OK thought I had a thread on this but can't find it, pulling engine tomorrow ( I hope) throwing in 4.6 crank and rods( plus everything else bottom end)

I am undecided if I should use the 4.6 pistons or 4.0 pistons ,

Thoughts?

 

That combo will make a 4.2 with a higher compression and higher revving motor. At least that what the old school machinist told me.

I have not done it myself, but a local guy did it with a crower entry level cam and loves the motor. Says it has way more instant power on tap.

I don't know what the compression ends up being though.

 

I know navy ordnance did this said it runs awesome, iirc other users did also

How is it only a 4.2? You are building a 4.6 bottom end with flat top pistons iirc this makes like around 11:1 compression?

 

I assume it's the piston profile, the are not exactly flat, at least in the 4.6.

I'll ask next time I'm there.

 

4.6 crank and rods = 4.6
Piston is just changing compression
4.0 piston is higher ratio but still 4.6 or you can get high comp 4.6 Pistons

Here is a chart
Buick 215 Rover 3.5 Land Rover 4.0 and 4.6 differences

 

Engine is almost out, broke some things but the dam starter bolts seem stripped heads, and can't get to 4 top bell housing bolts ugh

So far broke an exhaust bolt, oil cooler in radiator and a knock sensor

 

IF I was rebuilding from scratch Ford modular 4.6 V8 has in many cases the same or within tolerance dimensions on pistons, pins, and rods (length and centers too). Manley, Silv O Lite and Fedral Mogul have several different cc and weight slugs and much lighter "I" beam rods. Slugs are @ $800 a set, worth it to reduce rotational weight.

Nice link dusty, bookmarked that baby cuz I was fetching from several different sites.

Tom, are you going to flip a new cam in?

 

Good to know!

 

Tom, remove the engine mounts and lower motor to get to the top bolts.

 

We got top bolts with doubled wrenches, next 2 down used universal socket with swivel behind it and long extension from below, once loose I got em all out by hand

Scouts no cam swap , need this done and back running by end of week latest , cutting it close for return to work