Thread: Swapping out 4.2L V8 for a older 3.9 V8?

engine swap here look at this once, also have you considered looking at RPI engineering for new engines?

Quote: Originally Posted by GoGetTheHorzion So series tell me why you wouldnt just go with a 4.6? Its a 95 and im pretty sure the 4.6 would be more direct than the 3.9 would be I'm of the opinion that it would be cost prohibitive, but I'm not 100% sure of how much a 4.6 costs. From what I've read it looks like a $3,000+ proposition versus replacing my 4.2 with a 3.9 for $500.

Well as Paul has suggested, its not quite as simple as a 3.9. I presumed that Parkpy, already had a 3.9. To me its all about cost and availability. No real preference either way, i have driven 3.5 3.9 and 4.6 the 3.5 and 4.6 were both carb the 3.9 efi, I think they all do fine. i do love the torque available with a dual SU 4.6 ( I mean don't get me wrong) Mike

Quote: Originally Posted by parkpy I just want it to run, and run reliably. It's a rover. I would never have the expectation of it being reliable.

all rover v8 engines share the same bolt pattern 1969 classic up to the 2004 disco series 2....beyond that you have bmw and jaguar two different beasts all together even between them... the main differences between the 69 to 04 are displacement, electronics and h/p. than you get into pulleys lubrication etc.. but bolt pattern is the same....

Then it's definately not going to be reliable!!! Remember, snow is just frozen water, and Rovers are afraid of water!

Look, get a cheap 3.9 and stick it in the truck and be happy. A 4.6 will cost way more that the truck is worth and you will need to do a lot to get it to work in your truck. GEMS or Bosdh 4.6's didn't use distributors so you will need the front engine cover off either your 4.2 or a 3.9. You will also need a new cam to drive the distributor and new lifters. That's only the start. In this case, use the KISS principle and just get...

If you're able to get a complete 3.9, it's virtually a plug & play swap. The fans are different, and you may need to grab the fan shroud from the donor. Even if you want to swap over the serpentine setup to the 3.9, it's still very simple. 4.2L engines have a very underserved reputation. I personally believe very few cranks ever broke, but like all urban legends, the story got told so many times, it began to sound like...