3LT out 4.2 in

Submitted: Tuesday, Apr 08, 2008 at 20:26
ThreadID: 56444 Views:2224 Replies:9 FollowUps:5
This Thread has been Archived
a few thoughts needed please............my old 3lt rb30 is getting long in the tooth .and has some major.probs ......so for the miles i do am thinking of dropping a 4.2 petrol in ...q is will my old gearbox and such bolt straight ?????? any thoughts .on this one will b a help
Bundy
Back Expand Un-Read 0 Moderator

Reply By: Member - David P (VIC) - Tuesday, Apr 08, 2008 at 20:34

Tuesday, Apr 08, 2008 at 20:34
how many k did you get out of the RB30? what is failing?...silverback
AnswerID: 297436

Follow Up By: Member - BUNDY BOY (WA) - Tuesday, Apr 08, 2008 at 21:11

Tuesday, Apr 08, 2008 at 21:11
hay David.........with all the miles i do need a bit more power ....the rb30 is just old.......has a load of blow by....and pumps oil out of places unknown......on a long run under presure........not sore on kms as only had it for 3 years and counter wasnt working when i got it......im just spending heaps on trying to stop these leeks ...but keeps falling out ...lol ...so thought ill get a bit biger donk while im there
Bundy
0
FollowupID: 563453

Reply By: Member - Graham H (QLD) - Tuesday, Apr 08, 2008 at 21:39

Tuesday, Apr 08, 2008 at 21:39
Not sure if it will as I have read that the drive trains in the 3liters were lighter than the 4.2's hence the lower towing rating.
People to ask would be engine conversion mechanica I would think.
AnswerID: 297460

Reply By: Member - Davoe (Yalgoo) - Tuesday, Apr 08, 2008 at 21:40

Tuesday, Apr 08, 2008 at 21:40
pretty sure both the gearbox and diffs ar lighter duty fort he petrol 6 certainly the gearbox will be i think they are out of a 300zx.
Unquestionably the cheapest way to do an engine swap is buy the vehicle you need
AnswerID: 297461

Follow Up By: Leroy - Tuesday, Apr 08, 2008 at 21:54

Tuesday, Apr 08, 2008 at 21:54
Diff's aren't light duty but the ratio's will be too high unless running 35" tyres. So another cost to factor in.

Leroy
0
FollowupID: 563466

Follow Up By: Member - David P (VIC) - Tuesday, Apr 08, 2008 at 21:55

Tuesday, Apr 08, 2008 at 21:55
the wreckers must have some reasonable RB30s I would have thought, your plan sounds waaaay too difficult...silverback
0
FollowupID: 563467

Follow Up By: Member - joc45 (WA) - Tuesday, Apr 08, 2008 at 22:05

Tuesday, Apr 08, 2008 at 22:05
Yep, as I understand it, the RB30 had a gearbox out of the 300ZX and prob wouldn't take the torque of the 4.2. (transfer case was full-strength and diffs were quite a high ratio compared with 4.2's)
The 3 litre petrol engine has an excellent history of durability and long life, and you should be able to pick up one from a wrecker. The VL Commodore was basically the same engine, but with electronic injection rather than a carby. A bit of research should get you into a replacement 3L engine without too much cost. Comes down to how much you want to spend on an early 90's GQ.
Gerry
0
FollowupID: 563471

Reply By: Heefers - Tuesday, Apr 08, 2008 at 22:01

Tuesday, Apr 08, 2008 at 22:01
Why not try for a RB30ET, the turbo motor from the VL Commodore. Gives you the extra grunt you're after without the hassle of too much conversion work
AnswerID: 297468

Reply By: westozal - Tuesday, Apr 08, 2008 at 22:30

Tuesday, Apr 08, 2008 at 22:30
Hello,
From my own recollections the rb30 has a lighter gearbox than the 4.2 ltr.
I would respectfully suggest that it would be cheaper to sell the current GQ and invest in the purchase of a 4.2 ltr if thats what you want. Given its age I would consider that you would not get any money back that you spend on your current car by changing everything over.
I think the diff ratio's are lower too which means higher revs at cruising speeds.
Best of luck
Alan.
AnswerID: 297474

Reply By: Jim from Best Off Road - Tuesday, Apr 08, 2008 at 22:35

Tuesday, Apr 08, 2008 at 22:35
From a purely economic viewpoint, I reckon it would be throwing good money after bad.

If the thing is knackered dump it and update, it will be cheaper.

And I'm speaking as one who owned an RB30 GQ and loved it.

Jim.

AnswerID: 297475

Reply By: Member - Bucky (VIC) - Wednesday, Apr 09, 2008 at 08:10

Wednesday, Apr 09, 2008 at 08:10
The power/turque of the 4.2 motor may well rip that gearbox to bits.

I'm no expert, but think of the logistics

Basically a car gearbox, replaced by a genuine 4B motor,,( even though its petrol )

When you are asking it to give a bit more, one day, something will give,,

Then again it's your money $$$$$

Cheers
Bucky


AnswerID: 297518

Reply By: Camoco - Wednesday, Apr 09, 2008 at 11:48

Wednesday, Apr 09, 2008 at 11:48
As an owner of an RB30 GQ I have investigated this also.
My RB30 has 375,000 on it and still going strong.

The gearbox you have has an integral bell housing and not interchangeable with the 4.2.
From the transfer case back all is OK. I have a mate that had the same setup and he replaced the engine and 'box with a 350chev and 4.2 g'box. Nothing else major touched. Topped out a bit early but on went the bigger tyres and all has been fine. It had about 300,000klm added after the change of mostly rough tracks and dirt roads. It has now since terminated with the body succumbing to fatigue and the rear suspension also going south. (carrying too much load constantly)

I am still pondering on simply replacing the engine with a VL or going whole hog and slotting in a BF motor and auto. But at the moment things are sweet so I'll just wait a bit longer. The Chev is just too thirsty.

Cam
AnswerID: 297550

Reply By: Member - BUNDY BOY (WA) - Thursday, Apr 10, 2008 at 10:24

Thursday, Apr 10, 2008 at 10:24
Thanks everyone...for the input...i was just hoping to find a way to get some more out out of the old girl .as have spent way to much on her ..as we all do..but all running gear and most other things have been replaced within the past year ...so apart from the donk....its a good jigger...and with the hi miles need that little bit more top end power
Cheers Bundy
AnswerID: 297727

Follow Up By: ExplorOz Team - Kerry W (QLD) - Saturday, Apr 12, 2008 at 20:06

Saturday, Apr 12, 2008 at 20:06
Hi Bundy,
Brilliant engine;
Lots you can do with this motor, for much less cost than replacing donks or vehicles
Do a search on the forum or if you are really keen Member message me and I can give you some options for getting this motor working properly..
see post 34584 for a quick rundown of what to do

regards

Kerry W
Kerry W (Qld)
Security is mostly a superstition. It doesnt exist in nature. Life is either a daring adventure or nothing.
-Helen Keller

Lifetime Member
My Profile  My Blog  My Position  Send Message

0
FollowupID: 564247

Sponsored Links