Advice for 3.5 rebuild

**Mister_white_keys** · 23rd May 2019, 07:14 PM

Greetings all,

I'm in the process of planning a bit of a freshen up on the 3.5 motor from my '75 2 door. The car is currently running a P76 4.4 that I picked up and bolted in but it is quite a tired 4.4 and I figure if I've gotta rebuild a motor then the parts availability for the 3.5 is a big advantage over the P76 motor. I've also been building up the parts required to convert the motor from carb to EFI using a 3.9 injection manifold and a Megasquirt MS3X ECU. This will allow me to run full sequential spark and fuel injection using LS1 coil packs.

So my initial questions are as follows;

1. Am I right in assuming I'm better off rebuilding the 3.5 rather than the 4.4? I know the 4.4 is a torquey motor but I've also heard they have weak cranks and the crank bearings are NLA. I plan on a high torque cam and raising the compression in the 3.5 to compensate for the smaller capacity.

2. Is there any difference in gudgeon height or conrods between pistons from different motors? I've been looking at using either the 9.35:1 Rover or 9.75:1 SD1 Vitesse pistons on the existing conrods, does anyone know whether this would present a problem?

3. Does anybody have any experience with the Camshaft sold by British Auto Parts (Land Rover Parts - CAMSHAFT KIT - 3.5 V8 (CAR

(8.25:1, 8.13:1 c/r)(pre-detox))? Is this a new standard cam or an upgraded unit? Any other information on a good Cam would be appreciated.

The car is a weekend camping/moderate 4wd'ing vehicle. I want a nice smooth motor with some good pull but still want to be able to run on 91 octane and don't want to break driveshafts every press of the throttle.

Any other information I should be taking into account that anyone can think of? I'm not new to the world of building Engines but have played with Mini A-series engines a lot more than the Rover units.

Thanks in advance!
Cheers,
Steve

**DoubleChevron** · 23rd May 2019, 07:56 PM

all that work for crap fuel economy and bugger all power. I have found you a motor you can just bolt in

WK Holden Statesman LS1 5.7ltr Chev V8 engine motor VT VX VY WH | eBay

**101RRS** · 23rd May 2019, 08:21 PM

Likewise I would think long and hard about Megasquirt - not a lot of support and the MS nerds are not tolerant of newbies. It is not as simple as the MS Nerds would have you believe - the 1000 pages of poorly written information scattered all over the place is no help.

Garry

**Mister_white_keys** · 23rd May 2019, 08:47 PM

Shane, I'll go down the LS route just as soon as you put coil springs in all your Citroens

As for the Megasquirt, I've already got the ECU and have done quite a bit of research and look forward to the challenge of getting it up and running.

Looking for more advice in terms of the engine internals rather than just a "don't do it". If we all followed that advice we'd be driving Camry's!

**101RRS** · 23rd May 2019, 09:05 PM

While I dont agree with the point on the LS engine I do agree about not doing the 3.5 - a lot of money to spend on an engine that even in top condition will just be an also ran.

**DoubleChevron** · 24th May 2019, 08:59 AM

There's a 460 sitting in the back corner of my shed ......Everytime I see it sitting there my brain says " Go on .... Do it"

It is probably the only petrol motor made that would return worse fuel economy than the motor in there though

seeya
Shane L.

**350RRC** · 24th May 2019, 12:06 PM

Originally Posted by DoubleChevron

There's a 460 sitting in the back corner of my shed ......Everytime I see it sitting there my brain says " Go on .... Do it"

It is probably the only petrol motor made that would return worse fuel economy than the motor in there though

seeya
Shane L.

Would that bolt up to the front of a C9?

DL

**DoubleChevron** · 24th May 2019, 03:28 PM

Originally Posted by 350RRC

Would that bolt up to the front of a C9?

DL

I'm sure it would ... its from a F250 twin cab. Would it bolt up to an R380 gearbox though

Its not what I'd call a lightweight though!

**PhilipA** · 24th May 2019, 04:10 PM

IMHO the 4.4 may be a better bet.
There is a lot of info in the Leyland P76 car clubs. I am sure a member would love to help you and maybe talk to you for hours. One of my mates just restored a Marina 6 cylinder coupe so anything is possible ( if hardly desirable, but fun)
Some things I remember from years ago are that Holden 253 pistons fit. I seem to remember a work around with the bearings.
I have not heard of cranks in moderately revved engines.
A lot of blocks are porous by now but if yours doesn't use water it maybe OK. The valves are small but you can fit rover heads or have them ported and bigger valves fitted..
Regards Philip A

**Meccles** · 24th May 2019, 06:19 PM

If I had one and it was already in place - I’d also look Long and hard at the 4.4.

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