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Jan 13, 2012 18:12:24 GMT
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Evening all,
I'm having some musings at the moment and was wondering if anyone had an idea of any 4-pots that have a cylinder centre spacing of 6.667mm or 2.625". Specific I know but I have a reason.
Thanks in advance.
David
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Last Edit: Jan 13, 2012 18:13:52 GMT by worthidlj
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Bit of a threadbump!!
Some research has revealed that either the Kawasaki ZXR400 or Subaru EN07 motors might fit the bill but was wondering if anyone could confirm this?
Much appreciated.
David
p.s. in the original post, i meant to put 66.67mm, NOT 6.667mm :/
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Copey
Posted a lot
Posts: 2,845
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your best bet is to find a friendly garage and compare head gaskets, i have seen a ford pinto with a fiat (i think) twink head bolted of
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1990 Ford Sierra Sapphire GLSi with 2.0 Zetec
1985 Ford Capri 3.0 (was a 2.0 Laser originally)
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What engine is it? That sounds very small to me. A spacing of 67mm limits you to a bore of about 60mm, which isn't that big. If I'm not mistaken I think the small-block mini has bigger bore spacing than that? I would think that you'd be looking at motorbike engines.
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The bore of the block is only around 56m, it's for an Austin 7!
Admittedly this is only a pipe dream at the minuite; time, space and lack of funds all restrict any form of progress (especially working full time and studying for an engineering degree through the OU :/). I just want to check if it is theoretically possible to achieve such a thing as in the future I would like to build an Austin 7 special, and taking inspiration from the Mini/BMW cyclinder head conversion and build a little twin cam engine for it using the original bottom end.
This is all just for a little engineering project I would like to do in the future but would just like to check the feasability of it first before pushing on with it.
Thank you everyone for advice and feedback.
David
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I'll check my Imp engine when I get home - I know the bore centres are fairly close.
Might be worth looking at the small Reliant engines - they were supposedly based on the 7 lump.
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Wow, Austin 7, okay! That's a seriously ancient engine to be extracting power from. Before you get too carried away with cylinder heads you might have to look at what it would take to machine it for a couple more main bearings! Basically I would imagine that you would need to replace the crank, rods, pistons and oiling system to support the head. So what you would be left with would be the original block, heavily machined, with almost every part replaced!
If you want to go down that kind of route, fair play to you, as it would be impressive. However, in my opinion there's a couple of better ways to go. At the very least, certainly easier and cheaper!
Option 1: Mild 'period' hot-rod. Give the engine a little bit more power with an SU carb (or maybe a pair of Amals if you want it to be fancy), manifolds and higher-compression pistons. Keep it side-valve and generally stock architecture. This will give you a modest boost in power and make it look nice. Maybe even a tiny supercharger if you want to go crazy? I bet one of those tiny Aisins from the Subaru kei cars would do the job.
Option 2: 'Period' engine swap. Go for something that suits the era of the car, perhaps build the whole car as if it were done in the '60s or an era of your choice. Example engine choices could be a Morris A-series or vintage bike engine (J.A.P, BSA, etc.) Advantages are that you will get more power for less money than tuning the original engine (at least with an A series).
Option 3: Performance/modern engine swap. Your choice of any modern small car or bike engine. Advantages are light weight, low cost, high power and reliability. You can dress it up to look older if you like.
Just out of interest, what's the intended usage of the engine? Vintage racing or just for the street? If you're going to be doing any racing, obviously category rules will determine what you can and can't do. Superbike engines would probably not go down well with the VSCC!
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Seriously Ancient!! I know, thats why I think it would make an engineering project.  I want to se if I can keep the bottom end standard/ known modifications (i.e. Phoenix Crank etc), and basically see if I could just 'plonk' the cylinder head on top; more complicated I know but that's essentially what I am aiming for. I would look to keep the car (when i can eventually afford one!!) street only just as a fun little car to own and run. i have thought of the other tuning options; I just want to try something a bit different. I remember reading an article where someone used external oil/water lines when putting a Ford Zetec head on a Morris B-Series block so I think that might help make the project a little more feasable. The Reliant 750cc is based on the Austin 7 motor and I have seen Austin based specials with Ford 1172cc, Reliant 850cc and various bike engines. I'm not looking for a huge increase, I justwant to see if its possible to achieve what I'm thinking of then I will get to enjoy my achievement... and say I own an Austin 7 Twin Cam!!  |
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Imp is 3 and 3/16" - I hope you find something suitable, sounds like a fun project. ;D
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 This and a supercharger will give you: 116 bhp @ 9,000 rpm on sprint fuel (methanol added) Perhaps you could add 4x Honda GX120 cylinderheads on the block, valve train might be a bit challenging. Can I offer this; i.piccy.info/i5/21/23/642321/Kaiman16vcrossflow02.jpg as an inspiration? |
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 Click picture for more |
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I was wondering if someone would bring that up, lol. That Opel twin cam is certainly intruiging, I had thought of numerous single cylinder heads but that may be a bit beyond me at the moment!  |
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One thing that just struck me about four cylinder motorcycle heads, is that most of them have the cam chains running up through the middle, hence leaving a big gap between cylinders 2 and 3. Most of the sporty 600cc bikes have too big a bore to be useful for you, so you're looking for sub-600cc four cylinder bikes without a cam chain through the middle. I'm not sure how many of those there are. Here's a pic of the Honda CB400, which might have been perfect if it weren't for that pesky cam chain!   |
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Yeah i found that already, would have given me more options too!
Thats why, inthe second post of the thread, i mentionedthe Kawasak zxr400 motor as it has the cam gears at the end of the engine like a normal motor, same with the Subaru EN07 Kei car engine, they look about right, just need to confirm those dimensions to get me really thinjing on going forward with the project.
Cheers,
David
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Thread bump again!!
Uni work has restricted any reasonable research, but searching on ebay has found a supplier (cradleykawasaki - no affiliation!) who was kind enough to give me a couple of dimensions.
Turns out the bore spacing is approx 67.5mm; now the bore spacing for an Austin Seven engine is 2.625inch, converting this to mm means there's a difference is approx 0.83mm.
Does this seem too much of a difference or do you reckon I could get away with a bit of machining to allow the valves to movw without hitting the bores?
Further inspiration comes from a PPC article where somone fitted a zetec head onto an MGB B-Series block, even though the cylindes are siamesed, so maybe some hope!! :-)
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craig1010cc
Club Retro Rides Member
Posts: 2,993
Club RR Member Number: 35
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Alternative headscraig1010cc
@craig1010cc
Club Retro Rides Member 35
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If the block is anything like a mini's, then you could do some pocketing of the bore to allow a shrouded valve to open. Would also be worth reading up on the K series BMW bike head conversion on minis if you haven't already (specialist components are a good place to start  ) what about a Yamaha 600 fazer, they are cam chain on the end or KAWASAKI ZXR400L-1 ZX400L ZX400AE? |
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I have no practical experience here to offer but I have seen straight 6 heads that have been cut and shut onto 4 cylinders but the cooling is a headache. or even a v8 head
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sweaty palms slip off joystick
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Why not find a head with combustion chambers and valve size you want and forget the cylinder centre spacing.
Then cut head between the chambers, mill off the cut edge until the cylinder spacing is correct, align oilways and waterways, join together with studs, Araldite or what ever then use it as a pattern to get a complete head cast in alloy.
Paul H
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If the block is anything like a mini's, then you could do some pocketing of the bore to allow a shrouded valve to open. Would also be worth reading up on the K series BMW bike head conversion on minis if you haven't already (specialist components are a good place to start ) what about a Yamaha 600 fazer, they are cam chain on the end or KAWASAKI ZXR400L-1 ZX400L ZX400AE? The ZXR 400 is the head I was talking about, sorry I forgot to mention!  , and the BMW/BMC setup is one of the inspirations for the idea. Paul H - though probably not in hindsight, I currently believe that using a head that possibly fits (plus a bit of machining like the A-series setup). This is more of an engineering project and basically I just want to see if I can!! ;D |
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Why not make a replica engine? Find a crank, and a set of liners that would suit the head you want to use, turn a bright steel bar to the mains dia+shells, a bit of subtle sand casting, and your away
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"No............I think I'll stick with the Maxi"
Arther Daley
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Why not find a head with combustion chambers and valve size you want and forget the cylinder centre spacing. Then cut head between the chambers, mill off the cut edge until the cylinder spacing is correct, align oilways and waterways, join together with studs, Araldite or what ever then use it as a pattern to get a complete head cast in alloy. Paul H Doesn't quite work like that I'm afraid.... |
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You're like a crazy backyard genius! |
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)
, and the BMW/BMC setup is one of the inspirations for the idea.
