302 engine friendly discussion/education

[chuck1022]

I am going to eventually need a new motor, so i am reading everything i can about them. Right now it runs great, but here is what i know about it.

The previous owner had his neighbor "rebuild" the 302. I am inclined to believe that it was freshened up with piston rings and seals. The best I can tell, it has heads off of a 1986 mustang (e6, c6, I forget.) It has the 2150 carb and the stock exhaust manifolds. Here is my thought, If I buy a remanufactured 302 for a Ford explorer, I get a new motor with the GT40 heads. I put the 2bbl manifold and carb on, stock exhaust manifolds, I get rock solid motor good for another 40 years.

what am I missing

 

[sykanr0ng]

If I buy a remanufactured 302 for a Ford explorer, I get a new motor with the GT40 heads. I put the 2bbl manifold and carb on, stock exhaust manifolds, I get rock solid motor good for another 40 years.

what am I missing

Only the 1996 and early 1997 Explorer engines (those actually built in 1996) had GT40 heads.

All after that had GT40P heads.

The P heads have spark plugs that are straight out instead of at the angle all previous Small Block Ford heads since the 1960's were made with.
This means headers and even exhaust manifolds do not fit the same.

 

[73azbronco]

However I think a stock explorer P head exhaust manifold is pretty good at what it does.

 

[Timmy390]

Bronco Hut headers solves the P head issue........

As said, stock manifolds off the P head Explorer work too

Tim

 

[sykanr0ng]

The cast GT40P manifolds are not bad but the welded tube ones choke down to about 3/4 inch in several places.

 

[chuck1022]

I would definitely make sure i get the non-P heads, 1996 ones. But it should be a good running motor. The only change im making is better heads, which will breathe better than what i have, even though i am keeping the stock 2bbl carb 2150 ,intake and exhaust manifolds.

 

[JAFO]

For my build I bought a stock 302 rebuilt engine from AdvnaceAuto. I think the block is a 1978. It came with stock heads. Bought the engine back in 2007 for $1300. It sit on the engine stand for seven years while I pivoted to do the body work. I would turn it over every once in a while. I put on an Edelbrock intake and Holley 4 barrel. High volume oil pump and over sized oil pan. Everything else pretty much stock. Runs fine. Plenty of power for a little Bronco.

 

[Timmy390]

I would definitely make sure i get the non-P heads, 1996 ones. But it should be a good running motor. The only change im making is better heads, which will breathe better than what i have, even though i am keeping the stock 2bbl carb 2150 ,intake and exhaust manifolds.

I'm not sure you will see or feel any difference with just changing heads. The 1986 mustang heads you have freed up all the HP lost from the stock combo and 70's smog heads.

Not sure I would go with GT40's or GT-40P's. If dead set on swapping heads and staying with the stock combo, a set of E7's is all you need.

JMO.....

I run P's on my warmed 351w and Bronco Hut Headers. No issues......

Tim

 

[blubuckaroo]

Get the non-P heads.
With your manifolds and 2bbl carb, the motor won't know the difference, but future headers won't have to be so specific.

 

[Rustytruck]

If I were getting a new motor it would be a roller cam motor. But unless you are planning to drive much more spirited than normal your not getting a whole lot you are paying for. For the most part the Broncos spends its life at 3 to 4 thousand RPM. in this area you want a cam that peaks horsepower at 5000 rpm and Torque at 3500 rpm that means your looking for more compression rather than High rpm flow or more displacement. Building a motor that peaks a 6000 or more is a waste unless you plan to use it. Maybe you want to race it around or run fast in the sand or mud. Decide what you are planning to run and how you want to run it. First things you need to know is what tire size you want to run. What type of Bronco are you planning to drive, a 2900 lb. empty stocker or a 5000 lb. raised off road beast. 200 hp on a stocker was just OK 300 Hp on that stocker gets really fun fast. 200 Hp on a 5000 lb offroad beast is a dog and 300 HP is just getting it back up to stock speed. But for the most part your still only pushing 4000 RPM. The Bronco is a brick in the air and the taller it gets, the heavier it gets and now the rolling resistance becomes an issue too. Build a long winded motor and then you have to run a looser converter if running an automatic to get the engine up in its torque band before it will move. Think about the Bronco you desire and how you want to drive it before you settle on a motor. Tire size and proper gearing is a must and much more important than how much horsepower you make. The best Bronco I got a chance to drive was a semi built 289 motor with an automatic transmission with 30 inch skinny tires and 4.11 gearing. The rest of the 1970 Bronco was stock no lift and the top was removed. The Bronco just felt sporty and wanted to run. You had to be careful with it being light short and narrow or you could get in trouble fast. Unlike my personal 1974 Bronco running its stock motor and heavy offroad modifications there is nothing sporty about it but it still gets the job done. Just don't time me going uphill.

 

[chuck1022]

My 1977 bronco is original, the rear fenders were cut, that is it. No lifts or nothing. I believe it has 3.50 stock gears, i have 29 inch tires. The biggest tires will probably be 30 in. I have an automatic. I dont offroad, but it is my daily driver. I like the fact that it is quiet, i can have a conversation at 60mph on the freeway with the top off, and not have exhaust droning you out. So, it will be the 2900lb bronco. I just want to make sure i am not taking a step backwards

 

[Broncobowsher]

With as mild as you want the engine to be, non-P heads will make life easier. Any performance you may get with the P-heads will be negated by still running the 2-barrel intake. Even a mustang or truck 5.0 will fill the bill just fine.

Couple of things that can trip you up. Distributor gear. You need one to match the roller cam. Engine balance is another. The newer engine has a different balance than the original. The flexplate is easy, just use the correct one. The damper on the front, that takes some aftermarket creativity. To use the original accessory drive you need an aftermarket damper with the 3-bolt pattern and late 50 oz-in correction. Using the original bronco oil pan, don't forget to put a plug in the dipstick hole in the block.

That pretty much covers using a late 5.0 with early intake/exhaust/ignition/accessories.

 

[Joe473]

Don't forget the explorer did not have a mechanical fuel pump. If running a mechanical pump you need the early style timing cover and timing gear set with eccentric for an 86 mustang which had roller cam and mechanical fuel pump. This means not using the explorer serp and getting balancer and flywheel to match explorer balance. Also as previously mentioned use dust gear suggested by cam vendor.

If you are going that far with better heads why not a dual plane 4bbl intake and a small 500 cfm square bore 4 bbl? Smaller primary than 2bbl is actually more effecient and better throttle response. For a 302 with gt 40 head with a cam keeping it in the 2500-3500 peak tq range a 1.08" 470 cfm 4100 sounds like a good match. I'm running a 1.12" 4100 on a 96 explorer based 347 with BC headers gt-40 heads and it's more than enough carb and engine. Keep the cam small. comp 35-349 would be kinda big for a 302 IMO.

Explorer can be made to look very stock. This is before and after pics.

Sent from my SM-G900V using Tapatalk

 

[chuck1022]

Do you know how many miles are on the rebuild? That motor could last you years before you would really have to do something with it if it was a recent rebuild.

The previous owner did not drive it much. The owner before that did not drive it much. Just sat in their garages. If i were to guess.....5-8000 miles in 20 years. I was told that 2 cylinders have low compression...110, the rest are 140. But it drives great. I did notice if it idles for a long time, then i rev the motor, it puffs white smoke for a few seconds, then its gone,...maybe oil getting into the 110 psi cylinders?

 

[Timmy390]

Engine changes and or rebuild is a rabbit hole. If you want bone stock that's easy however if you want more power (and who doesn't) then my advice is to DO IT RIGHT.

In simplest terms, an engine is nothing more than an air pump. When moving away from stock, you can't just upgrade one part and expect a noticeable difference. Say you only change heads to the best there is. They flow like no others can but you don't change the intake or cam. No more air and fuel is getting into the engine than did before the head swap so the heads are not flowing any more than the stockers. Sure they're more efficient but not to the point you will see any gain. Now the 70's smog heads were junk and restrictive so there is something to be gained by using those 86 Stang heads but spending money on better is like burning it in the street. Now you take those same heads that flow like no others and pair them with a carb (or EFI), intake and cam and better exhaust (remember more air in has to get out) and you have power you can feel. Get the combo right and it's power you can scare people with.

If you truly want more power, power you can feel, change the stock gears from 3.50's to 4.11's You WILL FELL the difference. Like you added 100hp. Drive the rig with the new gears till the engine gives you real issues then consider a full Explorer swap (EFI and all).

I drove my stock 302 till it was on it's last legs. I upgraded gears to 4.11's first and when the engine was on deaths door, I popped for a 351W and EFI. I now have a beast....

Tim

 

[chuck1022]

I am not really looking for more power, just simple and reliable. In dont off road or nothing. I just see that these ford explorers have 200-300 thousand miles. But the previous poster might be correct...i might drive this motor for years with two low cylinders and a leaky pan gasket

 

[sykanr0ng]

I am not really looking for more power, just simple and reliable. In dont off road or nothing. I just see that these ford explorers have 200-300 thousand miles. But the previous poster might be correct...i might drive this motor for years with two low cylinders and a leaky pan gasket

Largely due to the Explorer EFI not allowing fuel to wash the oil off the cylinder walls.
If you want the benefits of the system you need to use the system.

 

[Joe473]

Agree if you go carb make sure it is tuned right but don't expect same longevity. Not all explorers got thst longevity. Mine was 100 engine and had significant cylinder scoring and detonation issues when I pulled heads. Also if it's not burning oil and has enough power leave existing alone. Just might want to inspect timing chain when you get a chance. I did mine cause it started burning a quart of oil every 300-500 miles.

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[chuck1022]

Just did oil change, it does use oil, will track how much. Given, it does leave it on the ground too

 

[Timmy390]

Yeah, the smoke you mentioned earlier means oil consumption.

With the engine sitting and not being driven by the 2 previous owners, I would drive the heck out of it and see if the compression comes up and the oil consumption goes down.

Thinking maybe the rings need to be re-seat.

Worth a try

Tim