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i have a 74 f100 with a 360 an i think a 550 cfm carb (its not the stock one) but it seems like the only way i can get any decent power out of it is by only going half throttle at wide open it just kinda bogs any idea what would cause this like to big of a carb or anything?
Vacuum leak? Take a can of brake cleaner or starting fluid and spray around anywhere there would be vacuum; intake carb gasket power brake booster ect.
It's time for you to do some investigating. As posted above check for vacuum leaks. Check air filter and fuel filter. Does it have a fuel filter? I ask because you said it was not the stock carb. Is the timing correct? Points in good condition and set properly? Did this condition come on all at once or over a period of time?
well i havent had the truck for to long bought a couple months ago but i change the fule filter an the air filter on but the whole time ive driven it its been this way the im sure it could use a tune up i havent been able to do much with it cause it seems like money is really hard to come by these days you know hard enough just to keep gas in the thing at 3.21 a gallon lol but yeah i think i try a few of your sugeations there an see what i come up with
Someone already mentioned timing but even more important then base timing, what is the advance doing, if your vac and/or Mech advance mechanisms aren't working right it will be really doggy in the mid and upper rpm ranges and fuel economy will suck even worse then normal so I would check with a timing light that it is at least advancing the timing as your rpms come up.
well i got the timing set to where it was firing right on the mark an it had even less power so i advanced it a bit a now it seems to have alot more power an performs alot better not sure why i didnt think of that before but thanks ofr the sugestions guys
go back and make sure the advance is working like i said in my post that would be a major cause of why it runs better once you advanced the timing. If you don't have the advance mechenisms working properly then it will be down on power unless you set base timing up fast enough to make it run decent. ON race engines we lock the timing out because it rarely see's under 3000rpm anyway so it's kind of the same thing if I put that engine at 10deg at idle it's not going to run good at all above 2000rpm and if your advance mechinsim are stuck you have the same deal.
Main jet may not be the right size. You really only use the main jet under heavy load and WOT. There are other circuits used when your rpms are lower.
Also, puttin too large of a carb on your motor can actually hurt your performance. If the venturi is too large, you don't get the right pressure drop through the carb and you won't pull the correct mix of fuel. High volume carbs need to be balanced by high flow exhaust, heads, and intake.