January 7

1975 Chevrolet Corvette EFI Conversion

Chevrolet, Podcast


Mark: Hi, it's Mark Bossert. I'm the producer of the Pawlik Automotive Podcast here in lovely, rainy Vancouver. And we're here with Mr. Bernie Pawlik, Pawlik Automotive in Vancouver. Vancouver's best automotive experience. 19-time winners of Best Auto Repair in Vancouver as voted by their customers. 19 times. And we're here with Mr. Bernie Pawlik. How are you doing this morning, Bernie?

Bernie: Doing very well other than it's rainy and extremely rainy.

Mark: Well, welcome to 1919. So, 2019 I guess.

Bernie: 2019.

Mark: Let's get in the right century. Although we are going back in time. We're talking about a 1975 Chevrolet Corvette that had an EFI conversion. What was going on with this classic vehicle?

Bernie: So this vehicle was pretty much stock Corvette. I mean, the engine had some work done on it. Not sure if much in the way of modifications, but essentially stock Rochester 4-barrel carburetor, HEI distributor. The client's concern was that the vehicle would tend to get flooded and it was hard to start, if not impossible. So we did some adjustment on the choke. Got it set up as best we could, but it still was never a really good experience. You start the car up, it would run for 10 or 20 seconds and stall. There was wear in the choke linkages and things. It was just things that wouldn't really allow us to get everything set up perfectly.

So that was basically the best we could get it and between cold start and a hot warm up and we're talking like 15 minutes driving, there would be some stalling issues or it would idle too high. Never quite perfect. That's kind of the best we could get it was to prevent it at least from flooding.

Mark: And so what did you do to repair this concern?

Bernie: Well, I talked to the owner about it and he said, "well, you know, I'm not super happy with that idea." He goes, "why don't we do an EFI conversion." Basically converting it to fuel injection. I said, "hey, what a great idea. You know, that'll eliminate all of those issues and bring the benefits of a modern fuel injection system to the vehicle." So that's exactly what we proceeded to do.

Mark: So what does that involve?

Bernie: Well, what that involves is removing the old fuel system. So we removed the carburetor, the old mechanical fuel pump, and then install a fuel injection unit. It's a throttle body fuel injection unit. It's made for quadra jet carburetor. Quadra jet carburetor has a smaller primary openings and larger secondaries. It's a unique GM feature. Anyways, this is a bolt on quadra jet conversion, so you bolt on a throttle body unit. Then there's a few sensors that need to be installed. A coolant temperature sensor. An oxygen sensor in the exhaust. And it need to be attached to the ignition system, to get an RPM signal.

Powers and grounds, of course. And then, the sort of larger part of the process is providing it with high pressure fuel. So, the gas tank has to be removed. A new fuel strainer put in. High pressure pump needs to be installed with fuel filters and then a return system also needs to be installed so the pressure can be regulated to the proper level and returned back to the gas tank.

Mark: So a lot of work basically.

Bernie: Yeah, a lot of work. I mean, it was a couple of solid days worth of work to do the job.

Mark: And how did the job go?

Bernie: Really well. It went fantastic. I mean, it just step by step, and the fuel tanks are kind of a pain to remove in this vehicle, but it was good mounting locations for the pump. The one little hiccough we ran into, for the fuel return line, fortunately there was actually two metal lines in this vehicle, the main fuel line and there was also a small, quarter-inch diameter fuel vapour line that ran parallel with the fuel line back to the vehicle. It hadn't been used in a long time. It was sort of just kind of disconnected, that emission piece so to speak. But the fuel return line was there, so we were able to tap into that. Unfortunately, when we fired the vehicle up, the return line had a big rust hole in it. 1975 car, you know, it's got quite a bit of miles on it and anyways, there was a rust hole, so we had to replace a couple of sections of fuel line. But other than that, flawless.

Mark: And do you have some pictures?

Bernie: I do. I got some pictures. We're going to start with a video here. This is ... I had a few videos I wanted to show, but due to technical difficulties, we'll just show the video here. This is the, you can see this okay?

1975 Chevrolet Corvette EFI Conversion
1975 Chevrolet Corvette EFI Conversion
1975 Chevrolet Corvette EFI Conversion

Mark: Yep.

Bernie: This is the completed job, more or less completed job. It's a Hawley Spider, that's the EFI unit installed on the vehicle. You can see down the barrels. The fuel and return lines are installed here. There's a cooling temperature sensor down around ... sorry I'm kind of moving the camera around too much. I'll just click back here with this look again. Cooling temperature sensor right here. Maybe just pause the video. You get a good view here. This cooling temp sensor here. And all the computer controls for this unit are actually all inside the throttle body except there's a little console piece that you have to install inside the vehicle so you can do all the tuning and adjustments.

But, it's really pretty much all takes place inside this unit right here. So that kind of gives a good idea of that. So this is basically the way it looked after the installation. For some reason, somebody put this chrome air clearer on top of the snorkel piece originally, but it worked fine. That's the way it looked on the carburetor when it came in and it pretty well, you can't really tell it's got a throttle body fuel injection unit underneath. That's the old system, of course, with the old carburetor.

Again, you know, not a huge amount of difference, but certainly the newer unit looks a lot cleaner. And as I said this little photo of the original tag L-48, 8-1/2 to 1 compression. This is a 1975, really probably one of the worst years in the US for performance cars with all the emission equipment they were forced to put on. I think, I looked at the specs and this engine has 165 horsepower. Whereas four or five years earlier, it would have had 300, 350, somewhere in that range. A huge drop in horsepower, so this fuel injection unit actually helps out a lot.

Mark: And how did the car run and drive after the conversion?

Bernie: It was awesome. As I mentioned, I mean, the owner's main concern was, you know, you start the car and it would tend to stall and just was fiddly. The moment we ... there's a few little tuning procedures you need to do before you start it up. We fired it up, started it up and it ran, like, perfectly the whole time. Just stayed at a nice steady RPM. I was kind of waiting for it to stall and it never did. Just expecting it to, but just like perfectly smooth the whole way. Went out and drove it. Tons of power. To be honest, I never really drove it before to kind of get a feel for the amount of power, but for certain it's going to have a lot more power than before. I would imagine the fuel economy would definitely be better, too, because now it also has it oxygen sensor monitored, so it's tune to the right, optimum air/fuel ratio.

As best as you could get out of an engine like this, that's exactly why it's going to have. Yeah, really fantastic. I was really thrilled with the result, and highly recommend it for anyone who has an older car that wants to get the benefits and feel of a more modern vehicle. And yet it still sounds like a '75 Vet, which is cool.

Mark: So any downside to installing an EFI system on an old car like this, other than perhaps the cost?

Bernie: Yeah, cost is ... it's not a cheap job. But I say, none, other than, if you want you car to remain stock all the way through, then there's an issue with that. But otherwise to me it's just a no brainer. If you like the car, you want to drive it around a bit and you want it practical, this is just the best way to go.

Mark: So there you go. If you're looking for some repairs or maintenance on your old classic vehicle in Vancouver, the guys to see are Pawlik Automotive. You can reach them at 604-327-7112 to book your appointment. You have to call ahead and book ahead, because they're busy. Or check out the website, pawlikautomotive.com. YouTube channel under Pawlik Auto Repair, hundreds of videos on all makes and models and years of cars and trucks. Or, thank you so much for listening to the podcast. Thanks, Bernie.

Bernie: Yeah, thanks Mark and thanks for watching.

About the author 

Bernie Pawlik

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