing cover and a V belt front crank pully? (this will be coming off the 3.5)

Thanks

Garry

I think the spacer pushed the pulley forward to clear the cover, else it rubs.

If running the original pulley it may be ok?

Have you considered ditching the dizzy and going to an aftermarket spark only computer? A fairly cheap option that'll give some more reliable results and you can use ford coil packs or other individual coils to keep it cheap.

Quote:

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Originally Posted by clubagreenie

I think the spacer pushed the pulley forward to clear the cover, else it rubs.

If running the original pulley it may be ok?

Have you considered ditching the dizzy and going to an aftermarket spark only computer? A fairly cheap option that'll give some more reliable results and you can use ford coil packs or other individual coils to keep it cheap.

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Yes the spacer does push the pulley forward - I will be running the 3.5 V belt pully rather than the later serpentine pully.

I have considered using coil packs - but if I use the dissy timing cover I retain the option of using one or the other.

Thanks for the feedback - keep it coming :).

Garry

I just compared the 4.6 low compression pistons and conrods with the 4.0 low compression pistons and conrods and for the life of me I cannot tell the difference between the two.

I got the calipers out and all the measurements I took indicated both pistons and conrods are the same dimensions. So is there a difference between the two.

Conrods on the 4.6 have part numbers HRC2382SDF4 for seven of the rods and the eighth rod ends with SDFS5 - why would there be a difference.

Conrods on the 4.0 have part number HRC2382SDF75 but the bits I measured seem to have the same dimensions as the 4.6 conrods.

So what are the differences in conrods and pistons between the 4.0 and 4.6 engines?

Cheers

Garry

Did you measure the distance between the piston top face and the small end bore?

Quote:

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Originally Posted by bee utey

Did you measure the distance between the piston top face and the small end bore?

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Yes - no difference.

It would seem the difference in the engines is just in the crank.

Garry

Well there must be a length difference in the con rods or the pistons would poke out of the bores at TDC.:eek: Are you quite sure the 4.0 isn't actually a 4.6 already? It had been relinered, after all. can you compare stroke with the cranks out?

Quote:

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Originally Posted by bee utey

Well there must be a length difference in the con rods or the pistons would poke out of the bores at TDC.:eek: Are you quite sure the 4.0 isn't actually a 4.6 already? It had been relinered, after all. can you compare stroke with the cranks out?

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Hmmmm - there is a saying something about measuring twice.:o

Just checked the 4.0 crank - beside having 4.0 cast into it the distance between the centre of the mains and the centre of the big ends is noticeably larger on the 4.6 crank which has 4.6 cast into it.

So - remeasure the pistons - no difference between the 4.0 pistons and the 4.6 pistons that I can see.

So measure the distance from the bottom of the little end to the top of the big end - oh dear :( there is now a 5mm difference that was not there before :angel:. So the 4.6 conrod is about 5mm shorter than the 4.0 conrod but from what I can see the 4.0 and 4.6 pistons are the same.

So I then measured the two 4.6 conrods that had different part numbers - except for the cast in part number no difference was observed.

Thanks

If you are going to run a dizzy why not use one from an early RRC, I have an 85 RRC with the electronic dizzy and seperate guard mounted amplifier with coil mounted on top,out of the engine heat unlike the later dizzy with amp on the side of it,my motor is a 19D 9.35:1 running carbs 175CD-SE, and LPG getting 5+klms to the litre of gas. set at 8 before starts on gas unless O/night temp drops below 8*then petrol until temp and change by running carbs dry and switch as the motor dies.;) Distributor is Lucas 35DM8 41980B plugs NGK BKR-6-EKB or NGK-BPR-6ES

Hope that is of help

cheers

G`day ,

the spacer your thinking of is for use when using the 3.9 crank oil pump cover or the normal 3.5 cover .

The spacer sits inside the balancer so the bolt in the end of the crank tightens on the balancer .


If you use the 3.5 you have or any other 3.5/3.9 V belt cover it will need a spacer .

If you use a cover of a 3.9 serpy belt it still needs a spacer .

The 3.9 and 3.5 V belt crank noses are the same length and keyway/key length .

The 3.9 serpy belt crank nose is the same length as the 3.5/3.9 V belt but the keyway/key is longer than the V belt nose keyway/key to fit the pump .

The 4.0 and 4.6 crank noses are the same length as each other as are the keyway/key but the noses are longer than any of the earlier 3.5/3.9 be they V belt or serpy belt .

If you need a spacer i used a crank timing gear with the teeth removed .

Nothing needs to be done to the 4.6 crank but it can`t use a 4.6 cam and run a dissy because the cam is too short and this is possibly what you memory is working on .

You are correct in finding the 4.0ltr rod is longer than the 4.6ltr .

The other thing about the high comp pistons earlier , if you got the Hammil book suggested , he stated that 9.25:1 ratio is max for running WOT on 91RON .
Your block has provision to fit knock sensors , which only retard the timing so i`d suggest that if have to get new pistons the lpg it will run on most of the time will work better and as long as you can hear ok you can drive to the pinging , if it does .

Peter