MGB & GT Forum

my engine is std bore, goldseal with liners. what are my options please?

i understand i can bore up to +20 off the original liner,

if i want to go further, does the liner need to be removed, then engine bored large enough to take a new liner of the new required size
or
do you just bore thro the liner enough to take a new liner of the new required size
or
can i just do one of the above but without a new liner?

I assume i need a new liner (as one was fitted in the first place for a reason)

I do have a second earlier engine that I could use instead as I was hoping to go to +40. But I am wondering if i am going to notice an extra 20cc!
G

Boring an MGB engine in pursuit of greater displacement and increased horsepower is chasing windmills. Each +0.010 in overbore only buys you about 11 cc's increase in displacement, which is only about 2/3 of a percent. So going from +0.020 to +0.040 only buys you a little more than one percent increase in displacement and, presumably, about the same increase in power, which is close to immeasurable, especially in a street engine...

Dick

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

X2 on what Dick just said.

I am not sure what your end point is, but there are some basic limits to both the block and what can be done to a cylinder head.

At some point, not too far, it begins to make better sense to seriously consider and engine swap, V6, V8 or some other rendition.

An American Vee motor can be installed with a lot less effrot and perhaps less expense than what it would take to do all of the maximum work on an MG four cylinder. If you don't have simple access to an appropriate Amearican V motor, you could start fishing around over there for information concerning what a similar one of British or Continental make would be.

Jack

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--------------------------------------- Services to Interesting British Automobiles-----------------------------------
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I am in the northwestern North Carolina mountains, right up against the Blue Ridge Parkway. Lawn chairs are in the shop and always time to talk. Drop in any time.

You could easily go 60 over 1850cc with stock style pistons and much larger with custom slugs.1950cc etc.
a good 1850 with higher compression and a decent mild performance cam is a nice start on a slightly over 100HP MGB engine which with that combination is measurable and felt. You are having machine work done anyway,you might as well make it be noticed.

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1957 Series 1 Land Rover electric VEHICLE CONVERSION

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i have a good head machined by peter burgess and a piper mild road cam. to be honest, more interested in low down torque that upper HP.

my mind always says - leave enough for another bore or two but I guess if i am that desperate (or rich) later in life i could install liners.

G

Displacement is torque. Horsepower is a function of torque.
No substitute for cubic inches or in your case cubic centimeters.

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1957 Series 1 Land Rover electric VEHICLE CONVERSION

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Ring up Peter Burgess. I think he likes a 1867 CC engine.
Don't start with a sleeved block if you have an un-sleeved one available.

Block just been inspected and it is not sleeved after all. panic over.
G

Hello Grayham,

Peter Burgess built my engine. He liners all his 1867 CC engines.
Get the liners from him. I think they are made by County and are not expensive.
My engine has got a fast road head, 270 Piper Cam and 1867 CC. The difference
to a stock engine is like night and day.

Regards
Danny

You stated, "I have a gold seal motor with liners" If it is a factory sleeved block, you got a boat anchor unless you can use it as standard bore. Factory sleeves were blocks that were out of spec and sent to local machine shops in the area of the factory and the factory provided them with these cheap ass horrid thin liners, we call them sleeves in the US, they hang the bottom of the bore rather than being properly stepped into the existing cylinders. Most machine shops avoid these like crazy as for as boring, because they are thin and can spin in the cylinder and tear up the cutting bits. I don't doubt you could bore a factory sleeved block at .020", don't know that I would want to vs getting another block. FWIW I don't bore block to achieve displacement most of times I bore block to have newly machined surfaces, I don't approach engine building as , how little can to get by, I approach as what can I do to make it a good as I possibly can,and most of time, that means boring and most of time for me that means .040, I don't want to dick around with the smallest over bore i can, that can lead to a wrong piston choice at time, because you couldn't clean up the bore. At the end of that day the only way I rebuild a factory sleeved engines, unless the bores are near perfect, and I uee new standard pistons in them. It's all about measurements, and never about visual inspection.

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

This is all very useful stuff. Thank you all.

Firstly, as stated above, block has been inspected and in NOT lined/sleeved, which of course is a big relief as i know the factory did that because the blocks were poorly cast.

So, I have standard bore, engine was giving me 150 on compressions dry and 185 wet before i pulled it so i have confidence in it. and i have been driving it for months.

A little back ground may be useful...
1] april 14 - bought car (it's an AUTO, borgwarner35) - i will never take it on a track, just road. gear ratios mean i will rarely go over 65/70mph
2] i will keep the car till i croak, and then my son will have to do the same ! my wife thinks i love it more than her. no comment!
3] head was cracked when bought, I knew that , trickle leak but drove ok, good compressions, no overheating or significant coolant loss. 48G739 engine # with a 1326 head. seemingly 18GB goldseal.
4] stuck K&N plus AAA needles, definite improvement. rebuilt rear, front suspension, GAZ shocks + parabolics on rear, again, great improvement in ride.
5] bought a used 1326 head, had Peter Burgess do 'Econotune' ( http://www.mg-cars.org.uk/peterburgess/page7.html ). planned just to swap heads.
4] oil pressure starts to gets low when hot, pulled the sump, main bearings to copper, pulled the engine. big ends the same.
5] had i done more research (but didn't think i needed to) i might have suspected it was actually an 18V, which it is. valve cutouts, 18V rods/pistons and a blanking plate for a mechanical fuel pump. so either WWW, clausager and MGOC have wrong info (they say 48G739 is 18GB manual only) or i have the wrong engine number plate.
so i could have gone for a more modern big valve head. b*ll*cks.

Soooo, i see this as a one time rebuild , nice to have some extra poke. i idle at about 900 as it's an auto and when stopped in gear it does put more load on engine unless in N.

my thoughts now....

q1] I do wonder if it really matters performance-wise if i go +20, 40 or 60 as we are really only talking about a few cc. comments?
q2] In Peter's book, he says +60 is ok without liners if block is sound, but no bigger without them. what is the benefit to installing liners if i go to +60 (or even +40?) ? they are only £100 a set (county brand) and a bit more engineering work i guess so not a huge cost.. are liners worth it no matter how far I rebore? does it not give a problem if I do decide to rebore again later to go super-sized (whilst unlikely).
q3] Hap - what is the reason you would go to 40 rather than 60?

Daniel, i would really value some info on your build. I have been exchanging a few mails with Peter Burgess and he is very helpful. is your car primarily/only a road car? are you pleased with the way it performs at the low end in heavy traffic? my only concern about going for the fast road piper cam rather than the mild road is what I hear about lumpy idling a sub 1500rpm pull. i think at this point whilst tempting to sell my Burgess head and get a later one for him to do another is probably a step too far financially. I have also seen a few fast road engines on ebay for sale because the owner is displeased with low end pull when on the road.

At the moment my thoughts are +60, no liners, piper mild road.

could i improve on this you think WIITHOUT going over +60?

many thanks,
G

Graham, no reason, I use .040" a lot, big enough to clean it all up, and small enough to have one more go at it. but some customer may want .060" which is the largest size until you get to big bore pistons, which cost more.

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



Edited 1 time(s). Last edit at 2014-09-03 04:48 AM by Speedracer.

40 over ,piper 270 low end grunt still present pulls more like an earlier engine. You already have a decent flowing head .

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LNDRVR4X4.COM
Home of Project "INCARN8'


1957 Series 1 Land Rover electric VEHICLE CONVERSION

FIXITUPCHAP.COM
FIXITUPCHAP INCORPORATED

RD3 Radar/ Electronic Warfare Technician
VIETNAM 1969-1972

when you say piper 270, are you meaning the BBP270 (fast road) or the HR270 (mild road).

seems that piper renumbering gets very confusing sometimes.

G

Burgess has the 270HR
PIPER has the bp270 with a bit more duration and more lift on the exhaust side.
For your use as stated with the BW35 you probably like the torque curve of the HR version.

---

LNDRVR4X4.COM
Home of Project "INCARN8'


1957 Series 1 Land Rover electric VEHICLE CONVERSION

FIXITUPCHAP.COM
FIXITUPCHAP INCORPORATED

RD3 Radar/ Electronic Warfare Technician
VIETNAM 1969-1972