1460 race engine
Discussion
The trouble is that re-build cost are huge, but in used and/or with unknown history it's very difficult to price such a unit.
I don't recognise the cam part number. The original cooper 'S' was an AEG 510, whilst the next generally used cam was the 731 (useless IMHO), followed by the excellent 544.
Thr trouble with very large engines is their propensity to 'blow up' and I would never want to pay very much unless I saw and heard the unit running, had a dyne print-out and could thoroughly inspect the unit. If you put that unit on a nice straight-cut bgearbox and it 'let-go' at big numbers, you would have destroyed an expensive box as well.
How was the big capacity achieved? What are the pistons (i.e. if they are Karl Schmidt the engine will be much better than if Omega or Hepolite.
You really do need a full specification with all the parts listed, plus a certified dyno reading to make any real money, otherwise it's just a bored-out block with the bits added. To use it in competition, anyone buying it woulod have to do a full precautionery re-build just to be safe.
I don't recognise the cam part number. The original cooper 'S' was an AEG 510, whilst the next generally used cam was the 731 (useless IMHO), followed by the excellent 544.
Thr trouble with very large engines is their propensity to 'blow up' and I would never want to pay very much unless I saw and heard the unit running, had a dyne print-out and could thoroughly inspect the unit. If you put that unit on a nice straight-cut bgearbox and it 'let-go' at big numbers, you would have destroyed an expensive box as well.
How was the big capacity achieved? What are the pistons (i.e. if they are Karl Schmidt the engine will be much better than if Omega or Hepolite.
You really do need a full specification with all the parts listed, plus a certified dyno reading to make any real money, otherwise it's just a bored-out block with the bits added. To use it in competition, anyone buying it woulod have to do a full precautionery re-build just to be safe.
74.7mm and according to Vizard, that's the limit 
They might clean up a bit perhaps but you'd be into running the rings a bit slack which would reduce friction a tad but make it a weeny bit smoky I suppose getting a block bored is no great shakes but thinking about preparing the bearings and the other block mods would be a hassle.
Sounds like an interesting engine though.
They might clean up a bit perhaps but you'd be into running the rings a bit slack which would reduce friction a tad but make it a weeny bit smoky I suppose getting a block bored is no great shakes but thinking about preparing the bearings and the other block mods would be a hassle. Sounds like an interesting engine though.
Hi, I am currently building a 1430 (1428) using old stock Vauxhall hepolite 74.79 pistons. The bores are offset to give even meat between cylinders approx. 0.100" (2.5mm). Incidentally the the same thickness as the head gasket steel ring.. Sounds thin but at the end of the day its only 0.65mm off the walls of the cylinder of my old 73.5mm 1380 block (that unfortunately dropped a valve that proceeded to make a hole in no. 4 piston as I limped the 200yrds home). That fine unit was 120bhp and had a life pretty much consisting of constant caning and full thrash and lasted for years, is it really that much weaker!!??
The compression height of the donor piston is pretty much the same but a 6.5 crown thickness will allow for alteration to bring about the desired compression ratio.. The gudgeon pin bore has had to be opened up from 20mm to the 20.64mm to suit the little end interference fit but apart from that and a few mm taking off the skirt they are pretty much like for like... So technically if this works it could well be the biggest bored A series ever.. Lol...
Vizard makes no bones about what works and what fails, I can't recall him saying that 74.7 was unreliable.
A lot of it comes down to the machining/build quality, and whether the comp ratios were calculated and not 'guessed', and its fuelled, timed and setup correctly.
It should be completed in the next few weeks I'll keep u posted (if anyone's interested.lol)
Would love to hear from someone who's tried non A series pistons with success..
The compression height of the donor piston is pretty much the same but a 6.5 crown thickness will allow for alteration to bring about the desired compression ratio.. The gudgeon pin bore has had to be opened up from 20mm to the 20.64mm to suit the little end interference fit but apart from that and a few mm taking off the skirt they are pretty much like for like... So technically if this works it could well be the biggest bored A series ever.. Lol...
Vizard makes no bones about what works and what fails, I can't recall him saying that 74.7 was unreliable.
A lot of it comes down to the machining/build quality, and whether the comp ratios were calculated and not 'guessed', and its fuelled, timed and setup correctly.
It should be completed in the next few weeks I'll keep u posted (if anyone's interested.lol)
Would love to hear from someone who's tried non A series pistons with success..
Edited by JonnyWowsers on Monday 11th February 14:42
Hi.. Good old stock Crank 81.28 stroke, balanced with centre main strap.. Decent vandervells bearings n thrusts.. Keep meaning to plug and crossdrill but to be honest there not much a stock crank can't take in standard form! Definitely not worth spending thousands on a 'posh' crank money better spent on the horses elsewhere. With an ultra light flywheel n back plate combined with the spec of the engine they rev like a motorbike anyway and the pump jet in the weber gives that instant blast of fuel when u blip the throttle... Ive got a set of s rods I suppose I could stroke it, (if I can source an early crank with the bigger rads) there's enough meat on the piston crowns to lose the extra 1.5mm if I did... Not worked it out but it'd gotta be 1480 ish... Mmm you got me thinkin now.. Lol
I'm goin for the 310 scatter cam this time (ran ordinary 296 b4) , back down to 1.5 rockers ( the 1.7's died with the last engine n I didn't rate em much to be honest). Heads a big throated chambered bugger but still on 35.7's n 31 rimflo valves.. Still undecided on my comp ratio but they recommend high for the scattercam, but I don't wanna start putting additives in the fuel n all that b
ks so I'm still deciding.. Obviously Cam timed in... (Gotta be number one schoolboy error for amateur engine builders.) ... Last engine was 120bhp on the rollers, be nice to get 130bhp or a touch more this time... Hope it holds together. Haha.
ks so I'm still deciding.. Obviously Cam timed in... (Gotta be number one schoolboy error for amateur engine builders.) ... Last engine was 120bhp on the rollers, be nice to get 130bhp or a touch more this time... Hope it holds together. Haha. Yes as I said in the initial post its 74.79mm bore size.. Vizard took his to 74.7 using triumph pistons (requiring a load taking off the deck to bring the compression ratio back). These are vauxhall hepolites, old 60's stock.. Standard 74.295, I had damage in my no 4 cylinder in my 1380 block (73.5)due to a valve letting go so went for the 74.295 +20's to clean up the damage making 74.79 mm.. But they have pretty much the same compression height.. The only difference is the gudgeon pin diameter (which is easily rectifyable) and there is a 1.5mm offset on the gudgeon pin.. If fitted the correct way round can actually in theory give slightly more power. It's nothing serious just another bit of a project.... Haha..
Ah, I see.
So, assuming you manage to take the block out beyond 1380 to accept those pistons, will the block still be rigid enough to resist flex at high rpm?
How many more HP do you think you might find chasing a super big bore, over and above 1380, assuming you can get there?
It's an interesting prospect for sure!
So, assuming you manage to take the block out beyond 1380 to accept those pistons, will the block still be rigid enough to resist flex at high rpm?
How many more HP do you think you might find chasing a super big bore, over and above 1380, assuming you can get there?
It's an interesting prospect for sure!
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