Post A Pic Of Your Latest Purchase Thread...

r3dn3ck

Active Member
Joined
Mar 3, 2007
Messages
470
Reaction score
279
I bought a set of C-heads. Judging from the casting data they appear to be from a late 99 or early 00 navigator. I picked navi heads deliberately. I don't have worries about the 4-thread issue or the driver side head cooling, one is not really a problem and the other is not at all a problem with the addition of one little hose. True, the 4.6 bottom is a little small for the port volume so it'll cost some torque at the lower revs but it'll sing at the top and the car will end up with 3.73 or 3.90 rear gears so it needs the rev range pushed a little to the right anyway so first gear isn't rendered completely futile. A little porting on the exhaust side and port matching on the intake side and they should be just right for 8000+rpm. Have to send them out for freshening which I'm betting will be probably 2 grand. Need to find some FR500 spec cams and snatch up Mr. Secondary Timing Chain's block so I can start assembling rotating assembly components.

I almost bought a 5.4L bottom end at the same time but decided an aluminum 4.6L saves me a lot of hassle and a huge amount of weight off the front end so I'll stick with it.

IMG_7065.jpg. IMG_7066.jpg
 

96blak54

Moderator
Staff
Joined
Feb 21, 2011
Messages
9,681
Reaction score
2,637
Location
In the shop
I bought a set of C-heads. Judging from the casting data they appear to be from a late 99 or early 00 navigator. I picked navi heads deliberately. I don't have worries about the 4-thread issue or the driver side head cooling, one is not really a problem and the other is not at all a problem with the addition of one little hose. True, the 4.6 bottom is a little small for the port volume so it'll cost some torque at the lower revs but it'll sing at the top and the car will end up with 3.73 or 3.90 rear gears so it needs the rev range pushed a little to the right anyway so first gear isn't rendered completely futile. A little porting on the exhaust side and port matching on the intake side and they should be just right for 8000+rpm. Have to send them out for freshening which I'm betting will be probably 2 grand. Need to find some FR500 spec cams and snatch up Mr. Secondary Timing Chain's block so I can start assembling rotating assembly components.

I almost bought a 5.4L bottom end at the same time but decided an aluminum 4.6L saves me a lot of hassle and a huge amount of weight off the front end so I'll stick with it.

View attachment 30406. View attachment 30407

Navi heads for a 4.6l and port match the intake side? Is that possible? Correct me if im wrong but arnt the navi intake ports substantially bigger?
 

r3dn3ck

Active Member
Joined
Mar 3, 2007
Messages
470
Reaction score
279
Valid points and it comes down to thinking about the system as a whole. Because I want more top end pull I need more port volume. Adding port volume causes a reduction in air velocity which reduces the tumbling effect of the C-head design which helps with fuel mixing especially at low throttle blade angles. I would probably have issues with emissions if I don't fix that problem. So, how to enhance fuel mixing without sacrificing top end flow? Easy. Science.

So, yes, they're quite a bit bigger at the mouth than a cobra/mach but there should be enough meat in the manifold where I need it. It will be a little thin around the injector boss but it'll hold. The idea isn't to improve air flow, it's to create a very small area of very slightly lower pressure right at the injector nozzle for better fuel mixing. That'll fix the issue of low air velocity at low throttle angles reducing the tumble port design's effectiveness in that regard. Liquids vaporize easier at lower pressures, so I just have to cause a brief pressure drop in the incoming air charge just as it passes the injector but not so much so as to cause too big of a temperature change. So, less than about 2000 pascals based on some very rough back of the napkin math. All I need to do is get the mouth of the intake to the same size as the mouth on the head or close enough that too much turbulence isn't induced. I'll have to do some work inside the manifold too in all probability. Won't know for sure until I test it with the makeshift flow bench I have at work (we use it to make sure some server racks that run insane power densities aren't going to have issues with condensation). I have a spare intake manifold that I can mess with so I'll just get my drill and tap on and instrument it with pressure sensors and see if I'm going to need to mess with the inside of the intake manifold. What I want to avoid is air density bouncing up and down before it gets to the injector boss. I want to see a more or less a flat line on the graph with a small dip at the injector and then a small rise about an inch farther down toward the valves.
 

rio_snek

New Member
Joined
Aug 2, 2020
Messages
58
Reaction score
95
Location
Athens, GA
20231201_002319.jpg
This is a new/old purchase for me. I owned this car for several years, then got to a point in the build where I felt like I had done everything I wanted to do with it, so I parted it out and sold it. I've regretted that decision pretty much since the day I let it go, but I finally had an opportunity recently to get it back. Now it's time to work on bringing it back to my vision of it.
 

96blak54

Moderator
Staff
Joined
Feb 21, 2011
Messages
9,681
Reaction score
2,637
Location
In the shop
The tri bars give the car a refreshing look. Not the same old wheel selection. Perhaps get the wheels corrected and widened? Or is their an aftermarket tri bar replica thats made to fit our desired upgrades. Anyhow....it looks great.
 

rio_snek

New Member
Joined
Aug 2, 2020
Messages
58
Reaction score
95
Location
Athens, GA
The tri bars give the car a refreshing look. Not the same old wheel selection. Perhaps get the wheels corrected and widened? Or is their an aftermarket tri bar replica thats made to fit our desired upgrades. Anyhow....it looks great.
The guy I bought these from had a set of 10" wide ones on his car, which was his reason for getting rid of the stock spec ones. I haven't been able to find any like that anywhere else though, so I don't know if they were widened by someone or what.
 

96blak54

Moderator
Staff
Joined
Feb 21, 2011
Messages
9,681
Reaction score
2,637
Location
In the shop
Could always widen the wheels then space them out or swap rear end to a longer rearend like from a crown vic. Probably more headache than its worth, but its all about what you want. But i have to say, im turned on the the tri-bars now....lol
 

Latest posts

Forum statistics

Threads
77,360
Messages
1,500,159
Members
14,850
Latest member
Gears468

Members online

Top