272 replies to this topic

[cradley-heathen]

personally i dont think they are worth spending £800 on then. minispares aus +120 thou (67.6mm) pistons are cheaper and maching a small dish and some fly cuts for the pistons will work out at least half the price if not more

http://www.minisport...au/prod1094.htm

with the shipping it looks like they work out at about £100!!!!!! for a set

^^^^got it in one^^^^ You'd regret spending £800 on pistons!!

phone derek chin, they'll be able to put you intouch with someone who will make you a set for about £400

hold your horses man, i didnt say i was having a set made! the whole project wont cost £800! never mind a set of pistons!

i have had a slight re-think in the build process and i think i have come up with a way of not messing about with valve cut-outs, or dished pistons, and if this works, then this will change the whole scheme of things, it will be much more like a bolt on process which will be better for me and for anyone wanting to do the same later on....

[AndrewJ530]

personally i dont think they are worth spending £800 on then. minispares aus +120 thou (67.6mm) pistons are cheaper and maching a small dish and some fly cuts for the pistons will work out at least half the price if not more

http://www.minisport...au/prod1094.htm

with the shipping it looks like they work out at about £100!!!!!! for a set

^^^^got it in one^^^^ You'd regret spending £800 on pistons!!

phone derek chin, they'll be able to put you intouch with someone who will make you a set for about £400

hold your horses man, i didnt say i was having a set made! the whole project wont cost £800! never mind a set of pistons!

i have had a slight re-think in the build process and i think i have come up with a way of not messing about with valve cut-outs, or dished pistons, and if this works, then this will change the whole scheme of things, it will be much more like a bolt on process which will be better for me and for anyone wanting to do the same later on....

Have a deeper block?

[cradley-heathen]

personally i dont think they are worth spending £800 on then. minispares aus +120 thou (67.6mm) pistons are cheaper and maching a small dish and some fly cuts for the pistons will work out at least half the price if not more

http://www.minisport...au/prod1094.htm

with the shipping it looks like they work out at about £100!!!!!! for a set

^^^^got it in one^^^^ You'd regret spending £800 on pistons!!

phone derek chin, they'll be able to put you intouch with someone who will make you a set for about £400

hold your horses man, i didnt say i was having a set made! the whole project wont cost £800! never mind a set of pistons!

i have had a slight re-think in the build process and i think i have come up with a way of not messing about with valve cut-outs, or dished pistons, and if this works, then this will change the whole scheme of things, it will be much more like a bolt on process which will be better for me and for anyone wanting to do the same later on....

Have a deeper block?

a deeper head, the combustion chambers are REALLY shallow, so in theory i could have a really thick spacer like the jonspeed kit for lowering the compression ration for use with a super charger, but that would need 2 head gaskets which i dont fancy, however i think i can come up with a way of doint it differently, its so obvious i dont know why i didnt do this in the first place!

now im only thinking out loud here so nobody shoot me down, but as long as i can afford to have a good thickness of "spacer" over 5 mm for example i can cut an alloy plate matching the bottom of the head, and tig weld it around the chambers and around the edge of the head, then have it skimmed again to get it flush, at 5mm (aprox) that would see my valves clear of the pistons, and the block (which would mean my previous pocketing of the block was pointless but nevermind!) and the compression ratio restored to normal instaed of 10000000:1 lol

however last night i did go for a drive in the car and whilst pondering it all i couldn't help but think i should just turbo it now and go thwe whole hog......?
calm down cradley.... calm down.... one step at a time!

[mini13]

ok, what chamber volume do you have in the head?

before you look at running the pistons waaay down the bore or having a spacer plate, are you sure you want to loose the squish/quench area that is given by the edge od the a series pistons coming close to the head?

persnally its not a compromise i would want to live with,

[Tomf]

Agreed work out the compression ratios you will be running before you go ahead and have a spacer tig'd in place as you might find that its just not going to work, but on the other hand if you are going down the turbo route you might need the spacer anyway...

[cradley-heathen]

ok, what chamber volume do you have in the head?

before you look at running the pistons waaay down the bore or having a spacer plate, are you sure you want to loose the squish/quench area that is given by the edge od the a series pistons coming close to the head?

persnally its not a compromise i would want to live with,

Agreed work out the compression ratios you will be running before you go ahead and have a spacer tig'd in place as you might find that its just not going to work, but on the other hand if you are going down the turbo route you might need the spacer anyway...

untill i get the head aback from its first skim i dont know the volume in the head but i can assure you its very small! by tiging the spacer plate to the head i will only be re-creating a head setup more like the original 5 port a series one.

im not going to run the pistons down the block by shortening the piston deck height or anything, the pistons will still be rising to flush with the blocks deck height at TDC.

it looks like i have just bought a 63 riley elf today so i may have to put the engine on the back burner while i do that......

[wolfys_mini]

paint it yellow!

the elf...not the engine

[mini13]

Ah, i see are you looking at having a spacer that doesnot have round holes then but a shhaped hole to match the chamber?

[cradley-heathen]

Ah, i see are you looking at having a spacer that doesnot have round holes then but a shhaped hole to match the chamber?

correct, it will be the same shape as the 998 head gasket, 4 "pear" shaped holes above the pistons not just round holes the same o/d as the bores

[cradley-heathen]

paint it yellow!

the elf...not the engine

lol, the elf is staying grey mate, keep it original for maximum return on it!

you can buy it off me and paint it yellow though, of comision me to do it for you?

[wolfys_mini]

how much?

[cradley-heathen]

having spent a few hours messing the other night with a few sheets of perspex i have made a model of the spacer i want to tig weld to the bottom of the head, its seems to work perfectly at a thickness of just 4mm, this corrects the c/r and will keep the valves 4mm further away from the pistons now, so hopefully when i put it together i shouldnt need any valve reliefs in the pistons.....

i have a pic of the perspex dummy i made to test the c/r but it wont load for some reason? anyway, its a breakthrough never the less!

[cradley-heathen]

nothing to report this week, the elf is taking up any spare time i have at the minute, and thats not allot of time either to be honest, this weekend i should make some progress!

still need a set of oversized small bore pistons if anyone has anything????

[Sprocket]

I would be a little concerned about using a spacer made of aluminium. Cylinder heads and pistons made of aluminium have been heat treated and hardend, you spacer plate wont have the same properties. Will it withstand the abuse of combustion?

Make sure you use the highest, strongest grade aluminium you can afford!

[cradley-heathen]

I would be a little concerned about using a spacer made of aluminium. Cylinder heads and pistons made of aluminium have been heat treated and hardend, you spacer plate wont have the same properties. Will it withstand the abuse of combustion?

Make sure you use the highest, strongest grade aluminium you can afford!

yes mate im aware of this, i wasnt going to use melted down saucepan grades aluminum dont worry lol, i have spoke to my old work to see what they have, im waiting for somthing decent to come in, we used to do testing for british aerospace and the MOD, some ally we had was so soft you could cut it with scissors up to about 4mm thick, god knows what they used to use that for!

i really want to get cracking on this now! the elf has gotta go!