Engine Engine rebuild suggestions


Jun 13, 2016

I have an 89 Mustang GT, manual. I've owned it for about 10 years. The engine leaks oil (I see it on the ground). Also periodically need to add antifreeze. I've been wanting to pull the engine and at the very least re-gasket it. Make a father/son project of it as well. Ideally, while the engine is out, would like to give it some more power. Was thinking of changing out the heads for something aluminum and would love to change the cams for something a little loopy sounding. Not planing to race, but would like the extra power. So here are the questions:

1. I thought the heads they sell online are plug and play, but you seemed to need to measure and change the pushrods, check valve clearance? I've done auto fixes before, but never actually pulled an engine, will be my first time. Are there any known heads/cam combo for the 302 stock engine that I can just purchase and install and know nothing will break?

2. I see heads for sale for like $1000+ per head. And when you're done with the extras, you're $3-4k in for just top-end engine parts. I may have been asleep for a while, but I bought the whole car for $4500. Paying that much in just engine addons is nuts. Are there any sources you know of where I can buy the new parts I need, heads, lifters, rods, cams, lower/upper manifold and gaskets and be around $2k or less? I've seen like AFR aluminum heads on eBay for about $600 with good reviews.

Finally, I know there's probably an ideal way of rebuilding an old engine-- take it all apart, send it to the shop to get cleaned, measured, honed and so on. I don't have the money to do that. The engine runs and the car drive, at the very least, I just want it not to leak and it's been my bucket list item to pull and engine and clean it up.

Your advice is appreciated.

Thank you!
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Short and sweet.
Pull the engine, fix the leaks, clean up the engine bay, stuff it back in. Enjoy the ride. The reason here is KISS. Scope Creep is a real thing with cars this old. AND you probably don't have the experience and likely the budget to dig deaper into the engine.
This way you can fix the leaks and drive the car, in the mean time grab a 5.0 engine you can tear into and learn together with your son.
Free opinion from an older hot rodder.
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Or, similarly, fix the leaks you can without pulling the engine, buy yourself a running 302, rebuild IT, then install it. That way you can enjoy the car even if it's still leaking and satisfy all of your desires. That would give you plenty of time to research different options and build it at a pace that you and your son can benefit from, both financially and mentally.
@General karthief "Scope Creep"-- Sounds like you're a fellow IT guy. I'm in IT as well.

I understand what you're saying, but I don't think I'll have a second chance to mod the engine, so if I pull it, it's all or nothing. The car for me is a toy-- I have a daily driver as well. Please let me know if there's known heads/cam combo on a budget that will be plug and play more or less. 40-50 extra horses would be enough for me.

Budget is a real concern. Whatever you think it will cost, double it.

It’s not the cost of the main parts (head, cam, etc) but all the nickel and dime stuff you find when you get in there. Gaskets, fluids, hardware, cleaning supplies, etc etc. all adds up. Then there might be a couple specialized tools you’ll find you’ll need, like valve spring tools to swap out springs. It all adds up.

You can do a simple GT40 combo ( gt40 heads, explorer intake, cam) and come away with 270-280 rwHP and that would be at the lower end of the cost range, or you can do a trick flow top end kit which would be near the top end.

Then comes the scope creep. “Gee, I’m $4k into this engine build, why not rebuild the bottom end into a 347 and make some real power”

Now you have to upgrade injectors, better clutch, better trans maybe?
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The afr heads for 640 are each, so a 2k budget is pushing it.... There a decent budget head and can be had with 1.9 valves now so will work on stock bottom ends easily without piston to valve clearance issues, but you will need rockers and push rods and head bolts or studs plus gaskets. If your not worried about performance too much I would find a cheap used explorer intake, 1.7 rockers and leave the stock cam but replace the timing chain and balancer while its apart. the afr small valve enforcers will run about $1280 for both, doesn't leave much of a budget for the rest of the parts.. Explore intakes can still be found for sub $100 in most u pull it junk yards. So gaskets, push rods, head bolts, timing chain, balancer and fluids then what ever is left of your budget on rocker arms. Some people get a way with low end steel rocker arms many places re brand for around $150 but I can't say I'm a fan.
@Mustang5L5 & @rednotch

Thank you for the advice. I guess to clarify, I was thinking $2k budget for the big purchases like heads, cam, rockers, pushrods. Gaskets and fluids and stuff are outside that number. So $1200 for heads that are brand new, aluminum, bolt on and will give me the power I'm looking for would work.

Just curious regarding the timing chain replacement. Was gonna do that as part of maintenance anyway while I have the engine out, but are you suggesting upgrading the chain, or just replacing?

As far as the explorer intake for $100-- do you need to send it to the shop for cleaning, checking, or is there a budget way to do it at home?

Finally, I really kinda had my heart set on that loopy mustang cam sound. I remember hearing about the e303 cam. How do I know if it'll work with whatever heads I choose?

Thank you!!
You really need to plan your build so that everything works as a unit.... Loopy sounding cams are not really very street friendly.....
Your $1200 heads will probably require some machine work to check clearances and straightness and springs, rocker arms.....
What will happen here is you are going to take multiple opinions here and what you end up with will be an expensive slug
Loss of coolant can be head gaskets and or warped heads or a worn area between the cylinders.....
That E cam sure does sound good when at idle, that loopy kinda burple sound coming from the tailpipes is unmatched.
But with EFI it can cause low rpm bucking, schlepping around a parking lot in first or second gear at low rpms can get challenging. The market has better cam tech now so there are better cam profiles even come in kits (heads, cam, gaskets and more) so bolt on and go is a reality. I
Shop around, also there are many threads here for info but I'm sure there are experienced members here that car help you bust your budget.
If you go the budget head route with iron heads, pay a few extra bucks to have the heads valve jobbed and port matched to the intake by a machine shop. At the same time they will do the springs and check seat pressure. Not only will they be more reliable, but there is probably about 15rwhp in it.
My guess is that is somewhere around $450 worth of work these days.

Just to be clear, there is only 1 cam.
Gt40 iron head springs won't tolerate a cam (which is way easier with the engine out).
You'll want to get roller rockers.
A 65mm TB
New timing chain and balancer.
The factory mass air meter is undersized for a stock engine.
At this point you will need to decide on factory 19lb injectors or 24's. (19's should handle it, but it starts to get close)

So even a budget build, isn't all that budget.
You have had a lot thrown at you but you can see that there are a lot of us on here that have been there and done that and have had some good success at head, cam, intake (HCI) swaps.

This is just me but you need to evaluate the health of the existing short block before anything else. Typically I look at it this way:
Motor has less than 50,000 miles on it - HCI swap is all that is needed.
Motor has less than 100,000 miles on it and you know the history - Put a new oil pump in it and move forward with the HCI swap.
Motor has over 100,000 on it and you know the history - Check the main and rod bearings and make any decisions on the rotating assembly based on this, check the cylinder wall lip at the top of the cylinders. If there is enough there to really hand a finger nail on then you may want to go for a full rebuild. If the lip is not of concern then run as is and move forward with the HCI swap.

Most of these motors can run up to 200,000 on the short block with the factory low drag rings and good maintenance. Once you have assessed the short block then stick to a budget. The AFE Enforcer heads are a good head as rednotch pointed out. You can read up on them here:

Mustang5L5 also mentioned the GT40 heads. If you can get a set for less than $200 then you might be able to freshen them up for a bit less than the AFR's. You will need a set of TFS springs as the ones on the GT40's out of the Explorers cannot support much lift and will most likely be worn out. Springs are here:

There is a good thread on this right now where one of the members is rebuilding a set himself. Really starts at about post #392

If you are more of a buy it and install it kind of person then get the AFR's and move on. If you enjoy the DIY approach source some GT40 heads and have some fun. Flow numbers on the heads are as follows:

Intake Flow @ 28" H20
Valve Lift .100" .200" .300" .400" .500"
E7 59 114 144 156 156
GT40 54 107 157 183 192
GT40P 61 128 169 195 196
AFR N/A 123 175 208 232

Exhaust Flow @ 28" H20
Valve Lift .100" .200" .300" .400" .500"
E7 42 78 105 115 116
GT40 47 94 119 128 128
GT40P 52 90 123 135 139
AFR N/A 105 143 163 166

So you can see that the AFR's right out of the box outflow the GT40's which means you will make more power if your intake and cam selection are correct. The other thing that I would recommend would be to port the Explorer intake. The guy for the job it TMoss as he and his son have done hundreds of them and did my old Cobra intake and did an outstanding job. If you are interested I can PM you his email address.

Camshaft...custom or off the shelf. I would say custom hands down but the lead times are way out there right now due to the lack of billet cores. Comp Cams and others may have stock on an off the shelf cam that will work 95% as good as a custom is you are wanting to get this done in the next few months. I ran an off the shelf Comp Cams Xtreme camshaft on my old 306 with ported 1969 DOZZ heads and the ported Cobra intake and that combo screamed for what it was. Have an Ed Curtis in the current motor and it was worth the money. Right now I am several months waiting on another one for a 351W based stroker motor but I would not run a off the shelf in this motor so we wait.

You can find good used parts like roller rockers on the market place here and the Corral so I would opt for that vs. the right at $300+ for a new set for the motor you are building. Most likely stock push rods will work but you will need to check them and there are a couple of guys on here that can walk you right through that. I can do it but I usually end up taking to a couple of my buddies with who dunnit cars to walk me through it as I don't do it enough.

Biggest thing is knowing what you want out of the motor hp wise and what rpm range you want to run in. Stock short block with a good heads, good intake and the right cam can build 250 at the rear wheels all day long and put a grin on your face. The guys here are all willing to help but you have to know what you are capable of turning wrenches wise, what you want out of the motor, and set a budget.
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@AeroCoupe Thank you for the post. Sorry I didn't respond sooner, the forum doesn't send me a notification email when there's an update.
Anyway, I bought the car used when it had 90k miles. It has about 101k now. I drove it for a few years, been sitting in the garage the last 4 with periodic starts.

I don't have any particular goals I'm trying to achieve. I guess the biggest goal is pulling the engine and getting it to the point where I can drive it and not worry about the next issue that comes up. Plus, it's been kinda bucket list item to pull an engine and be proud that my hands have been in it. Kinda like when I finished my basement :)

From your post, I think AFR heads are a winner. I think these days there's little to be saved by buying used and getting it back in to working order. Prices are just too crazy. Every time I look at items on marketplace, I think people are nuts. You take a risk buying something used, and I think the price should reflect that. But they don't.

It sounds like cams would add another close to $1k and I only cared about it for the sound. So I figure once I'm able to pull the engine and get it back in in working order, coming back to doing cams, if even the engine stays in, should be doable. As is, I know I'll be changing the timing chain, water pump, oil pump just to get those out of the way while it's on the stand.

Overall, I think all I'll be doing for power are heads, lower intake and upper intake.

Again, thank you everyone for your help. I'm planing to start in about a month-- once the snow here melts and I can move the car.

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Cam will not cost you $1000. Good cam will run about $400 and you can reuse your roller lifters. You will literally have to tear the entire front end of the motor back down to remove the timing chain to pull the old cam out and put the new one in. You will also have to pull the lower intake to remove the roller lifters which means removal of the valve covers, rockers, and push rods. I believe you will be able to remove the lifter with the AFR heads on the car but I do not know much about these as I have the old 185's on my T-Bird and Edelbrocks on the Coupe of which both allow for lifter removal with the head on the motor. Basically you will be stripping this back down to a long block and removing the cam with the motor in the car. My suggestion would be install the cam now as those heads with a stock cam will be underwhelming for the investment.

Also, pick up a good crank balancer like a Romac or a Power Bond if you just want a high quality factory replacement.
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I think you should be aware, once you switch to afr's (which i'm all for), every budget part is out of the window.
You will need either a custom or proven cam, a much better intake, 70mm or bigger TB and spacers 24lb injectors, 80mm or bigger mass air meter, stud mount rockers and so on.
Most likely you will come close or surpass what you have paid for the car (which pretty much everyone here has done)

There really isn't an option to slap basic parts on, you risk the car running or driving awful or plain old getting no power from the $1300 heads you just bought.
And i assure you, you don't NOT want to go back in there and do the cam again.
I think you are over thinking it. A 65mm TB and a 75mm MAF will be fine. 24 lb/hr injectors are a minimum but you can find a calibrated MAF with injectors on the marketplace here or on the Corral about once a week for low dough. Find an Explorer upper and lower on www.car-parts.com, clean them up, and tap the ACT.

This isn’t hard and if you take your time you can find all the supporting parts used for good deals.

My old 306 built 290 rwhp and just over 280 ft-lb of torque on a used Pro-M Bullet 75mm MAF and used 24 lb/hr injectors. Had out of the box Edelbrock Performer RPM heads that I bought used and a Cobra upper and lower intake that was also bought used with a new off the shelf Comp Cams cam that they recommended.

This just isn’t that hard to do it just takes patience and you have to hunt the for sale adds every other day if not every day.