Hi all...
First post from new member
Now, i'm 49 y.o. and been working on cars since 17, yet all on rotary engines and general vehicle repairs.
i have good knowledge of most things mechanical, yet lack the knowledge of the piston counterpart engine.
i have bought my son a 1200 ute running a A14 donk and am using this as a platform for him to learn as i did.

i plan on working on this engine to just tweak it and get it humming nicely.
I have a few questions which i'm sure can be answered well on this forum.
I wish to instal a mild cam and have the head worked on. It is a H75 head. I have a pair of SU's and 4 into 2 into 1 set of extractors.
My questions:

1. When having the head tweaked, what do i need to change or replace when refitting? e.g. Valve seals? Guides? (I know i need a new head gasket lol)
2. When changing the Cam, i have read on the forum i need to remove engine and turn upsidedown so as not to drop the pushrods into the block. Can this be avoided? Can i not just remove the rods when removing the cylinder head?
3. Can someone explain the "followers" that need to be refaced when having the Cam reground. Do these attach to the pushrods and come out when the rods are removed?

I look forward to some answers from those more knowing than I.

Kind Regards,
David

G'day David, and welcolme to the forum.
With the A series engine, the lifters are inserted from the bottom of the block before the cam is installed. they cannot be taken out from the top unfortunatly. When installing a new (or reground)cam, it is highly recomended to fit new(or reground) lifters at the same time. Any cam grinder can grind the lifters(followers) at the same time you are getting the cam done.
Th H75 is the low comp oval port head, the better one is the H89 from the A15. There is value in getting the guides done and a nice job on the valve/seat area. Seals would be the norm after that. Double valve springs would be recomended for revs past 6500 to 7000Rpm or you will start to float the valves and damage seats and not make power.

Have fun with it. They are great engines!

I should have been a little clearer with nwhat i was saying. The followers are stepped and have a slightly crowned surface for the camshaft lobe to run on. This crowned suface of the follower then steps down to the follower bore diameter. These are inserted before the camshaft with the engine upside down(otherwise they just fall out). The pushrod is fitted from the top after the head has been put back on.

All that being said..... It is possable to change the cam without removing the engine or head. I have 8 rare earth magnets attatched to extenders and springs to hold the lifters from falling into the sump when the cam is removed while in the car. The problem is, the followers wont be be resurfaced and could likly damage the new cam very quickly. So I wouldn't recommend doing it this way.

Hey,
thats great help....
q. though.
when doing guides (as suggested), are these an insert? are they specific to the valve or just a general replacement item?
As for the "seats". Does this refer to the seating of the valve in the actual head? is that what i've seen when the valves are suctioned to a dowel and then spun back and forth with a seating compound to make the valves fit the opening in the head? OMG i sound like such a 12 y.o. !!!
Valve seals. Where do they go? Is this on the valve stem?
I know i sound like such a noob, but i'm sure these questions are milling around in other peoples heads and just too scared to ask for fear of seeming stupid. I have no such problem asking.
I was always told as an apprentice : "the only stupid question is the one never asked"

Thanks for your answers in anticipation,
David

The guides are are cast iron inserts pressed into the head. Over time, the 8mm valve stem wears this out and the head of the valve fails to seat concentricaly on the seat. To repair this, the cast iron guide is reamed and a bronze insert is fitted and resized to get the required clearance and keep the valve seating concentrically. Once the guides are done, the seats can be re cut using a stone (ground with the right angle for the seat) mounted to a pilot that is snug in the reco guide. This ensures the fresh seat it centered and square to the valve. The valves are then also ground, usually with more than one angle to improve flow at low valve lift. The ground valves are then tested in the head to ensure a good seal and to check where and how wide the seat it.
On a performance build, there are other things that would be checked. Spring installed height, seat pressures and pressures/heights at full camshaft lift would also be measured/adjusted to ensure enough spring pressure without spring bind.
Once all this is done the head would be surfaced to ensure a good mating surface for the gasket.

All of this is done by a performance shop or head reco place. It cant be done at home.

For an A series head I usually pay about $350 for this to be done which includes new double springs. They will need to have your camshaft specs if it has a decent one in it.

Hi there,
that's exactly what i needed to know !!
Excellent coverage of the topic!
I will make sure i ask all these questions when having the Head done.
Did we cover this: "Seals would be the norm after that".

David

yeah, seals would go on the top of the guides before the springs went on, during final assembly.