Tuned 998 A+ setup advice

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I have finished building my (23 year-long) build of a 1985 City E, which I started while I was still worried about insurance costs, and hence retained the original 998 A+ engine and modified it (which also made sense, since the car only has an original 47k and the engine was perfect internally).

The spec is 998A+,
Minisport Stage 3 head (with enlarged valves and double springs)
minisport road/rally cam 731 profile equivalent (with Minisport followers)
LCB & superflow exhaust
Minisport alloy inlet manifold
Aldon ignitor electronic ignition
single SU HIF44 carb (with needle and spring supplied as an initial best guess by minisport)

I have the car running ok under no-load and have got it through MOT emissions, but does not like running under load, so I haven't been able to get it out and about. I have had a go at backing off the timing a little (unfortunately the engine was built before 4-star went away completely, so doesn't have unleaded inserts - so I am running unleaded with Castrol Valvemaster additive - so I have tried 4 degrees BTDC at 1000rpm), and it is not running much better.

I am certainly going to need it setting up properly, and will be calling on Peter Burgess - (I have seen his posts on here, and he seems knowledgable and respected - and more importantly also nearby!) to get it on the dyno to get it all set up - but wanted to see if anyone had any thoughts beforehand.

Firstly, I am not sure on the carb - looking around, not that many folks tend to tune a 998 to this level, as it is rather easier (and certainly at that time would have been much cheaper - I could have got a good 1275 engine with a metro attached for under £100!), but from what i have seen there is mixed opinion that any small-bore will be fine with just a 1 1/2" SU (so I should go back to the original HS2), others suggesting that the 1 3/4" will cover a broad power range, and so will be tuneable (but at the lower end of the needle ranges). Any thoughts on the best choice here - is it not an issue, or will I be better suited by one or other choice?

Secondly, I am running the standard distributor - could the advance curve on here be wrong for the modifications (the vacuum advance is definitely working!) - I am sure that I could get more power from an upgrade here, but I would expect that I should be able to get it to run smoothly with the standard part for now - or could this be an issue?

I want to be able to actually make a bit of use of it after all this time building, but I also want to ensure that I have the key parts correct before I start spending money (and potentially wasting time!) on trying to get it setup - so any advice or thoughts would be much appreciated!

[Lotobear]

My immediate thought before reading further into your post was 'over-carbed' and then you allude to the same thing.

I would try a 1.5" single SU and see how you go - nothing to lose if you already have one

I also wonder if you might be better with a 3:1 extractor on a 998 rather than a LCB?

[streetscreamer]

Indeed might be a little over carb'd, however if the flow f the head is right and your cam is timed in well, this might suit for the engine to keep power on high revs. For mid range (most of the time used) a tadd smaller will do. Stick to a small bore LCB for a small block. You have to keep the velocity in the gasses. A 3 to 1 is also a nice system, however this is for high revving screamers.

regards Bart

[Lotobear]

By 3:1 I was meaning the old 'chickens foot' Cooper mainfold, closest is this:

http://minispares.com/product/Classic/Exhaust_and_...

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Thanks for the suggestions all, I have also been in contact with Peter Burgess (and have it booked in for a rolling road session). He also suggested going down to the 1 1/2" carb would be beneficial - so I have bolted that on (but had lost the throttle return spring and also need a suitable filter to fit on - both en-route).

Interesting comments on the manifold - as stated, I do have the small-bore LCB, which I believe is reasonably suited to the 998 - I hadn't seen the other manifolds as an option - might be something to look at later, as to be honest, I am not after every drop of power from this engine, but want to get it running well so that I can at least get some use out of the car after such a long process to get it road-legal again!

I am hoping that once i have it running again on the smaller carb, Peter will be able to get everything else sorted on the fuelling and ignition - and can suggest improvements as follow-up.

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Just to loop back on this, after a wait for a slot (and refitting the 1 1/2" carb) I spluttered my way over to see Peter Burgess this morning for a rolling road session. I have never concentrated so much on such a short drive, as from that journey - with a max speed of 38mph, and some persuasion needed to get up any kind of gradient, it was clear that it needed a setup - thankfully traffic was light!

Peter was looking somewhat unimpressed when I got there - with the car not so keen to even pull itself up the slope into his workshop! He decided that it was best to not even try an initial power run, but to get a more appropriate needle in the carb straight away.

After working his magic on setting the fuelling and ignition, I now have a car that idles properly, and actually wants to pull. The end result giving me 36BHP at the wheels - or somewhere just over 50 at the fly. Definitely worthwhile spending the money on getting it sorted - and I would happily recommend Peter as someone with a lot of knowledge and experience (and a good chat!) about tuning and measuring performance.

The final verdict was that it could give a bit more with a slight head skim and also take a bit more cam - but for now it's a good 'un! Perhaps now after 23 years of (slow) building, it might be best just to drive it for a bit though!