My 4.6 V8 Rebuild Thread

[101RRS]

Will you be fitting the LPG rings under the throttle plates? Won't work with a regular LPG converter as full manifold vacuum will be applied to the gas inlets at idle.

My rule of thumb with LPG mixers on D1 style engine intakes is that a 42mm ID single mixer works on a 3.5/4.2 engine and a 46mm ID works on the 3.9/4.0/4.6 family. If you fit gas rings to the top of the carbies then you coud as Ron said machine them out a little in a ratio similar to 46/42. The mixer bore size required depends mainly on the peak airflow rate generated by each cylinder in turn.

For example a 4.2 Holden V8 requires a bigger mixer than a 4.4 P76 as the latter has a smaller bore. A 6 cylinder 3.3 Falcon uses the same mixer as a 4.1 as they share a bore size. A 4 cyl 2.6 Magna uses a bigger mixer than a 3.3 Holden.

Thanks - I have the correct mixer for the rings. I figured rings on each carby would be better than the ancient but reliable system currently on the 3.5 with the impco mixer in the air intake pipe.

I am just wanting to get the carby jets and needles initially setup that will be approximate for the new engine size so that the engine tuner can just make adjustments to fine tune the engine.

Cheers

Garry

[101 Ron]

[clubagreenie]

Your running the winch on LPG?

[101RRS]

Does anyone know what needles and jets are used in the Series 3 6 cylinder Zenith CD175 - are they different to the 3.5 V8 Zenith CD175. If no one knows - where might I find out?

Thanks

Garry

[Davo]

They are listed as different. Usually the V8s have adjustable needles and the 2.6 is shown with the older adjustable jet.

[101RRS]

They are listed as different. Usually the V8s have adjustable needles and the 2.6 is shown with the older adjustable jet.

Hmmm - it is never simple - thanks

Garry

[Davo]

Oh yeah, tell me about it.

[101RRS]

Well I haven't been doing much on the project lately so thought it was time to get things moving.

I took the 4.6 piston/conrod combo and the 4.0 piston/conrod to the engine builders to have the gudgeons pressed out so that I could clean the relavant bits - weigh the individual components and get the 4.0 pistons put on the 4.6 conrods and gudgeons. The heads are in the engine builders for a basic rebuild.

I have a very accurate set of electronic kitchen scales so I weighed the components - all pistons were exactly the same weight as were the gudgeons, however the conrods were a different matter.

Total conrod weight varied from 578 to 584 grams but little end weight varied from 172 to 187 grams

Conrod Weights
1. 584 181
2. 578 173
3. 581 173
4. 581 175
5. 582 172
6. 584 187
7. 579 183
8. 582 178

As you can see there is not a lot of correlation between the weights and is a bit much for me to resolve, so I might just hand them to back to the engine builder to so the balance and reassemble the piston/conrods.

Any thoughts - oh, I am not doing a dynamic balance just a static one - the performance requirements of the engine are such that a static one will do and I do not have the harmonic balancer and flywheel at this stage as they are on other engines.

Thanks

Garry

[davidsonsm]

Assume your engine builder has advised what the compression will be using the 4.0 pistons? My understanding is the bowl volume is smaller on the 4.0's. I couldn't use the 14cc version (err5553) in my 4.6 rebuild as the CR would have been to high.

You probably know this. The 4.0 pistons I had were HC. LC pistons may be the ones you have and may have the correct bowl volume.

I ended up bowling out some 4.6 HC pistons to allow the deck height to be reduced to zero tdc. Producing a CR of 10.2.

Not sure if this is relevent or helpful to you so I'll butt out.

[slug_burner]

Well I haven't been doing much on the project lately so thought it was time to get things moving.

I took the 4.6 piston/conrod combo and the 4.0 piston/conrod to the engine builders to have the gudgeons pressed out so that I could clean the relavant bits - weigh the individual components and get the 4.0 pistons put on the 4.6 conrods and gudgeons. The heads are in the engine builders for a basic rebuild.

I have a very accurate set of electronic kitchen scales so I weighed the components - all pistons were exactly the same weight as were the gudgeons, however the conrods were a different matter.

Total conrod weight varied from 578 to 584 grams but little end weight varied from 172 to 187 grams

Conrod Weights
1. 584 181
2. 578 173
3. 581 173
4. 581 175
5. 582 172
6. 584 187
7. 579 183
8. 582 178

As you can see there is not a lot of correlation between the weights and is a bit much for me to resolve, so I might just hand them to back to the engine builder to so the balance and reassemble the piston/conrods.

Any thoughts - oh, I am not doing a dynamic balance just a static one - the performance requirements of the engine are such that a static one will do and I do not have the harmonic balancer and flywheel at this stage as they are on other engines.

Thanks

Garry

Check out Youtube and search on "Connecting Rod Balancing" a fellow from Costa Mesa R&D automotive machine shop shows you what needs to be done, here is a [ame="http://www.youtube.com/watch?v=QLpiF0E0EJU"]link[/ame]. Briefly you will need to reduce the little ends down to that of the lightest, then take material of the big ends until the total weights equal the lightest total weight.

The 172 and 173 ends are the lightest so need to take off material off the others to get them down to that 172, 173 gm weight. I think they would probably not do much to the 175 but the 178 to 187 need to come down. Uses a belt sander to remove material of the ends of the small end. Watch the vid, it will be faster than me typing.