The Break Down of a '69 Pontiac OHC inline six

Concurrently I'm re-working the wiring because this isn't cool, lol


I removed the dash and pulled essentially all the non-stock or radio related wiring out of the car. Same with under the hood.



Drilling out some existing holes in the firewall I'm adding multi-pin duetsch connectors. I'm about ready to finalize my pinout on them, but being held up on trying to decide if I'm going to add an Input/Output (IO) board under the hood or not. If I do, then I'll likely reduce the number of wires going through the firewall by 6+ wires as the sensors will be brought into the megasquirt via the CAN bus with the EGT box.




Testing out the little white IO board with the Megasquirt. If it works as I expect, I'll install it in the same box as the CAN EGT under the hood and run in the same CAN loop. As a reminder, my 4L60e controller also runs on the CAN bus.


Another little project I'm dabbling in is modernizing the hood tach. The stock innards are junk. I found this $15 "boat" tach on e-bay and preliminary tests show it may work well. I would like a faster refresh rate, but all in all would get the job done. I would also like to put a few indicator lights in the hood tach as well. Such as a shift light, a "check engine" or "Safety" light that would come on if the engine was leaning out, over heating, losing oil pressure, etc. Maybe a green light to indicate if I hit my boost target or such as well. I think the hood tach is original and the housing has seen better days. I've covered a big part of it with epoxy and re-enforced the screw stands. I'll post up some pictures after I've sanded down the epoxy I just dumped all over it.




A short video bench testing the tach. I think I'm going to cut some tin or thin plastic sheet to block most the screen outside the rpm gauge.


I'm also starting on installing the screen behind the dash. FINALLY going to clean that up!

 

Poking away at smaller details. Since I'm more certain on using an external input/output (IO) box I've be re-viewing my wiring plan. Still making headway on sorting out the wiring cleanup.

Updating the firmware on the Megasquirt EFI, and testing out connecting external modules. The 4L60e has been connected via CAN bus for years, now adding the EGT box and a small IO board. Got them all connected up on the software side.



I've pulled the dash out, and finally getting around to putting a touchscreen behind the dash trim.

 

Just about done with the ECU to firewall wiring. Next up is finishing up the dash wiring and cleaning up the engine bay in prep for installing the new engine.







The loom is just stuff I had on hand, but plan on changing it out before it goes back into the car.


Another side project besides the digital hood tach is possibly installing 3 LED gauges next to the headlight switch. I still have to sort out the mounting since the dash slopes back so aggressively.

Here its just showing dummy numbers of RPM, AFR and an uncalibrated sensor, but thinking of having oil pressure, MAP/Boost and AFR.


A video of them running. At this point they were all set to just show RPM.


A crappy rendering of what I'm thinking. And still have the touch screen in place of the clock delete panel.

 

Got my webber intake manifold back with the injector bungs installed for intake manifold #4! The runner length of the Marshall intake is a little short and the fuel rail interferes with the thermostat housing, so I've been contemplating converting a Weber intake manifold over to EFI and have made progress on that.

The original concept mock up. I had the Weber intake on hand when making the header so I knew it would clear.


This would be essentially like the Marshall intake, except with longer runners.


But I'd like to add a little volume to the intake manifold and bring the air in at a 45º angle so #1 doesn't get by-passed as badly on airflow.


But now some actual progress. I found someone local to me to give it a go at putting some EFI bungs into the intake.


The fuel rail still needs to be cut down and fittings added to the ends.


Someone on Facebook commented about it would be interesting to use a cam housing as plenum and it looks like a funny DOHC engine, haha.




I should be able to experiment with different plenum volumes and shapes. I'm going to start with one out of steel that I can weld together, but will eventually have an aluminum made up.

 

Been doing other engine related work as well. I wanted to go back to a conventional flow cooling system, still electric, though so I removed the pump shaft and impeller. I want to put a metal core plug in the pump eventually, but for now an expansion plug does the job. One issue with the current EFI manifolds I have is the fuel rail interferes with the stock water outlet, so I cut some plate steel and hose barb to make one that will work with my current manifold. This will remove the two 1" water lines going to the head around the turbo and not require special core plugs.


Put a couple of 1/8th ports in the exhaust before and after the turbo to measure exhaust back pressure. Talking with folks that measure it they recommended expansion blocks to dampen the exhaust pulses before the pressure sensor. So with some scrap metal I put these boxes together with some steel wool in them. Pretty crude, but some black paint and they'll disappear into the engine bay. I'll run some steel brake line from the exhaust to the boxes.


I also made the external oil pump pick up line. It should tuck nice around the motor and frame mounts, but if I find when I get it in the car that its in the way, I'll run some 90º fittings over the top of the motor mount. This was done for a couple of reasons, one is with the windage tray I added a spacer so the pickup would of had to been extended downwards, two the baffles I put in the oil pan to keep the oil in the sump would of been further complicated working around the pickup, three the main studs didn't have provisions for the pickup tube bracket. It also allowed for a larger pick up to the pump.




I also drilled a hole in the belt cover to accommodate the fitting to the block's oil main galley. I wanted to be sure it would comfortably clear the balancer, which it does.


And lastly I was tired of buring my hand or arm reaching down around the turbo exhaust to check the oil. Since I needed to extend the oil dipstick anyways, I decided to raise the dip stick tube as well as add an o-ringed dipstick to control oil. The first picture is the before, with the stock dipstick tube.


Raised up for easy reach.


I added a pull down spring just to be sure it doesn't go anywhere. It blocks the old water inlet port so its good I'm moving away from that configuration.

 

Engine is in the car! I've been hung up on the routing and mounting of the external lash adjuster oil feed line and regulator. Decided to skip it for now and get the project moving forward. Worse case I'll zip tie it in place until I come up with a cleaner solution but it has had me stonewalled for awhile now.


Had to lay it over on its side for transport from the garage to the backyard, but no harm in doing that. Looks a little like German engineering on it side, lol


Thread the needle trailer.




No issues setting it into place. I was happy to see the oil pickup line fits as expected.






The nice thing about a crank trigger and EFI is once the wheel and sensor are bolted on, I know the timing is dead on accurate like it was when I removed it. Making the engine fire right up. Of course I'll double check it, but I do expect it to be spot on. For the cam trigger set up, I rotate the engine so the sensor is about 3 teeth (~30º) before the missing tooth, then line up the cam trigger. So the cam trigger hits first, indicating #1 is on the compression stroke, then the missing tooth. I use these Cherry/ZF hall effect sensors everywhere. As crank and wheel speed sensors on my Skylark, crank sensor on the Firebird, and now cam sensor and soon wheel speed sensor. Crank is the only critical need, so if it dies I can swap in one of the other ones.




Started putting some of the other stuff back in. I need to wait for better/warmer weather to re-paint the turbo hotside then re-wrap it. In the mean time I'll be getting the coolant plumbing re-worked and finish up the electrical.

 

When I was lining up the cam sensor last week, I didn't like the resistance I got rotating the oil pump to drop in the distributor so this weekend I pulled the accessory housing.

I don't know if its the cold or what, but the pump was not happy. I swapped out gears and end plate with no change. Soon as the bolts were tightened, the gears would bind up.



I ended up removing some material from the bottom of the original gears until they spun freely when lubed up. I'll loosely call this blue-printed, lol I cleaned out the whole assembly, re-lubed and put it back together. My assumption is that someone surfaced the pump housing and took too much material off. I'm happy to report it was easy to remove and re-install the oil pickup line.



I also made an aluminum cap for the cam sensor. I'll probably fill all the holes in the housing with JB weld and paint the body black, then put a red Pontiac arrowhead and the engine firing order on the cap.





My old cam sensor setup had a rough time. I used a plexiglass plate to hold the sensor on top, but eventually the engine heat got to the plastic and it cracked, multiple times. In the end, after 10+ years of service it was being held together by duct tape and zipties

How it started...


How it ended....

 

Did a little work on the hood tach update. A long while back I epoxied the inside of it up because the plastic is pretty degraded and flaking. I also put iron sleeves around the threaded stands, filled them with epoxy, drilled and tapped new threads into them.
I made a panel out of sheet plastic to hold the digital tach screen and red and orange lights. I'll use the lights as warning indicators for the EFI. Overheating, low oil pressure, lean condition under load, or as shift lights.



I took the boat tach out of its housing entirely. There is a settings button on the top of the tach that I'm looking at soldering some wires on to and mounting a remote button on the bottom of the hood tach assembly so I can adjust the redline, etc on the tach.




All assembled and I checked that it still powers up.


I may get some black vinyl and cover over the sides and Chinese writing on the screen. Just leave the actual bar gauge and rpm numbers visible.


Here is the video of my proof of concept from a few months ago.

 

Started filling up the engine bay some more and got the hood installed! I still have to sort out the cooling system changes and external oil lines, then I'll get to the wiring.

I have the EGT probes in place and most the hot side in. I haven't installed the exhaust cross under pipes yet, and still need to see if they clear the oil pan with the 1/2" spacer installed.




No changes here.


Exhaust of the front three and rear three cylinders are still kept separate all the way to the turbo, and merge at the turbo and waste gate.




Since I put the hood on, I thought I'd take a look at setting the hood tach on the hood. I haven't bolted any of the hood tach parts together. Visibility is a little better than the camera shows but I think I'm going to try either a polarized or anti-glare screen on it to improve it.


The screen isn't sitting level in the housing because its not bolted together.


I found that grounding the signal wire to the car chassis made the rpm float around 5,000 rpm. So I fired up the ol' Buick next to the car for some not matching video sound

 

Just poking away at it still.

I mounted the electric water pump. I had it mounted to the battery tray, but I removed the tray so I made another mount for it and set it on some bolt isolators to keep the vibration from humming on the fender well.

I enlarged one existing hole and used another as is.




From the bottom.


This is just a hose I had on hand. I may replace it with one that is a few inches shorter.


I also mounted the remote oil filter and made the high pressure lines. I'm sure I'll get grief for mounting the filter open side down, but it made the most sense for access and limited the length of the oil lines. The filter does have an anti-drain back valve and I'm going to augment that with the EFI not lighting off until it see's oil pressure. I've read that when removing the filter, punch a hole in the top of the filter and wait a bit and most the oil will drain out of the filter before removing it. I can soak most the filter media and have some oil in the filter before install. The reasoning I did this is the factory oil pressure port is pressure BEFORE the filter, so tapping it for the lash adjuster galley and turbo feed meant that it was unfiltered oil going to them. Also this gets by the convoluted internal passages from the accessory drive to the block. I'm going to use the adapter's inlet as an outlet source of oil for the lash adjusters and turbo. It will be backfilled from the block feed and be filtered.
I'm probably going to install a 90º fitting for the oil pressure sensor to keep the wiring along the core support.




Where I left off for the day.

 

Starting to look more like my engine with the coils mounted! Poking away on it.



About done with the cooling system. Just have to add hose clamps and cap a port on the water pump. I welded together a Y-fitting to merge the two water pump outlets into one. Painted it black and put a heater hose over it to hide my welding sins, LOL! Also tied the heater hoses to the heater box and fender well to keep them off the exhaust. At least one of the hoses always sat against the turbo exhaust and survived, but I didn't like it. That header wrap really works, plus it was just putting more heat into the cooling system.


Made a new turbo drain line to drain to the oil fill tube. I previously had it draining to the fuel pump block off plate, but I had to clearance the intake tube to make it fit. The new line doesn't interfer with anything and drains to the back of the engine so quicker return to the sump.


I still need to mount the lash adjuster oil pressure regulator and run the lash adjuster oil lines as well as turbo feed. I think I'm going to mount the regulator off the lower stud holding the turbo to the head. Keeping it down low.



I still need to install the transmission, likely mount an external transmission cooler, run the exhaust cross under pipes (possibly making new ones), install exhaust pressure sensor tubes, then lots and lots of wiring.

 

Still chipping away at it. The big change is I put the 4L60e back in.

I would like to put a different torque converter in it, but between not knowing exactly what the new engine/cam will want and likely going to a T-56 in the future, I didn't want to spend the money there.


Installed the 5/16" thick BOP to Chevy adapter plate. Red loctite'd the bolts in place. I installed longer dowel pins so they go into the bellhousing by a good amount. Nice to see the crank has a pilot bushing in it. Its a little deep, but at least its drilled for it for when the T-56 ends up in the car.


Installed the re-drilled Buick 455 SFI flexplate (with the weight cut off). These OHC's have one off crank register size (I'm using a spacer to get to the Chevy size) using the Chevy small block bolt spacing. Buick's using the same Chevy register size, but a bigger bolt spacing, In a previous post I went over all the flexplate differences, and ultimately decided that the new holes in the twice as thick Buick plate was better than running an O.E. plate. I'm on the fence on what I'll be doing for a flywheel for the T-56. I have an OE flywheel, but would prefer an SFI modern metallurgy unit. Right now the two options are a Chevy one where I can press/offset the ring gear closer to the block, or a Buick 455 one that is also re-drilled unless I can get a pre-drilled Buick one to have drilled with the Chevy bolt pattern.


All bolted up. Still have to connect the wiring, cooling lines, etc. But the big mechanical part is done. After the cooling lines are installed, before I put the car back on the ground I'll degrease the bottom side of the transmission.

 

Hmm, looks like because I kept this thread more of a summary, I didn't post up my flexplate test work and how I ended up with an old TA Performance Buick 455 flexplate on my Pontiac L6!

Since I figure this engine should run between 500-600+hp one of the things I wanted to use was an SFI flexplate, which has turned into quite the ordeal! The crank flange hub ID is much smaller than the usual Pontiac and is just a smidge smaller than a Chevy's. The machine shop made me a precision sized ring spacer to use a Chevy flexplate, which I got an SFI one to use..... The Chevy has a slightly different tooth count/diameter (166 vs 168) that I figured I could work around with starter shimming, but I just recently found out that the ring gear isn't welded in the same spot as the Pontiac's! The Chevy ring gear is centered on the flexplate and the Pontiac's offset to one side, which made it so the starter gear couldn't reach the flexplate! Can't shim for that! So digging into my spare parts pile, I found that the Buick 455 hub diameter is the same as the Chevy and has an off set ring gear BUT has a bigger bolt spacing. Using the torque converter bolt holes as alignment holes, I re-drilled the SFI rated Buick flexplate with the Chevy pattern.

My flexplate hub spacer.


A stock flexplate.


A Chevy flexplate


The re-drilled SFI Buick flexplate and I cut the balance weight off it.




The Buick SFI plate is twice as thick as a stock flexplate.


The diameter is ever so slightly larger than the OHC plate, but has the same tooth count. It was easy to shim the starter to tolerance.


And a short video of the Buick flexplate doing its job!
https://youtube.com/shorts/oNmyUPaNjbg?si=S3doK8zuSN6VMsio

 

Still poking away at this.

I didn't want to remove the cap on the "cam" sensor when ever I needed to check or set it so I added a viewing port to it. This lets me quickly line up the tooth with the sensor. This will be useful when I start changing cams out. I'm breaking in the engine on light springs and old engine cam, then will swap in the bigger new cam, then swap in stiffer valve springs. Each time the belt comes off I run the risk of the cam tooth moving and this will make it easy to verify.




I got the driveshaft and starter in (no new pictures) and went back to electrical. Finished putting together the fuse and relay panel and mounted it in the car.


With that I got all new pigtails for all the sensor and stuff so started laying out the engine wiring harness as well.




I need to put the down pipe back on the turbo, mount up the exhaust pressure accumulators and sensors, add spacers to the exhaust cross under, or remake the whole assembly, and finish up the under hood IO box.

I've completed all the electrical parts of the IO box. I need to finish the solid mounting of the two circuit boards and associated wiring, then pull it apart and paint it black.


I bought a handful of these 0-5v ammeter sensors off Amazon. The reviews say they are good for a lot more amps than the terminals that come on them, so I did as the reviewers said they have done and stuck heavier duty terminals on them. I'll use two of them to monitor amp draws on the two electric fuel pumps and maybe one on the electric water pump. The idea is to give me a heads up if the motors are going out or even if a fuel filter is starting to plug up.

 

Its been toasty out, but between yesterday and today I got a handful of things done.

It's been around 100ºF out, but single digit humidity so the shade does help.


I finished up the IO box, including painting the box black and sealed it up. It should be waterproof, but if not strongly water resistant. I mounted it under the hood on vibration dampeners. It should be a relatively cool spot under the hood getting fresh air from the fender. I wired up the EGT sensors to it. The other terminals are for power, ground and two CAN bus wires. I have to make the IO engine harness for the other circuit board in there but that won't take long.




Finished up all the hard external oil lines as well. The turbo feed, lines to the external oil pressure regulator (to keep pressure at 12 psi) and to the lash adjuster galley. Not the greatest picture, but its all there and the lines are not rubbing anything.


I wanted to work on the air flow through the radiator. I found when I added the 3" intercooler in front of the radiator that it had a hard time keeping the engine cool below ~60 mph unless the fan was on. My general assumption was that the air would get through the intercooler, but basically loose all speed/pressure and then escape around the radiator instead of through it. So I added some baffles on the sides of the intercooler and sealed up the radiator flush to the core support. The 400 panels on top will ensure air doesn't push upwards, and at some point I'll seal up the bottom and add an air dam. Not just forcing all the air through the radiator, but want to go through the radiator. I'm happy to see I still have plenty of room between the fan and engine.
Maybe hard to see, but the aluminum flashing between the intercooler and core support.




Before bolting the 400 core support panels on. I contemplated putting more flashing over and under the intercooler, but figured I didn't want to limit the open area of air coming through.


Looking down between the intercooler and radiator before bolting on the 400 core support panels. The radiator is flush with the core support. On the bottom I slit a rubber hose and put it on the sharp edge of the core support to take up space and seal it up. On the top I stuck 1/2" foam on the core support to seal up against the radiator.






I was quite happy that its still easy to pull the radiator with the hoses disconnected. Plenty of room.


Then a minor "oops". I went to install the air intake tube, just to have it in place for the wiring, and found the air filter couldn't fit between the re-located water pump and fender!! D'oh! The pipe itself fits over the pump fine, so I need to unbolt the water pump to slide it over a hair, stick the filter in the fender, and bolt the water pump back on. Not the worse thing in the world, but slightly inconvenient.


Oops.


Just moving along.

 

Calling it done for the weekend. Pretty much just have to install an alternator belt and the air filter and the rest is electrical.

Mounted the exhaust pressure dampeners and sensors to an existing fender well bolt and bent up some lines to them. If the bends I put in it aren't enough to deal with the engine vibration I'll get longer tubes and put a handful of proper loops in. I'm measuring exhaust pressure right before and after the turbo. I'm wondering if I'll see changes to pre-turbo pressure with cam timing changes, and if so make adjustments to improve spooling. Likewise with ignition timing on the 2-step. I'm going to be real surprised if there is much post-turbo pressure. It's a 4" down pipe and 4" straight pipe all the way to the rear axle before reducing to 3". After getting some baseline data I may stick a little straight through "race" muffler on the car to see if I can smooth out the exhaust tone a bit more. Then in the long term, use the data to pick out a more appropriate turbo for the engine.


Mocked up the cross under and tacked it together. Its more or less about 1/2" lower than the last one. Its located just a smidge further rearward than before to give a bit more room to the drain plug. Historically I always put a piece of cardboard on the cross under to funnel the oil into the pan and I'll probably continue to keep doing that.




This is what the old one looked like. Because I put the 1/2" oil pan spacer on it, the flex pipe hit the oil pan.


And just like that all my welds look better!


Connected up the rest of the exhaust and as I was doing that I noticed that the cross under really doesn't sit much lower, if at all, than the 4" exhaust.

 

Nothing dramatic this past weekend. There is a transmission firmware update so I thought I'd take a moment to put all the modules together at once and be sure they play nicely together as well as having all the firmware's up to date.

The Megasquirt 3/3x, CAN EGT, Tiny IOx and Microsquirt transmission controller.


Its a good thing I did, turns out I installed a transistor backwards on a TinyIOx sub-board and it let the smoke out when I powered it up, lol d'oh! For background, the Tiny IOx runs on 5 volts, and the two PWM output circuits to run the water pump speed and maybe someday the radiator fan speed run on 12 volts, so I made a separate board just to keep 12v away from the Tiny IOx board. I thought I had mirrored the circuits on either side, but I did not. So it popped the side that was mis-wired.


The "relay" kit I bought for the circuit came with little transistors rated for like 0.5 amps, but Amazon had bigger ones in stock that the Tiny IOx vendor says are fine to use and capable of driving 5 amps. Or at least if they don't overheat since they do have heat sink mounts. In my case, I shouldn't get anywhere near even 1 amp since it will be signaling a dedicated solid state PWM fan relay with a big heat sink on it to carry the water pump amperage. Soldered in, and powered up without issue.


All powered up and all modules recognized on the CAN network. I'm taking this moment to also put names to all the generic "ADC-input" names. So in the software I'll know what input is "Engine Oil Pressure", "Head Oil Pressure", "Crank Case Pressure", "Pre-Turbo Exhaust Pressure", "Post-Turbo Exhaust Pressure", etc. Get them all mapped out so its easy to check when its wired up.

 

This is beyond impressive. Please put some jack stands under the rear corners as backups to those ramps. Everyone wants to see you finish this amazing job!

 

Thanks! While I understand your concern, I will say this isn't the rust belt and those stands are in good shape. I do inspect my equipment before use. The rivets are tight, not bent up, no rust and not even close to being overloaded. I trust them more than I'd trust a set of harbor freight jack stands! (which I do not have!) Hopefully soon I'll have it back on pavement soon as I'm pretty much down to wiring.