hey all!
just bought a bare 460 block off a friend the other day and was thinking about building it and throwing it into my 97 f250 HD crew cab short bed 4x4. but the only thing is im not for sure how far to go. she is not a daily and mainly used to tow a goose neck trailer with whatever stuff or vehicle I'm hauling. i have a goal of 500-600ft TQ. So i was thinking maybe .30 or .40 over rebuild with a decent camshaft, edelbrock intake, hydraulic roller cams, efi 460 guys throttle body, adj roller rockers, and maybe port the cylinder heads. is that a bit over kill? this is just a ideas so any input is welcomed.

 

I'm building a 351W and going the stroker route. You said a bare block, you mean no crank at all? If that was the case, I would think about a stroker. It might be outside your budget, but you will not know until you look.

Look at your fuel system to see if you can tune it to the combination you are thinking about. If you can't I would find something that could before you get too carried away.

Same with the transmission. Making more power has to go through the transmission and if that is the weak link, you will be on the side of the road for that problem.

On my build, I built the transmission with all the heavy duty diesel stuff I could [extra clutches, 6 planet gear sets, etc]. I will be going all out with the engine, heads, cams, rockers, etc. Since I too am building a tow engine, I am not looking for a high RPM power plant. Not certain there are aftermarket heads for the 460, if there are, I bet they are way better than the factory heads. Probably lighter too.

 

Have the bores checked and the block magnafluxed. See what the deck height is. What are the casting numbers on the block?

 

Yup, I was going to send it to the local machine shop and have them check it out. Haven't had any time to check the block out. But my friend said it came out of an old thunderbird I think.

 

All production 460 blocks are interchangeable, none are superior and all are basically equivalent when it comes to strength, overbore capacity etc.

 

check out the prices of a stroker rotating assembly, then you can use a mild cam to work with the computer,which will need tuning

 

i thought about a stroker at first but i thought that would be way too much for what im doing with the truck. that would mean i would have to run aluminum heads right? just to get it run off 83 octane?

 

On a big Ford stroker it can be challenging to get the compression ratio to be really low but aluminum heads are not necessarily needed.

 

alum heads dissipate heat too well ,allowing for almost another point in compression to be added .

 

I just rebuilt my '95 F250's 7.5L (460) EFI engine, but it got to be too late in the year (snow on the ground here now) to get it installed, not a problem for me as this truck isn't winter driven anyway...

For this rebuild, I bumped the compression up from the stock 8.5:1 to 9.5 for increased torque. Lots of engines run that CR on pump gas with no issues. I am also doing a Sequential Mass-Air conversion for more accurate control of the engine operation (fuel injection, ignition timing, etc) using CA emissions factory mass-air parts, (SEFI can manage individual cylinders instead of batch-fire used on Federal emissions trucks.) An added bonus with going SEFI is 10-15% better fuel economy! That would take me from the stock 11.5mpg to around 13mpg. Not earth shattering improvement, but still... Also installed a mild computer-friendly aftermarket cam (Comp 34-255-5) with .490/.495 lift, 256/268adv, 212/219 @ .050. and a set of stainless mid-length headers. These changes should take the engine's output from the stock 245hp to well over 300, and a healthy increase in torque as well from the stock 400 lb/ft - I'm guessing somewhere near 480-500 lb/ft.

 

I'd be astonished if your economy was anywhere close to 13 with that camshaft. Even with 9.5:1 compression I think that your EGT will be excessive because it has too much duration and the lobe sep is too wide to be optimum.

 

That Comp cam is actually recommended for use with either speed density or mass-air applications. The total advertised duration is actually close to the same as the factory camshaft, but the .050 duration is quite a bit more - because it has much faster ramps. The LSA is still a computer-friendly 114. Multiple sources indicate Ford 7.5L EFI stock camshaft specs as .438/.459" lift, 273/287 adv dur, 193/206 @ .050 LSA 110 int/116exh Note the very lazy, long ramp between zero and .050 lift!

The Comp Cams Xtreme Energy series are known to have extremely fast ramps that aggressively open/close the valves. That 'area under the curve' where the valve is open/airflow is much greater with 'fast' camshaft ramps. Airflow=power! The combination of higher lift and relatively short overall duration promotes intake air charge velocity which is good for increased torque.

A stronger-than-stock dual valvespring is needed to ensure lifter/camshaft contact at all times - otherwise, one may experience an excessive noisy valvetrain and wear on camshaft lobes/lifters. My engine machine shop also performed some oiling mods to increase lubrication of the cam lobes - not just because of my specific camshaft choice, but he suggests those mods for any new engine build utilizing a flat-tappet cam due to today's low-Zinc oils.


EGT too high? That can be controlled by air/fuel mixture, and also better exhaust flow. The mass-air EFI system does a much better job of controlling A/F ratio than batch-fire Speed Density systems. Also note that I'll be using headers instead of cast-iron manifolds.

 

That cam is not going to get you the fuel economy or performance that you're expecting especially in an engine with moderately low compression. It has too much duration and the lobe sep is too wide. What does this do? Due to the amount of duration and the early exhaust centerline due to the wider than optimum lobe separation , you'll be opening the exhaust valve far too early to be optimum. This will reduce low speed torque and it will greatly increase the exhaust gas temperatures. This can't be controlled by the mixture to any great degree. With the mixture tuned correctly expect it to be 1450 degrees or so. This will make the header glow all the way to the collector on a pretty short pull. The reason for this is simply because as the compression is lowered the burn rate isn't as fast. There's more burn that takes place later in the power stroke which could be used to push down on the piston but instead is being blown out the exhaust port.

On the other side of the exhaust is when the intake valve starts to open while the exhaust is closing. This is the overlap period. With the lobe sep spread out 4 degrees this period is shortened by 8 degrees vs if the cam was ground on 110. This is good but the cam has more duration than it needs by about 20 degrees on the exhaust side so right there it has gained overlap which will tend to hurt manifold vacuum and mileage.

Continuing on through the intake cycle the intake opening cycle. This has started pretty early due to the extra duration and getting the intake valve open early is good for cylinder filling because it gives the valve a chance to get farther off of the seat as the piston demand increases. This happens at about 75 degrees after tdc and from then on the piston demand is falling max lift happens at about 110 degrees after tdc with the cam on a 114 sep if it is advanced 4 degrees. The end of the intake event is what really matters when it comes to what rpm the engine/cam combo is going to be optimum. The earlier this closing happens the longer the compression stroke and the higher the low speed cylinder pressures. Closing it later with excessive duration reduces low speed torque due to reversion simply because the gas speed is slow enough that the piston can push it out and right back into the intake manifold.

Cams that are intended to get good mileage manage the engine best at low speeds. This is best done by having short durations, a single pattern, tight lobe seps and not a ton of advance in the cam. Fast asymmetrical lobes are good for this. Your duration needs to be down at about 200-205 degrees at .050 and the lobe sep needs to be at about 108-110 and not wider. The 114 lobe sep is a crutch that's being used because the cam has too much duration.

The Extreme Energy lobes are a design that uses dwell at max velocity. This is done to give the profile more lift in a given duration yet still run on an .842 diameter lifter. The profile is essentially designed with no significant ramps and that's what makes them tend to be noisy.

Be extremely cautious with your spring loads seated but particularly open. Try to keep those under 100lbs and 250lbs open or your cam and lifter life will be very short.