Looking Good!

Nice work there BroPaul. When I modify a part it usually affects at least three others that need some work done to them. How you got away with only having to modify one header tube is pure luck. 🤪

BroPaul wrote:

When I have an idea for one of my Mustangs that isn't an immediate need, but a want, I put it on a list I call "The Parking Lot." Over time these can get long, but most tasks don't seem that big. Well, no task ever seems big until you get into the middle of it and the dozens of unanticipated complications all arise and then you ask yourself why in creation am I even doing this? 
Well, that hasn't happened until this month. To set the stage, back in 2024 I hurriedly threw my fb together for the Bako Bash so I could (in  theory) have my hot rod fastback in attendance. As MS will tell you "don't do that" - which is good advice - and I lived the myriad en route issues that an un-sorted car will give you. 
One of the many (many) compromises made to get the car going was using 5.0 plain valve covers. The idea is a mostly retro looking engine bay with shock towers, an export brace and a vintage looking carbureted SBF. I wanted COBRA Powered by Ford finned aluminum valve covers but I haven't scored any. For the bash thrash none of my VCs would clear the aftermarket rocker arms, so I just took the 5.0 plain janes and removed the baffles and used a die grinder to clearance the insides. Temporary. 
Then I asked MS what he did and he takes early aluminum VCs and JBWelds spacers to them and paints them black. Said with the mod the spacers almost disappear. Okie dokie - I'm game. 
Well, the passenger side went like clockwork. Easy peasy lemon squeazy. Even with needing fasteners that are 2.375" long to get through the Powered by Ford covers, plus the 1/2" spacers plus the laminated Fel-Pro gaskets. 
Then came the driver's side. 
I have the dreaded "up and over" Hedman Hedders to swap a 351W into a Mustang. They just just just cleared the Plain Jane VCs. They interfered with the cooler fined VCs. 
Tried to heat and bend the one tube to clear. No dice. 
Decided to remove the headers, take two judicious, modest, careful slices from the arch to tilt is ever so slightly outboard. Just just just enough to clear the new old VCs. 
Success!!! A small, simple little task on the PL list checked off. After days of futzing with it. Holy smokes. 

"Build a Mustang", they said.
"It'll be fun" they said.  

Wish I knew someone was needing some Cobra valve covers and spacers I have both just sitting in a box I never used....Cause I went with some of the 85 GT Mustang valve covers with spacers...I guess I need to take some pictures of the extra stuff I have laying around and sell them.
 

What I have that works in my 68:
351W. 5.0L cylinder heads, JBA Shorty headers, "Cobra Powered by Ford" finned aluminum valve covers. No clearance issues. Ditch those Heddman long tube headers...

50vert wrote:

The older I get, the more I prefer shorty headers.

 
The older I get, the more I prefer manifolds.

Ron68 wrote:

/// Ditch those Heddman long tube headers...

Welp, the day may come that I'm willing to rework stuff that is done, installed and working nicely, but that day aint today. The 422W that is in there has AFR heads, and a lumpy cam, so if I switched, it actually might be to freer flowing long tube headers. But as they sit, I have shock tower clearance, VC clearance, they are tucked up nicely under the car and match up nicely to the exhaust tubing. If it aint broke...



Not to mention that the 422 cubic inch air pump is generally moving a lot more air than a 305 cubic inch air pump. Maybe even 47% more. So there's that to consider.  
Airflow Comparison
Parameter                                 5.0L Explorer (GT40P)                  422 CID Stroker (AFR 185)
Displacement                           302 cu. in. (4.94 L)                               422 cu. in. (6.91 L)
Theoretical Max (100% VE)            481 CFM                                            672 CFM
Estimated Real VE @ 5500 RPM      ~82%                                                ~88%  
Actual Exhaust Airflow              ~400 – 435 CFM                             ~580 – 640 CFM

Last edited by BroPaul (8/20/2026 4:37 PM)

BroPaul wrote:

Ron68 wrote:

/// Ditch those Heddman long tube headers...

Welp, the day may come that I'm willing to rework stuff that is done, installed and working nicely, but that day aint today. The 422W that is in there has AFR heads, and a lumpy cam, so if I switched, it actually might be to freer flowing long tube headers. But as they sit, I have shock tower clearance, VC clearance, they are tucked up nicely under the car and match up nicely to the exhaust tubing. If it aint broke...



Not to mention that the 422 cubic inch air pump is generally moving a lot more air than a 305 cubic inch air pump. Maybe even 47% more. So there's that to consider.  
Airflow Comparison
Parameter                                 5.0L Explorer (GT40P)                  422 CID Stroker (AFR 185)
Displacement                           302 cu. in. (4.94 L)                               422 cu. in. (6.91 L)
Theoretical Max (100% VE)            481 CFM                                            672 CFM
Estimated Real VE @ 5500 RPM      ~82%                                                ~88%  
Actual Exhaust Airflow              ~400 – 435 CFM                             ~580 – 640 CFM