New headers

Highrisevii

Registered
hey i was lookin into new headers for my 84 vii and i cant find any for that specific year i find them for 86 and up but i was wondering if the bolt patterns were different on the heads... i got an 84 with the 302 H.O. any info would help me out thanx
 

billcu

Head Moderator
Staff member
Paid Member
I'm not sure what the difference is.

The people in the Mark VII section will know though.

I'll move your post there.:)
 

J

OCCUPY LoD :)
The bolt pattern on the heads are the same so any 302 HO Mustang headers will work buuuutttt..... you may have to modify the down pipes or get new exhaust.
 

JoshMcMadMac

Registered
You have an older CFI engine, as opposed to the EFI roller engines of 1986+. There was no "H.O." offering in 1984, so you are working with a 140HP engine. You might be able to get the headers to bolt on, but there would be little gain from them. If you have the go-fast bug you may want to consider a 1986+ VII, or an all-out engine swap on your current car.
 

Highrisevii

Registered
thats one thing that im confused on... because i took out the original motor and took it to a motor supply company where i swapped for a premium long block .. when i got the new 302 it had H.O. stamp on it and had different heads used different plugs... but i put the CFI back on it and the original headers... and it has more power than the origninal...
 

JoshMcMadMac

Registered
thats one thing that im confused on... because i took out the original motor and took it to a motor supply company where i swapped for a premium long block .. when i got the new 302 it had H.O. stamp on it and had different heads used different plugs... but i put the CFI back on it and the original headers... and it has more power than the origninal...

Then it is a later (1985) 180HP H.O. version. My previous statement still applies.
 

ggfrank21

Registered
That’s because the 302 that went in the bird was a detuned model (CAM). Today it’s cheaper to make a better motor than the original. If it’s a true HO it has forged pistons and the mustang gt stock cam, with 86 and up mustang headers exhaust work it will make 210hp and up. If it was mine id reinstall the heads that came with the 302 HO long block take off the CFI and swap for the 84 mustang GT holly 650 carb. Aftermarket mustang headers and have the exhaust reworked. Then you can do all the basic 302 upgrades, rocker arms pulleys etc. if you do that you will be very happy and each step you can do in the driveway in a weekend.
 

JoshMcMadMac

Registered
That’s because the 302 that went in the bird was a detuned model (CAM)...

I am not sure what you are talking about the "bird" for, and regardless there is more to it than the camshaft. The Mark VII did get the same engine as the Mustang, and by 1988 all VII's came with the 225HP H.O. engine. It was the first couple years where the engine output continued to climb from the original 140HP.
 

J

OCCUPY LoD :)
If it’s a true HO it has forged pistons and the mustang gt stock cam,

The basic difference between a HO and a non-HO is its a "roller" motor. The cam is slightly different and it has roller lifters on it. You cannot convert a non-roller motor into a roller motor because there isn't any studs to mount the lifter keepers on, unless you feel like welding. There is no such thing as a Mustang GT cam....the only difference between the Mustang and the Mustang GT is the body kit and spoiler, there is nothing changed in the engine. I don't even think the HO's come with forged pistions, on all the 5.0 engines I've worked on, all the pistons looked the same to me.

Here is my Mustang.
http://www.cardomain.com/memberpage/490364
 

ggfrank21

Registered
When I sead BIRD I mint Mark VII as they are nearly the same car. The Mark came with a 302 but it had heads that didn’t flow as good as the Mustang and a milder CAM + it was CFI. The 84 Mustang came with the 302 HO a better CAM (non roller), holly 650 4v carb, junk of headers and single exhaust and made 190 hp. All someone had to do and I did was get headers from a 86 or newer GT and change to duel exhaust and make 220 hp
IF he ordered a new motor and it has HO on it I’m guessing its probably a Mustang HO motor with a better cam and it might even be roller cam since most guys and shops ether drill the holes for the roller lifter bracket or just junk them and get a roller motor. (He has indicated it makes more power so I guessing its problem a mid to late 80 motor that came in the crown Vick or stang with roller cam). So if it was me I would return the heads that came with the new block get Stang or Stang compatible headers and convert to duel exhaust. Get a new intake manifold and a 650 Carb and that combo will make over 220HP and he can start doing 302 mods and it will all work with the auto trans.
 
Last edited:

ggfrank21

Registered
The 79 -89 Stang came with forged piston thin in 90 ford started cutting cost they went with lighter and weaker hypoeutectic pistons and removed the armrest out of the Stang.
And you converted a non-roller motor in to a roller by drilling holes and threading them and using bolts to hold the keeper in place.
The 87-93 LX 5.0 and GT had the same motor
And when I seed mustang cam I was just talking of the lift and duration, the cam that went into the Stang was more aggressive than other cars and trucks with the 302
 
Last edited:

Highrisevii

Registered
thanks guys i didnt know it was going to be this big of a discussion... right now im just going to order some new heads... and put duals on it and see how it goes from there.... i want to eventually put a new intake and switch it to a carb... but the only problem is im not familiar with all the electric gauges set up it has... i didnt want to loose my speedometer and everything...
 

ggfrank21

Registered
changing motor componints will not change any of the gauges. i cant remember if the distributer is electronic or vacume advance. thats the only real prob to go carb, you will need vacume advance.
 

ggfrank21

Registered
the only thing im not clear on is the intake manifod for the 84 mark, im not sure if the cfi used the same manifold as the carb, some simple mesuring can help figure it out. if its the same you can still get better flowing manifolds and still use the cfi
 

Highrisevii

Registered
really thats really good to know about the intake... because im honestly not worried about making it a hot rod... i just wanna make it where its a lil bit more fun to drive and hopefully help the gas a little in the process...
 
Top