Overhead Cam
Turbo Mini Forums

Okay, all, again, as with all my posts, run with this. Is it possible to turn an A-series standard head into a sohc cam? This would get rid of any pushrod problems, and it would make cam change a lot easier. What's people's thoughts on this? And yes, I know you can do a 16 valve ohc change, not what I'm looking for, I'm looking to stay a-series, and if any benefit can be derived from ohc on a 5-port head, then I may try it.

-James

there are some ohc a series kicking around, i cant see any practical way of converting a standard head..... would need way too much work to be worthwhile...... be far better off spending the time and cash making a k head fit....

And on the 7th day........... God created turbochargers!

do it!

get a cam carrier made that accepts a hydraulic lifter from a modern car,

use an A series cam as the spacing should be right for the valves

I think the easiest way, and this is just theory, is get some mounts for the cam made up that bolt to the head, close off, possibly, the pushrod holes, remove and plug the cam holes in the block(possible turbo drains?) Install a drive belt oil pump on the timing side, and get a new timing cover made up.

you will need a fair amount of oil going to the head to feed the cam bearings, hence you will need a fair amount of drainage, so use the push rod holes as drains,

leave the existing cam in place as per a K conversion.

getting a cam belt past the themostat part of the head could be an issue.

Howly racing made a SOHC 8 port head that I belive used a mini cam in a bolt on carrier, there are pics in the vizard bible.

Leave existing cam in place for the oil pump? And does anyone think better performance could be garnered from this kind of set up?

yep, leave the existing cam for the oil pump.

as for performance, with larger diameter followers, say 1" you can use higher acceleration rates before you go over the edge of the tappet.

So, what I would be able to do is get better acceleration. This would be great for turbo use, would I be able increase the rev range via this as well?

i mean acceleration as in opening the cam faster,

basically the larger tappet/ follower diameter you have the more radical cam acceleration rate you can have,

as an example with the mini's .81" tappets around 7 thou per degree is the limit, a lotus twin cam with its larger followers (1.25" iirc) can go to around 10 thou per degree.

Hmm, interesting. Now how would I go about clearing the t-stat portion? Ideas, ideas... What program did you use to make that by the way? I'm thinking of overhead camming the '63 when I do the rwd conversion. I might even do the american thing and add a blower that comes out the hood...

-James

weeeeell.....

to clear the thermostat i was thinking remove it...

cut the end of the head of flush with the end of the block, and fit a plate with a water take off and use an inline stat.


alternatively fit a 1.2 fiat 8v head,

And the benefits of an overhead cam 8v five port engine are?

If it doesnt have more than five ports, I dont see the point of all that work

More reliability, removal of the long pushrods(possible couple of bhp)? If you get rid of the longer pushrods then theoretically the motor should get a few more revs out of it, meaning a few more top end hp. It also makes for an easy cam swap should you find that your current set up is not good.
Mini 13- does a 1.2 fiat 8v fit straight on? And how effective are inline t-stats, same as regular, or are they prone to failure?

I am running an external thermostat from an Aprila. Lots of modern cars now run external thermostats. They are no more un reliable than a standard thermostat, after all its a thermostat in a housing but piped externaly

well,

for an equal lift your not going to get any more power, and you'll need a custom cam profile to make use of the larger lifters.

anyway,

obviously the fiat head will not be a straight fit, but i think it will be pretty easy,

you will need to plug and redrill the head studs and waterways, and sort out a pully on the crank to drive the head and a tensioner.

you'll probably have to mess ewith the water pump as i reckon it will get in the way of the belt, also you'll need to arange an oil feed.

th thinng with the 8v fiat head is it uses flat top pistons, meaning you should not need valve cutouts in the pistons like you do with the bmw head.

I dunno what the flow is of the 8v fiat head, but i suspect they are slightly better than a good 5 port. you can make proper use of injection though...

So lets say I keep the 5-port head, lop off the t-stat end and fit an inline one. As for the water pump, remove it all together and fit an electronic one, two problems solved. To drive the cam, I think I already have a solution(ish). Take a duplex set of gears, and fit two simplex chains. One for the lower cam to drive the oil pump and one for the upper cam.

that will be a PITA to get oil tight.

Efforts would be better spent with something other than a five port head In My Honest Opinion.

So I keep hearing. I'm just throwing ideas around. I might do it to an 8 port instead, but the theory would be the same on a mini.

If you where doing this on a RWD mini, then you would have more scope for cross flow head (in one side and out the other)

I'm actually thinking about doing that, with the mini I'm converting to rwd.