Slow V8

[whitewedge]

Hi All

Just bought a 1984 350i and I've a problem:-)

It's been fitted with a Webber 200/500 carb kit and mallory dizzy. It starts well, idles well, drives well, doesn't smoke and uses little or no oil - and the oil stays clean it's also just passed an MOT. But it is grindingly slow - I suspect it's giving nearer 120 bhp than 190 as my S1 Elise would skin it alive in a straight line and it struggles to the ton. I've been told that running so well/cleanly it's not likely to be camshaft wear? If so then could retarded timing be the cause? Something in the carb? (throttle is opening all the way). Just looking for blindingly obvious answers before I rip it down.

[dbv8]

Full throttle opening and timing should be checked first.
Check the plugs for a clue on the fuelling too.
Struggling for the ton? Havent you got a stretch of road with 7.3 seconds from a standing start

[Danny Hoffman]

I'd check the cam, also do a compression check.

[mrzigazaga]

Brakes stuck on?...Any smoke anywhere whatsoever?..Not sure about the V8 but my 280 has steadily lost power over the 3 years i have had it starting at 123bhp when i got it to around 90-100bhp now..A long drive to yorkshire this year revealed that the cam was wearing and had probably been so for ages..Even before i had it..Up to that point however the car seemed to run fine with no missing or backfire..So im not sure if cam wear is that detectable early on?..Although im probably wrong!!..Check all the other factors first though..Fuelling..Timing..Compression test on all cylinders..Check plugs for rating and performance..Has the carb been tuned properly?..Ziga

[whitewedge]

Thanks all - I'll have a play when I get recover from Xmas bloody Flu and report...

[grahamw48]

Check she's getting enough air too.

My mate had his 2.9 S series on the rolling road and I laughed my head off when it only showed 99bhp at the flywheel...first run. (He'd previously thought it was quite quick ).

The R/R operator had a quick look around and discovered that the air inlet pipe had some sort of blockage. Then more very minor fiddling.

Result...180 bhp ! I'm a witness.

(Now making 184.5 bhp with new zorst).

[GV]

whitewedge said:

Hi All

Just bought a 1984 350i and I've a problem:-)

It's been fitted with a Webber 200/500 carb kit and mallory dizzy. It starts well, idles well, drives well, doesn't smoke and uses little or no oil - and the oil stays clean it's also just passed an MOT. But it is grindingly slow - I suspect it's giving nearer 120 bhp than 190 as my S1 Elise would skin it alive in a straight line and it struggles to the ton. I've been told that running so well/cleanly it's not likely to be camshaft wear? If so then could retarded timing be the cause? Something in the carb? (throttle is opening all the way). Just looking for blindingly obvious answers before I rip it down.

I have the same setup needless to say, my car isn't slow and is quicker than the EFi setup I changed over from. A few of questions though.

1. What type of Mallory Dizzy do you have, is it Dual Point or Unilite?

2. Does the Dizzy have Vacuum Advance?

3. Is your carb running with the right jets and metering rods?

4. Is Carb tuned correctly?

5. Have you checked and adjusted the timing?

6. Have you tested for an air tight seal from car to inlet manifold?


Drop me a line and I'll give you some pointers to the above questions if you haven't already solved the problem.

[NTEL]

Which type of ignition is it running? If its luminition I would junk it and fit an MSD unit. If you have MSD check you have the correct rev limit module fitted. I changed the racer from luminition to MSD and got about 80 more horses!