NOOB
Senior Member
Joined: Jul 2005
Posts: 2,105
From: Central North Carolina
RE: 383 torque and hp
ORIGINAL: bkmc24
so a question for you, ive been wondering this for a while, what happens when someone re-jets their carb? what is going on when that happens and whats the benefit of it. and another question, if i were to put a procharger on, would i have to do the fuel injection swap or will it fit on the carbed motor. i know a blower will fit on it but i dont want something that huge comming out of my hood lol.
so a question for you, ive been wondering this for a while, what happens when someone re-jets their carb? what is going on when that happens and whats the benefit of it. and another question, if i were to put a procharger on, would i have to do the fuel injection swap or will it fit on the carbed motor. i know a blower will fit on it but i dont want something that huge comming out of my hood lol.
Jets looked kind of like a big allen head screw, they were usually brass, about 1/4 inch diamter, 3/8 long and have a tiny, very precisely diamtered hole in them, the were screwed/placed in the carb and it was through them (the precise hole) that the fuel is sucked out of the carburator bowl and down into the engine by the incoming air. If you have ever messed with nitrous kits, these are sort of similar to the jets you get with them. There was one for each barrel of the carb: 2 in a 2-barrel carb and 4 in a four barrel carb.
They came in all sizes of that tiny hole, say 68 thousandths, 72 thousands, 78 thousandths, etc., and you tuned the fuel/air ratio by changing jet size: a slightly larger hole gave more fuel. You would stick a fuel-air measuring sensor up the tail pipe and try various jets. There was a real airt to picking the right sizes for a modded engine and it was a critical tuning feature. When you added a new manifold or cam or increased compression ratio you have to re-jet the carb.
Most "modern" (new) carbs come with jets for a particular engine you buy them for. If you go modding the engine you may have to change the jets, otherwise it can run too rich or too lean
Thread Starter
Joined: Dec 2005
Posts: 9
RE: 383 torque and hp
ORIGINAL: Lee Willis
Jets looked kind of like a big allen head screw, they were usually brass, about 1/4 inch diamter, 3/8 long and have a tiny, very precisely diamtered hole in them, the were screwed/placed in the carb and it was through them (the precise hole) that the fuel is sucked out of the carburator bowl and down into the engine by the incoming air. If you have ever messed with nitrous kits, these are sort of similar to the jets you get with them. There was one for each barrel of the carb: 2 in a 2-barrel carb and 4 in a four barrel carb.
They came in all sizes of that tiny hole, say 68 thousandths, 72 thousands, 78 thousandths, etc., and you tuned the fuel/air ratio by changing jet size: a slightly larger hole gave more fuel. You would stick a fuel-air measuring sensor up the tail pipe and try various jets. There was a real airt to picking the right sizes for a modded engine and it was a critical tuning feature. When you added a new manifold or cam or increased compression ratio you have to re-jet the carb.
Most "modern" (new) carbs come with jets for a particular engine you buy them for. If you go modding the engine you may have to change the jets, otherwise it can run too rich or too lean
Jets looked kind of like a big allen head screw, they were usually brass, about 1/4 inch diamter, 3/8 long and have a tiny, very precisely diamtered hole in them, the were screwed/placed in the carb and it was through them (the precise hole) that the fuel is sucked out of the carburator bowl and down into the engine by the incoming air. If you have ever messed with nitrous kits, these are sort of similar to the jets you get with them. There was one for each barrel of the carb: 2 in a 2-barrel carb and 4 in a four barrel carb.
They came in all sizes of that tiny hole, say 68 thousandths, 72 thousands, 78 thousandths, etc., and you tuned the fuel/air ratio by changing jet size: a slightly larger hole gave more fuel. You would stick a fuel-air measuring sensor up the tail pipe and try various jets. There was a real airt to picking the right sizes for a modded engine and it was a critical tuning feature. When you added a new manifold or cam or increased compression ratio you have to re-jet the carb.
Most "modern" (new) carbs come with jets for a particular engine you buy them for. If you go modding the engine you may have to change the jets, otherwise it can run too rich or too lean
Junior Member
Joined: Dec 2005
Posts: 6
RE: 383 torque and hp
HI!
This is my first reply to a post
I have been looking around for a new engine for my Vette and have decided to go for a World Products/Bill Mitchell crate engine. Fully assembled, dyno sheet and even a 2 year 24K mile warranty all on pump gas too.
Jegs is a distributor for them you can check out this one,
454 Small Block Chevy 600 HP on PUMP GAS!
I am looking at one of the World Products Big Block engines. Also runs on pump gas
Sadly the Bill Mitchell website is down for redesign at the moment [:@]
Great value for the $$ too. They will also build custom engines too. Want an all aluminum engine, no problems, all aluminum big block? sure....
This is my first reply to a post
I have been looking around for a new engine for my Vette and have decided to go for a World Products/Bill Mitchell crate engine. Fully assembled, dyno sheet and even a 2 year 24K mile warranty all on pump gas too.
Jegs is a distributor for them you can check out this one,
454 Small Block Chevy 600 HP on PUMP GAS!
I am looking at one of the World Products Big Block engines. Also runs on pump gas
Sadly the Bill Mitchell website is down for redesign at the moment [:@]
Great value for the $$ too. They will also build custom engines too. Want an all aluminum engine, no problems, all aluminum big block? sure....
Senior Member
Joined: Jul 2005
Posts: 2,105
From: Central North Carolina
RE: 383 torque and hp
Well, JEGS has a good reputation, I won't think they would sell you something that wasn't good. And it ought to fit no problem.
This will be a big increase for you. You car would be rated at about 320-325 HP in modern rating terms (the 390 was the gross, not net SAE). Note that the 600 HP is a crate engine dyno rating and that corresponds to about 575 flywheel in the car. You are looking at more than a 50% increase.
Not to recommenda gainst this, but I've dealt with a C3 (72) that had such an upgrade and it stresses just about eveyrhitng in the drivetrain a lot. And a 600 Hp pump gas 454 is probably going to be a little bit ragged on the street. You have one the the all-time great combinations of sweet street disposition and power - the 390 427 was superb:::your new engine will be a bad boy, which is fine if that's what you want, but if you drive it daily, you'd be happier backing off to a tune with about 475 Hp on pump gas. Still a big increase and better drieability. The 600 is probably "streetable" in the sense you'll be able to drive the car to the dragstrip.
This will be a big increase for you. You car would be rated at about 320-325 HP in modern rating terms (the 390 was the gross, not net SAE). Note that the 600 HP is a crate engine dyno rating and that corresponds to about 575 flywheel in the car. You are looking at more than a 50% increase.
Not to recommenda gainst this, but I've dealt with a C3 (72) that had such an upgrade and it stresses just about eveyrhitng in the drivetrain a lot. And a 600 Hp pump gas 454 is probably going to be a little bit ragged on the street. You have one the the all-time great combinations of sweet street disposition and power - the 390 427 was superb:::your new engine will be a bad boy, which is fine if that's what you want, but if you drive it daily, you'd be happier backing off to a tune with about 475 Hp on pump gas. Still a big increase and better drieability. The 600 is probably "streetable" in the sense you'll be able to drive the car to the dragstrip.
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