Knackered Big End ! PART TWO: The Rebuild

[Griffith77]

Hi All

So, the engines coming out (either with or without the box – different thread!) and going off to be checked and rebuilt.

While it’s out I’m wondering what other areas are worth attending too to maximise the potential without going mad on the budget!

Engine’s a 4.3 BV pre-cat (allegedly factor original) which was giving 270 bhp & 240lb/ft last time it was on the rollers. It’s done 56k without problems.

Looking at using for the odd track day, defiantly some sprinting, but also looking for good drivability so torques going to be important.

At the moment having the following thoughts:
Baffle the sump
ACT smooth bore induction hoses (plenum to AFM to filter)
Top hat liners
Matching the ports on the heads and exhaust
Light port work to improve flow in the head (depending on what’s found)
Blue print
Slightly hairier cam
Piggy back the ECU to allow better fuel/ignition mapping

Presuming we don’t find any horrors when it’s stripped, and allowing for general wear items (rockers, clutch, etc.) being replaced where needed, what other mods/additions have people found to be a worthwhile expense?

TIA

[haircutmike]

A few additions;

Steel rockers.
JE pillar rocker supports
Enlarged and shortened trumpets
Double valve springs and head work, depending on what you find?
Ported inlet manifold
Cross bolt the block.

[spend]

You need to figure out what do about the ringed heads if they still have the wills rings in them:

1. standard composite gaskets and hope the metal fire ring accepts the compression ring
2. solid copper gaskets
3. have the rings skimmed off.

ARP the bottom end & heads as a matter of course IMHO, and make sure you get good quality bearings.

[carsy]

I kept the rings on the heads and used composite head gaskets. This was on the advice of v8d and all appears well.

[leerdam23]

Baffled sump. defo, but blue printing - why bother. you want the engine to have some life in it...

Also, add reinforcement to the chassis where the seat rear mounts are so they can be attached to it.

Edited by leerdam23 on Saturday 10th December 10:26

[haircutmike]

Andy.

Just tried to mail you from your profile but no luck!

Please contact me through my profile or [e-mail]

[spend]

carsy said:

I kept the rings on the heads and used composite head gaskets. This was on the advice of v8d and all appears well.

All the 430's had composite head gaskets, BUT they originally had copper fire rings to match the rings in the heads. I know Rob has found std (tin fire ringed) composite gaskets to be OK, big BUT I would only use the gaskets that Rob advises ~ I tried some cheapo britpart ones in a trial assembly to measure clearances (valve & piston) and the rings ripped those fire rings apart!

HairyMike, these are all small journal blocks & cross bolted versions are like hens teeth, even the versions with full size lower caps are quite rare. If he wants Rob could probably offset grind a 4.6 bottom end to suit his 430 rods+pistons but I don't think I'd class that as a rebuild.

OP, trumpets are a short fall, manifolds just need a bit of tidying nothing radical. At 270bhp it is more than likely you already have BV heads (if not upgrading to the slightly larger valves on std seats is worth considering). The main mismatches seems to be around the exhaust ports, mainly due to the hand made manifolds I'd say. You can enhance them further due to the 2 perpendicular 90 deg 'bends' the exhaust gas has to follow but then you get into having to use sealant rather than gaskets. Essentially you are likely to find that all the ports are already slightly larger than the inlet & exhaust gaskets that you will be trying to match. The guides will already be shortened & bulleted, with perfectly acceptable dual springs suitable for hgh lift cams. The only thing to be careful of is if you have one with std cam chain+gear (unlikley if BV heads) which is well worth replacing with duplex vernier particularly if you are going to install a better cam. Solid cams & lighter valve train would be my advice but you are best having a consultation with Dr Rob about exactly what you want in that respect.

[jesfirth]

if its for track work as previously said baffled sump is an absolute must and I suggest also an oil cooler to stabilise the oil temp. I destroyed my engine on a track last year bcause i didnt have a properly baffled sump

[spend]

jesfirth said:

if its for track work as previously said baffled sump is an absolute must and I suggest also an oil cooler to stabilise the oil temp. I destroyed my engine on a track last year bcause i didnt have a properly baffled sump

I'm not saying your wrong Jes, but I do wonder if baffling the sump is just to make the things still pick up oil when the level is low? The percetage volume of oil than can be 'held up' in the engine seems largely affected by quality of castings in the heads under the rockers and general 'roughness' of the casting in the valley etc, not withstanding how much the rocker shafts and spring seats can encapsulate... Add in all the stuff strirred up in the crankcase (smoothed rods & crank counterweights ((ie not just filed smooth but contoured to throw oil)) + scraper anyone?) along with the old chesnut of crankcase vaccum. I won't even mention how much oil those 16 darned humpty pumpty followers might be 'absorbing' when at chat?

Apart from the usual intensive care rebuilding I don't think I'd really bother much with sump baffling but concentrate on solid followers oiling the rockers up the pushrods (blocking rocker shaft feeds), and ensuring good return flow (head cast holes nicely contoured & smoothed valley) with possibly the addition of a crank scraper and screen above the cam in the valley. I also like to link the main galleries at the rear behind the cam to equalize pressure ~ but I still worry about how well the lifter bores seal those main feeds (pressure diff front to back). If I wanted to heavily race a small journal I still think I'd look at the old method of drilling the nearside main cap through to the nearside oil gallery, but it does seem easier to add a newer crank oil pump?

Funnily enough chatting with Pete Burgess about how misleading head flow data can be, I actually converted some of my water flowing test kit to looking at heads and valleys, and trust me it is quite significant the difference in flow back that can be achieved with minimal work ( the rover cast stuff which is not directly important can be of absolutely dire quality - just consider the all the fash when you look at cams downthe valley - it looks like someone has just tapped the holes out with a lump hammer ).

[jesfirth]

spend - i have very little idea on engineering and detail and will always bow to superior knowledge. I am sure there must be different solutions. Fortunately since i fitted the sump and cooler the oil pressure has been rock steady even on fast left handers with B list tyres. maybe a combination of all options would cover all the bases and give a fail safe solution

[Simon says]

And just to prove just how bad some of that casting is this is a very late Serp X bolter, all them years didn't learn much did they

[Griffith77]

Gents

thanks for the replies - haircutmike, i'll follow up with you tomorrow.

Jez "snap" - oil pressure on a track day was the root cause - oil flow back, baffling, poss cooler all now in mind.


Engines now delivered to builder for stripping and checking so we'll see where we go from here.