Poly-vee Belt on a Pre-serp?

[petepetrolhead]

Does anyone know if it's possible to fir a serp-type poly-vee belt to a pre-serp? Obviously the pulleys would have to be changed, but I don't know if it's possible to get poly-vee pulleys to fit the existing alternator and water pump, or whether these entire units would have to be changed. Likewise would a poly-vee pulley fit on the crankshaft? Could I tension the belt via the alternator, or would a separate tensioner pulley be necessary? I have no power steering pump (to state the obvious!). All advice gratefully received - thanks.

[rev-erend]

Why ?

It's an aweful lot of work to do .. but what gain ?

[Wildfire]

As said above why?

But rather than go half way, you may as well just switch to a full Serp engine. There is someone around who does the full kit.

[petepetrolhead]

OK - shoot me down in flames - I've got it coming! I've done quite a lot of work under the bonnet (alloy twin plenum, ACT manifolds, big induction kit etc) and I think the engine looks good as well as performing better. I just think the spindly little single vee belt looks weedy and not in keeping with the rest - don't tell me I'm sad, I already know! However, if it really is an expensive job then you'll rightly tell me there are better things to shell out on. I have no idea what's involved, hence the original question.
Dons flak jacket and prepares to run for cover...

[Wildfire]

If it's for looks, don't bother. I have a load of trick bits under the bonnet and no probs what so ever.

It's not a cheap job (depending on your view of cheap, mind). A new Sepr type alternator is around £150 by itseld. Then you need the oil pump, timing cover, crank pulley, belt tensioner and probably a load of other bits, I'm sure the plumbing changed a bit. I'm sure someone will post with the full requirement.

[rev-erend]

I suppose it's possible - afterall I'm doing it at the moment.

You need the following parts :

JE Crank pulley £80 - this may put the engine balance out !
Alternator - Approx £90~100
Water pump pulley (land rover) £12
Belt tensioner or JE manual adjuster £35
Belt £15

And once you have all that lot - you will find out whether it all aligns or not .. and whether the various pulleys above actually fit your crank, water pump etc..

Me installation is on a brand new serp crank, serp intermediate front cover (oil pump etc) .. and the reason for me going serp is the oil pump. It's a much better design than the older oil pump on the pre serps but I have to justify this extra cost on the fact that I might have a few extra horses than you do, probably a hundred or so....

[spend]

Water pump pulley would need to be ribbed if you dont change the timing cover & water pump.. its ok plain faced driving the back of the belt.

If you change to the later cover & water pump, you also need to revisit heater / water pump / inlet manifold coolant bypass plumbing, and probably add the serpentine swan neck (with the tee for the heater).

All the solutions would be far from trivial for minimal gain.

Have you ever noticed the lower oil pressures that folks report from the 'improved' pump BTW Rev? It certainly improves the problem if you have cam/dizzy drive issues, but for the rest I am not totally convinced

[rev-erend]

Maybe but a worn system is just that.

Comparing brand new, pre serp with serp and the serp is the winner for a highly stressed engine every time. I'm dizzy less - so that is one less issue for the oil system too.

[petepetrolhead]

Rev - many thanks for your info - much appreciated. If the worst should happen and the crank (or crank pulley?) needs re-balancing, do you know if this can be done in situ?
Cheers.

[Wildfire]

If you need to rebalance the crank, you really need to do the crank, rods, pistons and any pulleys/dampers all at once, not in situ, this needs to be done by an engineering shop. The closest you could get is to weigh the old pulley assembly and try and get the new one to weigh the same.

[rev-erend]

It is unfortunate that TVR to save costs when making the engine chose to externally balance the engines. This means that the flywheel and front pully are where the adjustments are made. If you change either then your engine is at risk. A snapped crank is a possibility.

[450Nick]

rev-erend said:

I suppose it's possible - afterall I'm doing it at the moment.

Is this engine ever going to run Alan?! You've been building it for years!

[rev-erend]

450Nick said:

rev-erend said:

I suppose it's possible - afterall I'm doing it at the moment.

Is this engine ever going to run Alan?! You've been building it for years!

After Thursday I have a lot of time on my hands .. been putting in a lot of effort recently, finished the exhausts and mounted them, fitted the heads, Friday I'm timing up the cam, next week I will start adding the ancilaries, starter, clutch slave, front cover etc..

So - hopefully very soon.

Naturally I have a few issues to resolve along the way but no big problems.

[450Nick]

Cool! I'll have to pop round and see it when you fire it up... Sounds like it will be a bit of a beast!

[rev-erend]

One of my big worries is the Emerald set-up and start-up ..

I'm pretty comfident I can get the ignition something like right but the mixture is up in the air at the moment.

I can run my old 22lbs injectors with my old map andf pressure setting but no that going up from 4.6 to 5.3 is an approx 15% capacity increase.. plus I never mapped the old set-up.

I also have some new 30lbs injectors..

Bit of home work needed on that side of things before start-up..

[450Nick]

I wouldn't worry too much... Are you running a IACV? That would make things a lot easier to get a stable idle to work from. As long as you can get the timing dialed in and a reasonable AFR at idle, then I wouldn't think the ignition map would change much from the 4.6 map, its just the fuelling that's going to move a lot, but if you're not flooring it then you can just work out at low revs roughly how far its moved and then scale the old map accordingly. The rest can be sorted out once its running ok. The key is getting the timing right first time (which I failed miserably at the first time by cocking up the trigger wheel/crank sensor position and ending up with the whole thing 180 degrees out!)

Edited by 450Nick on Wednesday 28th April 11:21

[rev-erend]

Nick - the IACV valve is a non starter as I'm using 48mm TB's.

[spend]

My TB's are plumbed into a 'balum?' for vac / balance / air valve. Does look like it was a mod done to the TB's though.

[450Nick]

Tb's eh? Cool! How do you set throttle bypass on these then? Or do you just set the throttles so they never quite close?

[spend]

Each butterfly has its own spindle so you could set the throttle stop on each throttle body to set base idle - the linkages are a bit of a work of art.

Alternately with the balance pipes into a 'reservoir?' you could pipe an adjustable base idle bleed, which is my plan B if A isn't good enough