Ok guys. In the next few weeks, I am going to start pulling the engine for a rebuild. I was going to build a different engine and put the original one on a stand, but there was a little sticker shock - especially since this would be a second engine eventually. I have decided to just get a mild performance build on the original engine.
I think I am going to go through the entire cooling system, A/C, heat and fuel system while it is out. I will also be stripping the engine bay and starting a heavy detail of everything while I can get to it. There is a little rust to be attended to on the passenger side inner fender apron and that is it. Also, all vacuum lines and miscellaneous will be attended to.
This leads me to my first question; What can be done to a 390 to make it appear stock and bump the horsepower? I don’t want to go crazy because I still want a street-able car that has decent vacuum for accessories. I also would like to keep the original heads on it.
What are the best options that will give horsepower, remain street-able and appear stock?
I have a strong attraction to doing a “period” style build, i.e., what someone might have done when the G was a year or two old. That is, after the internal freshening is done, quicken the centrifugal advance curve (the Mr. Gasket 925D spring kit is available again), maybe go to an aluminum intake but paint it like some of us did in the period…store the original Holley and replace it with a current similar one, but play with its secondary diaphragm springs for more subjectively satisfying opening action (the deadly purple or yellow springs!). Consider converting to adjustable rockers so you can set stuff up to minimum hydraulic preload.
As for the internals, do what’s needed to the short block and pay attention to getting a nice NHRA-legal but simple 3-angle valve job done with a small amount of cleanup down past the last angle cut - no porting. Since you won’t want to put in a used cam (it was good enough in its time that Ford reused it in the 428CJ), and no one makes a real replica, I did some looking. The Comp dual energy 265 seems interesting (http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=942&sb=2 but its LSA is tightened up a lot compared to your old 390GT cam (110 vs. 115 or 117). I bet it’d give a tremendous 390-style hit in the midrange. The “replica” 390GT/428CJ cam from Lunati (I just looked at it) seems more a replica of Ford’s over-the-counter hot C8AX hydraulic, a lower vacuum proposition.
I recall numerous rides in well-running 390-4Vs 1969-73 that had never been modified. In the hands of sharp owner, they were pretty good as is. Remember, one held the C/SA record in a Cyclone or Fairlane at the time (using the C8AX cam no doubt).
Wow, my head is spinning. I have been studying the different things I can do with the 390. I like the thought of a small stroker (410/425), but I am not sure if the stock heads will let it breathe. Keeping the stock heads are a necessity since they are the only thing keeping me from building another engine altogether.
One question. If you want a car with more performance than the stock G is going to give you, why didn’t you just buy a different car? You could have bought an X code for next to nothing compared to the G and modded away to your hearts content. Why mess with a collectible car?
^^^ As long as you’re not cutting or doing anything irreversible, why not? I mean, what car guy, when faced with an engine rebuild anyway, could resist improving the performance (and cooling, and gas mileage, etc.)? The only real question (and the one Matt is asking) is, how far to go?
Matt - it is interesting that we are doing a lot of the same work on our very similar Gs at the same time.
We pulled the engine and transmission on my G and I also will be cleaning and painting the engine compartment while the motor is out.
I met with my engine builder and we discussed all of the possibilities and I decided to resist the temptation to go too wild with the build. In my experience that can sometimes tax other components in the car and cause a sort of domino effect of problems. Plus, keeping the build on the mild side is cheaper. My main reasoning was also because I wanted to keep my one original factory head (with the VIN). The other head on the car was a '69 casting but I lucked out and found the perfect matching 1968 head cast the same month as my original head. So having the block, “new” head and original head all cast in Feb. of 1968 I decided to keep the build fairly stock.
So I am re-using my original crank, going with what my builder called a “one bump” cam (can’t put my hands on the specks right now), improving the oiling, doing some head work, etc. I had my original C6 rebuilt and improved it’s internals, my radiator re-cored, I’ll put in the Tru-Track and a better exhaust system. Oh, and I’m having my drive-shaft balanced with a stronger yoke.
Al - I know what you are saying and it is a question I struggled with when I bought the car. I was looking for a small block 4 speed car when I came across the G. It ended up being too good of a deal to pass up and I knew I would kick myself later if I passed up on a G, so I bought it.
Now I am struggling with how to have my cake and eat it too when it comes to performance and originality. I had given up on the idea of any performance mods until I saw Jim Pinkerton’s G car that he had put a 428 crankshaft into. Like Phillip said I don’t plan on doing anything irreversible. Hell, I may stick with a stock rebuild.
Phillip - That is pretty cool. I still have a couple of weeks to go until I will tear into the car. By the way, that Tru-Trac is great.
Totally agree, these are probably the best things that you can do as far as the crank and rockers. Get the Harland Sharp rockers shown in the photo, they are a great value for the price, and quality.
The stock heads actually are quite good if you install new stainless 2.09 / 1.66 valves (GT-E sizes). They cost the same as the standard size valves. Get a decent valve job done. Think about a set of shorty JBA headers for another 20 LB - Ft of torque.
Matt that would be Jim Pinkerton’s former G car. It has resided in our Cougar den for a couple of years now. The black cherry G is a pleasure to drive and it makes plenty of power. Much more than the black 67 s code. Neither of our XR7G’s or J code Cougars are driven hard. The pleasure on our end is driving them and every now and then “stretching their legs”. I do agree with Al on one point the XR7G is a rare car. When you look at the registry you get a clear understanding of the rarity of these special Cougars. Don’t do anything that can’t be undone as Philip stated. At the end of the day enjoy your Cougar.
Steven
Ok, that sounds like the plan. I will look into that rocker setup and setting up a 428 crank. If my math is right, that will make it a 410ci motor. It doesn’t sound too radical. We had planned on bigger valves anyway so that shouldn’t be a problem.
Are there any suggestions for a cam? I am not looking for anything radical, just enough to take advantage of the extra stroke and bigger valves. A little lope would be fine, but I would like to keep as much vacuum as I can.
Of course I knew the discussion would come back to “your car do what you want.” And I agree with that 100%, I was just curious as to the thought process. I tend to separate cars into two classes, collectible and vintage. Collectible is what you would imagine. A vintage car is just an old car that really isn’t significant except they aren’t generally seen on the roads anymore. If I drop a 427 stroker in my X code and dress it with a hood scoop, spoiler, etc., the only thing people would say is “nice ride.” If I stick front and rear spoilers and a hood tach on the GT-E, people will likely say “you’re a dumb ass.” And I would tend to agree.
Big Matt, see my cam remark above - not sure how much idle vacuum the Lunati 10331003 would lead to, but seeing as it’s wilder than the real 390GT/428CJ cam of 1966-70, I bet you’d get that lope!
I’ve used the Comp Cams 268H grind in 390 and 427 / 428 builds. It gives decent vacuum signal and adds low and mid range grunt. Makes the car lots of fun to drive, even with a stock torque converter.
Note that I have also tried the Comp 265 DEH and have to warn it is a real snoozer of a cam. Not recommended
Thanks for the cam suggestions. I will look into them.
That probably sounds like the cam for me Royce. I am wondering about roller vs. flat tappet though. All I hear is how there is no more zinc in oil nowadays and how cam lobes get wiped out.
You know I have heard all those stories Matt and have yet to have any problem with camshafts. I’ve always followed the instructions that come with the cam when breaking it in - then use Valvoline Racing oil which is still a zinc rich product same as always.
Roller lifters is an expensive proposition in an FE. I have looked at it and the number that I come up with is about $2200 to get there. It has always been financially out of the question compared to spending money on something else.
Matt that would be Jim Pinkerton’s former G car. It has resided in our Cougar den for a couple of years now. 
The black cherry G is a pleasure to drive and it makes plenty of power. Much more than the black 67 s code. Neither of our XR7G’s or J code Cougars are driven hard. The pleasure on our end is driving them and every now and then “stretching their legs”. I do agree with Al on one point the XR7G is a rare car. When you look at the registry you get a clear understanding of the rarity of these special Cougars. Don’t do anything that can’t be undone as Philip stated. At the end of the day enjoy your Cougar.