Serpentine versus per-serpentine engine

[dmjw01]

Apologies if this is a dumb question; I've searched both Google and PH and can't find a nice simple answer!

Whilst researching what kind of Chimaera I should be looking at, I've seen references to "serpentine" and "pre-serpentine" engines. Can somebody explain the difference? And which is better?

I'm guessing it's something to do with how the engine ancillaries are driven off the engine. Serpentine = all driven off one big, long winding belt; pre-serpentine = er...?

[scotty_d]

yeah serpentine is the drive belt type thick banded one pre serp is v belt drivien

[dmjw01]

So is there any advantage to one over the other?

[spend]

The belt drives take up a lot of space and the serp tensioners & mounts make the front of the engine pretty untidy & overcomplicated IMHO. Main advantages of serp are the crank driven oil pump, not that it really affects oil supply just it removes the loading on the dizzy / cam drive which is how the pre-serp pump is driven. If you want to remove the dizzy to use coil packs it can just be pulled out with the serp, but not all engines had cam retainers so you end up having to take care of cam 'walk'..

It's not really straightforward, but TBH in standard forms both engines are fine. In TVR world you have more chance of getting a pre-serp engine produced in a better state of tune from when it left the factory I would guess

[haircutmike]

On the oil pump side of things, aren't the oil pumps on the serp more reliable/efficient?

It is certainly easier to prime a serp pump then a pre-serp after loosing oil pressure, (wadsapple).

[spend]

Plenty of folks finding wear on the serp pumps, 2monkeys even had a crack failure of the gear. Pre-serps have been abused to create higher pressures so stressed to destruction, yet very few have raised the pressure spring on the serp pumps to make them work that bit harder - just accepting the lower pressures they produce.

If you have to prime the pumps, it's hell of a lot easier to squirt oil down the timing cover galleries on the pre-serp, everythings obscured by the damn belts & brackets on the serps! There have been just as many questions recently on priming the serps BTW..

Do not forget either that all LR serps had water/oil cooler built in, personally I wouldn't use a serp in anger without an oil cooler.

Overall I'd say six of one half a dozen of the other, but plenty of Mary's have been extolling the 'latest is greatest' myths. I certainly wouldn't be happy to run with some of the oil pressures that many of the later car owners deem 'normal', anytime under 30psi and Houston has a problem

[scotty_d]

Cant get a s/c power kit for a pre-serp so there is one draw back to pre-serp.

[dmjw01]

Thanks for all the replies - interesting stuff. Sounds like it's not something that should influence my buying decision either way.

[TV8]

scotty_d said:

Cant get a s/c power kit for a pre-serp so there is one draw back to pre-serp.

That is a surprise (and potentially a disapointment!) do you you know why?

[jsr]

TV8 said:

scotty_d said:

Cant get a s/c power kit for a pre-serp so there is one draw back to pre-serp.

That is a surprise (and potentially a disapointment!) do you you know why?

I asked SC Power that very question a couple of years ago. They believed there was not enough demand for pre-serp s/c's to warrant the development costs. Understandable, but very disappointing as i too have a pre-serp.

[450Nick]

To drive the charger, you really need the big fat serp belt which is the main issue. SC-Power did find a place that do a conversion kit for a couple of hundred quid IIRC. If you're thinking of getting an SC and have a pre-serp it might be worth an ask...?

[spend]

It's not hard to get an aux pulley made up to drive the charger, but you end up having to make adjustable brackets & relocate the swirl tank (remember its on the ns cyl head)..

[Barkychoc]

There was - I think - an intermediate solution on the Ranger Rover where water pump was V belt driven but the alternator (on the near side head) has a flat serp type drive belt - as I said I think. It might be worth a bit of investigation.

Edited to say I forgot I had put my pics on photobucket for someone else - they were in relation to fitting a power steering pump to a pre serp but there are various pics of the engine front end here.

http://s181.photobucket.com/albums/x311/chrisbark/...

If I can offer any advice its that you will just not believe how many variations there are of V8 pre serp pulleys - to the point I gave up and fitted an electrically driven hydraulic pump. I have a garage full of pulleys, none of which I could make do what I wanted to do.

Edited by Barkychoc on Monday 16th August 20:18