RV4.6 scrap engine "rebuild"

tobbjo · Post by **tobbjo** » Wed Nov 04, 2009 7:18 pm

That's a really neat trick, Chris!
That should be doable!
50 psi is about 3,5 bar. 8-9 Bar, as I have out from the air compressor should be better?
Really need to get a lot of really hot water in the tank, though. Will have to think of a way to get it out of the wood chip burner...

I did strip down the timing cover and sump today. Removed the centre main bearing cap, as well. The bearing had slight marks in it, but no significant wear. The crank bearing area was as new.
There were only thrust washers in the block side, not on the bearing cap side. OK?

This is how much stretch there is in the timing chain. Too much?

Tobias

ChrisJC · Post by **ChrisJC** » Thu Nov 05, 2009 7:49 am

I kept the pressure down to 50psi as the cooling system only normally runs around 15psi. I didn't want to 'blow' it up........

That timing chain looks pretty normal to me!

Chris.

chodjinn · Post by **chodjinn** » Thu Nov 05, 2009 12:06 pm

I would replace the liners anyway. There isn't a 4.6 block that isn't at risk of slipped liners, even the new 'coscast' wallet-rapers suffer from the issue.

Is it really worth not getting it done to save money now, only to need new liners and a complete rebuild a few thousand miles down the road?

There is no way to be sure. Pressure test the block for sure, and even if it is ok, there's still a chance it would drop a liner or three.

tobbjo · Post by **tobbjo** » Thu Nov 05, 2009 12:14 pm

To answer my own question about allowed warpness of the heads it's maximum 0,05mm according to the 2002 MY Disco2 workshop manual.
Will need to resurface, then. This might be the reason for th eexchange, if I'm allowed to hope for a while. E.g. customer complains about blown head gasket. Workshop change without measuring/marginal warpness and hea gaskets blow again soon and engine is changed because two symptoms of head gaskets occur on same engine.

I have not talked about the intended usage of the engine. It is for a portal axled RRC which only is driven off road. It sees maximum one trip each month of a few hours, hence a large hesitance at spending too much effort on longevity.

I will do a DIY pressure test, but at max pressure my compressor giver 8-9 Bar and if it's OK i will build on.

How about camshaft selection? I will ned a camshaft for the camshaft driven oilpump and distributor. Can that be done with the original 4.6 cam?

Tobias

Eliot · Post by **Eliot** » Thu Nov 05, 2009 12:28 pm

tobbjo wrote:I have not talked about the intended usage of the engine. It is for a portal axled RRC which only is driven off road. It sees maximum one trip each month of a few hours, hence a large hesitance at spending too much effort on longevity.

My mate ran portals on a RR hybrid with a 350 chevy and described it as slow!
http://www.mez.co.uk/dcam/DSCF0554.JPG
Handling was terrible, brakes terrible and he had issues with the diff bearings - now removed and sold.

sidecar · Post by **sidecar** » Thu Nov 05, 2009 12:33 pm

Doing the pressure test is fine but be careful, if the pressure gets to high and the block blows it could do you some real damage! (The water round the block should help reduce the danger)

I run a 4.6 non top hat block in my cob replica, its knocking out about 285 BHP so its in a fair state of tune.

If you are running a carb then you can run them fairly cold, 75-80 degree and not too lean. Around 13.5:1 AFR is the leanest that you would want to go.

If you are running EFI you will either have to run the lump hotter or at least fool the EFI that its hotter to get round the mixture enrichment circuit.

I run a 74 degree stat.

tobbjo · Post by **tobbjo** » Thu Nov 05, 2009 4:09 pm

Sidecar: I'll do EFI with Megasquirt'n EDIS. So I'll be free to run whatever mixture I like.

Eliot:
Well, it's not built for speed. 38,5" tire diameter helps, but for what I do, speed is not lacking. It's water prrofness and the crisp acceleration response from my 3,9EFI RR i miss.
See latest trip at:

http://www.youtube.com/watch?v=7XoeXpxJ ... re=autofb/
at 1:52 I want to accelerate crisply but have to reverse farther than optimal to give the carbs time to react.
At 6:41 I loose a few cylinders due to ignition going through the pond, although at a silly speed. To impress the chicks

Tobia

Eliot · Post by **Eliot** » Thu Nov 05, 2009 8:04 pm

tobbjo wrote:At 6:41 I loose a few cylinders due to ignition going through the pond, although at a silly speed. To impress the chicks

Tobia

Edis will sort that...

Just need to drop a twin turbo 5.7 in there next then....

tobbjo · Post by **tobbjo** » Thu Aug 12, 2010 5:38 am

Well, I'm slow but finally got round to pressure testing the engine yesterday.
No pics

Dipped it in a tank with 65°C water. Pressure at about 9Bar / 125Psi
Leaks around my blanking plates and around one of the water jacket emptying plugs, which turned out to be only finger tight. No leaks whatsoever around the liners.

I decide to build it up from where it is now.

Still no decision on whether to keep the serp front cover or not. Do not want to run a serp belt, since I've built up a complete circuit for all ancillaries on the old engine using vee belt. I need to find serp pulleys for all of them and I'm not sure I can do that. Also I think a serp belt is less forgiving for slight misalagnment than vee belts.

One idea is to make a hybrid front cover. Lower serp and upper, with waterpump vee belt. I have a good friend who can do magic with the TIG. Doable?

Tobias

topcatcustom · Post by **topcatcustom** » Thu Aug 12, 2010 7:36 am

I did that and posted some pics on here (somewhere), it came out ok but never used it myself as found myself an interim cover and used 100% serp. Do a search on modifying front cover and you may come across it, though dont forget how many hundreds of thousands of RV8's have used the old style oil pump with no problems.

tobbjo · Post by **tobbjo** » Fri Aug 13, 2010 8:40 am

topcatproduction wrote:I did that and posted some pics on here (somewhere), it came out ok but never used it myself as found myself an interim cover and used 100% serp. Do a search on modifying front cover and you may come across it, though dont forget how many hundreds of thousands of RV8's have used the old style oil pump with no problems.

Any chance of you still having the cover and wanting to sell it?

My main concern is not the oil pump, but that I would need to change camshaft and so on if I change to old style cover.
I'm cheap!

T

TVRleigh · Post by **TVRleigh** » Fri Aug 13, 2010 9:02 am

SuperV8 wrote:There are way more cam option with the earlier cover. I'm using the latest GEMS timing cover and could only find 2 performance cams to choose from!

Speak to JE he will make you any cam you want for the GEMS cover.
I've got a fast road one from him, plus a full race solid one. both cut with the keyway in the right position so you can use the standard timing chain gears.

topcatcustom · Post by **topcatcustom** » Fri Aug 13, 2010 9:16 am

Sorry I put it in with a load of RV8 parts which I sold as a job lot to fund parts for the mx5!

ian.stewart · Post by **ian.stewart** » Fri Aug 13, 2010 11:12 am

I know there is a sealant thet people seem to have used with some success, Im sure somebody will come up with the name.