Engine rebuild

[broke bronco]

This is my first project vehicle so I’m not trying to go to crazy with it, but I’m trying to rebuild the engine to keep it dependable but have a little more power than stock. I was thinking a cam and valve job. Would anyone happen to know a good size cam that I won’t need to change the piston heads to avoid hitting the valves?

 

[Angie]

what engine size?

 

[Uncle Gump]

My guess is a 2.9L based on year.

I would spend some time researching the 2.9L. Not that they're a bad engine... but they're not a good engine. They had their share of issues and for myself I just wouldn't put any kind of money in one. If mine goes... it's gone.

 

[dvdswan]

Do some research as @Uncle Gump said, you may find that you might want to upgrade to a 4.0 or something else. It may seem daunting but lots of folks on here have been there done that thing and are very willing to impart their knowledge with you.

 

[lil_Blue_Ford]

@gaz did a good rebuild to a 2.9 and has stated some nice numbers. @PetroleumJunkie412 also has done a bunch. I talked with the local machine shop/engine builder about it in general terms and he agrees that there’s room for performance building of the 2.9 and 4.0 OHV. From what I’m understanding, a set of balanced internals, cam, free-floating rockers and flow porting among other things can make a world of difference to these motors. Europe did a lot to these motors, especially the 2.9 and over there it doesn’t have the bad rap that it does here because the motors were built with better quality control over there.

 

[gaz]

@broke bronco ,

For a 2.9l FORD 60°v6, I would not do less than this:

-quality headers (JBA, Borla, Edelbrock)
-2¼" exhaust
-Melling oil pump
-remote oil filter and oil cooler
-Cloyes timing set
-Gates water pump
$100•switch from crank fan/clutch to electric +7% efficiency
$150•Ford 2.8l flat top pistons + one compression point 3-6% hp
$200•bored stock T/B +2 hp across RPM band
$100•free floating rocker arms, open oil holes, deburr/chamfer = yields better oiling and less friction in the valve train


If I demanded all the efficiency the the 2.9l had to offer I would do the minimum above and the compliment below:

•custom reground cam +20hp
•flow bench port polished heads to intakes +20hp
•mill the heads 0.035" for an additional point of compression and +3-6% hp (6-12% with the 2.8l flat tops)
•high output ignition +3% efficiency
•balanced bottom end +10% efficiency
***if all these changes were incorporated, then use a single 2½" exhaust vs a 2¼"

IN THE END
A multi angle valve job must be done no matter what. Insure that your valve train components are serviceable and that your hydraulic lifter preload is correct.

@Moderators, move to 2.9l.

 

[broke bronco]

Yes it is a 2.9L sorry for not saying it. I was thinking of 4.0 swap originally but wanted to keep the original engine as long as possible. Though I will be swapping the 5 speed in it for a 5 speed and transfer case from a ranger. And will I need a new ECU and wiring harness for the new electronics?@gaz how difficult would it be to find and install those parts myself?

 

[lil_Blue_Ford]

Ranger transmissions were the same as Bronco II transmissions of the same year. If you’re looking for a stronger transmission you can do the M5OD from a 4.0 and use the 4.0 clutch

 

[gaz]

@broke bronco ,

I am uncertain whether you are asking about my list or the tranny swap that you mentioned

There are only 2 components that I listed that may require patients to locate:
-Quality headers
-free floating rocker arm spacers

I do not know your level of mechanical skill or what tools you have in your shed but in regards to ease of installation...if you are capable of rebuilding an internal combustion engine, then you could could do everything I mentioned except balance the bottom end. If you gathered all the parts except for the bearings, pistons and cam (your machinist needs to take measurement to determine the correct size for a rebuild and the porter, if using a flow bench, can make the best cam recommendations based on your engines ability to flow air), then an engine builder could assemble it for you. They could outsource or even balance the complete bottom end too.

Nothing I suggested requires a new computer, wiring, flashing, reprogramming or Dyno tuning. The electric fan requires power but it can be run by simple fused, relay to off/on toggle or a store bought temperature control kit.

If you were only asking about the tranny swap, since it's a 5 speed for a 5 speed I'm pretty sure you will not need to do much more than a little clearance adjustment to the hole in the floor for the M5OD shifter.

 

[gaz]

@broke bronco ,

If this engine runs well and is not in need of a rebuild, then:
1) swapping to an electric fan will make a HUGE difference in fuel economy and available power (I recommend installing a new water pump when switching from the crank driven fan/clutch to an electric fan).
2) An oil cooler is just a smart inexpensive way to help keep temperatures under control.
3) removing the valve covers and verifying that your components are serviceable and performing a complete rocker arm tear down, cleaning, deburr/chamfer with oiling holes enlarged to next standard hole size (example, from 1/16" to 3/64" or one drill bit size larger in a Machinist's but set), then reassemble, install and ensure correct hydraulic lifter preload.
4) quality headers
5) drop in K&N air filter

These five changes with a good coil, 8mm silicone suppression wires, fresh plugs/distributor cap+rotor (aka, a FRESH tune up) will dramatically improve the engines performance. With these 5 changes and a Hypertech Stage I CHiP in my 87 regular cab/long bed Ranger on 32" rubber with 6" of lift it ran 28mpg on the highway and 25mpg city all day long; that was with 185k miles on the bone stock engine with a 5 speed!!

 

[broke bronco]

Thanks for all the advice. @gaz I have rebuilt engines before but me and my friend were always putting OEM stock parts back in, so I wasn’t sure if adding those new parts would cause it to run rough until a tune.

 

[gaz]

Any questions just ask

 

[ecgreen]

I agree with the 4.0 hypothesis for sure. But I also understand re-building and keeping the original. Something about my crappy little 2.9 speaks to me (for better or worse). When mine dies, I can totally see myself rebuilding one.