Hey guys, I have a 1989 Ford 5.8 351 Small Block Windsor in an F-150. I plan on having the motor rebuilt, but slightly modified. It's pretty simple:

- Factory Heads; Decked Between 0.008-0.012 Thousands Of An Inch (Maybe More If Possible)

- Higher Compression Flat Top Pistons (Not Sure What Brand Yet)

- Comp Cams High Energy Valvetrain; Factory Replacement Comp Camp Non-Roller Rockers; Comp Camshaft Part #: 35-255-5

- Edelbrock Performer Truck Intake Manifold System

- Airaid Throttle Body Spacer; Airaid Factory Air Filter; Factory Air Intake System

- BBK 61 MM Throttle Body

- JBA Shorty Headers; Straight Dual Side Exhaust Pipes; O2 Sensor

- No EGR Delete

- Smog Pump Deletion; Factory EEC (Computer)

My question is will I need bigger fuel injectors for this camshaft swap with mods? I know Ford Motorcraft has factory replacement injectors with 20 lbs./hr, but I was looking into some Trick Flow Specialties TFX 24 lbs./hr injectors. Another question is will I need a tune for the Trick Flow injectors?

 

Also, another thought guys. If the 24 lbs./hr injectors will not work with my factory computer, what about the Ford Racing/Bosch 4-Hole 19lbs./hr fuel injectors. I know my factory lbs./hr is 19.

 

OK I'm gonna save you a whole bunch of money, with stock heads on the motor you don't need the Edelbrock intake, the Airaid throttle body spacer; the BBK 61 MM throttle body, or larger injectors.

And even if your had better heads your stock EFI system has no way to adapt to larger injectors, you would need a MAF conversion and a tuner.

 

I wouldn't feel, or see any horsepower gains if I put the aftermarket intake mods on? What about the cam and pistons? I wouldn't need bigger injectors for those?

 

Is it even worth changing the pistons out?

 

The aftermarket heads and throttle body, are more suited for an engine that's capable of stronger mid to upper rpm power but not capable of increasing power in a significant way, on a stock headed engine.

The cam you've chosen is mild, stock injectors are fine.

Increasing the compression ratio, also increases engine efficiency, which in turn increases power, even economy.

Make sure you know what the final comp ratio, actually is, too much compression ratio, combined with a torque or smaller cam, don't play well together, and a different camshaft may be more ideal. Be sure to talk about this with your cam provider.

Its possible to tune your speed density but with the cam you chose and a minor compression increase, not required.

 

Well I believe I'm just going to shave the heads to what they need to be shaved in order to be flat. I'm looking into two types of pistons, though, the Sealed Power cast aluminum flat top pistons with four valve reliefs, or the Wiseco forged aluminum flat top pistons with two valve reliefs. Another question is, do I have to have 4 valve reliefs, or can I have a piston with only 2. I'm just curious to know, because I know the factory piston is a dish piston with 2 valve reliefs diagonal from each other and not side by side like on the Wiseco. Between the two pistons, will it benefit from only having two valve reliefs instead of four, or will I never tell a difference? Also, the cylinders more in likely will be bored 0.030 over. So with the decked 61-65 CC factory heads, one of the type of pistons named above and the block bored 0.030 over, would this give me a decent compression ratio for the camshaft I have chosen. I chose that camshaft, because it is the only one I could find that would work with a factory motor with a little bit of valvetrain upgrade, of course.

Another thought, what if I had my heads ported and polished?

 

Don't know if this matters, but the motor is in a 1989 Ford F-150 XLT Lariat Longbed Pick-Up 4X4 rolling on 33's and a 3 Inch Body Lift. Along with having the factory differential gearing which is only like 3.08. I do plan on switching them out, but I don't know if I should go with like a 4.10, or 4.56.

 

Another thing, throttle body spacers are a gigantic waste of money on port-fuel injected engines. They don't do a single thing, but people seem to love 'em.

 

Yeah I was debating on that idea too @leadhead. I didn't know if that $150 piece of metal was worth it, or not.

 

The stock motor has a CR of 9:1 and you don't want to go too much past 9.5:1 on pump gas or detonation will start to be a real problem. There is nothing wrong with using pistons with 2 valve reliefs or 4, the one with 4 will act as a bit of a dish lowering compression a bit which may help keep it within an acceptable range. Forged pistons do require you ensure the motor is warmed up correctly and the added expense isn't required if you don't plan on adding forced induction later on.

 

Thanks Conanski! So I will go with the Sealed Power Flat-Top pistons. So should I port and polish my heads and factory intake, or will that be a waste of money?

And should I decked the block to zero just in case for detonation?

 

Polishing is a waste of time on a street motor IMO, but you can port out the exhaust side of the heads as much as you dare and open up the exists in the lower intake to match the heads, these things will show real gains.

 

Should I decked my block to zero? Oh and since I am going aftermarket pistons will I have to have my rotating assembly rebalanced?

 

Agreed....polishing ports is a marketing gimmick. "I'll charge you an extra 10 hours to polish your heads" . It is quite possible to lose power on some head designs by polishing the intake and reducing atomization.

Polishing combustion chambers, without removing any material, is good though.

If you can afford it, ditch the stock heads altogether....if you want to mill for compression, keep in mind if you take a lot off (there is a lot to take off) make sure you align your intake and get it milled if necessary.