1700 x/f and other animals..

[J05H]

Hi all,

 

I've had my Caterham for a couple of weeks now, it's basically a 1700x/f (De-dion) with a couple of bits 'n pieces. The engines had a few mods (4:1 manifold, dry sump, 3D mapping and 45's.) and I think it was stripped and rebuilt around 6K miles ago.

 

I'm pleased with the car (love the noise + flames!!!!) but I have a couple of quries. I've looked in the archives and I'm fairly new to these so please excuse my ignorance but..

 

It seems to 'knock' under part throttle, is this normal? (Sounds ok on full!)

Is it worth having the engine balanced? (I've seen this advertised for £80-£100)

I know the benefits of having the sump and the mapping but what about the 45's and the exhaust?

 

Sorry if these things have been covered before but I'd sure appreciate the help.

 

J.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

[Roger King]

Difficult to know about the knocking noise. This may be nothing more than induction noise, in which case it's harmless, but we'd have to hear it to know more.

 

It depends what you mean by 'balanced'. If we're talking about balancing the carbs, this may make the engine run better at idle and very light throttle, but £100 seems a little excessive! £10 - £20 would be nearer the mark if that is all that is being talked about. If we are talking about balancing the crankshaft, flywheel, conrods, pistons, etc, the price would seem more reasonable, but you would have to strip the engine down to it's component parts first! This would not be cheap and I wouldn't advise it unless you are certain that there is a problem.

 

45s are of benefit over approximately 150bhp. If your engine is less powerful than this they really aren't needed, although if they are set up to suit the engine it won't matter too much. On the other hand, you are in great shape if you want more power later.

 

The exhaust is the one that most people want. It becomes important if your engine is tuned to greater than Supersprint level. Once again, you are in good shape if you want to upgrade later.

[J05H]

Thanks Roger,

 

I guess I'm off to the rolling road first then!

 

The 'knocking' is more pronounced under load (up hill / higher gear etc) so I guess induction noise is likely.

 

Ah - there's a catch, yep it's the full balance, I'm not QUITE ready to start stripping engines down just yet!

 

Thanks again,

 

Josh.

 

 

 

[ashaughnessy]

Under load in high gear? Are you putting your foot down going up a hill in high gear with very low revs? What kind of revs are you doing when you get this knocking and what gear are you in?

[J05H]

Hardly noticable in 1st, 2-4K in the rest, accelerating under part throttle or holding speed on an incline.

 

The engine sounds perfect when nailing it though!!

 

J.

 

[russb]

Are you sure you are not experiencing 'pinking' ????

[J05H]

Yeah - could be, I've tried different petrol, Unleaded (as reccomended in the documentation), Super (more and more difficult to come by), 4 star and Unleaded + additives, all with little noticable difference. Unleaded + Add's produced the most flames though ;o)

 

 

 

 

[russb]

JO5H,

try retarding your ignition by a fraction, 1 - 2 degrees will be enough to effect a cure if is is detonation.

 

Russ