Thread: 4.9 V8

This Rangie looks like it has had the same treatment.

Project Rangie

Originally Posted by Traco

This Rangie looks like it has had the same treatment.

Project Rangie

That one has been around a wile now. Good luck finding those heads he's using these days.

Originally Posted by whitakerb

Gday guys, back on the net after a short while, and just chasing some info.

Due to sticky/burnt out valves, i have the heads off this week and to my surprise i have nearly a 89mm stroke in my supposedly 3.9 V8, turns out it has a p76 crank in it and it 4933cc or therabouts.

Basicly, I'm just interested who else has this mod and if anyone has any info on what they change to do this i.e. machining the block ect, and more importantly what sort of pony power should it put out. The rest of the engine is sweet so hopefully she should run beautifully next week.

Cheers

I've never done this but have two mates that have They are limited by the Rover heads for big HP but produce some serious torque.
I would expect between 250 to 270 HP depending on head work etc.
Low and mid range torque will be impressive I'd think with all that port velocity happening with those wee little ports and valves that come with the Rover heads.

Originally Posted by whitakerb

Gday guys, back on the net after a short while, and just chasing some info.

Due to sticky/burnt out valves, i have the heads off this week and to my surprise i have nearly a 89mm stroke in my supposedly 3.9 V8, turns out it has a p76 crank in it and it 4933cc or therabouts.

Basicly, I'm just interested who else has this mod and if anyone has any info on what they change to do this i.e. machining the block ect, and more importantly what sort of pony power should it put out. The rest of the engine is sweet so hopefully she should run beautifully next week.

Cheers

Do you by any chance know what the piston pin heights and rod lengths are?

Originally Posted by Waxenwane

Do you by any chance know what the piston pin heights and rod lengths are?

Sorry i never stripped the engine that far. The pistons were more or less flush with the top of the block at tdc (explains 185psi comp test with bad valves) the pistons appear to be std 3.9 ones so perhaps you could work out the length of that info. ON the flip side however at bdc half of the piston hangs out the bottom of the liner

Thanks, I have a spare 3.9 and forged P76 crank so just toying with the idea at this point

Sorry to disappoint Wayne but all P76 cranks are cast iron.There were some flat plane steel cranks for Leyland F 5000, billet not forged.Factory Rover 3.9 pistons cannot be used in a Rover block in conjunction with a long stroke (3.5 inch ala P76 or after- market crank). The underside of the pistons seriously collide with the counterweights on the crank.You can use 3.9 pistons in a P76 block if you want to outlay some serious money to have a big bore conversion done properly,on top of sorting out the flywheel bolt pattern and the inlet manifold etc.

Originally Posted by series 3 and a half

Sorry to disappoint Wayne but all P76 cranks are cast iron.There were some flat plane steel cranks for Leyland F 5000, billet not forged.Factory Rover 3.9 pistons cannot be used in a Rover block in conjunction with a long stroke (3.5 inch ala P76 or after- market crank). The underside of the pistons seriously collide with the counterweights on the crank.You can use 3.9 pistons in a P76 block if you want to outlay some serious money to have a big bore conversion done properly,on top of sorting out the flywheel bolt pattern and the inlet manifold etc.

Sorry I should have said Terrier Crank, they are forged. I was thinking along the lines of slipper pistons or modifying the ones I have, short rods and slightly destroked crank. All of which cost's more money than I have. I am being greedy because I still haven't finished the current project.