V8 Head home porting

[Darkspeed]

Hi all

Just about to take the die grinder and some carbides to the RV8 in an attempt to clean up the nasty ridges just behind the valve seats match up the ports to the manifolds etc. and grind the little ridges off the backs of the valves - the "Stage One" mods that are the mainstay of every tuning book ever written and if Peter Burgess is to be believed liberate 50 Horses along the way

Late 3.9 heads.

Any other hints and tips?

Oh I may also mop round the chambers with some scotchbright pads to polish them up if I have time to spare.

Andrew

[CastleMGBV8]

I think Peter Burgess suggests +30BHP for his Econotune (Stage 1) Heads on a 3.5 so probably a bit more on a 3.9 but which includes bulleted guides, you can just grind yours down and clean them up to leave smooth edges, about a 1/4" from the roof of the port seems to be the norm. The throat area behind the seat needs to be opened up to seat size. you should have waisted stem valves on late 3.9 heads but not sure if they have a three angle valve job which would be beneficial.

Kevin

[Darkspeed]

Cheers Kev - The Speedpro book by Peter states 35 at the wheels for a 3.5 for the mods listed so I extrapolated a little. Its still a significant power to labour ratio for a bit of metal tickling

Seats are 3 angle and look good enough to leave alone.

No other secrets then ? - Had a quick search around the net and the board and nothing jumped out which I thought quite unusual bearing in mind the popularity of the engine.

Cheers

Andrew

[Eliot]

Have a read through this if you have a spare month...
http://www.mez.co.uk/TuningTheRoverV8-intro.html

[Darkspeed]

Cheers Eliot,

Was thinking something along more practical lines - I pretty much have all the theory - and just looking for the lazy mans porting secrets to a 500HP Rover -

Cheers

Andrew

[katanaman]

Cheers Eliot,

Was thinking something along more practical lines - I pretty much have all the theory - and just looking for the lazy mans porting secrets to a 500HP Rover -

Cheers

Andrew

Thats easy, just put your hand in your pocket and pull out 10K plus! you cant get any easier/lazier than that

[Eliot]

Cheers Eliot,

Was thinking something along more practical lines - I pretty much have all the theory - and just looking for the lazy mans porting secrets to a 500HP Rover -

Cheers

Andrew

My late father gas flowed heads for over 30 years. Done many top road and bike engines. I inherited his workshop and have all his l die grinders and flap wheels - many of which he made and developed over the years - quite often he would cover them up when he had vistitors to the workshop!
Patience and practice - but there are some easy gains to be had by general clean up and port match.
http://mez.co.uk/mezporting/

[Darkspeed]

Looks like your dad was a gifted engineer and built up a comprehensive workshop over the years - I like the clock

Having a long weekend this weekend and in between stripping the bathroom the carbides and calipers will be whirling about and I will use what I read about your dad as a bit of inspiration.

All the best

Andrew

[Darkspeed]

Well I got stuck in with the burrs and sanding bands and I am quite pleased with the results

A quick measure before hand had the port diameter behind the seat insert at around 33.6mm the seat diameter at 35 mm is now the main port restriction. As the casting "neck" further into the port has now been removed.

The 1.4mm increase in diameter does not sound much but its an 8.5% increase in the port area alone without taking into consideration removing the rather sharp ridges just behind.

I was also quite surprised how restrictive the exhaust port is, the casting really creates a dramatic narrowing of the port far worse than the inlet.

I have an old pair of P6 heads that I will knock a guide out of to see just how much can be opened up with the port clear.

Cheers

Andrew

[sidecar]

Well I got stuck in with the burrs and sanding bands and I am quite pleased with the results

A quick measure before hand had the port diameter behind the seat insert at around 33.6mm the seat diameter at 35 mm is now the main port restriction. As the casting "neck" further into the port has now been removed.

The 1.4mm increase in diameter does not sound much but its an 8.5% increase in the port area alone without taking into consideration removing the rather sharp ridges just behind.

I was also quite surprised how restrictive the exhaust port is, the casting really creates a dramatic narrowing of the port far worse than the inlet.

I have an old pair of P6 heads that I will knock a guide out of to see just how much can be opened up with the port clear.

Cheers

Andrew

Hi Andrew,


Sounds like you've been having fun!

I read in Des Hammills book that you need to be careful when removing valve guides from the heads as the ali can be damaged and therefore lose its grip on the guides. The book suggests the old guides are actually machines out of the head rather than pushed out. I reckon that if you are going to take the guides out of your head and plan to re-use them after shortening them or bulleting them then it might be worth sticking each head in an oven to expand the ali.

By the way the book is worth getting, especially whilst your motor is in pieces. There is a lot of stuff that you can check by following what the book suggests. You could end up with one 5hit hot motor!

Regards,

Pete

[Eliot]

My dad always heated heads up to remove the guides (with a press) - but not for re-using. I think on the last set of rover heads he done for my mate, he machined the guides down with a milling machine.
On other occasions, I do recall him heating them up and just pressing them down flush for the porting work and them pushing them back when done.

Look about halfway down this page to see what he done to the 3.9 heads:
http://mez.co.uk/westfield/

The seats and valves are standard, but he machined them out to make them larger, he said there was plenty of meat on the seat and could be made larger without actually having to fit bigger valves or seats. I think he left about 1-1.5mm of seat width.
This was just a general porting job, not a full-on spec - as that takes longer and cost more £££

The more I look at those photos - the more I fancy getting some heads and having a play with the windys (thats what we called the die grinders)

[mgbv8]

Can someone show me a picture of a die grinder please. I've done a bit of polishing on mine with the big dremmel, and I've used the carbide paper on small drums. The knobbly stone things I have just clog up every ten seconds.
I've got 4 spare heads I want to practice on over the winter.
Ta
Perry

[katanaman]

these are air ones http://www.justoffbase.co.uk/Tool-Shop/Air-Die-Grinders sa671 is like the one I have. The paper drums are ok for smoothing but your better with a carbide bit for the rough work. As you have noticed stones are useless on alloy. http://www.coastaltool.com/cgi-bin/Soft ... E+coastest shows a range of the carbide bits you can get. This is just a quick google by the way I am pretty sure machine mart and screwfix carry all the stuff as well.

[Darkspeed]

I have the Des Hammil book and its quite usefull - as are the Hardcastle books and those together with an old Speedseries book by Vizard and the Speedpro book by Burgess there is some good reference material. I should do less reading and more practical

I am not worried about guide damage as the heads would be scrapped any way, Just looking to see just how much can be removed - I drilled the boss down on one previously an then ground in flush with the port roof and it ended up not dissimilar to the milled bosses shown. Further removal to the extent I am looking at would leave the guide a bit short to control the valve properly.

I have access to a mill so I may well see about taking the seats out a little, be good to get some practice in.

I will get a few pictures taken and posted up if anyone is interested in what can be done with some cheap tools - Must admit that an alloy head was a peice of cake compared to a Pinto head I had a go at previously.

Edit

Just to add I am using the long reach Sealey Die grinder and the SE type double cut burr linked to - I have about a dozen different types that made it real easy for roughing out before using the paper rolls to smooth things out.



Cheers

Andrew

[katanaman]

be careful with the P6 heads as they aren't the same as the later heads which are different again to the newest heads.