SD1 head port work - worth doing on a standard motor?

ratwing · Post by **ratwing** » Tue Jun 24, 2014 7:45 am

I've got a pair of SD1 heads to go on my P6 motor but am wondering if its worth smoothing out the 'lumps' around the valve seat inserts? Hard to describe but if you've seen these heads you know what I mean.
I'm not doing any tuning as such, just the new heads, a new standard cam & timing chain set (and a bigger oil pump kit) but if it gives a bit more power or economy or makes it run smoother then for a few evenings work I'll have a go.
Any thoughts, worth doing or a waste of time?

sidecar · Post by **sidecar** » Tue Jun 24, 2014 2:56 pm

In my humble if it costs you nothing other than a few hours of your time yet will give you a few BHP then it's worth doing! I have seen the 'lumps' that you are referring to, you need decent tungsten carbide burrs to smooth out the lumps as they are part of the valve seat inserts rather than the aluminimum that forms the head. Dip the burr in white spirit every couple of seconds to keep it cool, even then I found that I went through about 6 burrs when doing two heads.

Blown v8 · Post by **Blown v8** » Tue Jun 24, 2014 4:17 pm

While your at it,I'd lap the valves in,and smooth out around the rocker pedestals,deburring,(it helps the oil flow back )

ratwing · Post by **ratwing** » Tue Jun 24, 2014 5:47 pm

Cheers for the replies guys, time to dig out the die grinder then.
Valves have been lapped in, thats when I spotted the sticky-out-bits but thanks for the tip about smoothing out round the rocker pedestals, I hadn't come across this on my internet searches but it sounds like a good idea.
I also found a Morgan site (gomog.com) that suggests drilling a hole each side of the lifter gallery to get a bit more oil onto the timing chain and distributor drive gears, I can't see it doing any harm so will do that too.

stevieturbo · Post by **stevieturbo** » Tue Jun 24, 2014 11:18 pm

A good carbide burr should last for many many heads. But be careful, they can remove some amount of material very very quickly. At least when using a die grinder.

Never tried one with a drill, would probably be nowhere near as effective.

But take your time, and dont risk damaging anything, especially the valve seat surface itself.

Dont get big ideas about reshaping etc, keep it simple, smooth things out, keep the short side turn a nice long smooth radius etc

ratwing · Post by **ratwing** » Wed Jun 25, 2014 5:00 am

stevieturbo wrote:A good carbide burr should last for many many heads. But be careful, they can remove some amount of material very very quickly. At least when using a die grinder.

Never tried one with a drill, would probably be nowhere near as effective.

You're right, they need speed to work well and its much easier using a die grinder than a drill too.

stevieturbo wrote:Dont get big ideas about reshaping etc, keep it simple, smooth things out, keep the short side turn a nice long smooth radius etc

Sounds good, I didn't plan on any major reworking of the port shape because I don't really know enough about it and would a standard engine really benefit from it anyway, also I'd guess its easy to go too far and makes things worse.

chodjinn · Post by **chodjinn** » Wed Jun 25, 2014 9:35 am

You can do up to approx. Stage 3 porting yourself relatively easily, as above have said, if you are careful. Such porting should release a good amount of power relative to standard. From memory, a decent set of worked heads in such a spec could get up to 20bhp, bit more (30bhp) if you upgrade the cam, so it's certainly worth doing if it is only costing you a bit of time!

stevieturbo · Post by **stevieturbo** » Wed Jun 25, 2014 12:05 pm

Whilst stages mean little, the term stage 3 to me would mean proper porting backed up with supporting evidence from flow bench testing, and done by a competent person with lots of experience, combined with new valves, guides etc etc

That isnt to say a DIY person wouldnt be able to achieve results....but a DIY person can just as easily screw things up too.

That's why keep it simple, light smoothing is a safe approach for an inexperienced or unskilled person.

But heads can be bought/exchanged with all machining/porting done for not a lot of money really, relatively speaking.
And when bought from a reputable source, you know it has been a good job.

sidecar · Post by **sidecar** » Wed Jun 25, 2014 12:36 pm

In agree that 'stages' mean little in reality but in 'my head' stage III meant bigger valves have been fitted. Stage 1 was a three angle valve cut, and stage 2 was the three angles plus gas flowing the tracks.

Anyway the lumps where the inserts meet the tracks can be pretty bad on the Rover heads, there must be a decent amount of BHP lost because of this.

Darkspeed · Post by **Darkspeed** » Wed Jun 25, 2014 9:17 pm

Just smoothing out the machining cuts and ridges in the casting will not give any worthwhile increase in power the work to make the head flow better and give a power increase is a little further pack in the port. Do a search as there is plenty of detail.

chodjinn · Post by **chodjinn** » Thu Jun 26, 2014 6:50 am

I did say stage 3 porting, not replacing the valves. My stage 3 heads did indeed have upsized valves, but you can still do the porting yourself with a bit of research and care. The standard rover heads are shockingly bad with respect to casting so any work you can do will help.