Help!!! Do I need to break in new heads

[CarMichael Angelo]

I don't think that he's done anything so radical that the combination is a complete mismatch. From my take, OP is complaining on lack of bottom end throttle responsiveness (friction) until 3000 RPM, when everything gets good. The fact that the intake and heads are rpm range rated from 1500-5500 RPM, he should not be experiencing any loss of bottom end. I think something is wrong other than combination.

 

[CarMichael Angelo]

You're not feeling a whole lot of action below 3000 RPM because your cam and meter are having difficulty filling those heads with air. Your exhaust scavenging probably leaves something to be desired as well.

What heads and more importantly, what size are the heads? What size are the combustion chambers?

*Sigh* Am I the only guy that just doesn't read the last post before responding?

I just installed new Edlebrock performer heads.

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Edelbrock #350-60379​

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Ford 5.0L/5.8L Performer Aluminum Cylinder Head​

• 170cc Intake Ports

• 60cc Combustion Chambers

• 1.900'' Int/1.600'' Exh Valves

• 1.460'' Valve Springs, .575'' Max Lift

• Assembled, Sold Individually

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$599.99​

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[Noobz347]

From what I've heard, cars are dogs if you add H/C/I without converting to MAF.

Not necessarily true. Speed density runs like a raped ape with a cam designed for it (or tuned SD).

i say you need a bigger cam

^This^ Some lift/duration to make use of those heads should wake it right up. Each and everytime you improve something on your motor, you're shifting the bottle neck to something else.

Get with Rick 91GT He's one of the guys that comes to mind, who can help you get that combo tied together.

 

[Rick 91GT]

I agree with Mike, while the stock cam is not IDEAL he shouldn't really have a major loss in bottom end BUT the RPM II intake is too large for that combo. IMO, It needs a cam to properly take advantage of what the heads and intake can offer, if you need help with that I can help. I would swap the MAF as well....

Does it rev clean and smooth up to redline? Im thinkng valve adjustment might be a little tight....only a guess over the keyboard What rear gear is in the car? AOD or 5spd? What is the timing set to? What is the Fuel Pressure?

Since I own a shop I have to ask.... Have you talked with your mechanic that installed all the parts yet? If not, he needs to know and might be able to give you more insight since he installed the parts and actually had his hands on the car.

 

[Codydubb]

Agreed...i say cam and bigger MAF. Your running 24# injectors right?

 

[NIKwoaC]

I agree with Mike, while the stock cam is not IDEAL he shouldn't really have a major loss in bottom end BUT the RPM II intake is too large for that combo. IMO, It needs a cam to properly take advantage of what the heads and intake can offer, if you need help with that I can help. I would swap the MAF as well....

Does it rev clean and smooth up to redline? Im thinkng valve adjustment might be a little tight....only a guess over the keyboard What rear gear is in the car? AOD or 5spd? What is the timing set to? What is the Fuel Pressure?

Since I own a shop I have to ask.... Have you talked with your mechanic that installed all the parts yet? If not, he needs to know and might be able to give you more insight since he installed the parts and actually had his hands on the car.

What do you mean by that, Rick?

 

[Rick 91GT]

What do you mean by that, Rick?

If it is slow to rev through the entire rpm range that is a good indication that the valves are lashed too tight

 

[Boydster]

If it is slow to rev through the entire rpm range that is a good indication that the valves are lashed too tight

I have nowhere near the engine experience that you do, but I was thinking the same thing.

 

[NIKwoaC]

If it is slow to rev through the entire rpm range that is a good indication that the valves are lashed too tight

Gotcha, I assumed that was what you were getting at, but I wanted to be sure.

On that note Rick 91GT, if I was to pop the valve covers off to play around with the rockers, how long would you expect the lifters to take to fully expand before I'm safe to set lash/preload again?

 

[Rick 91GT]

You would need to prime the motor a few minutes, making sure you rotate the motor in 90 degree increments to get oil everywhere.

I go 1/4-1/2 turn...at 1/4 they can be a little noisey under a alum valve cover but it will make powwe, especially if you have the oil pressure to get the lifters pumped

 

[NIKwoaC]

You would need to prime the motor a few minutes, making sure you rotate the motor in 90 degree increments to get oil everywhere.

I go 1/4-1/2 turn...at 1/4 they can be a little noisey under a alum valve cover but it will make powwe, especially if you have the oil pressure to get the lifters pumped

Does the lower preload just help you get tighter valve seal during compression?