im tired of the tuning issues with my 93 Trans Am. poor driveability, poor fuel economy, and whenever i want to change something like injectors or cam for example you have to start fresh all over again. its just too much of a hassle. not to mention my opti is going dead again.

does anybody know of any good websites that have detailed info on swapping the LT1 to a carb setup but still retaining the LT1 motor?

i dont want to get bashed or hear about what a mistake im making by going carb, just looking for info, thank you.

 

I guess it would be pretty simple. GMPP sells a block off plate for where the opti went and they also sell a dual plane intake with a distriputor hole in the back. Just drop in any old distributor. I'm sure there is a single plane intake available as well. Hope this helps.

 

Well to let you know I don't think there are any websites to give us the info we are looking for. I have been researching this for a while now and have not found much on the web. I do know that whatever intake you use you will more than likely end up having to cut the cowl for the carb. And I have researched and found that a crab cap distributor that uses a crank trigger will allow us the change over much easier than "any ol distributor" will. Just a tid bid o info for you there.

 

i really dont see where it would be that hard. people are telling me ill have to redo the whole fuel system, but i dont see why you cant do like on mustangs, and just run 2 fuel press regulators with the EFI pump/lines, and regulate the pressure down to 7psi or so for the carb.

from what ive read and seached so far, it looks like dual plane is the only one available as a bolt on manifold, to use a single plane, it will require buying one for a SBC and fabbing it to work, which doesn't sound that hard.

 

I never thought of the double regulator! I don't see why it wouldn't work. your biggest problem will be the distributor if you plan to use an hei or anything other than a crab style. I know the crab style is only like 4" from the intake to the top of the cap and the wires attach in the side instead of the top. th only thing is you will have to run a crank trigger which from what i have heard is better than any hei distributor. I'm doing a 400sb stroked to a 427 for my changover. I am doing a complete engine not just a carbed LT1 I will be chaging the cooling system as well. I am shooting for 500hp na and a 200-300 shot of Nos on a direct port system. I have a couple years so I am taking my time with it. Good luck and let me know if you have any ?'s

 

yea the mustangs work great with the EFI pump and lines and 2 FP regulators.

i talked to a guy at the turkey rod run and he said the distributor really isnt that big of an issue. i know some say you've got to pull the motor if you take the distributor out, but the guy i talked to said if you just take the intake out with the distributor, its a breeze.

 

You will have all that with a Carb too.

 

Finally, someone else who's as sick of F.I. as I am

I'm switching over to a carb too on my '93 Formula Firebird. I'm doing a stroker right now and working my way up from the bottom of the motor to the top, so the intake and carb will be the last pieces to get.

As far as I know, the GMPP LT1/LT4 carb intakes are the only ones available for the LT1. On GM's site they advertise a 30+ # of torque increase over the stock F.I. intake and with no loss in HP on the top end. Sounds good to me ! The only thing is that it's a duel plane manifold which may be a problem for you if you want to build an all out race motor. You'd probably want a single plane for that.

My mechanic told me today that he's seen a couple of single plane intakes for the LT1. He just can't remember what make they were but he think they might have been from Willson or something like that. I'm looking into that already.

Good luck and let me know if you learn anything new about the conversion I might want to know. I'm still researching it too!


Ps. if you really want a single plane intake, you could always just get the GMPP duel plane, and grind out a bit of the centre section divider. It wont be a TRUE single plane, put it would provide a bit more on the top end as far as HP goes. That might be the route I take, if I can't fint a true single plane.

 

I converted a single plane over for a guy to run a carb on a LT1 headed 383. If you are going drag racing it's the way to go. He ended up putting a huge N2O shot on it and splitting the block, but it ran really well NA before that (600hp) I think he might have the intake for sale, but I'm not sure about that.

Bret

 

There are numerous threads on the "Advanced Tech" forum regarding the single plane intakes, distributors that fit under the cowl, ignition types, etc. Just try a "search" with "single plane LT1" for starters.

 

heh, then why does the mustang me and my brother built that has a 302, AFR heads, 254-260 @ .050 duration cam, single plane intake, and a carb drive 100 times better than my car and is just as fast on motor, as mine is on the bottle? it has no surge/bucking under 2k rpms at all. its fuel economy really isnt much worse if its highway driving. and if any changes are made motor wise, youre nothing but a 10 minute jet change away from being tuned?

in technical discussion there are threads on using a standard SBC victor jr or equivilant and you have to drill new bolt holes and do a lil fabing, so i dont think thats a problem.

one question i just hought of is if i convert to mechanical ignition and distributor, how do i set the timing seeing how my LT1 just has a hub and doesnt require timing marks? can you put a balancer with timing marks from a 350 SBC on the car?

 

I guess you do live in Florida come to my part of the country and try to drive your carb'ed car when its 0 degrees out. It takes less time to tune your LT1. Fuel injection is 100x's better imo. I see no real reason to go carbed.

 

Here are a couple right off the top of my head

1. Cleanliness- no more wires,sensors,plugs,computer boxes etc. cluttering up the engine compartment

2. Additional space- also a benefit to not having wires,plugs,sensors,etc.

3. Tuning- Not everyone can afford a laptop and software/chips required to do the tuning themselves or have the knoledge. Not everyone can afford to pay someone else the $$ either. Carb tuning = 10 minutes/ some jets and a screwdriver

4. Reliability- I know a lot of people won't agree with this one but the way I see it, there are 1000001 sensors on these F.I. cars and all it takes is one of them to go bad and the whole car runs like crap. More sensors = more oppertunities for stuff to go bad. Carb = simple

There are a couple more but I'm too tired to think about them right now.

EDIT: Almost forgot.

5. - NO OPTISPARK !!

EDIT AGAIN:

6. Is it just my imagination or do carb'd motors sound 10X better than F.I. motors

 

My wifes third gen is a carbed distributed LT-1. I'[ve got pics of the entire buildup on my home computer, but I have no how to page.

I'll be able to awnser any questions if you want to email me though. We are using the GMPP intake BTW.

-Shannon

 

I can't argue that its probably cleaner

You really are eliminating nothing in the way of space.

You can use your desktop PC to tune. Everyone on this board probably has one as they are all on here. Its not extremely hard to tune. Many people on here figure it out. My buddy is a pretty good tuner and he learned it all from this board.
There are only about 5 sensors actually needed for our cars to run. I have a 140k on my car and never just had a sensor go out besides O2's

The optispark isn't that bad of a deal. I think most people just botch installs or something. I've never had one fail. If you really want to you have the Delteq as an option.


Not really when you consider the fuel economy, easy start ups, less emissions=less of a headache at stop lights. Carbs have their problems too. Cold starts a pain in the Azz, poor fuel economy, sticking floats. I've had brand new Holleys do that to me. If Carbs were so much better i'm sure thats why we have fuel injection on our cars now.