Rebuild 4.2 or should I bolt in a 4.6

[RoverLen]

I was looking to have my 95 Classic 4.2 engine rebuilt but the mechanic was telling me that he felt that if i bought a short block 4.6 and had my head and valves redone that I would get more bang for my buck.

Mind you I am looking to get more power out of this truck as well so I was looking for upgrades and this is why we talked about upgrading to the 4.6.

What do you guys think about this and let me know if this would be a good option. If anyone has had this done please ring in.


Thanks,

Len

 

[Velocewest]

There's not a huge diff in power/torque between the 4.2 and 4.6, but in a RRC every little bit helps. AB has distributor ignition 4.6 shortblocks for about $4500.

 

[Ron]

Bolt in a used 4.6 short block.

 

[Cambo]

Not sure if this comparing apples to apples, but pretty close. My 4.2 in my 95 RRC works greats and actually has a lot of pep, even with oversized tires and no mods to the engine. The wifes 1998 P38 with the 4.6, only 6k miles on it, seems like a dog. They both weigh close to the same. There probably aren't a whole lot more smog items that restrict power from 95 - 98. So, I am guessing there wouldn't be much more power. Anyone else have similar experiences??

 

[Blueboy]

Bolt in a used 4.6 short block

yep - totally agree and did in my '93LWB when the 4.2 acted up.

actually there is a pretty big difference between the 2 engines power wise.

4.2 - 200hp, 251 ft-lb; 4.6 - 275hp, 305 ft-lb (at least my 4.6 which was a modified RPI engine)


Jaime

 

[ptschram]

Do you really need a complete rebuild on the 4.2? If it has good oil pressure, consider a new cam, rocker shaft assemblies, and injectors.

Might get you everything you want at a fraction of the cost.

 

[agbuckle98]

yep - totally agree and did in my '93LWB when the 4.2 acted up.

actually there is a pretty big difference between the 2 engines power wise.

4.2 - 200hp, 251 ft-lb; 4.6 - 275hp, 305 ft-lb (at least my 4.6 which was a modified RPI engine)


Jaime

Yeah, ok, but in a NOT RPI MODIFIED 4.6, you only get 222 horses in GEMS trim, who knows what it really puts out with 14CUX. The real upgrade with the 4.6 would be the bigger and cross bolted main bearings.

 

[rover4x4]

I dont know why people get so excited about the cross bolted mains. Makes sense for a high reving high power engine. I think the 4.2 was better on paper. Naturally having said this Ill sping a main bearing on the way to church this morning.

 

[agbuckle98]

I dont know why people get so excited about the cross bolted mains. Makes sense for a high reving high power engine. I think the 4.2 was better on paper. Naturally having said this Ill sping a main bearing on the way to church this morning.

I wouldn't say that I'm all that excited about cross bolted mains on the 4.6, but in the end, it IS still an upgrade from the 4.2. There's no denying that it is a stronger design, and regardless if the engine needs this added strength, stronger is better.

 

[ptschram]

If one needs that much strength, they should also consider a girdle to further add to the rigidity of the lower end.

I think it's much ado about nothing. Even when I was using dual carburetors on small block Chevys and tearing teeth ring gears and destroying transmissions, I never needed the four bolt mains, much less a girdle.

Given the usage we have for these engines, I don't think the lack of cross bolting will ever be the reason for an engine failure.

 

[MUSKYMAN]

cross bolting on a 9.3-1 compression normally asspirated motor is overkill.

 

[agbuckle98]

cross bolting on a 9.3-1 compression normally asspirated motor is overkill.

so what? so is 1/4" plate used to build Rovertym front bumpers but everybody seems to love that. I have one, I like it too.

 

[wooderson]

Bolt in a used 4.6 short block.

fella is right. buy a used 4.6

 

[rover4x4]

so what? so is 1/4" plate used to build Rovertym front bumpers but everybody seems to love that. I have one, I like it too.

yeah if I was going to be pulling out a 5000 pound truck I would want something with a little ass. Cross bolted mains are good but really there are more important things to be worried about on a Rover V8.

 

[Timmy!!!!!!!]

I think the 4.2 was better on paper. Naturally having said this Ill sping a main bearing on the way to church this morning.

God is angry at you for owning two rovers thus saith the Lord. That is what I learned in seminary yesterday.