4.0L OHV Perf. Questions

Alright- haven't found the answers I am looking for through Search- so I'm asking you guys to help...

I can see there being some advantage to tapping the big back hole on the rocker arms & inserting set screws to direct more oil to the pushrod tips...
Anyone done this? If so- did it help? Any trouble caused by it?

I have Red injectors- are they still 19lb? I have injectors from my 3.8SC and from a 4.9L that I might be able to use if desired (haven't checked length, but connectors appeared to be the same)... Bigger injectors really won't help unless I Super or Turbo Charge it later, but will they Hurt anything now? Won't the Computer compensate, or would I have to get a tune (and then re-tune)?

I bought an M128 Melling oil pump & have already installed the pickup & primed the pump for install... Then I learned that there was a HV pump (M328) that would probably be preferred. They do not share the same internals (different gear size, etc)- so I can't just swap the pressure spring... Anyone use the M128 with success (anyone have trouble)? Anyone want to buy my 128 so I can buy a 328?

Could I make the 90 T-bird SC TB work on my engine? If not- what is the cheapest way to improve intake airflow? 5.0L TB? Blade/shaft mod on stock TB?

Still searching for a good deal on a 410 cam & pushrods... Anyone want to make me a deal?

Got to get back to the garage & get some work done! I'll check for your input tonight... THANKS!

I forgot one question (probably others)- The intake doesn't have coolant crossover holes in the back... Has anyone drilled holes & put fittings/hose together to remedy that? Any advice? I haven't got enough back together to mock it all up- is there something that prohibits a crossover from being installed? Thanks again!

Anyone? Perhaps I'll ask in my rebuild post...

Tnashua said:

I can see there being some advantage to tapping the big back hole on the rocker arms & inserting set screws to direct more oil to the pushrod tips...
Anyone done this? If so- did it help? Any trouble caused by it?

Click to expand...

Yikes. No.

The holes in the rocker arms are there to allow oil to get in there between the pushrod tips and the rocker arm. Tapping it and using a set screw won't help anything, and will probably do the opposite.

The best thing to do on rocker arms for the 4.0L OHV is to use new Ford rockers that are harder than the originals, and so won't get the indentations or wear, and will allow the valves to open up as much as possible.

You can always get roller rockers if you want to spend the money.

I have Red injectors- are they still 19lb? I have injectors from my 3.8SC and from a 4.9L that I might be able to use if desired (haven't checked length, but connectors appeared to be the same)... Bigger injectors really won't help unless I Super or Turbo Charge it later, but will they Hurt anything now? Won't the Computer compensate, or would I have to get a tune (and then re-tune)?

Click to expand...

The stock injectors should be 19lb ones. The stock PCM/ECM won't "compensate" for larger injectors, you should either use stock injectors with the stock ECM or get a custom tune if using higher flowing injectors.

I bought an M128 Melling oil pump & have already installed the pickup & primed the pump for install... Then I learned that there was a HV pump (M328) that would probably be preferred. They do not share the same internals (different gear size, etc)- so I can't just swap the pressure spring... Anyone use the M128 with success (anyone have trouble)? Anyone want to buy my 128 so I can buy a 328?

Click to expand...

A high-volume oil pump isn't "preferred" in a street application, except maybe for high-performance engines with lots of internal modifications, and that usually see high-RPM use.

The 4.0L V6 is a low-RPM engine that is designed for TORQUE at 2000-3000 RPM. You'd have to do a lot of work and replace a lot of parts and do a LOT of tuning to get it anywhere near being a "performance" motor that would begin to need a higher volume oil pump, and even then there are usually modifications and considerations required for that.

Could I make the 90 T-bird SC TB work on my engine? If not- what is the cheapest way to improve intake airflow? 5.0L TB? Blade/shaft mod on stock TB?

Click to expand...

You can make just about any similar throttle body fit on the engine, but it will do more harm than good. The best and cheapest way to improve airflow is to mod the butterfly valve shaft on the stock throttle body. More expensive way is to buy the BBK throttle body.

Still searching for a good deal on a 410 cam & pushrods... Anyone want to make me a deal?

Click to expand...

Post in the "parts and vehicles wanted" forum.

Thanks for your input! The thinking on the rockers was that if the large hole in the back were plugged- oil would be forced down into the pushrod pocket. My rockers appear to have a small hole for that purpose, but the oil would take the path of least resistance (the big back hole)...
Do your rockers not have that hole?

The hole in the back of the rockers is most likely to allow more surface area for cooling of the large solid area on that end of the rocker, as well as a path for oil to go down into the pushrod pocket from above.

Tapping into it and installing a set screw would not only defeat the original design, but would also pose risks of weakening the area, and an even greater risk of catastrophic engine damage if something removable like a set screw ever came loose and was being pushed around the valvetrain area.

The small hole in the pushrod pocket serves to allow some oil through, while retaining some oil, so the pushrod and rocker arm contact surface is always lubricated. The best way to ensure proper lubrication of these critical areas is usually to use the proper viscosity (5W-30) of motor oil, as thicker oil won't always get to these critical areas as quickly and easily.

I'm not sure if all the original 91-94 rockers had the rear hole like the newer rockers do, but all 4.0L OHV rockers fit, and when Ford revised the rocker arms in the late 90's, they were spec'd for all 4.0L OHV motors from 91-onward, so any 4.0L OHV with new Ford rockers will have the same rockers that were used in the late 90's Explorers.