Too much for a street driver?

[boy83]

Recently rebuilt 1983 sc with 98 mm P & Cm Mahle, 10.2 CR, twin-plugged, 120/104 cams, Tec 3r, carrera intake manifold, SSI with Dansk sport muffler 2 in 1 out, Magnecore ignition wires, wide band o2 kit, GT3 fuel pump.
Engine made 223 rwhp and 202 torque on dyno. Was tuned on dyno.
Problems: Sometimes will not idle, other times will idle high, 1200-1600 rpm. I was told by the mechanic that the low idle was due to low engine vacuum. Can I expect it to idle better than this? I can live with an idle around 1100-1200 rpm as long as it stays there.
The other problem is surging. The car will not run steadily at rpm below 3000. Is that to be expected with this set-up?

[Steve@Rennsport]

Hi:

A few thoughts,....

120/104 cams in a 3.0 or 3.2 are race cams and will not idle nor run well below 4000 with the single-throttle Carrera manifolds. Its an intake reversion problem. To use those cams you must either use carbs or an ITB intake. The most cam one can use with the Carrera intake are 964 or 20/21 ones.

Dyno tuning only maps part & full throttle sections of the fuel and ignition maps. The rest must be done in the car to get the best drivability. Sounds like some further work with the Tec3 is needed for idle control and part throttle timing and fueling.

Your engine configuration is not matched well and I would recommend either a cam change or a different intake system. Further, if you have the early small-port SC heads, the Carrera intake runners are too big (unless port matched) and you are really over-cammed for that setup.

[BReyes]

Welcome.

Do you still have same builder/tuner working on the car? Did your tech work on it twice. Are you going to track it ever? Otherwise, I would say the cams can come out easy and reground, getting them retimed is the only thing to be concerned about because we're talking some hours. Steve is not saying after it is retweeked it is still streetable. Wayne may be right 'no amount of money or points help for the street'.

Any paperwork on the port/valve size or TB/injectors? It does sound trick.

[boy83]

Thanks for the responses.
Steve, I failed to mention that the intake heads were opened to match the carrera intake.
My mechanic has been suggesting that I take the car back for more dyno tuning. Is that necessary? I feel that in-car tuning with the TEC3 should be sufficient to give it a better idle at least. Do you think that it's possible to achieve an idle somewhere around 1100-1400 RPM?
I understand that with my present set-up, to drive this car smoothly, I'll have to keep the RPMs above 3000.
As it is, the car is a pain to drive in traffic, but a lot of fun on the open road.
I can't do ITBs or carburetors right now. It won't pass visual for emissions testing. Perhaps in 2 years I won't have to worry about emissions testing anymore.
Bernard, it has the 1983 sc injectors. I was told there was no need to change these. I may track in in the future. I've been thinking about it. But right now, it's a street car which I drive around twice a week.