Burning rich

[foggy]

After a visit to see Paul at Circuit Motors, finally found out why my engine is running so rich, I really need 45 webbers,not 40's, which are fitted in the Hood. It did'nt take him long to find that! He said the choke is wrong as well and someone has been mucking around with the jets, so its back up there Weds to have new choke, this is the cheaper option, I beleive a new set of 45 webbers are around the £400 mark. Don't want to get any off e-bay in case there is a problem with them, unless any one in the club has a set of 45's they want to sell me. In a way I am releved that I know whats wrong with it.

[paintman]

Trouble with 45's is they really drink fuel if you "boot it" a lot and at todays prices worth considering.     I thought about changing the Dgav on the Hood but seeing as it was going well and returning 30+mpg with "spirited" driving i soon dismissed it! 

                                  Tony

[foggy]

hi tony u got a point i think what paul was saying my engine would run a lot better with the 45s they would up the hp i think because i cant see me taking it on a track i will have the bigger chokes and rejeting he said that would make a lot of difference  and probabley stop it running rich as for the m p g  its never been very good   

['The Gaffer']

Always nice to know whats wrong at least, hope you get it sorted. Maybe a trackday would clear the cobwebs

[Richardp]

This is something I need to look at as well. I've got bike carbs, so it might be tricky finding someone to set them up.

With the right chokes and jets, I think you will be surprised at the difference. Also the MPG will improve no end, if the mixture is right.

With any luck, when they are set up, you will find things much better / smoother.

[foggy]

Just got back from my visit with Paul at Circuit Motors, rechoked it and rejetted it. The old chokes were 32m the new chokes were 36m and 145 jets and 175 air. Although the engine runs really smootha and does'nt burn rich any more,but what surprised him, was the horse power has hardly changed. He said  that  could       be because of a low quality cam shaft or the engine is not a 2.1, he did another compression test and they were within 10% of each other. I have the paper work stating that it was re-bored to a 2.1, but the question is-is that the same engine?  This could be another pit fall of not building it yourself. Driving it back down the motor way earlier, it was more responsive on the throttle and I did'nt get that awful smell of burning rich that usually gives me a headache!  Overall I am very pleased how the engine runs now,compared to what it was like earlier. I did ask him how you could tell the difference between a 1600 and a 2 litre,he sais without taking the head off, it would be very difficult to tell.

[paintman]

Is the car very responsive.....what bhp did it make???    Mine is a 2 litre and it will happily pull 85+ mph in 3rd at 6500rpm and that is with a standard weber Dgav.....with 40's it should be faster.  (on the track of course!! )

           Tony

[foggy]

it made 111 .4 hp at 5,814rpm as for speed in each gear  i dont know  i surpose there is another answer re engine next winter it is a lot more responsive 

[Richardp]

Hmmm.

That seems a little low for a 2.1, though if it's a 1.6 that's about the most you could reasonably expect, without massively wild cams.


Funnily enough rich mixtures don't hurt power that much, at least on low turbulence combustion chamber engines. Drivability suffers before full throttle power. It's only fast burn, high turbulence combustion chambers, like jap / chamber in piston (if using squish zones, eg. Porsche) that hurt badly from too much fuel.

[foggy]

dont know if this means anything numbers on cam are G C O 916  on the end of cam K 95  S 723         this means nothing to me as i dont know that much about engines

[paintman]

I take it you've inspected the lobes on the cam for obvious wear ie...pitting and burn thro' to the none hardened metal.      I thought the lobes on my cam were a bit too rounded and sure enough, on replacing it an identical cam measured them and they had lost almost a milligram from each lobe! ....that's a lot of lost lift and power.

[Richardp]

dont know if this means anything numbers on cam are G C O 916  on the end of cam K 95  S 723         this means nothing to me as i dont know that much about engines

I'm sure it means something, but a web search doesn't help

I guess if anyone will know, it would be the folks at burton power. It might be worth making an enquiry about a new camshaft, and ask if they can identify the one you have now.