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Anything new post Burgess in heads and pistons?

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tvrgeek Avatar
tvrgeek Silver Member Scott S
Hillsborough, North Carolinia, USA   USA
1965 MG MGB
Just wondering, we all (should) know the details of the Burgess street head. I was wondering if any further advances had been made? Specifically in chamber shape to promote easier ignition and maybe, just maybe leaner idle. Had anyone developed any alternative to flat or dish top pistons? All still full skirt? Street only, not interested in race compromises.



Cogito ergo sum periculoso

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Speedracer Avatar
Speedracer Platinum Member Hap Waldrop
Greenville, SC, USA   USA
1967 MG MGB Racecar "The Biscuit"
There are two manufacturers of off the shelf pistons for the MGB engine XRN/County, and AE/Nural. I don't know how much more burn friendly a conical dish could be be. Flat top pistons are not really a good option for street engines and totally u-usable for the 18V, which why the only US vendor for these quit selling them, too many buying items like this simply assuming if they sold it, it was OK to use. Truth beit, there are many items vendors sell/offer that are not good idea, oversized exhaust valves come to mind. OH none of the off the shelf pistons offered for the 5 main engines are full skirt, all of them are slipper design, and have been for decades.

I never put much faith into trying to reshape the MGB combustion chamber, all attempts make it larger, it's too large as it is, to be honest with you, there are real gains there. Porter do to impress you because you can see in assemble head, to see the real magic in a port job, you need to remove the valves. On my street port jobs, I leave the combustion alone, because it a waste of time to do otherwise, and not place to seek decent gains. On my upper level street and race heads, the goals is simple, smooth it out a bit, but do so in a manner you remove the least amount of material, as to compromise how much I have to cut head to hit my CR target. It's pretty simple most street folks want large gains for little investment, the combustion chamber is not a place that will net that. It looks cool, but does very little, it's one of the deal here you don't mind spending the money for a small gain.

Most should spend more time tuning their cars to run leaner, as most of these cars are tuned horribly rich, you don't need reshaped combustion chambers to achieve this. I built a 1900cc MGB engine, with fully ported 1.7" intake head at 10.0 to 1 and was able to flirt with 30 MPG, trust me it can be done, and it would immediately fire up when you turn the key, you can haul ass on twisty roads, or drive thru town at 3500-4000 rpm, and do both well.



Hap Waldrop
Acme Speed Shop
864-370-3000
Website: www.acmespeedshop.com
hapwaldrop@acmespeedshop.com


Member Services:
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HiPowerShooter Avatar
HiPowerShooter Gold Member James Booker
Lake Winneconne, WI, USA   USA
1973 MG MGB
As Hap said, most of these cars already run WAY rich and I was able to also see very good results using 1.70" tuliped intakes with a 5 angle grind and stock 1.34" exhaust valves with a radius cut, doing a little re-shaping. I bumped my CR up to a calculated 9.7:1(using shallow dish pistons/shaving the head) and have no issues running regular 87octane whatsoever. What I found did NOT work (street) was going larger on the exhaust valves(1.50" ) and opening up the ports too much/port matching. Lost low end which I suppose wouldn't be an issue if I were just constantly winding it up but everyday driving suffered noticeably. So did the idle.

Oh...and I "rifle" cut the intake runners. Basically I took a "hog" and worked outside-in using a spiral cutting motion. Seemed to slightly improve the intake flow numbers over the OEM surface finish.

It's nice having a full machine shop to "play" in!lol! Even IF I'm just winging it sometimes.

I've ruined a couple of castings but all in the name of improvement!



"One test is worth a thousand expert opinions"--Alvin "Tex" Johnston...Boeing test pilot.

73 MGB. Tires: Round, black, hold air. Oil: Sometimes old, sometimes new...always slippery. Oil filter: Yellow, usually full of oil. Carbs: 2 SU HIF. Distributor: Yes. Headlights: Not that bright but bright enough. A bunch of other stuff most cars have but not really important enough to itemize. Oh, wait...it has a cool sounding exhaust with stickers on the chrome tips. Really slays the ladies...



Edited 1 time(s). Last edit at 2018-04-14 09:52 PM by HiPowerShooter.

ingoldsb Avatar
ingoldsb Silver Member Terry Ingoldsby
Calgary, AB, Canada   CAN
1971 MG MGB
I suspect that compression ratio is the biggest factor, or at least a major factor, in improving the performance of these engines. I've always wondered why the pre-1970 era MGBs had only 8.8:1 compression. It seems to me that would have been a near zero cost improvement in performance. Perhaps the fuel (of the era) in Europe didn't take kindly to higher compression?



Terry Ingoldsby
terry.ingoldsby@DCExperts.com

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benhutcherson Avatar
benhutcherson Gold Member Ben Hutcherson
Louisville/Frankfort, KY, USA   USA
1970 MG MGB
In reply to # 3716964 by ingoldsb I suspect that compression ratio is the biggest factor, or at least a major factor, in improving the performance of these engines. I've always wondered why the pre-1970 era MGBs had only 8.8:1 compression. It seems to me that would have been a near zero cost improvement in performance. Perhaps the fuel (of the era) in Europe didn't take kindly to higher compression?

I don't begin to understand the mechanics of it, but I know that the off-the-shelf combination of mating a factory high-compression bottom end with a low-compression head(small chamber) gives a very workable 9.3-9.5:1 and a nice "butt dyno" difference. I have just that in the form of an 18GH block(with original pistons) and 12H2923 head.

ingoldsb Avatar
ingoldsb Silver Member Terry Ingoldsby
Calgary, AB, Canada   CAN
1971 MG MGB
Quote: I don't begin to understand the mechanics of it, but I know that the off-the-shelf combination of mating a factory high-compression bottom end with a low-compression head(small chamber) gives a very workable 9.3-9.5:1 and a nice "butt dyno" difference. I have just that in the form of an 18GH block(with original pistons) and 12H2923 head.

Exactly - so why didn't the factory do it? After 1972, the answer was the need to meet emission laws, but prior to 1970 they could easily have run 9.5:1 compression ratio and probably picked up 10 HP.



Terry Ingoldsby
terry.ingoldsby@DCExperts.com

ohlord Avatar
ohlord Gold Member Rob C
North of Seattle, N.W., USA   USA
1957 Land Rover Series I "EYEYIYI"
1971 MG MGB
1971 MG MGB "Bedouin 2"
And with iron head forced owners into using sunoco 103 or esso HP
That would limit the market as a street gas friendly small cheap fun sports car.



"I'm a long way gone down this wild road I'm on
It's gonna take me where I'm bound
It's a long way around"



"These are the days that must happen to you"

RD2 Radar/ Electronic Warfare Technician
Vietnam 1969-1972

tvrgeek Avatar
tvrgeek Silver Member Scott S
Hillsborough, North Carolinia, USA   USA
1965 MG MGB
So, sounds like nothing new. Usual smarts is to remember street, not kiddy racer. Just thinking about my fall project. Sounds like nothing new. Clean up, de-burr, good valve job, a touch of compression. Just asking as sometimes we learn new things over the years.



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Speedracer Avatar
Speedracer Platinum Member Hap Waldrop
Greenville, SC, USA   USA
1967 MG MGB Racecar "The Biscuit"
In reply to # 3717079 by tvrgeek So, sounds like nothing new. Usual smarts is to remember street, not kiddy racer. Just thinking about my fall project. Sounds like nothing new. Clean up, de-burr, good valve job, a touch of compression. Just asking as sometimes we learn new things over the years.

That's not what I said, there is value in a port job, 8-10% gain in power, just not that much of it in a combustion chamber. The magic of a port job is in the bowls, when you see a shiny ported head with valves in it, you cannot see the magic, here's the magic, which is a little more than de-burring, being able to do this didn't happen overnight, it involved thousands of hours of research and hands-on practice. Most folks who to do do this for themselves, don't do the research and tend to overlook the area that net the most gains, then there is hours and hours of learning how to make the die grinder do what you want it to do, and having all the supplies to help you that.

As for CR, I've built more 10 to 1 street MGB engine than I can count that run fine on unleaded premium.



Hap Waldrop
Acme Speed Shop
864-370-3000
Website: www.acmespeedshop.com
hapwaldrop@acmespeedshop.com



Edited 2 time(s). Last edit at 2018-04-15 09:25 AM by Speedracer.


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tvrgeek Avatar
tvrgeek Silver Member Scott S
Hillsborough, North Carolinia, USA   USA
1965 MG MGB
I can see the difference around the guides for sure. Not something done casually I understand. Efficiency does help at all RPM, even though I am not that concerned with max HP at redline.

I did a TR-6 head following the old comp prep guide many years ago. No where near as precise as the 1500 Spit head I had Ladd do for me, but it did seem to work pretty well. Then I decided 10 more HP in a TVR was not going to cut it and put in a 300 HP 5.0. smiling smiley By the time I was finished, I realized my days for overpowered monsters were long gone. It is on the road somewhere in Pa. I think.

Many years ago in the Bug world, the fad was "anti-revision" exhaust ports. Basically a bevel on the header. The idea seems to have gone away. I once say intakes where the large radius was dimpled. Again, probably an idea not worth it.

The most exotic LBC head I have seen was done by Wally Hicks for a friends 2500. It used smaller Datsun exhausts and bigger Chevy intakes. It was about a year of off and on work. He ran crazy compression and had to run Cam-2. Gad did it scoot. It ran well over 200 HP and still had the long stroke TR-6 crank in it with the low redline. He ran HS-8 carbs. I think I spent less on my new 5.0 than he did on the head and it was lighter.

Anyway, just thinking about fall projects as I have a good used big valve head in by shed. Getting the dash back in today and maybe get it started. Every step is a fight as I changed everything, like routing the heater cables so now I have to change their length. Same with the choke.



Cogito ergo sum periculoso

dickmoritz Avatar
dickmoritz Platinum Member Dick Moritz
Philly 'burbs, PA, USA   USA
Many years ago in the Bug world, the fad was "anti-revision" exhaust ports.

For those who may choose to Google this term for more info, it's actually anti-reversion, not anti-revision. Here's a good explanation..,.

http://www.hotrod.com/articles/ctrp-1011-race-engine-reversion/

Dick





In reply to # 3717192 by tvrgeek I can see the difference around the guides for sure. Not something done casually I understand. Efficiency does help at all RPM, even though I am not that concerned with max HP at redline.

I did a TR-6 head following the old comp prep guide many years ago. No where near as precise as the 1500 Spit head I had Ladd do for me, but it did seem to work pretty well. Then I decided 10 more HP in a TVR was not going to cut it and put in a 300 HP 5.0. smiling smiley By the time I was finished, I realized my days for overpowered monsters were long gone. It is on the road somewhere in Pa. I think.

Many years ago in the Bug world, the fad was "anti-revision" exhaust ports. Basically a bevel on the header. The idea seems to have gone away. I once say intakes where the large radius was dimpled. Again, probably an idea not worth it.

The most exotic LBC head I have seen was done by Wally Hicks for a friends 2500. It used smaller Datsun exhausts and bigger Chevy intakes. It was about a year of off and on work. He ran crazy compression and had to run Cam-2. Gad did it scoot. It ran well over 200 HP and still had the long stroke TR-6 crank in it with the low redline. He ran HS-8 carbs. I think I spent less on my new 5.0 than he did on the head and it was lighter.

Anyway, just thinking about fall projects as I have a good used big valve head in by shed. Getting the dash back in today and maybe get it started. Every step is a fight as I changed everything, like routing the heater cables so now I have to change their length. Same with the choke.



Errabundi Saepe, Semper Certi
(Often wrong, but always certain)

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HiPowerShooter Avatar
HiPowerShooter Gold Member James Booker
Lake Winneconne, WI, USA   USA
1973 MG MGB
Go find a copy of David Vizards "Tuning BL "A" series engines" and Peter Burgess's "How to power tun MGB 4 cylinder engines". They're probably the best "One stop" reads for getting a pretty good idea of what does and does not work. Should be required reading for those wanting to go more than skin deep...

Yeah, the real benefit is had in the bowls and ensuring the proper shaping is done. And there is "too much of a "good" thing" meaning "more"(removed) doesn't equal better. From what I've learned on the flowbench although it's very beneficial to open the intake however the airflow "in" is relatively uniform in velocity. Due to the characteristics of dynamic combustion, the exhaust side can see pretty radical velocity change from just past the valve to the exhaust manifold gasket. So you must try and shape both low velocity and high velocity air at the same time. THAT is where the experience pays off. I found that there's quite a bit of excess iron to work with unlike some other heads which come through the shop pretty much already at their minimums as well. I've yet to punch through to the water jacket...the same can't be said to another I ruined(practice though) one night!lol!



"One test is worth a thousand expert opinions"--Alvin "Tex" Johnston...Boeing test pilot.

73 MGB. Tires: Round, black, hold air. Oil: Sometimes old, sometimes new...always slippery. Oil filter: Yellow, usually full of oil. Carbs: 2 SU HIF. Distributor: Yes. Headlights: Not that bright but bright enough. A bunch of other stuff most cars have but not really important enough to itemize. Oh, wait...it has a cool sounding exhaust with stickers on the chrome tips. Really slays the ladies...


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tvrgeek Avatar
tvrgeek Silver Member Scott S
Hillsborough, North Carolinia, USA   USA
1965 MG MGB
Quite correct. I stand corrected. Many years ago. So, this link describes it, but nothing about the fad of a bevel on the header. Fad I guess, going the way of magic turbine carb spacers and magic, well anything.

The porting job I did that really worked was on the TR-6 water pump. It's no wonder they overheated. Casting flash almost blocking the port, the studs sticking right into the middle of the flow, and the turbine itself with almost no "tooth" and set too far from the back wall. A bit of grinding and an Audi impeller they would actually pump water. The MG one looks a lot better. At least in the pump, you did not have to make two the same!



Cogito ergo sum periculoso

gray Avatar
gray Graham Moore
CAMBRIDGE, CAMBRIDGE, UK   GBR
Hap

I would very much like to hear more of your build approach for a 30mpg MGB.

are we talking trade secrets? just wondering what the big avoids are - 270 cams for example? twin SU? and where the mods SHOULD be targeted.

i realise that fibreglass here, aluminium there will always help, but diminishing returns usually determines that most of the gains come form well targeted changes. so i am thinking street car, street cost.

so may threads talk about power, but not many about economy.

in fact - i shall start a new thread. 30mpg MBG.

G



Edited 1 time(s). Last edit at 2018-04-15 04:04 PM by gray.

tvrgeek Avatar
tvrgeek Silver Member Scott S
Hillsborough, North Carolinia, USA   USA
1965 MG MGB
Step one: solid ignition. You get better mileage if you actually burn every charge. Gear ration maybe next. Even with a stock engine, I wish we had a 3.5 rear.

Yes I have Vizard's book on the B series and used to have his A series book. No question about his expertise. My question for the forum is if anything much has changed in the 20 or so years post. Kind like what has changed in TR land post Kasner. Not much, but some.

Got my dash back in. Woo Hoo! Next to get those last two bolts right above the steering in. The guys who built them must have had small hands. Then double check everything and it should be running.



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