Serpentine engine differences- pros an cons?

[Dan88]

I'm looking to change the 3.5 v8 in my '86 90 to a 3.9efi. I have a serpentine engine, ecu, etc. an also a standard 3.9efi. What is best an why?

Thanks

[zardos]

I'm looking to change the 3.5 v8 in my '86 90 to a 3.9efi. I have a serpentine engine, ecu, etc. an also a standard 3.9efi. What is best an why?

Thanks

my thoughts of 3.5 v8 vs 3.9 efi serpentine.

3.9 has more power and should be better fuel economy.

33% more efficient oil pump

runs a better alternator

runs at more extreme angles than some carbs.

Enough said.

[zim]

The serp oil pump is better than the dizzy driven oil pump

[ThreeSheds]

Serpentine gets my vote

Advantages as stated above plus the following:

• The improved oil pump drive which (since I am a Megajolt fan) means the ability to run it without a distributor.
• Ten bolt heads
• The ability to change the auxiliary drive belt with one 15mm spanner in about 10 seconds...

As a comparison: On my old 3.9 there were three belts, the adjustment of which involved undoing the tensioner, the steering pump and the alternator mountings and a LOT of grunting and levering to get them all back tensioned again. The job was made easier if I removed the distributor first for access to the steering pump. Also, although apparently not necessary, if replacing one of the belts I also found I had to to remove the fan cowl - which meant removing the viscous fan... So when away from home I would need to carry 3 spare belts (they are all different), six spanners, a Phillips screwdriver, a big tyre-lever for use in tensioning, and a fan-spanner just to cover the possibility of a broken belt. Now I will carry one serpentine belt and one spanner.

[mickeyw]

Totally agree with Three Sheds and Zim ^^^^^

[Bowie69]

Serp every time for me, oil pump and ancillary belt being the main reasons

I went one stage further and got a P38 4.0l engine, no dizzy at all then

[ThreeSheds]

Sorry - just thought of some small down-sides:

The serpentine engine has it fan in a different position so your fan-cowl wont fit properly. It also rotates the other way so make sure you get one with the engine.

The power-steering, water and oil cooler pipes are all different - you may need to get some made up from your old ones.

HTH

Roeer

[Hybrid_From_Hell]

^^^

As above for Serp V8s, plus the Serps tend to be cross bolted blocks

makes stonger unit IMHO

Nige

[mickeyw]

Sorry - just thought of some small down-sides:

The serpentine engine has it fan in a different position so your fan-cowl wont fit properly. It also rotates the other way so make sure you get one with the engine.

The power-steering, water and oil cooler pipes are all different - you may need to get some made up from your old ones.

HTH

Roeer

On the fan cowl issue, the one from a 50th V8 fits perfectly

My serp engine came from a Disco, the oil cooler pipes line up perfectly with the Turbo D rad I am using.

Hoses - use bottom hose from donor vehicle, and header tank. Mods will be minor and pretty easy. Top hose can be cobbled from the serp top hose and your original with a joiner/piece of pipe and a couple of hose clips.

PAS hoses are indeed different, but again, if you have the pipes from the donor car you should have enough bits to cobble together what you need.