803 cc 1955 Performance

[jimboreid]

New to 803cc. when warmed up runs fine on flat but on any incline in 4th dies! shift down , lots of revs does help but usually need to go into 2nd! is this normal fopr a 803cc?

[mike.perry]

What do you expect from 30bhp???
If all 30 horses are working then the performance is probably adequate, however the gearbox is blessed with a set of ratios which are closely stacked from 1 to 3 then a gap from 3 to 4, the diff is also low geared resulting in the need to rev the nuts in 3rd before chugging away in 4th.
Check the timing and overall tuning to get the most out of it or upgrade to 948 running gear

[Dean]

Never driven an 803cc (mine was upgraded to 948 centuries ago), but speaking to a guy that used to own mine... his words not mine "An 803 only has to get the slightest whiff of a hill and it will slow down."

[MarkyB]

803 cc and Performance rarely occur in the same sentence

[David53]

I have to stick up for the 803! If the engine is in good nick and well tuned then it is only a VERY steep hill that will require 2nd gear. I have just returned from a long trip and ran up a number of long hills in top gear. The gap between 3rd and 4th is too wide, true, and means on steeper hills you do find yourself shifting back and forth between them. But overall, if you keep the engine well tuned and don't expect sports car performance the 803 is perfectly adequate both in town and out on the highway.

[jimboreid]

Many thanks for all the replies, looks like I have what I have and that I need to lower my expectations.

Cheers

[David53]

From your original post when you say "any sort of incline" results in it dying I'd suggest perhaps the engine is a little out of tune. On my recent trip I encountered a very long steep climb which,keeping my revs up as I approached, I was able to climb in top gear. Check your plugs, points, timing etc. The thing with the 803 is that even being slightly out of tune is noticeable.

[chickenjohn]

Well done David53 for keeping your car original!

I have to agree- if the car is slowing on hills then that suggests it needs tune up or a service. Try cleaning and re-gapping the points, spark plugs and cleaning the distributor cap contacts as a starting point. And check the ignition timing as well.

Make sure the air filter is not blocked!

[Simon83]

I have an 803cc engine and it copes with hills pretty well. I did notice a big difference when I changed from the Zenith to an SU carb.

I've got a diff from a 948cc which I believe will make it a little quicker in top but for the sake of keeping the origional engine I'm quite happy with the performance from the 803.

[Dean]

David, you may have a better grade of petrol in Australia as you aren't a diesel market, perhaps closer to the original stuff the car was designed for. I think European fuels are more bio, so may affect performance more.

[JONT345]

Hi just a thought is the timing chain noisy? i have a 55 803cc split screen,when i bought it the performance was very poor,i replaced the worn timing chain and tensioner and reset the ignition timing (way out after chain was replaced)reset the carb,it now drives much better hope this helps Jon.

[MarkyB]

The grade of petrol shouldn't be an issue as it's a very low compression engine.
I'm sure a good tune up will help too.

If it's nice and oil tight a thinner grade of oil should help a bit, anyone tried this?

[chickenjohn]

Another thought- de-coking the head and grinding the valves in can help restore lost BHP on an A series that has not been touched in years. Do a compression test and see if the compression is down.

[David53]

Speaking of compression I've always wondered what the compression should be on an 803?? I know it's lower than a 948 but does anyone have an accurate figure?

[bmcecosse]

I wouldn't be surprised if it's as low as 120psi....... maybe 140 when it was new !

[David53]

Last time I checked mine were all around 120. Why is the correct figure not published in any of the specs anywhere?

[mike.perry]

As a rough guide the 1098 is HC = 150psi, LC = 130psi,
803 = 120psi (Australian Workshop Manual)
My 918 = 130 psi when newly rebuilt

[dellerie]

best thing i ever did on mine was to replace the 803 with a recon 948. the difference is very obvious.

i'd never have an 803 again.

[bmcecosse]

Can't help but agree with that!

[David53]

Where was that in the Aussie manual Mike? Looked everywhere but couldn't find it..

Yeah I know a 948 is a better engine but I want to keep my car 100% original and experience driving 1953 style - I have a modern car if I want to go fast