Setting Up 1.9 8v, 285 Cam, 45's Dhla, Help...

[fyfethegreat 0]

Hi all, i'm needing advice or a helping hand with my 205. It's a 1.6GTI fitted with a 1.9 8v, piper 285 cam and dellorto DHLA 45's. I was told the best place to take it to was Ecosse in Bo'ness and living just down the road that's what i did. I wanted them to tune the carbs as the plugs and exhaust were very black with carbon. When it went in it was running great but rich and i thought it would come back a little faster and a good bit more economical.

When i got it back it would hardly drive, running on 3 cylinders. They only gave me 1 dyno printout that was after they had butchered it, it said 133 bhp and 124lb torque and the guy said that's pretty good for a 1.9. I was totally gutted. They said that it was low on compression on one cylinder and i would have to fix it.

I got it home to find out the compression was good on all 4 cylinders and that they hadn't put in the pilot jet holder in the carb, it was lying inside not screwed in. I had all ready bought a head gasket, so i took the head off and reground the valves and set the shim sizes to Piper specs.

The car was still not right, so i had another look at the carbs and discovered they had drilled the jets instead of changing them. I downloaded a program that calculates jet sizes by Dave Andrews and ordered new ones. Now the car is smooth at tickover but just touching the pedal it wants to dye. once it gets past 3000 rpm it really flys all the way to 8500 rpm. So i ended up putting back in the pilot jets that had been drilled out and it's pretty good below 3000 rpm and still great above 3000 rpm.

The pilot jets that i got were 50's and i don't know what the old ones were drilled out to, if anybody has advice or can guide me in any way i would be forever greatful. I live in central scotland and would be willing to travel pretty much anywhere to get my car set up right.

Thanks in advance.

[hcmini1989 16]

i dont really think i can help you here mate as im not clued up on carbs.but why dont you take it back to them get them to set them up again tell them your findings .youre not happy with the service etc etc and see were you go from there

[fyfethegreat 0]

If they don't know how to set up carbs, i don't want them near my car again. It's terrible that they would say they would get it spot on by changing the jets, when they didn't have any to change with. It's not the kind of service i was expecting from such a well known company. Hopefully someone can recommend one that has experience and can do what they say.

Thanks for your reply.

[opticaltrigger 52]

I ran a set of Dellortos some years ago on a 1900 and found the best combination for my motor,which was very similar in spec,was.............

 

36mm chokes

145 mains

65 idle

 

Start off with that and you should be pretty close to the mark.

Sounds from what you said that your air correctors also need to be changed but I would set it up with the above first and then deal with the air correctors.

 

All the best O.T.

[welshpug 1,661]

what's the compression ratio of the engine?

 

It sounds typical of the behaviour from a standard compression ratio and a very lumpy camshaft, it means the engine can't burn properly at the lower end of the rev range making it very difficult to set up, I'd imagine using carbs would exacerbate the issue as its near impossible to get them to fuel correctly right across the rev range and load range on a standard engine let alone something with an unsuitable cam.

 

My experience was of a very similar cam (PTS gravel, longman design made by Piper) on the standard intake allbeit on MAP and TPS based motronic, sod all part throttle tractability under 2-2.5 in lower gears, then a beast from there right up to 6600 rpm, needless to say I've ditched that for a much lower duration PT36

 

 

If your printout was for a totally stock engine on the standard management at the flywheel, I'd be perfectly happy (mine makes about that much torque and a little less bhp)

 

I'd firstly check what the compression ratio of your engine is, rectify that issue if needed then find a carburettor specialist (or fit throttle bodies and an ecu...)

[fyfethegreat 0]

I don' know the compression ratio of my engine but the four cylinders were reading 12 bar each. The head is ported but not polished. The air correctors in the carbs are 7850.1 and should be 7850.2 according to the program by Dave Andrews. I'm going to order 7850.2's anyway. the engine can tick over at 500 rpm but i keep it at 1100 rpm.

 

How would i be able to tell if the compression ratio is standard or raised? I know i should have checked when the head was off, i can take it back off to have a look and measure the valves as they looked bigger. It's the first petrol 205 i've had and i can't believe how quick it is, it should be illegal, i've already been caught speeding on the motorway and i was only in 3rd...

[fyfethegreat 0]

Update, I've put the 7850.2 pilot jet holders in the carbs and it's very smooth apart from a slight hesitation at very low revs and putting the foot down too quick. I've learned a lot from this forum already and would like to thank you guys for the good info on here. I think my next step with the engine is new rings as my compression seems low for the type of setup. I'm also going to order 65 pilot jets for the 7850.1 holders and see if that cures the slight hesitation. I'll wash the car and take some photo's and post them up for anyone who's interested.

[davidc 0]

Update, I've put the 7850.2 pilot jet holders in the carbs and it's very smooth apart from a slight hesitation at very low revs and putting the foot down too quick. I've learned a lot from this forum already and would like to thank you guys for the good info on here. I think my next step with the engine is new rings as my compression seems low for the type of setup. I'm also going to order 65 pilot jets for the 7850.1 holders and see if that cures the slight hesitation. I'll wash the car and take some photo's and post them up for anyone who's interested.

 

Thats it, get some pics up !

 

Keep up the good work, theres mountains of info & help on this site, it really is a great place !!

 

Cheers,

David