Dual sidedraughts with a stock cam? Probably not the optimum combination. Even a single sidedraught can easily be too much carb.

thanks. with side drafts it shifts latter due to insufficent vaccum. but, i was considering a shift kit (stage 2). so maybe side drafts are the way to go.

thoughts?

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True that...

Quote:Mate, I did not think for one instant that you were having a go at me & I appreciate your reply.

I guess that I look for a different kind of 'performance' in my dotage than I did when I was a nipper & the performance characteristics of a viscous fan, often called an Air Conditioning fan, fit my driving style.

I will differ on the assumption that the fan controls the engine temp though as this is the job of the thermostat & the radiator temp can be 1 degree above freezing, but the engine itself at normal operating temp if the thermostat is doing its job properly.

becuase a thermo fan costs a lot more to manufacture than a engine fan...

also an engine fan is more reliable becuase it has no moving parts or electricals

but as was said the thermo can be swiched off and that is where the power advantage is

from experience in playing with 4x4 you can get a range of fans for bigger motors and putting one that has more blades seriously affects power and revability... so if thats noticable then there should be gains to have on our smaller scale


getting back to topic.....

electronic ignition is one i forgot... best to get an elec dizzy for ease and tidiness... but they arnt particularily easy to get

p.s. i just noticed the stuff about ceiling fans.... i would love to see you try to stop one spinning at 3000rpm...(no i wouldn't)

I have alot of faith in the car manufacturers. they are very clever people and I'm sure that if they thought a thurmo fan worked any better they would use one. I might be wrong but I don't know of any new north south engined car that uses a thurmo fan. They use viscous fans because you don't need any fan all of the time and when they freewheel they cut down on the noise which is probably why you think your car revs better without one. Thurmos are used as an easy alternative when the radiator isn't at the end of the motor as in east west configeration. If you want to find out how much power it takes to spin a fan then look at a house or even a ceiling fan, they use very little power and only require a very small motor and they are much bigger than an engine fan. Try stopping a housold fan, it dosn't take much.
Thats what I recon anyway.
olboy

First off datspeed, sorry for the thread hi-jack.

Dodgeman, I hope you didn't think I was having a go at you you, I just have a weird way of bringing my point across...

Anyway, I agree with your statement about it pumping the maximum amount of air at below 3000 rpm. However viscous fans have even more weight hence inertia to overcome than stock direct drive fans. It's almost like adding another flywheel to your car, with the difference that it now has "paddles" that tries to stop it from turning. One can literally hear/feel the difference, in my Mazda 2.5 TD for instance, between when it's coupled and when it's not. There is quite a difference in the speed at which the motor can spin up.

Other than that they still don't pump air as efficiently as thermos, because of the way they are "mounted" in relation to a thermo. Probably the biggest reason I dislike them, is because they are unreliable, I have very rarely seen any of them last for much longer than a 100K. They tend to either lock up or disengage altogether, with obvious consequences. That's also reason why I would then choose a stock fan over them...

Then onto the reason I would still choose a thermo over any of the above. With a thermo you can control your engine temp to within 5 degrees of variation, which is very, very good for engine life. You can't achieve this with a stock fan or a viscous, no matter how hard you try.

For instance we live in a country where the difference in temperature between winter and summer could be as much as 20 degrees, up to 30 and more in some places. If you now have a stock fan, or viscous for that matter, in the winter months it's constantly cooling the engine when it shouldn't. So you end up with an engine that never reaches it's working temperature.

You make valid points, & I expected a reply along those lines. I do not have access to actual facts & figures which is why I used the words "in my view" as the whole thing is just my opinion.
I also wrote that the stock fan has "some of the load lifted from it etc. etc." as you are correct, there is not enough airflow to cancell out the load altogether.

I was interested in your comment about the viscous coupled fans as I rather like them. They pump the maximum amount of air at low speeds, when you need it most due to lack of road speed, but are speed limited, usually cutting out completely at somewhere near 3,000rpm, so they drain no power from the engine when you floor it.
They are also thermo controlled, cutting in when the temp rises above a predetermined figure, but simply freewheeling when below it.
If you have a dislike of them then I presume it's for a reason, probably something I haven't thought of, & am interested to know why.

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I want to differ with you on that. At any speed above 50-60km/h the thermo should never turn on, and you'll be reaping the benefits of not having a stock fan all the time. Wind speed under the bonnet won't be great enough to cancel out the negative effect the stock fan has through you're so called windmill effect, not nearly enough to make it as energy effecient as the thermo anyway.

Even though the thermo does sap power from the engine indirectly via the alternator when it does kick in, it'll mostly do so only when you're driving at slower speeds than what was mentioned, and never when the air moves through the radiator quickly enough to give enough cooling effect. It'll turn on very infrequently, and when it does it'll take much less time to cool the radiator to where it can switch of again. It'll do this because you can mount it flush with the radiator, and it'll be much more efficient moveing air through the radiator than what a stock fan could.

So probably 80-90 percent of the time you're turning a fan(which has enertia to overcome), trying to move air with it (which saps even more power because the blades act like paddles) and you're listening to that ugly whine of the stock fan. All of this when you don't need to.

Why then would most manufacturers eventually move over to either electrical or viscous(I hate these even more) fans? Because they save engine power which translates into better fuel consumption and better performance, because they don't use engine power when they don't have to.

Don't try to convince me that an A series engine with a stock fan will rev up just as quick as one without. 80-90 perent of the time it simply won't, and is probably the reason why guys shave of 2 of the stock blades sometimes...

I'm sure that even 80-90 percent is an understatement.

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For all practical intents & purposes, the A15 is nothing more than an A14 with 5mm more stroke, so a head & cam change will not produce any real benefits by themselves.
If you have a water heated inlet manifold, then you can switch to exhaust extractors without any negative effects.

Webers [plural] on your engine would be the biggest step backward you could take, however a low cost adapter & a single twin barrel downdraught Weber from any one of a number of cars will add a nice measure of pickup & pep to an otherwise stock engine.

The thermo fan is another myth too in my view. It requires electrical power to run it & this drain imposes additional load on the alternator which in turn sucks the additional power from the engine. A stock fan has some of the load lifted from it when you're driving by virtue of the windmill effect when the air is pushed onto it through the radiator as a result of the forward movement of the vehicle.
If you have overheating problems, then fix the 'cause' of the problem first before adding additional fan capacity.

Again, in a near stock application, the stock fan will be fine. Your money would be better spent on a Pertronix electronic conversion ffor the ignition. These are basicsally a points replacement system but provide a more reliable spark.
I run platinum plugs in mine & these require a lower voltage to fire across a given gap at a given compression pressure. Combined with the GT40R coil, & silicon plug leads, I get every cylinder firing every time, no matter what the load or engine speed.

You will probably need st spend a quid to ensure that the carb is correctly tuned to your engine.

Make sure that all the factory tune up specs are right on the money & that little car of yours will scoot right along, but it will be right thrifty about it at the same time, particularly with fuel at more than $1.50/Litre.

The longer stroke of the A14 will give you a nice boost in torque & the single Weber, when correctly tuned, will help maintain a good vacuum signal, which is what your auto trans wants to see as it relies on the vacuum signal to help with the shift points. Bad vacuum & the shift points will be higher. This becomes a drag pretty quickly in a streeter & is why twin sidedraughts [which will have almost no vacuum] are so bad.

Stick some tidy but low cost 13" wheels on it & run 185x60x13 on the front & 205x60x13 on the rear & you get a nice bit of rubber 'rake' with an agressive stance at an affordable price.