what happens when the jets are swapped on a holly 5200 carb on a auto transmission car? does it gain horse power? i did and it doesnt seem to be running to bad better than before actually not really rich or any thing just wondering if it will hurt anything
thanks,
lostandfound
Quote from: lostandfound on July 30, 2006, 02:26:12 AM
what happens when the jets are swapped on a holly 5200 carb on a auto transmission car? does it gain horse power? i did and it doesnt seem to be running to bad better than before actually not really rich or any thing just wondering if it will hurt anything
Swap the jets and it will run richer. Will it run better...Well if it does it was running to lean anyway and had a problem causing it, Carb needs rebuilt, vaccum leak, added headers causing it to lean out.....
Will it hurt anything? Well if it wasn't lean before it will hurt the gas milage. If it was lean it still maybe too rich now. With the primary jet in the secondaries it will run lean at wide open and at the very least hurt power.
Actually, it all depends on what jets are in the primary and secondary sides before you switch them. If someone had already been playing with the sizes of jets before YOU got to them, anything is possible.
SOME 4 cylinder cars with automatic transmissions may even use the SAME size jets in both primary and secondary applications, (especially if the carb has the same size or close to the same size throttle plates in both bores) or even a larger primary side jet to help the car move without excessive pinging or having the distributor constantly backing the timing off when the engine is not making much torque when running at lower engine speeds and/or smaller throttle openings.
The only sure way to know what you have in your carb. now is to directly measure the jets actual orifice sizes using small drill bits, as even clearly MARKED jets may have been drilled out to a larger orifice size, or filled in and and drilled out to a SMALLER than the originally marked size. I confess to having done both drilling out and filling in and downsizing jets (downsizing for altitude) over the years myself, rather than make a special trip to a speed shop or dealership that probably didn't have the correct sizes in stock anyway. Now, I most commonly use small drill bits*to check sizes and clean out jets, and for both jobs they are the perfect tool.
*Here's a tip:
Anyone who intends on working with carb. jets should really have a set of #1-60 numbered drill bits and probably also a set of #61-80 bits on hand.
These bits are sized in such a way that through the smaller size part of their range, the bits are within a few thousandths of an inch from one size to the next. To give you some idea of their sizes, #1 is .228", #60 is .040, and #80 is .0135".
These sizes cover the entire range of carburetor fuel jets that you are liable to come across unless possibly you're running a top fuel dragster, monster truck, heavy earthmoving equipment or maybe a champion tractor puller machine. These used to be fairly pricy items, but now that cheap stuff is coming in from China, both sets together would probably be under $20, instead of around $50 from a USA maker.
so im safe? or should i change them back?
Hello lostandfound,
If the carb jets are the only modification to your engine?
You are Most likely just wasting fuel.
I agree with onefarmer in his previous post.
To give yourself an idea of what is going on inside your engine.
Install new plugs with the way you have your jets now.
If they look sooty then you should most likely swap them back.
If your engine was pinging under hard acceleration and with the jet-swap it is not???
Check you ignition inital advance. if it is OK?
then leave the jets swapped.
Ideal air to fuel a/f should be 14.7 to 1
From Pintony
goodolboydws 8) Gets a 1-UP for a nice article on this subject.
I too agree, if you are not getting more air, then more fuel is a waste.
These are some ways of getting more air: performance cam shaft, free-er flowing exhaust manifold/exhaust, better flowing air filter, head porting, bigger valves, better flowing intake.
Keep in mind that at some point you will need a bigger CFM carb, not just bigger jets.
One other note on the jetting and carb work: I have used a small amount of Chap-Stik on the gaskets when rebuilding carbs so they are easy to take back apart; I have never had any leak issues, or damaged gaskets.
Bill
Quote from: 77turbopinto on November 22, 2006, 07:13:43 AM
I have used a small amount of Chap-Stik on the gaskets
That is great idea I hadn't thought of! Good stuff to know