MGB & GT Forum

Hey David Kiehna

You had mentioned something about 40 over flat Lotus pistons that fit an MGB????

Were can I get them and what are the applications. I have a GB motor. 1967. Are they for that 5 main bearing engine or only the 18V??



My block was bored to 40 over not too long ago and I was going to put in new rings because I took my car out on the racetrack after a rebuild and didn't really run them in properly, I really got on the engine right after rebuild and since now I'm restoring and putting in a SC, I wanted new rings. I have only run this engine on the track once since the rebuild, so only rings would be sufficient, but since I heard about these pistons, it picqued my interest.

Please advise.

I'm not an expert, but these gentlemen will answer your question right away. I didn't know you had a supercharger. You'll need pistons that won't put you over a 9.0:1 compression ratio.

The UK MG BBS Supercharging Forum!

http://www2.mgcars.org.uk/cgi-bin/gen5?runprog=mgbbs&access=&mode=tlist&subject=115

On the bottom of that page is the "Start New Thread" option.

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David Kiehna- 30 year old British Car Enthusiast!
'74 MGB Chrome Bumper
'74 Jensen Healey 5-Speed
'77 Porsche 911S Targa
'77 Porsche 911 Carrera 3.0 Targa

Run from Lotus TC pistons! I've got a set in a 2.0 engine I built and will never use them again. They use wire circlips to hole the wrist pin in place, which I have had fail on other engines AND are shorter from wrist pin center to piston top by around 0.100" This will require you to remove this much off you block to get normal compression. Once you do this, the block is usable only for these pistons forever. If you have to make a big bore engine there are better pistons availiable. Oh, with Lotus TC pistons you also have to use the proper rods to fit the wrist pins as well

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Lord, please give me patience because if you give me strength I will have to ask for bail money, too

Chris at Octarine Services in the UK can get you a set of 0.040 flat forged Accralite pistons for about 450 Pounds the set with rings. It was too rich for me. I simply shaved my intact head to achieve the same effect.

http://www.octarine-services.co.uk/

email Chris Betson: info@octarine-services.co.uk

http://www2.mgcars.org.uk/cgi-bin/gen5?runprog=mgbbs&access=51642645707008&mode=tlist&subject=71

Bill Mertz, Oakland California, USA, billyballer@hotmail.com

I'm looking to rebuild the motor in my '69, its an 18GH block. I've seen many sources for the standard 8:1 and 8.8:1 pistons in .20 .40 .60 over, and all the 2 liter big bore kits. But I'm looking for a flat top piston that will give me somewhere between 9.5:1 and 10:1 compression ratio. Does anyone know a source for flat top pistons for MGB that would give me a little more compression. I don't want to hog out the block, .20 over should be fine. Also, can anyone advise me on the advantages of hepolite pistons, is the material just lower friction?
Thanks
Bill
Posted 15 October 2003 at 22:50:19 UK time
Les Bengtson, Arizona, USA, ragnar@aztec.asu.edu

Bill. I think Doug Jackson has some custom made pistons that he sells. The two main piston brands seem to be the AE Hepolite and the County brand. Both of the sets I have (one of each brand) are marked "Made in India". One wonders if there are that many factories in India making pistons for obsolete Brit cars or whether both brands are made at the same plant and packaged in different boxes. A physical inspection shows no differences in the pistons, but the oil control rings seem to be different. Les
Posted 15 October 2003 at 23:02:29 UK time
Chris at Octarine Services, Essex, United Kingdom, chris.betson@btinternet.com; http://www.octarine-services.fsnet.co.uk

Bill,

County produce a flat topped MGB piston with 9.5 to 1 CR.

No advantage to Hepolite - just a Brand name - these days produced by Dana.

IMHO County are now better quality.
Posted 15 October 2003 at 23:02:33 UK time
Barry Parkinson, Lakeport CA, parki44@hotmail.com

Bill
There's a company in Australia, I think it is JR that sells flat top pistons of the 4 ring design, up to .080 oversize. I think they will work with either type of rod. They are cast, not forged. I picked up a set off ebay for my engine. I had Crowther racing open up the stock style alloy head combustion chamber for better breathing. The car goes great but is running about a 7:1 CR and I'm pulling it down to replace a cam/lifter that went bad in the typical 3k miles, and while I'm at it the pistons too. The price with rings shipped from AU about a year ago was around $300. US. One of the small MG shops in Calif had a spare set .080 over for about the same price. The shop has a web site and is located in Lafayette (sf bay area) as I recall.
Barry
Posted 17 October 2003 at 05:38:20 UK time
Bill Mertz, Oakland California, USA, billyballer@hotmail.com

I can't find a website for County or Hepolite. Anyone know who distributes them. And how about JE do they make B-series pistons?
Posted 17 October 2003 at 08:41:50 UK time
Chris at Octarine Services, Essex, United Kingdom, chris.betson@btinternet.com; http://www.octarine-services.fsnet.co.uk

Bill,

You won't - they are trade wholesalers only, JE, Accralite and many others make MGB pistons - generally forged ones which are typically four times the price of cast ones.

I can supply any piston you want and the County ones that I use are in my parts shop.

Just e-mail me if you have other requirements.
Posted 17 October 2003 at 08:46:15 UK time
Chris at Octarine Services, Essex, United Kingdom, chris.betson@btinternet.com; http://www.octarine-services.fsnet.co.uk

PS

The flat topped ones would work out at 315 USD including p&p.
Posted 17 October 2003 at 16:21:29 UK time
Steve S., Virginia, USA

Chris-
Are the County brand flat topped 9.5:1 compression ratio pistons of four or three-ring design? Do they use floating or press fit wrist (gudgeon) pins?
Posted 17 October 2003 at 17:42:15 UK time
Chris at Octarine Services, Essex, United Kingdom, chris.betson@btinternet.com; http://www.octarine-services.fsnet.co.uk

Steve,

Its a 3 ring design but I don't know offhand whether it is press fit or floating - my guess would be floating - but I need to check with my supplier.
Posted 17 October 2003 at 18:41:06 UK time
Steve S., Virginia, USA

Chris is the distance between the gudgeon pin and the crown the same as the Original Equipment Hepolite pistons? Is any milling of the deck of the block necessary to establish the 9.5:1 compression ratio?
Posted 17 October 2003 at 19:33:07 UK time
Barry Parkinson, Lakeport CA, parki44@hotmail.com

My reference was to JP pistons not JR.
the web address is www.jp.com.au
Barry
Posted 17 October 2003 at 20:40:25 UK time
Chris at Octarine Services, Essex, United Kingdom, chris.betson@btinternet.com; http://www.octarine-services.fsnet.co.uk

Steve,

AFAIK the piston is the same as the dished piston but flat topped.

I don't use these pistons so can't say for certain - but I can find out next week when my supplier is about!

As I have also said, the OE piston ends up too far down the bore for good performance and I always have the block skimmed - a) to get the peiston 15 thou down the bore and b) to ensure a 100% clean surface, properly finished to guarantee good head gasket sealing.
Posted 17 October 2003 at 20:52:21 UK time
Steve S., Virginia, USA

Chris-
A wise move. Installing a skimmed head onto an unskimmed deck is just asking for a cracked head and maybe even a blown head gasket! Email me after you speak to your supplier next week as this thread will probably have disappeared into the archives by then!
Posted 17 October 2003 at 21:21:37 UK time
Jim, Sacramento, jim@jbsenergy.com

Bill -
British Car Specialists in Stockton (CA) sell the County brand. I got a new dished 8.7:1 set as part of a 1977 MGB purchase. They cost $200 for the set last year. Their phone number is (209) 948-8767. They're close enough for you to pick them up if they can get the flat topped ones you want.
Jim
Posted 20 October 2003 at 06:49:21 UK time
Ron Kluwe, Seal Beach, CA

Bill;

I am running a 10.75 to 1 compression ratio using JE forged pistons. I bought these thru Doug Jackson in a flat top and then had them machined with a slight dish to get the compression ratio I wanted. As a flat top, the ratio for the JE piston is over 12.5 to 1, which is not a recommended street ratio.

BTW, I dished the pistons based on the advice of some old time machinists who used to work for Drake-Offenhauser and built the Indy car engines. The theory is that the dish helps with the flame propagation, producing a more even burn. I figured those old boys knew what they were talking about and the engine I have has plenty of power and torque and runs all day on pump premium. Just something to think about.
Posted 20 October 2003 at 07:53:33 UK time
Bill Mertz, Oakland California, USA, billyballer@hotmail.com

Ron, I don't know if Doug is selling the pistons anymore, he doesn't do rebuilds any longer. Who did the machining on the pistions?
Bill
Posted 20 October 2003 at 13:50:34 UK time
Chris at Octarine Services, Essex, United Kingdom, chris.betson@btinternet.com; http://www.octarine-services.fsnet.co.uk

Steve,

My supplier confirms that these flat top pistons are floating pin with circlips and they have the same compression height as the dished pistons.
Posted 21 October 2003 at 03:49:56 UK time
Ron Kluwe, Seal Beach, CA

Bill;

I had a local machine shop do the work, I just gave them the dimensions on how much dish I wanted.

If Doug isn't selling the pistons anymore, ask him if he will give you the dimensions for the JE pistons he ordered. JE can fabricate the pistons in almost any way you want and pretty much all their pistons are machined to order. The main dimension they are interested in is the distance from the center of the wrist pin to the crown of the piston (in flat form).

The nice thing about the JE pistons is that there is enough material to machine the dish and not worry about making the top of the piston too thin.

Posted 22 October 2003 at 13:42:21 UK time
vem myers, Nevada, USA, vemarooski@aol.com

Gents- My understanding is that Doug has retired from service/rebuilds, and is now in research and sales. I believe he still markets the forged JE in whatever spec you may desire. I believe I was his last rebuild client for the crossflow/Ford Sierra 3 years ago, and I continue my sincere gratitude for the bullet-proof product he engineered and that I get such a daily pleasure out of driving

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1969 MGB roadster "Camille" Pale Primrose, OEM hardtop and vinyl soft top, Nostalgic AC, Prestige Sunfast tonneau cover, four MWS 14" 60-spoke painted wires with 175/70R14 Kumho Solus KH16 tires, OE spare, OE dealer optional luggage rack, M4+OD, balanced and blueprinted (so said my builder) engine rebuilt w/all ARP, OE head 3-angle P&P w/large valves, Moss +0.040, Crane 342-0010 camshaft, duplex vernier timing gear chain, Crane PS91 coil, Crane XR3000 ignition, dual SU HS4 carbs, OE exhaust manifold, HD clutch and oil pump, flywheel lightened and balanced, Hella E-code H4 headlamps, Hayden electric fan, NGK BPR6EIX Iridium IX spark plugs, K&N air filters, Wix oil filter, Valvoline 20W50 VR1, Chevron Supreme. Entire car restored to reliable weekend driver level and ongoing. Hagerty C3+

2012 Mercedes E350 sedan palladium silver/grey leather
2011 Audi A6 3.0T Avant Quattro oyster gray/amaretto and black leather
2006 BMW M Roadster Interlagos Blue/black extended leather & carbon fibre dash 6M 3.2L I6 S54 330 hp