Running Too Lean?

[paolow]

can anyone help? ive a standard 2.0 pinto powered 2b but running with a 38 dgas which i where i think my probs may lie. its got 140 primaries, 45 idles and standard 2 litre pumps. the trouble is that below about 3k revs its really grouchy under acceleration. cruising at these revs is ok but if i boot it the engine sounds like it drops a cylinder, and, while it sounds like my cars got F1 style traction control, it gets tiring having to deal with it!

it doesnt matter if i crack it to WOT or just accelerate gently, the problem occurs no matter what and seems to be really started off when i open the throttle by any amount. interestingly, when i open it up and it grumbles, just when i shut the throttle (when i get to the top of a hill for instance) the car will surge forward for half a second before deceleratiion.

ive had the plugs out and ive never seen whiter! surely then my problems are caused by an overly weak mix? am i barking up the right tree? i could rolling road the car but for that price i could buy every single jet there is and still save money so im keen to try and learn a little about why it is behaving like it is, rather than just get someone else to fix it. my current thoughts are that the mains might need beefing up to 147 or 150, but will that really make a difference in low speed running? all the jets are clear and the carb seems to work ok (ie) pump jets all pump etc, its a cracking car, but just not very tractable at lower revs.

thanks in advance

[Guest rizla]

id be inclined to check for air leaks,maybe where the carb mounts to the manifold..........possibly

[Big Jim]

I agree with Rzzo, it does sound like air getting in where it's not wanted. I only had 145 jets in mine with an FR32 cam fitted as well.

Your problem is either air leaks, or incorrect ignition timing.

[Guest daveg]

What ever you do fix it quick...before you hole a piston :boohoo:

 

Dave

[paolow]

thanks for the tips guys, ill get out there and check whats what. as well as looking for tightness ill also replace those ropey vacuum hoses and see if that helps. hmm, thats an idea, ill also chech to see if the advance on the dizzy is working while im at it. ill let you konw how things develop

thanks again

[Guest Steve.G]

Sounds very similar to the problems I was having on my 1.6L (see previous posts).

 

Was cleared by a trip to the rolling road - they rejetted and cleaned the carbs but also altered the distributer to remove the vacuum advance. Technically, I'm not sure how they did this but I'm sure others on here will chip in.

 

From my experience I would go with timing followed by carbs - but then I'm certainly no expert.

 

Cheers

 

 

Steve G.

[Peter Bell]

140s are possibly too big for a std pinto so if it is running lean then the jets are not the problem. unless they are blocked. Is the fuel level ok in the carb? is the fuel pump working ok? have you tried it on a std. carb? where do you live?

Peter.

[paolow]

well, heeding rizla and big jims advice i tightened down my carb and also cut 20 mil off my vacuum hoses and then refitted them to get rid of the perished bits.

i can only say WOW!

honestly, when i first took it out the engine revved so cleanly and so fast i thought my clutch was slipping! is there anything you guys dont know about pintos?

thanks also for the tips steve and pete, im not 100% the timing is where it should be, ill have to get out the strobe and check, any ideas for a benchmark?

im in bromley, SE london pete, whys that? what im thinking of doing is getting a 145 and a 135 jet and just playing around with the sizes a little for a bit of fine tuning.

interestingly, even though it runs cleanly now, it will still surge forward when i back off the throttle for about half a second. i cant figure that one out. any ideas?

 

thanks again for the top advice everyone, not only did it fly but it sounded so much healthier too. and to think it would otherwise have been £100 and a rolling road, when it was 10 mins and free. i owe you all a beer!

[Guest rizla]

or £15 towards membership instead of a bear

[Guest TerryBarry]

instead of a bear

 

Hey Rilza - is that a brown or polar beer

[Peter Bell]

Hi Paolow the reason we ask where you live (if you haven't put it in your details) is that there is often someone nearby who could help or at least pop around to drink your tea and commiserate. Glad you have got it running ok, going any bigger on main jets will just be a waste of fuel on a std. pinto I would say. I have a dgas with a reasonable cam and flowed head with 137 jets and that is slightly rich according to my exhaust pipe colour. As for timing that has been a popular topic recently try a search on here but at tick over with the vacuum advance disconnected (and blocked off) start at 8° btdc. As for the surge it sounds as there may still be a bit of an air leak somewhere, also check that both butterflys fully close together. sometimes they get out of sinc there is an adjustment on one of the gear quadrants to do this.

Peter

[Guest salty_monk]

There are loads of us near you... Sanspeed in Bexleyheath have just tuned my car... £88 all in incl of jets..

[paolow]

thanks again for all the continued help everyone, ive been looking at the cost/benefit of buying a load of jets compared to a rolling road and, though I do know Sanspeed well, its gonna have to wait as i cant stretch to almost £100

the carb, i believe is in good order and the jets are clear so ill probably experiment with leaning it off and seeing where that gets me. that would seem the best place to start and its not too much for a few jets to tinker with.

also, youre absolutely right rizla, its high time i was a member, so i definitely will at last be a paid up member!

as a side note, the butterflies indeed dont close at the same time, so well spotted there! its not out by much, but if its enough for me to see with the naked eye, its something else i can rectify to help things along.

im going to order the jets now, ill report back at the next step!

thanks again.