CarburetorsCarb discussion and questions. Upgrading your Third Gen's carburetor, swapping TBI to carburetor, or TPI to carburetor? Need LG4 or H.O. info? Post it here.
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Well I finally fed up with my TPI setup not running right so I decided to swap it over to a carb. While I was in there I thought it would be a great time to put a cam in as well so tell me what you think....
Edelbrock 600 CFM carb
Weiand X-celerator Intake
Comp Cams 268 High Energy Cam
Jegs Fuel Pressure Regulator
and a bunch of AN fittings
The Jegs regulator I bought comes with a return, I have it all hooked up with 5 psi to the carb. Here's a pic of the setup.
i was told that 8psi was the way to go? anyways i do have a question which line is the supply for the fuel? the upper one or the lower? thanks
we have this regulator Summit SUM-G3131-1 - Summit® Fuel Pressure Regulators. how and where do we put the gage and the return line?
The Summit SUM-G3131-1 will NOT work with an in-tank fuel pump - it is NOT a return style regulator. You HAVE to get a return style regulator if using the in-tank fuel pump - there's no way around it. They run about $80, there's no cheaper ones, they are all that expensive. You need the Jegs model listed and used in the pic above, or the Mallory 4309 that alot of folks use - there's also a Barry Grant model, and a Holley model IIRC, but it HAS to be return-style.
I believe the supply line is the smaller of the two, and the return line is the larger - but do a search on here for "supply line", read through the posts, and verify because my memory ain't what it used to be.
why do i need a return style regulator? i can just block off the return line right since the carb doesnt have the need for return and i can regulate the pressure for the carb? just curious why i would need a return style? does it have something to do with the fuel pump? thanks.
OK - The pump in the tank pumps what it pumps (psi). These systems were designed as a return style system for environmental concerns (ie regulations). Thus it was designed to accept more fuel than necessary, restrict flow and/or volume to adjust to the needs of the induction system, and return the unused portion of fuel to the tank. The TPI pump pumps more pressure than the others, as the TPI system needs more pressure, so your TPI pump creates alot of pressure. If you simply plug it off by not returning to the tank (think of this as too many bacon cheeseburgers) the pump will try to pump more than it's designed for (same as you trying to run farther and faster than you can with all those cheeseburgers clogging your arteries) - and eventually it'll kill itself from being under too much pressure all the time (in your running case, you just had a stroke).
In order to keep the pump from working too hard and killing itself, the lines can't simply be clogged (ie plugging the pressure with any old pressure regulator) - the excess must be released somewhere (ie returned to the tank).
Thus, a return-style regulator MUST be used.
The other alternative - drop the tank, and insert a carb pickup, and use a mechanical pump on the block. In the end, you'll have spent as much cash doing so, and spent a day dropping the tank to do it.
It's the system you have, don't fight it, just work with it. All of us that have done the carb swap had to do it, you are no different. If there was a different way, we'd all done it - none of us like spending $80 on a regulator. But as Bruce Hornsby sings, "That's Just The Way It Is". I promise - there's no other way - it's not like I get any commission from Summit for selling these - I'm too busy selling dog food (I'm a pet store manager).
the return is necessary because of all the fuel aka psi, that the stock pump is putting through the lines and because the regulator is only putting so much fuel in through your supply and the excess fuel needs a place to go and that's back into the tank which the regulator puts it.
the bigger line is supply and the smaller is the return. if you were wondering.
going with the regulator is a good step because if you decide down the line you want to do a different pump you already have a great regulator for it, i have the Mallory one and its got a lot of ports and works with the stock pump. plus a pump is not that much more just get a good one.
So does your computer still run your tranny? ugh,just noticed it was a 5-speed,my bad.
However would my computer still run my 700r4? (lock up)
Did you pull the engine to get the cam out? thx
So does your computer still run your tranny? ugh,just noticed it was a 5-speed,my bad.
However would my computer still run my 700r4? (lock up)
Did you pull the engine to get the cam out? thx
no the computer is rendered useless after a carb is installed. you will either have to put in one of the kits from various aftermarket places such as tci and such or put in a manual switch as i did. it is in the tech articles.
im getting ready to swap mine to carb,just got stuff yesterday i got the mallory 4309(heard good things and bad guess we'll find out) i have an electronic 700r4 and believe you have to rig a toggle switch up so it will lock up the converter, any way post up tempest im curious to see how yours went and what u found out.
Well, I finished my carb conversion Thursday night and decided to take it for a spin. The car ran great, it has soooo much more power than the TPI did although I did put a cam in it. So much power in fact that I blew my posi unit and had to tow the car home. I posted some pics of the destroyed rear, I'll get some pics of the motor for you guys soon. As for the torque converter lock up I really don't know because my car is a stick.
No I didn't have to take the motor out to put the cam in, I took the radiator, and those reinforcement rods that run in front of the radiator out. It just barley fit, I had to take the timing chain gear off.
What part number is the regulator you have? Or a website link would be even better, I really like the style of it. Sorry about your rear end, were you trying to play around a little? lol
Ya I was messin around doing burnouts, it's not a big deal I already have it back together and running. As for the reg. it is a jegs style one part #555-15909 here's the link
not trying to jack the thread but if you dont mind me asking Tempest22:
What cam did you put in and did you use the stock heads?
I used a comp Cams 268 High Energy Cam I had laying around, the only thing I changed is the lifters. I used the stock heads even though you are supposed to change the valve springs I haven't had a problem yet.
For the wiring harness I left most of the wires there, I cut out all of the injector and sensor wiring. For the Distributor all I had to do was cut the coil plug off and run the two wires to the HEI. I left all of the computer wiring and relays in tacked just to get the car together but over the winter I'm going to rip out all of the wires I don't need. I used the TPI throttle cable and it works fine but I don't think I have full throttle, I'll have to try and get a Carb or TBI cable.
Alright I kinda hate to ask more questions but where did you get fuel lines like that? That thing looks really really nice and I plan on doing it so I was hoping you could tell me lol
Alright I kinda hate to ask more questions but where did you get fuel lines like that? That thing looks really really nice and I plan on doing it so I was hoping you could tell me lol
Consider leaving some of the wiring harness from the passenger side intact. Why? Well I left all of my wiring intact, and I've been making use of them, and it's been really handy. I installed fog lights, a seperate fan controller with manual on switches in the cabin, a torque converter lock up switch in the cabin, and seevral other goodies. Having the stock computer wiring on the pass side made it really easy, as I already have a ton of wires running form the engine bay to the cabin, so I didn't have to run any new wiring. On things like fans and foglights that require higher loads, I used relays under the hood, and just used the small computer wires to run 12v to enable the relay, where the main source of current runs off the battery.
It's just nice to have wiring already to use without running new stuff through the firewall. So, don't hack them all out just yet.
As for the wiring I really don't have any need for it, my fan is already hooked up and I don't see any thing else I would want to hook up so its going. Its too much of a mess under the hood.
How did you setup the convertor lock up with the toggle switch?
My car is a 5 speed I didn't have to worry about that, but when my brother switched his Monte Carlo from TBI to Carb he bought a TCI converter lockup kit that has a switch and is also vacuum operated.