Gday,im currently running an a14 basically stock with minor headwork.twin delorto;s with extractors.its very competive in kanacross but finding it is bogging down a little which brings up the question about putting another cam in it.this motor was out of a vanette and they tell me this has a towing cam in it.so does anyone now what type of cam to put in it to give it a better edge.its running a h165 ute diff aswell which is a lot better.always looking to improve to try and keep up with these dam wrx's haha.any help would be great,we cant let these buggers getting away from the good ole datto!!!

Bogging down indicates low power at low RPMs. Is that the problem you face? The Vanette cam is already the best one for low RPMs.

yes thats whats happening!its good at high rpms but its the power out of cnrs is the problem.like its not bad but still lacking at that low rev range.

In that case, it is not the camshaft...

maybe you need some richer jetting now that the engine has been modified?

I also tend to think that the carbs need finer tuning.

what size chokes are you running in your carbs?
With too large a choke size, the low rpm air speed will be too low to achieve a crisp throttle response. Also, A van cam is pretty tame on the grand scheme of things.

I dont know what size chokes,i will have to pull them apart and have a look.and as for the cam i will look into putting something better in it but dont know what grind.

Don't need to pull apart the carbs. Just remove the air filters and shine a light into the barrels. They choke size casting should be visible.

Quote:
Better than what? Vanette is the best cam for low-RPM power. Forklift cam is even lower, but low power.

Oh ok i will check the choke sizes and change to electronic dizzy and a good tune and see how she goes..thanks everyone!!

When you say it bogs down at lower rpm - just what sort of rpms are you talking about? Even with std style cam, you'll still have an rpm range too low for it to have great output and come out of a corner (or whatever) hard enough.

If it is below 2000rpm, there probably WON'T be a better cam for lower rpms.

definitely add me to the people suggesting checking (and pssibly running smaller) choke sizes. and also about general carb setup - making sure that tweaking the acc pump circuit is done, which should remove most flat spots (as opposed to 'genuine' bogging down because rpm is too low period.

If that isn't enough, and assuming the ignition advance curve suits the current setup, there's not too much you could do to improve it., but there are a couple of things:

Check the compression ratio, and depending on what it is, you might be able to machine the head and increase the compression ratio. Obviously you can't go too far with that, before it will be on the verge of pinging/detonation/pre-ignition. And just how high ytou can safely run depends on cam duration - the later the intake closes the more static comp you can run safely.

The other thing you could do, wth a mild cam like this is to alter the cam timing - i.e. advancing it say 2-4 degrees more than it currently is. This will close the intake valve sooner, and create more dynamic compression, and essentially will lift hte lower rpm output a bit (will drop a little up top though.) Obviously those two go hand in hand, so work out your current comp ratio and dynamic comp ratio and find how much you can increase the comp ratio with a cam that s 4 deg advanced, and basically do it). It won't be a night and day transformation, but it will certainly help.

If it is viable/convenient enough to source and allowed to be used, you could always go for a much higher comp ratio, even with the short cam duration and possibly advanced timing at that - and run it on e85. That'll boost the powr across the entire rpm (even the fuel alone with no increase in comp ratio, as the cooling effect of the ethanol ends up with a denser intake charge getting in there, but might as well get best of both worlds and up the comp ratio at the same time) - it'll boost output across the whole rpm range, but make throttle response and lower output noticeably better.

I'm wondering if _maybe_ just maybe this would be a case where a small port head, which would have decent velocity at lower rpm, esp on an a14 (vs say, an a12) will give it the wake up down lower that it needs. Of course that wouldn't be cheap, presumably still need 'some' portng and a new intake manifold.

If all of that wasn't enough the other thing I'd genuinely suggest, if you can source it cheaply enough, perhaps consider a different diff ratio, that means the rpms don't get too low. Other than that - an a15 with its longer stroke will get into its powerband at a lower rpm than an a14 wth the same head and cam - probably somewhere in the neighbourhood of 200rpm earlier. This might just be enough to prevent it droping off the bottom edge of the powerband.