'68 Coronet project EFI/4 speed conversion up and running!

[rmchrgr]

Finally posting up about my '68 Coronet that I have been working on for the last two years or so.

Little backstory first. I bought the car in May of 2018 from a guy in Quebec, Canada. It was a US market car originally from the mid west somewhere, 1 of 934 big block Coronet 440s if you care about that sort of thing. Mr. Previous Owner brought it up there in the early 2000s and did an "amateur resto" on it using mostly original/stock parts. At some point the car had a 470" motor in it and was drag raced it but the original, stock 383 went back in to sell it. It has a decent, driver paint job but the mechanical side was an afterthought. Car was definitely a driver but the body and paint were good which is mostly why I bought it.

Got it home and drove it regularly for about 6-7 months. It was just OK. Literally bone-stock 383, bench seat, column shift, 3.23 gears. I guess it handled and stopped OK, ran cool and had no major drivability issues but performance was just kind of meh. The bench seat was sloped towards the driver's side door and the column shifter was so sloppy you couldn't tell what gear you were in. Not the thrill ride I was hoping for when I bought it.

So as I'm driving it while half falling asleep, the wheels started turning and the inevitable tinkering commenced in hopes of making it a little more responsive.

There was a point where I attempted to swap the stock intake for a Performer and replaced the Edelbrock 1407 for a Holley carb on it and wound up doing more harm than good. I tried to band-aid some things but eventually I threw in the towel. Most everything was original and used well beyond it's useful service life. The wiring was wasted and literally crumbled when touched.

Truth is, I probably spent too much on the car which made me realize I was kind of stuck with it. So instead of selling it at a loss and searching again for something closer to what I wanted, the decision was made to make it more fun and reliable - 4 speed, console, bucket seats, Holley Sniper EFI, re-wire the entire car, new suspension including frame connectors, Borgeson steering box, Firm Feel T bars and tubular control arms, new ball joints, strut rods, HD leaf springs, Hooker headers, full TTi 2 1/2" exhaust, new radiator and on and on.

So that was Septemeber/October 2018. That November, I broke my hip skateboarding (yep) and was out of commission for several months into the winter. At that point my garage did not have heat yet either so unfortunately the car sat half-apart until the Spring of 2019. I have been working on it steadily since then.

 

[rmchrgr]

Like every project there were ups and downs. The wiring turned out to be pretty involved because I wanted to integrate the Holley Sniper harnesses into the American Autowire harness in addition to removing anything that was not going to be used because I hate unused, un-terminated wiring just hanging there. I managed to get it done but there was a lot of missteps on my part. If I had to do it again, I'm not sure I would go about it the same way, I created a lot of extra work for myself and wound up undoing some of it because it didn't work.

Integrating the Holley "can bus" gauges into the stock, standard dash was another involved project. Not sure I'm completely happy with how it turned out, feels incomplete without a lens. I gutted the back of the OE instrument panel and made some new panels to mount the gauges and make it blend in with the speedo. You don't realize how narrow the instrument panel is until you start trying to fit stuff into it that was never meant to be in there.

Unfortunately I'm going to have to take it out because two wires are crossed and some of the backlight bulbs are out. Other than those things and programming the Holley gauges, the dash seems to work.

I'm not a bench seat guy at all so ditching the jacked up slippery blue couch was one of the primary things I wanted to do. I still have to finish the passenger side seat but so far the buckets are light years away in terms of comfort and driver position. It took a lot to piece everything together. At some point I'm going to pop for head rests.

The console was a nightmare so I won't go into how miserable it was dealing with it. I like the look of it but other that, I will never put another console in a car that didn't have one.

 

[rmchrgr]

For the most part, I left the engine alone but did replace a bunch of parts that were worn out. The original 906 heads were running but ugly. Someone put new valve guides in and cracked the top of the castings. The valves were OK though, they are nice Mopar Performance ones.

Found a pair of clean, re-done 452 heads on Craigslist to use which were a nice upgrade. Swapped the valves and springs and had a nice set of heads ready to go.

The pic above shows the set of Cal Custom valve covers I had planned to use but one of them was cracked. I wound up topping off the heads with some "NOS" 1968-vintage Edelbrock finned valve covers which I've had on the shelf for a long time. Just made sense to use them, they were not meant to collect dust on a shelf.

As for the rest of the motor, it has a "Roadrunner" cam in it which I believe was the cam that came in the 335 hp 383s. I put a new balancer on just to have engraved timing marks. Performer 383 intake, Hooker 5101 full length headers, new clutch fan, Denso 60A alternator and a Borgeson Saginaw-style power steering pump.

 

[PRND21]

Looks pretty good from your pictures. Frustrated at times? Sometimes you just gotta walk away and clear your head, come back later. Pretty cool though when you work things out.

 

[rmchrgr]

I suppose the big-ticket item here is the Sniper EFI system. I got it running today and I can say with 100% confidence it was the right thing to do. The car runs sooooo much better than it did when I first got it. Starts right up every time. I only drove it down the block briefly but when I shifted into second I could feel the car take off like never before.

I went with the whole kit and caboodle -Sniper EFI throttle body, Holley/Tanks, Inc. EFI fuel tank, Hyperspark ignition box and the Hyperspark distributor. I also made all-new fuel lines from front to back.

Getting everything as a package made more sense as opposed to trying to piece things together and make all the different parts play nice together. I'm glad I did that because as I mentioned earlier, I did manage to screw some things up with the Sniper wiring by attempting to combine it into my main harness.

Without going into too much detail, there are definitely some things you just can't do and expect things to work. I learned though so it's all good but up until today, I was pulling my hair out with a no-start condition which was the direct result of me trying to make up my own way of doing things.

Frankly the generic Sniper main harness left a lot to be desired. My guess is that it was designed around something other than a Chrysler product and was made "universal" enough to fit. Oh well, such is life with aftermarket parts.

 

[rmchrgr]

So after two years, I got the car running today.

https://www.dropbox.com/s/glag7vrep20dys8/Coronet 10.20.20.sm.mov?dl=0

Definitely needs to have some things sorted out, especially the clutch and/or shifter. Not sure if I have the hydraulic throwout bearing set quite right and the shifter will not stay in gear unless I hold it in place. Obviously these issues will be addressed before taking it out on any significantly longer drives.

Also have to re-do some of the wiring since I ran some temporary wires to get the car running. The front end needs to be aligned for sure. But that's about it for now. Once things are finalized then I'm going to drive the wheels off of it until winter comes.

Thanks for reading!

- Greg

 

[erikcroissant]

Do you have a link for that efi tank? And how did you go about making the fuel lines? Looking to do the exact same thing to my 68 Coronet.

 

[rmchrgr]

EFI tanks are readily available from all your normal vendors.

https://s.yimg.com/aah/chucker54/road-runner-sniper-efi-fuel-tank-system-20.png

For the lines I used 3/8” tubing and -6 Aeroquip push lock type hose. I get a coil of each from Summit. Wound up ordering more of both, lots of trial and error when figuring out the optimal routing.

The fittings are -6AN type. They are expensive but I prefer to use them over rubber lines and hose clamps.

I used steel lines this time with gravel guard because I plan to drive this car a lot. As you would expect steel is much tougher to bend than aluminum. Its also a pain to straighten, even with a fancy tubing straightener-outer device.

Once the tubing is straight you just follow the surface of where you plan to route them. Having plenty of adel clamps helps.

If it makes sense, I like to be able to take the lines apart if needed so I made connections at various points. This way should a need arise, I don’t have to take the entire front-to-back line out, just the section I need.

For tools I use an Imperial Eastman 3/8” bender. I have several varieties of benders but that’s my main one. For the flares I have a Rigid Flaring tool. In case you didn’t know, AN type fittings utilize a different flare angle so you need a specific 37 degree die to form them.

 

[watermelon]

an old Mopar with stick shift and efi....whats not to love?

that Rigid tool came in handy when i did my fuel lines too.


watermelon

 

[erikcroissant]

EFI tanks are readily available from all your normal vendors.

https://s.yimg.com/aah/chucker54/road-runner-sniper-efi-fuel-tank-system-20.png

For the lines I used 3/8” tubing and -6 Aeroquip push lock type hose. I get a coil of each from Summit. Wound up ordering more of both, lots of trial and error when figuring out the optimal routing.

The fittings are -6AN type. They are expensive but I prefer to use them over rubber lines and hose clamps.

I used steel lines this time with gravel guard because I plan to drive this car a lot. As you would expect steel is much tougher to bend than aluminum. Its also a pain to straighten, even with a fancy tubing straightener-outer device.

Once the tubing is straight you just follow the surface of where you plan to route them. Having plenty of adel clamps helps.

If it makes sense, I like to be able to take the lines apart if needed so I made connections at various points. This way should a need arise, I don’t have to take the entire front-to-back line out, just the section I need.

For tools I use an Imperial Eastman 3/8” bender. I have several varieties of benders but that’s my main one. For the flares I have a Rigid Flaring tool. In case you didn’t know, AN type fittings utilize a different flare angle so you need a specific 37 degree die to form them.

Great info, thank you. Looking forward to doing the same.

 

[furious70]

Got mine from tanks inc, they are in the next town over from my hometown in rural Iowa

 

[Markzx14]

Hey good looking build. I saw where a skateboard got you. Well a damn Hoover board about paralyzed me. I could go on it but when I tried to get off I was hanging on to some chest of drawers. That damn thing took off out from under me and I landed on the corner of a project. My spine and my neck landed directly on the corner I saw a bright flash then I was lying in the floor. My whole body was numb for a good 20 seconds. Needless to say when my 10yr old son comes through egging me on to get on that 2 wheeled devil. I just give him a stern look then he just laughs and wheels off

 

[rmchrgr]

Thanks!

Never been on a Hover board myself. I've been skating on and off for 35 years. It's the "off" part that always gets me. I must really like that shirt too because I'm wearing it in the other video I posted.

 

[Markzx14]

Thanks!

Never been on a Hover board myself. I've been skating on and off for 35 years. It's the "off" part that always gets me. I must really like that shirt too because I'm wearing it in the other video I posted.

Yeah I ain't doing that. Now I'll cut up on a motorcycle, street or dirt. They do exactly what you tell them to

 

[rmchrgr]

So have a couple updates. First off, I washed the car for the first time in two years which was nice. Got all the wiring back in and at the moment everything seems to be functioning correctly. Car fires right up, lights all work etc. however I had one big bummer to deal with.

I am using a set of fancy Holley "can-bus" digital gauges. Unfortunately, I did not realize that I can't use the oil pressure gauge I bought and installed until it was too late. For whatever reason, Holley did not make a provision to monitor oil pressure through the Sniper. Reading the Holley forums I know it can be done using some work-around techniques with the software but there is no direct output for the gauge. It was a lot of work to get the gauges in and wired, it was annoying to have to take it apart again. My fault for not realizing that from the get-go but Holley needs to make it clear that the oil pressure gauge does not work with the Sniper.

Seems like a simple thing for a software engineer to design, I think they kind of dropped the ball on that. I mean, you can monitor coolant temps which uses a piezoelectric sensor similar to an oil pressure gauge. There needs to be a pressure transducer involved which they even sell but who knows why this one particular parameter was left out of the Sniper ECU program. Coolant temps are used to regulate the fuel curves and such but I can't see why adding another input would be out of the question. When I was finishing things up I started wondering where the gauge was going to get the pressure input from but kept telling myself I'd cross that bridge when I arrived at it. Well, I arrived at the bridge and wouldn't you know, it's out.

So out came the Holley gauge and in it's place is now an old SW mechanical gauge. Looks out of place but it works at least. Not real happy about it. I spent all this money and effort on these gauges and can only use three of them.

There were some hurdles to cross with the SW gauge too. The original incandescent light bulb does not give off nearly enough light compared to the super-bright digital gauges. Down to Advance to get some LED 194 bulbs which definitely helped brighten things up. I am planning to change out some more of the dash bulbs with these but am getting tired of reaching up behind the instrument panel and fishing around for stuff. That will be a job for a cold winter day.

Next thing on the punch list was to deal with the shifter. Waaaay back in post #6 I mentioned there were some issues with shifting. I have since come to realize the long-tall 4084 Comp. Plus console handle is the culprit.

That giant shifter handle is just a pain in every way possible. It looks cool but that's about it. It's well known that in most applications it hits the dash and in my case it definitely does. The other issue is that the console top boot must be misaligned enough to where the rubber is pulling on the handle preventing it from fully engaging into gear. Sounds crazy but it was true. There were actually a few instances where I had to hold the shifter in place after shifting which was really awkward while driving. 2nd and 4th are fine but 1st and 3rd were not happening without help.

The console had to come out to be able to drive the car. I did try trimming the console body to get it sit farther forward (See the pic below, I cut almost 1 1/2" off the front edge that goes over the hump) but that didn't really do anything either because even with the console out, the handle is still to far forward; it barely stays in gear on it's own. I've got too much invested in the console to give up on it now so on the phone to Brewer's to order the OE-style round-handle pretzel looking shifter. I can't see continuing to try and make the 4084 handle work.

My other concern with the 4 speed is that the hydraulic throwout bearing is releasing too quickly. It's subtle but it feels like there is a point where it grabs and it's not where I am expecting it. Reading on the American Powertrain website FAQ, they say this is a pedal ratio issue. The clutch rod is in the stock position so I'm not sure why this would be an issue in this particular case. Not sure that one malady has anything to do with the other but maybe once the shifter issue is resolved this will be less evident. We'll see.

Fixed what seemed like a major oil leak coming from the back of the block. There was a generic threaded plug in the port where the OE low pressure warning light sensor goes and it was leaking bad, all down the back of the block onto the passenger side headers. I was pissed, everything was nice and clean beforehand but now the header collectors are totally stained. Time before I drove it last there was a ton of smoke trailing behind the car, the people behind me must have thought I was a lunatic. I used that port for the mechanical pressure gauge in the dash and it seems to be dry now, no more smoke show.

The car needs to be aligned badly. The camber is way off and both tires are toed in. There are not many shops around here that can do this type of job since most of them rely on computerized equipment. I'd almost guarantee that none of them have the correct data for a '68 Coronet with 15" radial tires, aftermarket tubular control arms and 1" t-bars. Looks like I am going to have to try my hand at a DIY alignment, it's really not drivable as-is - steering wheel is off, tires squeal and it likes to dart unexpectedly in some situations.

Last really annoying thing is the power steering, it seems to be making all sorts of noise at low speed, like when trying to maneuver the car out of the garage. There's plenty of fluid in it, the pump and steering gear are both brand new Borgeson, the pressure hose is new for a Saginaw-type pump. In my research I have read that sometimes a different pressure hose can solve this issue though I am not sure which hose I need to use.

Well that's all to report now. Hope to get these this stuff sorted out over the next few weeks or so and start driving the car for reals before it gets too cold. Wish me luck.

 

[andyf]

I suppose the big-ticket item here is the Sniper EFI system. I got it running today and I can say with 100% confidence it was the right thing to do. The car runs sooooo much better than it did when I first got it. Starts right up every time. I only drove it down the block briefly but when I shifted into second I could feel the car take off like never before.

I went with the whole kit and caboodle -Sniper EFI throttle body, Holley/Tanks, Inc. EFI fuel tank, Hyperspark ignition box and the Hyperspark distributor. I also made all-new fuel lines from front to back.
View attachment 1016849

View attachment 1016848

Getting everything as a package made more sense as opposed to trying to piece things together and make all the different parts play nice together. I'm glad I did that because as I mentioned earlier, I did manage to screw some things up with the Sniper wiring by attempting to combine it into my main harness.
View attachment 1016850

Without going into too much detail, there are definitely some things you just can't do and expect things to work. I learned though so it's all good but up until today, I was pulling my hair out with a no-start condition which was the direct result of me trying to make up my own way of doing things.

Frankly the generic Sniper main harness left a lot to be desired. My guess is that it was designed around something other than a Chrysler product and was made "universal" enough to fit. Oh well, such is life with aftermarket parts.

Looks good. I see a few of my parts on there. I'm getting ready to drop the 426W with Sniper and Doug Nash 5 speed back into my '65 Coronet. I had to build my own gas tank since nobody sells an EFI tank yet for the early B body cars. Otherwise our cars are fairly similar.

 

[andyf]

You shouldn't have any issue getting the car aligned. I take my car to the local tire shop and the guy dials it in. Alignment specs are fairly generic. They'll just set it up for radial tires and power steering. Shouldn't be a big deal, you'll be in and out of there in 30 or 40 minutes.

 

[furious70]

Your low speed ps issues might be alignment based? Fix that first and see if you have less effort and then less stress

 

[rmchrgr]

Looks good. I see a few of my parts on there. I'm getting ready to drop the 426W with Sniper and Doug Nash 5 speed back into my '65 Coronet. I had to build my own gas tank since nobody sells an EFI tank yet for the early B body cars. Otherwise our cars are fairly similar.
View attachment 1022654

Thank you Andy! Yes, I've bought many of your parts over the years, have a bunch of your stuff on my Duster too.

You shouldn't have any issue getting the car aligned. I take my car to the local tire shop and the guy dials it in. Alignment specs are fairly generic. They'll just set it up for radial tires and power steering. Shouldn't be a big deal, you'll be in and out of there in 30 or 40 minutes.

Got an appointment to align the car at a local tire shop tomorrow. Called to make sure they knew what I was bringing them and they seemed confident they could handle it even though the guy on the phone said it would be two hours. OK? Whatever, guess we shall see tomorrow.

 

[rmchrgr]

Your low speed ps issues might be alignment based? Fix that first and see if you have less effort and then less stress

Well back when I was a tech this would have been a come back because I found that the P.S. belt was loose. Must have left it loose when I installed it thinking that it might have to take it out or something and obviously forgot to go back and tighten it. Doh! Seems like the return hose might be leaking a little too. Honestly it was a bear to get on, might have to try and pull it up further on the fitting. I hate power steering fluid.

But I do agree with your theory. The caster was way off and it makes sense that turning at low speed could put extra strain on the pump and cause the noise.

I talked to Firm Feel and described what I was dealing with. They told me to max out the caster so I did which helped a ton. Took it out for a longer drive today and it was 400% better and much closer to be aligned than the other day. So as mentioned above I am bringing it to a shop to have it aligned properly but at least it's much closer now.

Gratuitous beauty shot. Looks so nice when it's clean!