Fitting 3.5 heads to p76

[GURU]

Getting a short motor. so was wanting to fit my 3.5 heads onto it.

whats the advantage of this except it gives all mounting holes for alt, pwr steer and a/c ??

does it change the compression ratio? can i fit the P76 inlet manifold? what about the extractors.

[ISUZUROVER]

A mate of mine did this when he fitted a 4.4. He said that the 3.5 heads have a lot better cooling than the P76 heads. However, it is not completely straightforward, you need to do some drilling to the heads as the oil galleries on a P76 and a 3.5 are different. When my mate did this he initially made the drilling too large and had too much oil being pumped up into the back of the head, and had to fit a restrictor into the hole.

[Ralf the RR]

I've got Rover heads on my 4.4.
The oil flow IS different.
The oil on a P76 comes up the hollow push rods, and has paired "tappets".
The oil for rover heads flows through the rocker towers and has "rockers".
I hope this makes sense.

As to what has to be done to achieve this, I don't know as I bought the vehicle already modified.

Another difference is the head bolts.
The P76 has 10, and the rover has 14.
Mine was drilled and tapped to take the extra 4 bolts, and uses Rover head gaskets.
I believe this may not be necessary, but someone should be able to confirm this.

I've go a couple of pics on the AULRO gallery from my burnt valve experience.
http://www.aulro.com/modules.php?set_al ... _album.php
Don't know if that link works from here.

I am also lead to believe that the compression ratio is increased, but this is only hearsay.

I assume the P76 inlet manifold fits, but again am not sure. Mine has the Rover manifold with spacers (extra home made gasket required).

[Philip A]

You have to drill oilways in the block not the head. they are near number 7 and number 2.
I would think that this is quite an exact job as the drilled passages would have to meet up with a gallery in the block.

Regards Philip A

[grungle99]

I have my motor stripped at the moment - 4.4 with 3.5 heads.

I didn't do the original build but the guy who did failed to drill the oil feed holes - and subsequently the valve guides are shot from a lack of oil - only getting minimal oil from the push rods but not enough.

The oil veins in my block are next to (above and slightly behind) the number 7 and 8 pistons, not like the 3.5 where they are fed from opposite ends of the block (7 and 2).

I will drill them - yet to research if they are straight or on angles but the size will be very important as both being fed from the one location off the cam could lead to a drop in pressure on the cam itself.

I will post pics when I get back out there. The other caution is when you spacer the rocker posts to allow the use of the 4.4 rods - make sure you drill them as the feed seems to be through the rocker post itself.

Pics to come.

G

[Bush65]

If you fit rover heads you do need to drill the block to provide oil to the valve gear. Also fit rover cam followers and push rods.

If you want p76 heads, I have a pair. Hardly used after being reconditioned. Have tella terra roller rockers. I initially put them on a new 4.6 short motor, but went back to the 3.5 heads because too much oil was going out the breathers on the rocker covers - turned out not to be fault of the p76 heads though.

[GURU]

Bush65. where do you drill the hole exactly? as I pulled my 3.5 heads off I can see only one small hole on either side both towards the front of the motor. it's only about 5 - 6mm hole. is that the one?

Should I just use the cam follers (hydralic lifters?) and push rods from the 3.5 as they are in very good condition. or should I get new cam followers?

[Bush65]

Bush65. where do you drill the hole exactly? as I pulled my 3.5 heads off I can see only one small hole on either side both towards the front of the motor. it's only about 5 - 6mm hole. is that the one?

Should I just use the cam follers (hydralic lifters?) and push rods from the 3.5 as they are in very good condition. or should I get new cam followers?

Yes, thats the one, in the head it leads to one of the posts for the rocker shaft.

The reason that I said to change the hyd lifters and push rods was to close of the oil that the p76 sends up the push rod. The 3.5 pushrods will be too short. If you change to the rover lifters the p76 push rods may be ok, but check that the ends are compatible with the rover rockers and lifters.

[grungle99]

The rockers on my 3.5 heads have the oil holes through them, as well as the hole from the vein in the block - and the Rangie manual shows oil flow up the 3.5 push rods as part of the oil flow diagram...... I just don't think they feed enough oil for the 3.5 heads due to the type and shape of the rocker rail as opposed to the pressed steel rockers of the 4.4 heads.

I use the 4.4 lifters, and pushrods. You will need to shim/spacer the rocker rails on the 3.5 heads as the pushrods are a little long.

The hole to be drilled would only be about 1/16th of an inch, just upward and inbound from the outer upper head stud. ie find the top row of head studs, go to the end one, then just back from this is the oil feed hole. It appears that everybodies engines are different........(or they count from opposite ends of the block than me for piston numbering) I know both my 4.4 blocks have the oil veins definately next to piston 7 and 8 - at the back of the block. - My only question is do we drill straight into the vein - ie perpendicular to the head surface - or on an angle of some amount?

I will get some piccies tonight and post up if I find somewhere to host them.

Cheers

G