Need help w/ a few things! 🙏 TBI conversion to Carb.

MonteLS_84

Not-quite-so-new-guy
Jul 28, 2021
28
3
Google has failed me. Hopefully I can get some leads or solutions on what was said to be the go to site for g body related questions.

So, two days ago, I finally managed to save up enough money to buy my dream car...1984 Monte Carlo LS. Clean, solid, no rust. So, the previous owner is basically a flipper - owns a body shop, fixes/sells cars. The frozen original 305 was swapped out for a...1995 TBI 350 - out of a chevy pickup.

*NOTE: TBI was removed, and an intake and carburetor put on, as well as an electric fuel pump. All else - to the best of my knowledge - is mostly the original carburated setup as intended.

I'm still fighting to see/check any numbers on the block...but I did find the 5.7 liter casting mark, and the heads have the 4 center bolts holding the valve covers on. I'm not sure on the trans., as I still need to crawl under tonorrow...but I'm assuming either th350 or th400. Rear end...NO IDEA. Only one tire is spinning...thats all I know so far.

Now for the concerns and questions...

I see a lot of people saying this setup would need a fuel pressure regulator but there is none. Just an elec. fuel pump.

It starts up fine. Idles fine. Floats down the road like driving a cloud. The issue is when I'm in drive, especially when at speed and stomp on it...I get what sound like spark knock. I can feather it and get up to 70 with little knock and once I'm at speed it seems to go away.

Most have told me that the timing needs to be set right. Others told me that that can't be the case, as it is running so well at start. 🤷‍♂️

The 2nd part to my query is...the car is super sluggish! If I try to brake-torque it...no. It kinda just sits still. If I punch it from sitting...it goes at a snail pace w/ a little spark knock, then eventually just gets to speed. 🙄

I figured I should at least be able to get the 1 tire to squeak or anything?! Rear end needed? Timing holding me back that much?

I did notice a couple/few lines (vaccum?) plugged, etc. but assuming they should be plugged?

I'm really at a loss here and to be honest...I have no experience with the differences in engines here, or older engines in general. Any help or advice is greatly appreciated. I want to make the most out of what I have until I get some money to throw at a build. Thanks.
 

ck80

Comic Book Super Hero
Feb 18, 2014
2,796
113
You got a lot going on there to unpack.

You're on the right track in trying to identify what you've got. You're going to want to figure out if you have a roller cam to know whether you need to add a zddp product to your oil (flat tappet) or run whatever you want without it (roller).

Because it's a swap of unknown quality by a flipper who really just cares that cars survive a test drive You're going to want to go through everything, including checking the timing, and finding out of the distributor could be off a tooth or not.

In your inventory you'll look at what type and brand carb you have, how much emissions equipment you have. Has egr been deleted? Is the charcoal canister still present/hooked up? Was it a cruise control car, is that hooked up? All of these could be sources of disconnected vacuum lines, among others.

Once you've figured out everything that is, or isn't, going on there then you'll know what kind of vacuum hose diagram to pull and trace the hoses, looking for leaks, so on so forth. From the factory you shouldn't have rubber lines for the vacuum that are plugged off.
 
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ELCAM

Greasemonkey
Jun 19, 2021
166
43
What carb does it have?

Check the accelerator pump to see if it is working. Remove the air cleaner and look in the primary bores and operate the throttle linkage you should see the streams of gas being pumped in.

 
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tkruger

Master Mechanic
May 6, 2015
256
43
NY
This bit me on another vehicle that had slow acceleration and no power. Check that your exhausts is not clogged anywhere. Or that the cats are not clogged. The motor has to breath.

Also check that the plugs are clean. Cap, rotor, wires and plugs may make a big difference if there is an issue with spark. I have an 87 with the TBI 4.3. It started to miss at idle, cut out when accelerating when moving and just started to have less pep than normal. Also it would back fire occasionally when stomping on the gas. Changing the plugs and wires fixed it.

As for the vacuum lines are they from accessories or from the motor? If you trace one back to an accessory and it is connected to nothing else then don't worry about it. If it goes to something that is connected, or the motor better find out where it should have gone.

Depending on the transmission I thought some of the 4 speeds had an electronic lock up. Someone can correct me here please but I thought this was computer controlled and needed a modal to replace that if the computer was removed.
 

ELCAM

Greasemonkey
Jun 19, 2021
166
43
Depending on the transmission I thought some of the 4 speeds had an electronic lock up. Someone can correct me here please but I thought this was computer controlled and needed a modal to replace that if the computer was removed.

I think it was in 1981 on (first year of computers in cars ?) all automatics have lockup torque converters the 3 speed 200c 250c 350c and the 4 speed 2004R and 700R4 when they came along.

The TCC needs 12V to engage so missing the computer or wiring is going to make the TCC inoperable.

From my experience when a torque converter clutch won't disengage the engine will die when you put it in gear.
 

MonteLS_84

Not-quite-so-new-guy
Thread starter
Jul 28, 2021
28
3
Okay, I have some updates.

Carb.: 17084201 Rochester RF-EME QJet (can't find what CFM this carb. is)
Trans: th350 (has diagonal cut on pan)
Intake: 14057053 aluminum spread bore gm

Taking some photos of unplugged lines or wires now, as well as looking for more engine identifiers.

Will also be looking for plugged exhaust. Here is a link to a video - maybe you can hear the "spark knock" - I can barely hear it though. You can maybe get a feel for the lack of punch it has?

 

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ELCAM

Greasemonkey
Jun 19, 2021
166
43
Vacuum Gauge readings can help you diagnose blocked exhaust and other problems.
vacuum3.jpg
 
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MonteLS_84

Not-quite-so-new-guy
Thread starter
Jul 28, 2021
28
3
So, it doesn't appear that I have too much disconnected, etc. I took photos of everything I could find. Still not having any luck with seeing any numbers on the block 😒. I'll be checking the heads hopefully tomorrow - to see what they are, and hopefully tell if I have a roller or flat tappet. 🤔

Again, seems all they did was take off the old (newer) TBI setup and put on an intake and carburetor.

Here are some photos of plugged hoses and disconnected wires if anyone can help. I also have a photo if the carb. (info on the carb., trans., and intake are posted above). There is a plate missing. Guy said it was the choke.

The engine seems/sounds good, revs hard when just sitting in park. 🤔 I did notice that the carb is getting more air when I disconnect the air cleaner hose.. but I suppose that is normal? Anyhow, off to get some vacuum test gages and I still need to attempt the timing today. Here are the photos I have:
 

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MonteLS_84

Not-quite-so-new-guy
Thread starter
Jul 28, 2021
28
3
So, it doesn't appear that I have too much disconnected, etc. I took photos of everything I could find. Still not having any luck with seeing any numbers on the block 😒. I'll be checking the heads hopefully tomorrow - to see what they are, and hopefully tell if I have a roller or flat tappet. 🤔

Again, seems all they did was take off the old (newer) TBI setup and put on an intake and carburetor.

Here are some photos of plugged hoses and disconnected wires if anyone can help. I also have a photo if the carb. (info on the carb., trans., and intake are posted above). There is a plate missing. Guy said it was the choke.

The engine seems/sounds good, revs hard when just sitting in park. 🤔 I did notice that the carb is getting more air when I disconnect the air cleaner hose.. but I suppose that is normal? Anyhow, off to get some vacuum test gages and I still need to attempt the timing today. Here are the photos I have:
 

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