H.O. Vs. Non-H.O.

Phil Ossifer · 01-14-2001, 08:47 AM

Help please,
Other than the roller cam; What other differences are there between the H.O. 302ci engine used in Mustangs and the one used in say, a Mercury Grand Marquis?

A couple of years ago I swapped in a GT-40 long block into my '89 Mustang. Very easy, no problems. Now I want to do the same to my '89 Merc which has the non H.O., non-roller cam 302.

Is is possible or would it be too much trouble? I just want a few more ponies for the old Merc (which is in mint condition).

Thanks,
Phil

QuantumMotorsports · 01-14-2001, 12:45 PM

Actually, if your 89 has the factory motor, it has a roller cam, it's just not the same firing order as the HO. You could use a GT40 long block, but you really would need to change your intake and exhaust to get the power you want. The difference between the non HO and HO motors is:
Throttle Body
EGR spacer (diameter)
upper intake
injectors
heads
cam
headers

That's about it. And you need a new computer. So, you'd probably be better off getting all of those parts off of a Mustang for pretty cheap (I got mine for my Cougar all for about $400) and bolt all that on and be running at 225HP pretty easy. If you want some more info on this check out www.coolcats.net Go to the tech section and find HO conversion. Like I said, I've done this conversion on my 88 cougar and it was not very difficult, took about a weekend. Have fun, if you have any questions, email or post. Good luck.

------------------
Michael Black
Quantum Motorsports
Norman, Oklahoma

1988 Merc Cougar 5.0 HO, P&Ped heads, 2.25" custom mandrel bent dual pipes, T5 five speed tranny
15.43 @ 91.08mph (not shabby for a 3600 pound car)
60' 2.453 Street tires suck!!!

Phil Ossifer · 01-15-2001, 01:00 AM

Michael,

Thanks for the info and the web site!

I've already got most of the parts. I didn't realize my Merc had a roller cam.

Looks like a great weekend project once I get all the parts together. I'll be stealing the intake from my Mustang as I'm soon planning on adding an Edelbrock intake to it.

When I installed the new motor in the Mustang I used the stock upper, lower and throttle body. I also saved the cam and heads from my old motor, they're still in good shape, the heads will need freshening.

Looks like all I'll have to deal with is getting the computer and freeing up the exhaust system...

Thanks again,
Phil

QuantumMotorsports · 01-15-2001, 12:13 PM

Phil,

Sounds like you're pretty much set since you've got the parts off of your stang. One thing to look out for that I'm not too sure of is differences in the wiring harness of the grand marquis and the stang. Since you will be running the stang computer, you might want to find a pinout for each computer (I have one for a stang and a cougar) and make sure all the wires go to the same pins. I didn't have to change any at all so maybe the grand marquis will be the same as well. I do remember however that if you are running mass air stang computer you will need to relocate two wires to accommodate the mass air. ( I believe the web page said something about it, but it fails to mention that it's just if you're running mass air, not speed density) Anyway, have fun with that swap. I always love to hear about big old Mercs getting an engine upgrade so keep me posted.

------------------
Michael Black
Quantum Motorsports
Norman, Oklahoma

1988 Merc Cougar 5.0 HO, P&Ped heads, 2.25" custom mandrel bent dual pipes, T5 five speed tranny
15.43 @ 91.08mph (not shabby for a 3600 pound car)
60' 2.453 Street tires suck!!!

01-14-2001, 08:47 AM	#1
Phil Ossifer Registered Member Join Date: Jan 1999 Location: Sterling Heights, Michigan Posts: 217	H.O. Vs. Non-H.O. Help please, Other than the roller cam; What other differences are there between the H.O. 302ci engine used in Mustangs and the one used in say, a Mercury Grand Marquis? A couple of years ago I swapped in a GT-40 long block into my '89 Mustang. Very easy, no problems. Now I want to do the same to my '89 Merc which has the non H.O., non-roller cam 302. Is is possible or would it be too much trouble? I just want a few more ponies for the old Merc (which is in mint condition). Thanks, Phil

01-14-2001, 12:45 PM	#2
QuantumMotorsports Registered Member Join Date: Jul 2000 Location: Norman, Oklahoma, USA Posts: 597	Actually, if your 89 has the factory motor, it has a roller cam, it's just not the same firing order as the HO. You could use a GT40 long block, but you really would need to change your intake and exhaust to get the power you want. The difference between the non HO and HO motors is: Throttle Body EGR spacer (diameter) upper intake injectors heads cam headers That's about it. And you need a new computer. So, you'd probably be better off getting all of those parts off of a Mustang for pretty cheap (I got mine for my Cougar all for about $400) and bolt all that on and be running at 225HP pretty easy. If you want some more info on this check out www.coolcats.net Go to the tech section and find HO conversion. Like I said, I've done this conversion on my 88 cougar and it was not very difficult, took about a weekend. Have fun, if you have any questions, email or post. Good luck. ------------------ Michael Black Quantum Motorsports Norman, Oklahoma 1988 Merc Cougar 5.0 HO, P&Ped heads, 2.25" custom mandrel bent dual pipes, T5 five speed tranny 15.43 @ 91.08mph (not shabby for a 3600 pound car) 60' 2.453 Street tires suck!!!

01-15-2001, 01:00 AM	#3
Phil Ossifer Registered Member Join Date: Jan 1999 Location: Sterling Heights, Michigan Posts: 217	Michael, Thanks for the info and the web site! I've already got most of the parts. I didn't realize my Merc had a roller cam. Looks like a great weekend project once I get all the parts together. I'll be stealing the intake from my Mustang as I'm soon planning on adding an Edelbrock intake to it. When I installed the new motor in the Mustang I used the stock upper, lower and throttle body. I also saved the cam and heads from my old motor, they're still in good shape, the heads will need freshening. Looks like all I'll have to deal with is getting the computer and freeing up the exhaust system... Thanks again, Phil

01-15-2001, 12:13 PM	#4
QuantumMotorsports Registered Member Join Date: Jul 2000 Location: Norman, Oklahoma, USA Posts: 597	Phil, Sounds like you're pretty much set since you've got the parts off of your stang. One thing to look out for that I'm not too sure of is differences in the wiring harness of the grand marquis and the stang. Since you will be running the stang computer, you might want to find a pinout for each computer (I have one for a stang and a cougar) and make sure all the wires go to the same pins. I didn't have to change any at all so maybe the grand marquis will be the same as well. I do remember however that if you are running mass air stang computer you will need to relocate two wires to accommodate the mass air. ( I believe the web page said something about it, but it fails to mention that it's just if you're running mass air, not speed density) Anyway, have fun with that swap. I always love to hear about big old Mercs getting an engine upgrade so keep me posted. ------------------ Michael Black Quantum Motorsports Norman, Oklahoma 1988 Merc Cougar 5.0 HO, P&Ped heads, 2.25" custom mandrel bent dual pipes, T5 five speed tranny 15.43 @ 91.08mph (not shabby for a 3600 pound car) 60' 2.453 Street tires suck!!!