advised timing for an A2 or a 234 cam

[eric]

For road purposes, these 2 cams seems to be OK. if the 234 seems to be more modern than the A2, it is more tiring for the valves and the head. The 234 is also more acceptable for the gas emissions. As I have an A2 in my 1600 sprint, I have tried a 1700 supersprint but compared with my engine, it is flat under 4000 and more powerfull after (but after is often too late on the road ). The A2 is more fun, more race, more temperamental that is is finnally charming. As everybody thinks different, the timing question is obvious : my cam is perhaps well set and my friend's cam was not.

Who knows the best torque/ low rev power timing for an A2 and a 234 ?

 

Many thanks for your advises

 

eric

[elie boone]

Eric, go for the Kent 244 cam and apropriate Aldon dizzy, even better is the 3D ign

it will be much more tractable.

 

[eric]

Hello Elie

 

I like the torque and low rev power, so the 244 is not for me

 

eric

[elie boone]

Even the Aldon dizzy on it's own is a big improuvement over the std Lucas system

you will find that the engine is much more tractable.

[eric]

Good point : I already have the aldon

 

eric

[Revin Kevin]

Eric,

From my experience some gains can be made by timing kent 234 cams at 106 degrees ATDC compared to the recommended 103 degrees. This gives a little more at the top with little or no loss lower down. But ALL engines are different and the only way to know for sure is by putting your engine on a dyno and swinging the timings until you hit the sweet spot. As very few people get the chance to do this I would go for 106 ATDC in a light car like a caterham.

As for which cam A2 verses 234, as long as you check for valve clearance the 234 will be a better all round product, with better low down torque but still give as good at the top if not better. Also emissions will be better with the 234, if that matters.

 

Cheers

Chris

[eric]

my 7 has a very bad result on the verge on emission tests. So a 234 could help me to be honest

 

 

[eric]

I spoke yesterday with a supersprint owner, he confirmed the power comes after 4000 revs, so I will keep the A2.

 

Even if it is more powerful after, I do prefer for road more hp at lower revs.

 

eric

[OliverSedlacek]

4000 RPM My 234 cam came on at about 3000 RPM. I've now got a 244 cam that comes on at 3500 RPM and I rather miss the difference.

[Revin Kevin]

Eric,

Where the engine/cam pulls from is very dependant on the full spec of the engine but I would be very surprised if a 234 cammed engine was not pulling until 4000rpm unless it was a very odd spec, designed for a specific reason but limited to what cam they can use. I would expect a reasonable specced 234 cammed engine to be pulling from 2500/3000 rpm. A 234 by design IE low duration /high lift compared to an A2 long duration/low lift will give better low down torque and emission for any given spec and as I said from experience will produce as good performance higher up. The only down side of the 234 is you need to check for any valve to piston contact when building the engine.

The 234 is an excellent road cam!

 

Cheers

Chris

 

Edited by - Revin Kevin on 17 Dec 2010 11:37:42

[eric]

damned, I always try the bad 234 ones

[bstark]

My Supersprint with 234 cam used to come on cam about 3000rpm, then pull to 6000rpm when the power would start to tail off (that's with an Aldon Ignitor).

 

Now on a Megajolt on a safe map (so not optimised yet) and it pulls from nearer 2000rpm, then hard from 3000-6500rpm plus (probably higher but don't want to push my luck )

 

Suits the car very well, and no problem with it just have the 4 gears.

 

Bob Stark

Supersprinter

[Richard K]

Hi Eric,

My supersprint (1988 vintage) was built by Vulcan Engineering

234 cam that pulls well at low rev's but starts to come on strong at 3,000.

This is their website http://www.vulcanengines.com/

If you scroll half way down the 'brochure' page they have some graphs that show the power output of thier engines.

Supersprint is the 135 / 145 bhp.

 

By the way - my engine is 'tired' having never been touched and the valve springs have now soffened such that it won't rev over 6,000 but still managed 110 bhp. at a recent rolling road session. Not bad for a 22 year old engine.

 

Go for the 234 you won't regret it.

 

Richard

[eric]

I think about it ... but not sure

 

What I can see that there is nobody for the A2, in a way it is normal becouse in fact Caterham sold very little 1600 sprint with an A2 .

The best seller was the 1700 supersprint

 

eric

[bstark]

Eric,

 

My car was a 1600 Sprint when I first tested it (not that I knew it during the test - long story) and subsequently had a new Steve Parker Racing 1700 engine to Supersprint spec fitted prior to my picking it up.

 

Basically, I found it transformed the car - went from feeling quick-ish and capable but not extending the chassis to simply feeling alive. All things are relative of course (and this was at the time on rock-hard Goodyears, but over the years as I've improved the car I have never once wished I had kept the original engine. Quite the opposite in fact.

 

All I would say is make sure you get it properly set up - mine wasn't initially and it drove horribly off-cam, then came alive all rough and guts. Once it had seen a rolling road and had the timing and carbs properly set up it was as smooth and tractable as you like. With a Megajolt it's almost modern-car like in its tractability but with that lovely twin 40 throttle response and noise. I occasionally wish for more power (who doesn't) but the car is pretty nippy on track (has a local class championship trophy to back that up), great on the road and if something happens to the engine I'd still stick to the 234.

 

Bob Stark

Supersprinter

[Iamscotticus]

Eric, fellow 1600 Sprint lump here,

you've been out voted.  234.

But, something that isn't being argued here, you never said you intended to upgrade to 1700.

How can anyone claim a 234 will be better in your 1600 when they are happy with it in their 1700s with uprated pistons and springs?

I am not yet convinced a 234 is justified in a 1600. As many have stated, especially Roger King, that the rest of the engine needs to be built up to support the bigger cam.  This is why the A2 was/is a good choice for a low spec engine.  It gives plenty of low end pull in a basic tune that remains a reliable driver.

Im not saying the 234 isn't worth doing, but getting the most out of it, you might as well do the whole race tune, machined pedestals, iron crank, pistons, etc.  Oh, and while you're at it, 1700! The upside of doing all this bottom end work is you will be able to try all the cams you want till you find the one!

What a hole!

I want to pep up my Sprint as well, but I have to be concerned with that Ital rear end and how much it can take.  Perhaps a map is the better route?  The maps seem to help out a lot.  These are really light cars. Throwing more "power" into them change the character of the handling.  I still like the idea of the Super Sprint, but before all that investment, I will try a map on the A2. If that doesn't do it, a 234, map and dual springs that will clear. If I still need pistons, then its full race or back to the A2.  Also, there are other cam profiles like Pipercross that will work in a road engine.

[7 wonders of the world]

With ECU controlling the fueling and ignition you will make significant gains in low end tractability when using wilder cams allied with more power and better economy too.

I would also look to modify the timing cover to enable you ro alter the cam timing whilst on the rollers, and then look at trying different inlet lengths too once you have optimised the cam timing. 

The timing figures some of the cam grinders publish are way out.