Need help with parts list- converting TBi to old school carb

[406Maverick]

Hello everyone, and yes I have searched the threads (before I get flamed haha). I have an 01 Regal with the Volvo Penta 5.0 gi pefs TBI. It appears that my ECM is bad after having it diagnosed by Bob @ OBD.. There is one more company I am going to have check it out before I scrap the ECM altogether (per the recommendation of a member here).. But if it still checks out as not being repairable I have decided that I am not willing to shell out the 1800$ for a new mefi setup.. I will just go carb. There has been lots of discussion here of converting, but I am hoping to get precise info as to what parts are the MOST plug and play.

I wouldn't mind upgrading my intake if there is a performance gain to be had. But what other parts will be needed? Part #'s are greatly appreciated if you have them--

Distributor
Carb
Necessary throttle brackets
Fuel pump

Thanks for the help!

 

[406Maverick]

Well after thinking about it, I decided to just go carb rather than chasing electrical gremlins.. so here we go!

What stays plugged in from the engine harness?

 

[406Maverick]

Also wondering if after going to carb if I will need to time the engine..?

 

[Lou C]

First, what ignition system does this engine have? Is the Delco EST? you might post up some pix....because if that has a stand alone module not dependent on the ECM, then you can get rid of all the EFI stuff, keep the EST ignition stuff leave it connected to the OEM wiring harness and either a Holley 4160 or an Edelbrock 1409 4bbl carb. That and a low pressure fuel pump which you may already have as part of your EFI system. Ultimately a carb and off the shelf Delco EST ignition system can be maintained for years without chasing expensive and sometimes NLA EFI parts. As good as EFI is in vehicles, in boats especially in older inboards the execution was not that good, they tend to be troublesome and difficult to repair.

Ignition - 7797478 - volvopentastore.com
your ignition should be either one of these, the one on the left is the Prestolite BID system, the one on the right is the Delco EST....

Fuel System - 7797478 - volvopentastore.com
here are the fuel systems, I assume you have the one on the right, which is for EFI, the one on the left is only a low pressure pump for carbed applications...
in either case I'd forget buying any VP fuel system parts and just use a low pressure aftermarket Carter electric pump make sure to wire it up to the safety switch that connects to the oil pressure warning system, you probably have the wiring already in place....
like this one:
Electric Fuel Pump Kit (michiganmotorz.com)

Next for the intake:
Intake And Exhaust System - 7797478 - volvopentastore.com

Now if your intake looks like this one in the left side pic then you don't need a new intake, you might just need a spreadbore to square bore adapter for the Holley or Edelbrock carb as they are both square bore carbs, or Holley makes a spreadbore 4bbl (4175) that you can use with no adapter, in fact I think they used it in some years when they were all carbs.
A new carb is a bit of change but much more affordable to maintain than EFI whether it's throttle body or port fuel injection.
My opinion anyway. Here's the Holley spreadbore 4bbl:
Holley 0-80552 650 CFM Spreadbore Marine Carburetor

and the Edelbrock 1409 marine carb, a good deal less expensive than Holley and some prefer it to Holley....
Edelbrock 1409 Edelbrock Marine Carburetors | Summit Racing
PS your V/P model # comes up as a 2000, not a 2001....if you try to find that model # in the 2001 and up section it's not there, only in the 1994-2000 years. Is it a charcoal paint color engine, not red? Red is 2001 and up, charcoal is 94-00, its actually from the joint venture with OMC, because the charcoal is an OMC sterndrive color....

 

[406Maverick]

First, what ignition system does this engine have? Is the Delco EST? you might post up some pix....because if that has a stand alone module not dependent on the ECM, then you can get rid of all the EFI stuff, keep the EST ignition stuff leave it connected to the OEM wiring harness and either a Holley 4160 or an Edelbrock 1409 4bbl carb. That and a low pressure fuel pump which you may already have as part of your EFI system. Ultimately a carb and off the shelf Delco EST ignition system can be maintained for years without chasing expensive and sometimes NLA EFI parts. As good as EFI is in vehicles, in boats especially in older inboards the execution was not that good, they tend to be troublesome and difficult to repair.

Ignition - 7797478 - volvopentastore.com
your ignition should be either one of these, the one on the left is the Prestolite BID system, the one on the right is the Delco EST....

Fuel System - 7797478 - volvopentastore.com
here are the fuel systems, I assume you have the one on the right, which is for EFI, the one on the left is only a low pressure pump for carbed applications...
in either case I'd forget buying any VP fuel system parts and just use a low pressure aftermarket Carter electric pump make sure to wire it up to the safety switch that connects to the oil pressure warning system, you probably have the wiring already in place....
like this one:
Electric Fuel Pump Kit (michiganmotorz.com)

Next for the intake:
Intake And Exhaust System - 7797478 - volvopentastore.com

Now if your intake looks like this one in the left side pic then you don't need a new intake, you might just need a spreadbore to square bore adapter for the Holley or Edelbrock carb as they are both square bore carbs, or Holley makes a spreadbore 4bbl (4175) that you can use with no adapter, in fact I think they used it in some years when they were all carbs.
A new carb is a bit of change but much more affordable to maintain than EFI whether it's throttle body or port fuel injection.
My opinion anyway. Here's the Holley spreadbore 4bbl:
Holley 0-80552 650 CFM Spreadbore Marine Carburetor

and the Edelbrock 1409 marine carb, a good deal less expensive than Holley and some prefer it to Holley....
Edelbrock 1409 Edelbrock Marine Carburetors | Summit Racing
PS your V/P model # comes up as a 2000, not a 2001....if you try to find that model # in the 2001 and up section it's not there, only in the 1994-2000 years. Is it a charcoal paint color engine, not red? Red is 2001 and up, charcoal is 94-00, its actually from the joint venture with OMC, because the charcoal is an OMC sterndrive color....

1st off thank you SO much for the help, this is exactly what I am needing!!

Ok- I have the 2nd ignition setup- the distributor with the square notch at the bottom. I think you said this one is the Delco EST..

I have the 2nd fuel system with both the low and high pressure pumps

I believe I have the square intake- not the spread bore- will post pics to make sure..

Engine is charcoal

 

[406Maverick]

Here are some pics

 

[406Maverick]

Hmm maybe I do have the spread bore after all.. so here is my next thought.. The price difference between the Holley 650 and the Edelbrock 1409 is somewhat substantial. It would almost be the same money to buy a new edelbrock intake and carb than just the holley alone.. are there any performance gains to be had with a new intake? That would make it worth it to me..

 

[Lou C]

That's the standard spread bore intake, so for either the Holley 4160 or Edelbrock you will need an adapter unless you use a Holley 4175. Yep looks like the EST, lucky because you can't get parts for the Prestolite BID.

 

[Lou C]

Hmm maybe I do have the spread bore after all.. so here is my next thought.. The price difference between the Holley 650 and the Edelbrock 1409 is somewhat substantial. It would almost be the same money to buy a new edelbrock intake and carb than just the holley alone.. are there any performance gains to be had with a new intake? That would make it worth it to me..

You can look at the Edelbrock marine 4bbl intakes, but it has to be a marine one for this application, they are bronze lined to prevent the aluminum from corroding, yes it may add some HP, but they are pricey.

OUT OF STOCK ETA 4/11/2021 Edelbrock Marine 5.0L, 5.7L, 6.2L, 4 bbl. Intake Manifold W/BRASS (1996-Current) (michiganmotorz.com)
see it adds $400 or so to the conversion.
Cheapest deal is keep your intake, get a spreadbore to squarebore adapter and use the Edelbrock 1409. If you search on Holley vs Edelbrock you will find that there are fierce loyalists for both, myself I prefer the Rochester Quadrajet but those have not been made in like 30 years. I have a good original one on mine, its been rebuilt about 3 times since I have it, but the rebuild kits only cost $55 or so and I do it myself in a couple hrs.

 

[406Maverick]

You can look at the Edelbrock marine 4bbl intakes, but it has to be a marine one for this application, they are bronze lined to prevent the aluminum from corroding, yes it may add some HP, but they are pricey.

Found it! How much HP you think would be gained with a new intake? Also, what would I need to do with my distributor to make it work since it currently gets some info from the ecm..?

 

[406Maverick]

And my engine has the vortec heads?

 

[Lou C]

I'd check Edelbrock's website to see what they say, I'd guess maybe 15-20 hp or so...
for the ignition, I'd have to see a V/P wiring diagram, but unless your engine has a knock sensor, I think it is a self contained ignition system, so you just would keep the same connections to the OE harness. The Delco can be used on carbed engines that don't have any ECM, so I think you can run it that way. I'd have to look at VP wiring schematic for your model # and year to be sure.
I did some more checking, it looks like the EFI models had a knock sensor, the carbed ones did not (comparing the wiring harnesses) but the Delco ignition is the same for both, so I take that to suggest you can run it without the knock sensor. I'm not 100% sure but that's what it seems like to me.

 

[Lou C]

And my engine has the vortec heads?

if the intake manifold has only 8 bolts holding it down to the cyl heads instead of 12, then yes, the vortec heads came on line about 97-98 or so. They add 25 or so hp by themselves.

 

[Lou C]

Found it! How much HP you think would be gained with a new intake? Also, what would I need to do with my distributor to make it work since it currently gets some info from the ecm..?

See above, I THINK you can use it as is, because its the same distributor for a carbed (no ECM) vs EFI (ECM). You just lose the knock sensor system.

 

[406Maverick]

See above, I THINK you can use it as is, because its the same distributor for a carbed (no ECM) vs EFI (ECM). You just lose the knock sensor system.

Once again thanks SO much for your help! Ok, so far I am following you. It's confusing to me how much will still be controlled with the engine harness after I swap to the carb. Will the ECM still be controlling anything at that point? Things like the trim, oil pressure gauge etc all are contained in the harness..

 

[ChrisCraftFan]

Hmmmmm You are making me think I should have gone this direction. I will be VERY interested in how it works out. I thought a LOT more had to be replaced to make it work! I should have asked.
Anyone know of performance differences between TBI and swapping a 5.7GSi to Carb?

 

[Lou C]

Well guys if you can get and post up a V/P wiring schematic then we can figure it out. Because I can tell you based on my old OMC Cobra a carbed boat has a very simple wiring harness. Just guessing if you simply disconnect the connectors for the ECM, next you'd have to figure out how to hook up the aftermarket electric fuel pump to the V/P fuel pump relay, that and to make sure its connected into the safety wiring that cuts power to the pump if the engine stalls. This uses an on-off oil pressure sensor, and if the engine stalls (no oil pressure) it cuts power to the fuel pump.

 

[Lou C]

Hmmmmm You are making me think I should have gone this direction. I will be VERY interested in how it works out. I thought a LOT more had to be replaced to make it work! I should have asked.
Anyone know of performance differences between TBI and swapping a 5.7GSi to Carb?

I'm thinking the only real differences is that the carb engine is not going to run as well after a cold start. Remember that some of us were driving long before fuel injection became standard on our vehicles and we are used to cold starting carbs. So that's one difference, power wise I thing a well set up 4bbl carb might make more power than a throttle body EFI system.

 

[ChrisCraftFan]

I am good with cold starts I do not care about that! Here is what I have

 

[406Maverick]

Right now I'm trying to sort out how to make this distributor work- it doesn't appear that it can be adjusted to set timing like a typical carb distributor.. also working out the details of what fuel pump would be suitable..