Putting A Little Pep In My 390's Step

[6667fan]

Like Etta sang, At Last.

Love that throttle response!

[Nightmist66]

Where to start.........Oh yeah, why the engine came apart to begin with. During the last 50-100 miles I put on in fall of '20, I noticed a little oil showing up in the radiator. No big deal, suck the oil off the top and top off the oil. Well, I also had at the same time a hairline crack at the drain plug bung on the oil pan. So, to fix it I decided to pull the pan and weld it up. After I removed the pan, I looked up and noticed a couple drips of water coming off the #4 main/cam bearing. Now the problem was going the other way. So, out came the engine for repair....I also noticed the glyptal was questionable in the pan, so I just removed everything. Welded the crack in the pan and added a new drain plug/bung in the rear.

I sleeved the oil passage in the block on both sides and had my machine shop pressure test it with hot water-checked OK. So, more good news, my machinist was checking over the crank and magged it. Thought there was a hairline crack starting on #5 rod journal radius. I wasn't there to see the mag being done, but he does good work and I trust him. I can't see with my eye anything at all, so must be extremely faint. I dug out another spare 390 crank and decided, why not do the things I thought about last time.

I spent a couple minutes and removed all the glyptal inside and smoothed things out:






Here's the new(used) crank as it started after a pass from the magnaflux:




I decided to bull nose and knife edge the counter weights as well as remove all the rough casting. So I started hacking and grinding....











I figured since I was this far, I would take it to a semi-local place to have it cryogenically frozen. This crank was already .010/.010" and needed to go to .020" on mains and .030" on the rods to clean up. So this is what it looked like after it was frozen and machined:




I also had it REM polished. It's my poor boy billet crank.

[Nightmist66]

I was also debating throwing a set of Molnar rods in to lighten up some more. I acquired a set and at the same time, I came across a deal on a set of used Crower rods. They are at least 100g lighter than the Scat rods I had previously.

The Crower:



I had to have the pin holes honed in the pistons for the slightly larger .990" pins in the Crower rods. My pistons already used a .984" pin, so just a slight hone to the pistons for the new pins to fit. All the main/rod bearings and pin end bushings in the rods were coated. Piston pin bores and skirts were coated on the pistons.

Crank installed and checking thrust:



Slugs and rods installed:

[Nightmist66]

I didn't really care for the pickup tube from Milodon that matched the #31130 pan. I like the look of the Moroso, as it has very large radius bends. I thought I could improve on the pickup "box" on the Moroso though. Here's a comparison between the Moroso and the Milodon:





I started my Frankenstein project. I took a factory bell pickup tube and cut it apart:





I cleaned it VERY thoroughly and smashed the flange back down where the screen was sandwiched. I also welded in a washer in the center for a little more strength.



I also made a new screen out of 3/16" holed mesh. I countersunk the holes till the edges just about touch on the inlet side and trimmed to fit the dia. of the bell.



I'm well aware the larger screen will allow possible debris to enter the pump, but I'm willing to take that chance. Plus, I have strong magnets all over. Anyway, I needed to make a new inlet tube for the pickup. I cut the whole box off the Moroso unit and measured the length that I should need for tubing. I grabbed some 3/4" tubing placed it in the vice. First step was to make a nice radius for the entry. So I heated the end of the tubing a found a socket that slid inside the tube and also had a radius that I liked and hammered it home:





I cut the tubing to length and welded it into the bell.



Then I welded the tube to the now modified Moroso piece:




After rechecking fitment, I fully welded the bell to the tube and the screen around the perimeter.

[Nightmist66]

Oil pump was next on the list. I decided to make an external bypass pump myself, since nobody offers one that I'm aware of for an FE. I started on one and didn't like how it was going, so tried again on another pump. I tapped the internal relief hole for a 7/16-20 set screw. I needed to make sure the plug wouldn't move, so I drilled and tapped the outside for a 4-40 cone-tipped set screw and dimpled the screw to accept the cone tip for a positive stop. I figured all I would have to do is drill a hole 90° from the one inside the pump to have the external bypass and have the relief start at the same psi. The set screws are held with red thread locker.





I tapped the external relief hole for 1/4" NPT and used a 45° -6AN fitting to dump back to the pan.
The inlet and inside of the pump were ported to improve flow. The casting is atrocious out of the box. Here's a before and after:







Another point of attention is the mounting flange of the pump. Casting is very uneven. I made a quick tool to spot face the surface.



The pump assembled after coating the gears and inside of housing:

[Nightmist66]

Using Jay's timing set, I started with some grade 9 bolts for the thrust plate and trimmed them to get .020-.025" clearance behind the hub.





Degree-ing the new "unspecified" solid roller that I picked out. Decided against putting the old cam back in. I also added a second dowel pin to the cam and made my own pins out of 5/16" tool steel rod. The camshaft, like the crank, wrist pins, rocker shafts, and a couple other parts, was also REM polished.





Buttoning up the short block:





Same windage tray and scraper as before.






Slapping on the Street Pro Port heads.

[Nightmist66]

Back-tracking quite a bit, I had gotten the bug early-on to maybe try out a tunnel wedge this time. I had my block back from the machine shop, so I dropped it back in the car and sat a Dove tunnel wedge on that I had. I was hoping to keep everything under the stock GT hood. So I began to mock everything up. Thanks to Ross for the 450 Holley's. They came in handy for mockup.




Checking for air cleaner clearance...



I figured if I ran a 1/4" wood spacer under the carbs and didn't use any base gaskets for the air cleaner base and also cut the stepped flange off on the base of the air cleaner, so the lid is flat on top of the carbs, I could run a 2 1/4" filter. This means poking holes in the base for the needle and seat adjusters.



I also tried to lay out the fuel system with the same regulator I had.





After seeing the tunnel wedge might be a go with the clearance, I pulled the trigger on a Trick Flow unit. The Dove tunnel wedge I had I felt was going to be too big for my 390, so that's why I got the Trick Flow. A little comparison with the Dove and TFS. The TFS is a beautiful casting and is definitely a smaller volume than the Dove.




Then, I picked up a new set of carbs and began to figure out the fuel system and linkage.




I also had to drill a new hole and tap for my fuel pressure sensor in the regulator. I could've run it to the outside, but having it in by the linkage and under the air cleaner will look much better and be hidden almost completely.






The air cleaner with base trimmed down:






I also noticed the base of the Blue Thunder had oversized holes for the carbs. It is a very loose fit over the carbs. So I got some aluminum square stock and bent it around and fit it in. After I was happy with it, they were welded in place.

[Nightmist66]

I also wanted to try something different on the linkage. I got a replacement 2x4 linkage kit and mocked it up. I wasn't quite satisfied how it looked and fit with my fuel regulator and lines, so I decided to try and make something. I have a simple threaded rod with rod ends going to both primaries on the pass. side for 1:1 linkage. Easy. I added nut serts to the linkage arm so I don't have to fiddle with fishing nuts on the back side while servicing.




Now, I had to come up with something to actuate the driver side from the firewall rod. I didn't like the first attempt, so I tried again. I took a piece of secondary bracket that has the slotted hole and trimmed the outside down. I bent a piece of flat stock and welded the two together and smoothed it off. I then welded a 1/4" fine thread Allen bolt from the back side of the lever. Again, so I don't have to fiddle in the car with a nut and bolt. I will have another threaded rod with rod ends that connects the firewall rod the the primary lever. I just have to slide it over the "stud" and install a lock nut. I also had to come up with a solution for a return spring setup. So this is what it looks like:





I gave the bracket a more finished look.

[Gregwill16]

Awesome job!

[Nightmist66]

Back to the tunnel wedge......I mocked it up and had to have .030" cut off both intake faces and both valve cover rails needed a trim as well. Lined up pretty well after that.





Pushrod holes needed some clearancing.



After that, I gave it a port matched to the heads:

[Nightmist66]

Awesome job!

Thanks!

[Nightmist66]

Now the intake is ready for a little paint...




Ready for final install.







Adding a few more bits.





Installed Jay's covers for pre-oil check.




Was nervous whether my highly modified oil pump would sink or swim.....Whew...

[Nightmist66]

And that pretty much brings us to where it is today. Installed on the test stand last Fri. afternoon.





I have another set of carbs that I built from scratch for this that are highly modified. Too tired to post all that right now....

[Stangman]

Very nice a lot of attention to detail. Looks great.

[mike7570]

Someone has a lot of time on their hands, looks great!