dellorto 48 set up
18-04-2013, 01:52 PM
#1
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dellorto 48 set up
iam running twin dellorto 48 on a 2.0 pinto with fr32 cam,has anyone got a good carb setup to use on this ,any advice greatly welcome.thanks
25-04-2013, 11:45 PM
#2
Ive run similar setups open (no filter at all) in the past but i would not do this now, and always now use some sort of filter
Even an NA Pinto can benifit from a cool air feed and/ or vented bonnet to keep the inlet temps down
Balancing - The carbs have to be balanced, the butterflys have to close down to the tichoverstops identical, they have to open simultaniously, you can use feeler guages but an expert can set them up by ear, if they are set up right they will tickover nice (tickover may be quite high depending on cam) and pick up clean and rev/ sound nice, if they are not balanced you will get a lumpy tickover and they don't pick up right/ sound right - even the floats have to be identical so the same amount of petrol is in each chamber
Jetting - you cannot allow the engine to run lean - you need to start mega rich, run the engine/ car and carefully go down the jet sizes untill it is right, you can do a plug chop to check how its running, i would go for a grade colder (harder) plugs. there is no "right" or "wrong" in jets, i had to triple the jet size once, if you go miles to big, the jets may not atomize, if you go too big for the engine/ setup you run to rich/ loose power coke up the combustion chamber, too lean, burn out plugs/ eehaust valves / even hole pistons - you could have 2 seemingly identical engines (same "on paper" spec) and they may need totally different jet sizes
The jetting can be set up on a dyno, or even on track, checking the color of the spark plugs to avoid running lean, when you find the "sweet spot" the engine/ car can really fly
The carbs should match the head ports perfectly, with no step/s or bumps where the gas- flow goes from the carb to the head, this can also be sanded & polished (along with the piston tops/ combustion chamber in the head, and exhaust ports)
I recon i got about 15mpg on mine, these sort of carbs often require constant fettling (i had webbers) but when they are set up nice they have a significant advantage over a single twin-choke and sound amazing!
Even an NA Pinto can benifit from a cool air feed and/ or vented bonnet to keep the inlet temps down
Balancing - The carbs have to be balanced, the butterflys have to close down to the tichoverstops identical, they have to open simultaniously, you can use feeler guages but an expert can set them up by ear, if they are set up right they will tickover nice (tickover may be quite high depending on cam) and pick up clean and rev/ sound nice, if they are not balanced you will get a lumpy tickover and they don't pick up right/ sound right - even the floats have to be identical so the same amount of petrol is in each chamber
Jetting - you cannot allow the engine to run lean - you need to start mega rich, run the engine/ car and carefully go down the jet sizes untill it is right, you can do a plug chop to check how its running, i would go for a grade colder (harder) plugs. there is no "right" or "wrong" in jets, i had to triple the jet size once, if you go miles to big, the jets may not atomize, if you go too big for the engine/ setup you run to rich/ loose power coke up the combustion chamber, too lean, burn out plugs/ eehaust valves / even hole pistons - you could have 2 seemingly identical engines (same "on paper" spec) and they may need totally different jet sizes
The jetting can be set up on a dyno, or even on track, checking the color of the spark plugs to avoid running lean, when you find the "sweet spot" the engine/ car can really fly
The carbs should match the head ports perfectly, with no step/s or bumps where the gas- flow goes from the carb to the head, this can also be sanded & polished (along with the piston tops/ combustion chamber in the head, and exhaust ports)
I recon i got about 15mpg on mine, these sort of carbs often require constant fettling (i had webbers) but when they are set up nice they have a significant advantage over a single twin-choke and sound amazing!
30-04-2013, 05:59 PM
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thanks for reply
got the carbs back ,new sceals, now bolted back on.runs good but small leak at the carbs,were the trumpets bolt on to the body,might try new inlet manifold ,slight tilt up,and will check the fuel pressure at the fuel regulator.
got the carbs back ,new sceals, now bolted back on.runs good but small leak at the carbs,were the trumpets bolt on to the body,might try new inlet manifold ,slight tilt up,and will check the fuel pressure at the fuel regulator.
14-05-2013, 01:00 AM
#6
Could be the float chamber gaskets, the floats are set too high or the fuel line needs a return/ pump pressure forcing the float needles open.
The Webbers would probably be a lot less hassle
The Webbers would probably be a lot less hassle
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