Hello everyone,
I am currently rebuilding a Rover V8 3.5 litre engine and I would appreciate advice from people with experience rebuilding and developing these engines.
The engine is fitted in a 1986 Land Rover 90.
The intended use is:
- normal road driving
- occasional off-road / trail use
- occasional longer journeys, but not regular long-distance touring
I am not looking for a high RPM performance engine.
The priority is strong low and mid-range torque, reliability, smooth running and good drivability.
Engine details:
- Rover V8 3.5 litre
- Block number: 21G00369
- Original compression ratio: 8.13:1
- Originally fitted with carburettors
- Later converted to Lucas Flapper EFI
- Engine is now completely stripped for a full rebuild
The engine will be rebuilt from the bare block, so I would like to make the correct decisions before purchasing parts.
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CURRENT BUILD PLAN:
## Block and bottom end:
- Complete block cleaning
- New core plugs
- Oil gallery cleaning
- Inspection for cracks and corrosion
- Cylinder measurements before final decision
- New pistons (considering 9.75:1 compression ratio)
- New piston rings
- New main bearings
- New big end bearings
- Crankshaft inspection
- Connecting rod inspection
- Full rotating assembly balancing
The cylinders have already had an initial taper and ovality check.
The final decision between standard bore and rebore will be made after professional measurements.
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## Camshaft and valvetrain:
Planned:
- Kent H200 hydraulic camshaft
- New hydraulic lifters
- New timing chain and gears
The priority is:
- low and mid-range torque
- smooth idle
- good throttle response
- reliability
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## Oil system:
The engine uses the early/pre-serpentine Rover V8 front cover oil pump.
Planned:
- Front cover inspection
- Oil pump inspection
- New oil pump gears if required
- Pressure relief valve inspection
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## Cylinder heads:
The cylinder heads will be fully checked:
- Valve seats
- Valve guides
- Valve seals
- Springs
- Surface condition
- Resurfacing if required
The objective is torque and reliability rather than maximum horsepower.
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## QUESTIONS:
### 1) Compression ratio
For a Land Rover 90 application, where low speed torque, reliability and temperature control are important, would you recommend:
- 9.75:1 compression ratio
or
- a lower compression ratio such as 9.35:1?
The engine will run on pump fuel.
Is 9.75:1 a good match with the Kent H200 camshaft?
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### 2) Pistons and machining
If the original cylinders are within acceptable limits:
Would you keep standard bore and fit STD pistons?
At what point would you recommend a rebore?
Would you recommend any particular piston manufacturer for this type of build?
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### 3) Camshaft choice
Is the Kent H200 a good choice for:
- Rover V8 3.5 litre
- 9.75:1 compression ratio
- Lucas Flapper EFI
- Land Rover road/off-road use?
Would another camshaft profile be better suited for a torque-focused build?
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### 4) Balancing
Would you recommend balancing the complete rotating assembly:
- crankshaft
- pistons
- connecting rods
- flywheel
- harmonic damper
for this type of engine?
Is this worthwhile for a reliable road/off-road engine?
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### 5) Fasteners
Would you replace:
- connecting rod bolts?
- main bearing bolts?
Are ARP fasteners worthwhile for this specification, or unnecessary?
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### 6) Oil pump
For the early/pre-serpentine Rover V8 front cover oil pump:
Are new oil pump gears normally sufficient?
Would you replace the complete front cover if measurable wear is found?
Are there any specific checks that should always be carried out?
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### 7) Lucas Flapper EFI
The engine currently uses Lucas Flapper EFI.
Would you:
- keep the Flapper system with this specification?
- upgrade to Hotwire 14CUX?
- consider another EFI solution?
Reliability and drivability are more important than maximum power.
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### 8) Exhaust system
I also have a Range Rover 3.9 exhaust system:
- HRC1583 exhaust manifolds
- HRC1584 exhaust manifolds
- Y pipe with lambda sensor bosses
- NTC1484 centre silencer
Would this be a worthwhile improvement on a 3.5 litre engine?
Would it improve torque and drivability, or would the original system be better suited?
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## FINAL OBJECTIVE:
The aim is to build a strong and reliable Rover V8 3.5 litre engine for a Land Rover 90, suitable for road use and occasional off-road driving.
The final specification currently considered:
- Rover V8 3.5 litre
- 9.75:1 compression pistons
- Kent H200 camshaft
- New hydraulic lifters
- New timing set
- Balanced rotating assembly
- Refurbished cylinder heads
- Lucas Flapper EFI initially
- Range Rover 3.9 exhaust system
I would appreciate advice from anyone who has built or used similar Rover V8 engines.
Any recommendations, experience feedback or things to avoid would be greatly appreciated.
Thank you.
Lots of questions, I'll try a few answers and hopefully there will be others.
Either CR should work but will depend on the dynamic compression ratio of the cam, maybe go for something in the 7 to 7.5 range but I'm not the expert on this so do a little research first.
Roller cams are available for this engine if you can spend the money. Lets you use modern oils. Art has cores which can be ground to about any profile.
Do a search on oiling mods. The most important ones are tight end clearances on the pump and tight bearing clearances. By tight I mean in the region of .001" and never more than .0015" Your front cover is not likely to be worn to the point of needing replacement. You can add a steel booster plate to the cover if you like for a new wear surface, it can be ported for better flow. Use sealant and copper washers with the bolts. Should be no need to replace rod or main bolts. Use anti-seize liberally on external fasteners. Should only need balanced if new pistons are a significantly different weight from the old ones. There is often no need to replace oil pump gears.
What was your cylinder taper? If less than .007" you can keep the old pistons and fit new rings provided the ring lands aren't worn.
The hotwire would be a nice upgrade and doesn't need much in the way of tuning or so I've heard. If not that, a 4bbl intake and TBFI system is popular.
Jim
"The priority is strong low and mid-range torque"
Why are you spending time & money on a 3.5L? Unless this is the original engine that you want to stay with, I would using a 4.6L.
Calculator below will give static & dynamic compression ratios
https://www.uempistons.com/p-27-compression-ratio-calculator
Less data required, but you need to already have the actual static compression ratio
https://www.uempistons.com/p-28-effective-compression-ratio-calculator
More engine calculators
https://www.uempistons.com/rt-4-calculators