To start at the beginning. From cold, the engine is quite mechanically noisy, which had me concerned. It quietens off a fair bit once warm, but the 'clatter' still worried me. Decided to get a second opinion and arranged to drop in at Williams-Crawford so we could get it up on the ramp and have a listen. The first thing that Graham Kidd said was 'Does it have JE pistons?'… Which it does. 'That's the reason - all the engines I've built using them have been noisy like that. It's pistons slap because of the clearances JE run.' That made sense, and I'd been trying to overthink things – as I hadn't built the engine, it hadn't occurred to me this might be the cause. Time to relax. Or not.
The engine has never felt very 'punchy' and even though it should probably only produce around 125bhp, in a car as light as the 914, I'd have expected more. I decided to head over to Graham Rawlings at Rawspeed in Plymouth to have a chat and arrange to get it on the rolling road. So my Friday was spent listening to my new toy doing power run after power run – we did 15 in all. Two things became very obvious: first of all, the carbs were throttling the motor – the 40IDF Webers only had 28mm chokes, and need 32mm – possibly 34s. They are on order and should be with me Monday or Tuesday. The main jets were too small, too – 115s, now 135s – while the air correctors were too big – 200, now 185. That helped find another 6bhp, taking it to a massively crap 77bhp! Or about the same as an average 2.0-litre (77bhp at the wheels equates to around 100bhp maximum at the flywheel). Considering it's a 2056 with cam and big-valve heads, we'd certainly expect better.
So, let's look at the exhaust system... 914s came with two basic designs of heat exchanger. One design (1.7/1.8 and early 2.0) had individual primaries running from each exhaust port to the silencer, while the other ('74/75 2.0) had horrid primaries which merged almost right out of the exhaust ports and then bent through 180 degrees to head as a single pipe back to the muffler on each side. These are generally regarded as scrap – without the 's'. Guess what my car had? You got it.
Now, what about the muffler? It appears to be a Bursch but, hold on, what's this – and what's that? A previous owner, presumably in an effort to quieten the rather noisy Bursch system had welded in a pair of small in-line glasspack mufflers in the pipework ahead of the main silencer. During the power runs (if you can call them that), pieces of blackened glassfibre wadding kept blowing out of the tailpipe! During each run, the engine would produce power up to about 3500rpm and then effectively 'flatline' from that point on. We seriously think the original Bursch silencer is partially blocked, meaning the engine's strangled in every direction.
So, I now have a pair of SSI heat exchangers and a Dansk twin-pipe sports muffler on order. Hopefully that, along with the larger chokes and a rolling road session, will finally unleash some power. If it doesn't, then it's time to get serious…
Beardy Graham Rawlings doing his stuff..
