MGB Port and Polish MGB head

[LeeMcKee]

Does anyone know where I can find a good resource for porting and polishing a MGB head?
I know I saw some great info on a website while surfing one day and said, "Man, I Really need to book mark this site, I'll need it one day....." guess what?
I'm sure that someone out there has seen the same site and thought the same thing.....and actually book marked it.

It had step by steps and some really good photos.

Thanks in advance All!
Lee
/ubbthreads/images/graemlins/thumbsup.gif

 

[Nunyas]

hmmmm... I guess you're looking for a guide on how to do it. To which, I might suggest picking up a copy of Peter Burgess's book "How to Power Tune MGB 4 Cylinder Engines". No step by step hand holding in there, but he does show the flaws in the MGB cylinder head and what you can do to improve it.

Outside of that, the only links I have for porting/flowing MGB heads is this one:

https://www.flowspeed.com/

hope this info helps in some way

 

[Steve_S]

Peter Burgess, Sean Brown, Huffaker, APT Fast, John Twist. Those are all places that know their stuff when it comes to performance mods on MG engines.

 

[PAUL161]

Hap Waldrop, Acme Speed Shop. Greenville, SC. www.acmespeedshop.com

 

[LeeMcKee]

I agree that Hap is the man when it comes tuning these LBC but, I just wanted some good finished pictures of completed heads. I've got plenty of info on doing the MGB heads but, All I've ever tweaked like this is Triumphs. I just wanted to see how far others go before enough is enough.

 

[jaybird]

Chuck ported and polished the head for Binabox when we were working on her.

 

[PAUL161]

Being around the racing scene for many of my childhood years, (I still have two old racing engines), We almost always noticed that when you port and polish an engine, the results don't usually show up until you max out the RPMs. The work involved to do it right means weighing every bit of the grindings in each port so that you know how much material you have removed. It must be equal in all ports. To do this to a daily driver that is not being raced is a waist of time. I know that it seems that the engine in the normal everyday street driver will run better if the ports are polished and nice and slick inside, but in all reality, for a daily driver, It's only satisfying to the mind. /ubbthreads/images/graemlins/rolleyes.gif PJ

 

[artmck]

What were the results of the porting job? I'm thinking of this on my '74 18V head for street use. I'm looking for a bit more fun in the 3500-5000 rpm range without losing too much in low rpm torque. Wishful thinking?

 

[darrenb]

i always heard that for a daily driven engine, the best thing to do is match the ports of both the manifolds and the head to the gasket. tried to do it myself one, was more work than i wanted to do, and didnt seem to make a bit of difference

 

[jlaird]

Read Vizard, he has all the skinny with charts and stuff. He say porting and polishing is way way over rated and has dino charts to prove it.

 

[Steve_S]

That's surprising. I've heard high praise of the various Burgess heads, including the econotune. And it has always been known that on an MGB, the biggest gain in performance in a single mod is to rework the head. They are fairly restrictive and inefficient creatures.

 

[twigworker]

This subject has been hashed over for eons and IMHO for a street engine driven by an adult the best thing that you can do using a stock cam is to clean everything up, remove all of the obvious obstructions and gross restrictions in both the entire intake track and the exhaust passages, slick up the exhaust walls and leave a mild "texture" on the intake runners. If you want to take the time match the intake and exhaust manifolds with the head and carbs using a gasket and drilled roll pins that might be great too.

As far as specific photos are concerned, I would suggest just using the drawings in the Burgess and Vizard books as general guides and add some other books to your collection that deal with other makes and models. Smokey Yunick's books are down home and dirty but after a few passes through them and other publications you will get the general drift of what things are supposed to look like and can make up your own mind.

There is no real middle ground in my opinion. Either you choose to do a good home handy man clean up like most of us or you hand the stuff over to a guy who really knows what he is doing, like Hap or Sean, that has a flow bench and perhaps even a dyno to get exactly what you want. It boils down to no bucks or big bucks. LOL

Jack

 

[Nunyas]

"Port and Polishing" I think it a bit different from what some of us are thinking about when we want to modify our MGB cylinder heads. I think most of us want to remove the major obstructions to gas flow. In the Burgess diagrams, you can see there is a major choke point where the valve stem enters the ports. The cross sectional area at this point is cut in half (possibly even more) severely reducing the ability to efficiently flow gases in and out of the cylinders.

Some of us may want to actually polish up the ports so they look pretty and maybe even open the ports up to a larger cross sectional area. In these cases, I think it's obvious you need to have a 'hot' cam, carbs, exhaust, etc. in place to fully utilize the larger flow capacity.

For a street MGB, I believe just opening up the choke points will have tangible real world usability even with a minimum of modifications to the rest of "the system".

On the later ZS carb cars, that intake runner is horrible, as is the exhaust manifold. So, 'the system' will have to be modified to fully utilize a modified head of any type, or even a stock head for that matter...

 

[mgbnew]

Jaybird, thanks for the last twenty minutes. Your restoration pictures are great. That is a fantastic album you put together not to mention the car. Ver nice.
Al

 

[DrEntropy]

David Vizard and Clive Trickey are two of the past masters at head mods. /ubbthreads/images/graemlins/thumbsup.gif

Inlet and exhaust runners shouldn't be "mirror smooth" as is sometimes suggested. Laminar flow tests back in the early '70's found a slightly irregular surface is better: it keeps the mixture "moving"... picture water on a glass surface... it will tend to "stick" on the surface. Roughing it up a bit makes for less surface adhesion.

Matching ports/gasket/manifold IS a benefit: the fewer vortices to inturrupt smooth in/out gas (by "gas" i mean intake or exhaust vapours) flow.

CC'ing, "porting" and smoothing out any irregularities in head casting makes a wonderfully smoother difference in the way these engines run in my experience.

 

[rhoamish]

I used to have a '73 with a Peter Burgess head, and several other mods: LCB manifold and freeflow exhaust, 276 (?) cam, modified dizzy, rebuilt SUs with plain butterflies and richer needles, bored to 1850cc with hepolite pistons and a lightened, balanced bottom end.

It didn't exactly set the world on fire, but it felt a lot quicker. It was very fussy about tuning, but when it was running well, it was quicker than a standard BMW Z3 on a long drag up to 110mph(hey, that's not saying much, but it WAS satisfying!!).

The only thing that really embarrassed it was a modified BMW 2002, but I didn't mind that so much: at least he waved.

It sounded lovely, though: in some ways, it sounded better than my BGT V8, which is pretty muted (but certainly quicker).

If I was to guess, I'd put the power of my old 1850 at around 130 bhp. It had to be near that to pull so well at the top end.

0-60 was still pretty poor though: the gearing just didn't suit a tuned B series.

 

[GB1]

I am very happy with the work that APT has done on my 1275 A series BE. They are highly recommended. More expensive then a local shop, but the lil guy roars.

Patrick

 

[Steve_S]

I just got home from APT ten minutes ago. /ubbthreads/images/graemlins/smile.gif