HO conversion/differential questions

[Stealthlead]

Hello, I'm still fairly new and trying to learn all the terminology hear. Any help is really appreciated. =)

I have saved up around 5k to put into my 91 MGM this year. I have the entire summer, a place to work and a spare car to drive. My MGM only has 121k miles on it, has never been in an accident and very well maintained (Owned by grandparents). Things to mention about this car is that at some point it had an MAF conversion, and it has had a custom steel top fabricated for it. I also plan to paint it on my own after the conversion.







I'm going to stick with my stock 302 and do my best to get as much power out of it with the money set aside. A few questions regarding the HO conversion...

For the heads I was thinking along the lines of GT40's and obviously shorties for the headers. Is this a good idea and should they be ported? I was reading somewhere that Shorties don't work well with GT40's. Is this true?

As for the exhaust, are there any suggestions here? I definitely want cat back H pipes.

I was reading up here http://www.grandmarq.net/vb/showthre...ferential-Info
and here
http://www.grandmarq.net/vb/showthre...=differentials
and came to the verdict that 3.73, 8.8' differentials are the best way to go (I think). I was planning on going to the junkyard, finding one used and rebuilding it. Is this the best option for me? (I read that Ford racing diff's are crap). Also, please excuse my noobness, but what exactly is a track-lok's function, and is it necessary? And how is a clutch system installed in a limited slip differential?

A friend told me the best place to start is from the ground up, so I'm planning on working on the differentials, rear shocks, springs, and brakes first. I'm planning to do a disc brake swap in contrast with the rear end swap. I was told that in order to perform the disc brake swap with the rear end I have, all I need is the backing plates and calipers from a 92-95 CV. With a 3.73 rear end, would that still be the correct size?

If anyone has suggestions for the route I should take with this car please feel free to comment or post links I can read up on.. I'm planning on some kind of performance upper/lower intake as well. I'm also considering a T5 swap possibly...

~Stealthlead

[BerniniCaCO3]

I'm just finishing with my own HO swap on a 1990. I've got dual exhaust, a complete engine rebuild, and also am doing the 3g alternator and electric fan. Sounds like what you're doing.
It turns over and runs Still a bit to do before I can drive it-- should be a daily driver again by the end of the week!

I've also replaced every coolant hose, degraded vacuum lines, and added some gauges.
All in all I think I've spent $1500. $450 for the exhaust headers to tailpipes, clamps and mufflers and such in between; and $250 to clean up my heads (ground valves, new guides, new seats) were some of the highest expenses. Basic rebuild kit was $200, other parts like the oil pump, timing chain, and so on are cheap but add up. $1500 total. $5000 will be PLENTY if you're doing it all yourself.

Feel free to ask any questions! I've asked plenty on this forum doing my own, time to pay it forward

There's plenty of literature: the GT40P heads are better, but the spark plug angle is different. The "FRRP" (I think) headers have been offered by ford racing to work with the gt40p heads, once they realized the demand. Those particular compatible headers are $250. Honestly? That might be easiest, and gt40p heads are better and cheaper and easier to find. If you find gt40s cheap, more power to you. That's what I did, $90, but of course I ended up spending $250 to make them like new. 6 in one hand, half a dozen in the other.

Somewhere there's a lengthy thread with a precise formula for the exhaust, which I followed. About a month back-- I'll find it for you if you strike out.

The matching explorer intake --do you care about egr?-- works great. It's $150 on craigslist if you do care about egr, <$100 if you don't! There are some modifications you need to do both to the egr spacer and to the throttle body to make the explorer --or the HO-- intake work, nothing that either $200 for the machinist or a few hours of your own time and a few basic tools can't fix.
I opted to use the HO intake because I wanted egr, didn't have the spare $150, AND in fact it's better for low end torque. But I'm not driving this as a fast car, just, faster than the lowpo engine that was in it. Sounds like you'd prefer the explorer intake; it flows a lot better than the HO.

[87gtVIC]

I think he will care about egr functions as the car sounds like it is in Cali.

[Stealthlead]

I'm just finishing with my own HO swap on a 1990. I've got dual exhaust, a complete engine rebuild, and also am doing the 3g alternator and electric fan. Sounds like what you're doing.
It turns over and runs Still a bit to do before I can drive it-- should be a daily driver again by the end of the week!

I've also replaced every coolant hose, degraded vacuum lines, and added some gauges.
All in all I think I've spent $1500. $450 for the exhaust headers to tailpipes, clamps and mufflers and such in between; and $250 to clean up my heads (ground valves, new guides, new seats) were some of the highest expenses. Basic rebuild kit was $200, other parts like the oil pump, timing chain, and so on are cheap but add up. $1500 total. $5000 will be PLENTY if you're doing it all yourself.

Feel free to ask any questions! I've asked plenty on this forum doing my own, time to pay it forward

There's plenty of literature: the GT40P heads are better, but the spark plug angle is different. The "FRRP" (I think) headers have been offered by ford racing to work with the gt40p heads, once they realized the demand. Those particular compatible headers are $250. Honestly? That might be easiest, and gt40p heads are better and cheaper and easier to find. If you find gt40s cheap, more power to you. That's what I did, $90, but of course I ended up spending $250 to make them like new. 6 in one hand, half a dozen in the other.

Somewhere there's a lengthy thread with a precise formula for the exhaust, which I followed. About a month back-- I'll find it for you if you strike out.

The matching explorer intake --do you care about egr?-- works great. It's $150 on craigslist if you do care about egr, <$100 if you don't! There are some modifications you need to do both to the egr spacer and to the throttle body to make the explorer --or the HO-- intake work, nothing that either $200 for the machinist or a few hours of your own time and a few basic tools can't fix.
I opted to use the HO intake because I wanted egr, didn't have the spare $150, AND in fact it's better for low end torque. But I'm not driving this as a fast car, just, faster than the lowpo engine that was in it. Sounds like you'd prefer the explorer intake; it flows a lot better than the HO.

Hey thanks for the reply. It does sound very similar to what I'm doing!

I've been reading a bit about the 3G alternator installation and that the 2G's are underpowered and can potentially cause fires, so this is definitely something I will add to my list! I've also noticed an underpowered performance in it as well.

I'm fairly OCD when it comes to my own vehicle, so obviously all the hoses, vacuum lines, clamps etc. will be replaced/painted etc. I've maintained the car myself for quite a while. There are no issues besides a bit of a leaky oil pan, but definitely not excessive.

Wow, that is very cheap for what you mentioned! Were all of your parts used and then cleaned? I'm going to put in a new timing chain as well.

If I understand you correctly, your telling me that the GT40 ported heads are the best way to go, even though the spark plug angle will be different, and that shorties won't work with them but the ford FRPP's will? (I'm pretty sure this is what you mean)
http://www.atomicperformance.com/frp...v8mustang.aspx

Would you recommend buying new GT40's or used ones and cleaning them up?

I searched and read multiple threads on different exhaust systems people have in there MGM's. I came to the conclusion that I'd LOVE side exit exhaust (I.E in front of the rear wheels) but I'm not sure if that's legal here. And by the way, I live in Gilbert Arizona, and the car is from Utah. Since I still have to pass emissions, the O2 sensors, EGR and cats will have to remain intact. If at all possible I'd like to avoid above the axle dual exhaust, but I'm not sure if its something I can avoid.

Still wondering about the route I should take with my differentials too.

[Lincolnmania]

91 california cars had mass air

[Stealthlead]

Interesting. I've personally found out from the strange expansion tank it possesses.

[zoomie]

gt40s will respond well to porting and can use regular shorty headers, gt40ps on the other hand dont repond to porting as much ,however blending the bowls and putting bigger valves in it does make them perform quite well. you can use the frpp offering for headers or you can use BBK 1515 headers with some 90 degree boots and some heat socks. either way you go you will have to upgrade the springs on either head.

for shocks KYB gr2 police shocks are most excellent. also polyurethane bushings and end link kit will help out as well , also sway bar both front and rear too.

[Stealthlead]

for shocks KYB gr2 police shocks are most excellent. also polyurethane bushings and end link kit will help out as well , also sway bar both front and rear too.

I totally forgot about the rear sway bar. What models can I part it off of? And by the front sway bar you mean swap my current one for a PI sway bar (both front and back)?

Any suggestions on pistons? Any opinions on a stroker kit?

[GM_Guy]

What is the DSO code on the door sticker? (two numbers, above 'DSO'). If that number ends up being a California DSO it'll be a factory MAF car, which from your other thread means everything under the hood is factory, so no 'lincoln tank' conversion.

Alex.

[gadget73]

I totally forgot about the rear sway bar. What models can I part it off of? And by the front sway bar you mean swap my current one for a PI sway bar (both front and back)?

box police cars are the only game in town for a factory bolt-on piece. 79-91. There are some non-police cars that have a bar, but its smaller. If you can't find a cop car, a civi model bar is better than nothing by a long shot. If you find one, take the spacers out of the lower control arm. The bolts pass through the arm, and there are pieces of what look like pipe in the middle of the arm where the bolts go to keep from smashing the arm. Front bar can come from a police car, or a station wagon. Wagon ones are 1/16" larger but they are hollow. Net result is damn near the same stiffness but the wagon bar is significantly lighter. All things told, you're probably better off with the lower weight bar. Handily, its usually easier to get ahold of a wagon than a cop car.

[BerniniCaCO3]

I bought this guy, took me a couple hours to install (mostly cursing at chinese drill bits), and you can probably do it faster:
http://cgi.ebay.com/ebaymotors/79-91...Q5fAccessories

At some point you end up asking yourself, if the part is the least bit uncommon, if it's worth your time and gas trolling junkyards on the chance you find it.
The yards that pull it for you, wanted $100 if they had it-- $160 gets brand new and better made shipped to your door.

[BerniniCaCO3]

that said, many parts I did get from junkyards, just the swaybar is one I gave up on 3g alternators are common as dirt, you have your pick to find one in good condition; grand marquis trim, there was usually 2-3 cars and one of them had an unbent piece. For examples.

[zoomie]

I totally forgot about the rear sway bar. What models can I part it off of? And by the front sway bar you mean swap my current one for a PI sway bar (both front and back)?

Any suggestions on pistons? Any opinions on a stroker kit?

there is also the box limo swaybar as well, which should bolt up with no problems.
the box limo K code axles bolt in with no issues as well.
pistons? i could say Ross pistons or Keith Black, however i think its probably more feasible to just find a HO motor from a mustang (87-92)or mark vii as those have forged pistons.
as far as a stroker kits go , you looking for something steetable or just flat out dragrace?
im not sure what kind of monster your planning to build, perhaps that would be the first thing i need to know what exactly are you looking to do? i can reccomend parts and such but thats about it.

[Stealthlead]

Hrmm, that doesn't look so bad. Any other opinions on $160 for that rear sway bar? It sounds good to me, I was going to say I've never seen a rear sway in a junkyard here. As gadget said I don't think I'll have nearly as hard a time finding a front sway bar, I've seen a few wagons around.

I've been trying to dig up some exhaust ideas. I'll definitely need two cats, and I've read good things about purple hornies..

pistons? i could say Ross pistons or Keith Black, however i think its probably more feasible to just find a HO motor from a mustang (87-92)or mark vii as those have forged pistons.
as far as a stroker kits go , you looking for something steetable or just flat out dragrace?
im not sure what kind of monster your planning to build, perhaps that would be the first thing i need to know what exactly are you looking to do? i can reccomend parts and such but thats about it.

I'm thinking along the lines of drag. I'm going to stick with my 302 assuming the block is still good (I'm very sure its not bored out either) and try to build up as much power as I can with the money/time I have.
I'm planning the HO conversion and a bit more; I'm looking at new heads, possibly pistons, cam (thinking stroker), HO upper/lower intake, exhaust, new differentials, shocks, springs etc. Eventually I'll do the T5 swap but not this summer.
I'm thinking the best way is to start out with the shocks/springs/rear end, and build it up from there. I'm a bit confused on track loc's still, and am also confused on the best exhaust setup I should run.

Thanks for the help guys~

[hypostang]

How about this sway bar option ?

http://www.grandmarq.net/vb/showthre...-rear-sway-bar