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MG MGB Technical - improving performance

Hi

I know I will be opening a can of worms with a question that many of you will be totallt bored with because it has been asked so many times but here goes......

I run a pretty standard chrome bumper as my everday vehicle on a typical round trip of 40 miles which includes A roads and motorway driving. Although the engine is running well enough in its standard form, I feel that I could do with a little more zip.
I've bought both the Peter Burgess and the Parker V8 conversion books which both make a good read,but now have a dilema regarding tuning the present engine or just go for a V8 conversion. I am aware that the V8 will involve a lot of work which I am prepared to do, but on the other hand I could well be satisfied with a burgess head, cam change and a peco red exsaust.
What I would like to know from some of you guys who have done the latter especially, is whether or not the end performance justified the cost and time, or if you had you time over again you would have put your energies into a V8 conversion.
I would like folks not to speculate or pontificate, but rather to offer their actual experience. The bottom line for me is I want to continue using my gt as everday transport for several years to come, but with some more sparkle!

gary
G Roberts

Add a buxom blonde to your passenger seat.

That modification will definitely add more sparkle to your commute and relieve you of your boredom.
Marvin Gardens

Gary-
6? X 3? K&N air filters
SU HIF4 Carburetors
Maniflow Intake Manifold
Peter Burgess Fast Road Head
9.5:1 CR
Austenitic 214N Stainless Steel Valves w/ 3-Angle Grind
Nickel-chromium Valve Seats w/ 3-Angle Grind
Peter Burgess Tapered Manganese Silicone Bronze Valve Guides
Top Hat Valve Stem Seals
Dual Valve Springs
Piper 270 Camshaft
Piper Vernier-adjustable Camshaft Drive Sprocket
British Automotive Modified Tappets
Crane Tubular Chrome-moly Pushrods
Nitrided Rocker Shaft
Peco 1 ? Dual Box Exhaust System
Aldon-modified Lucas 25D Distributor
Crane XR 300 Pointless Ignition
Crane 40Kv Coil
Crane Silicone Spark Plug Leads
6mm Dish AE Hepolite Pistons, Matched to within .1 grams
Late 18V Connecting Rods, Matched to within .1 grams
Indexed & Equalized Crankshaft, Grooved and Cross-drilled, Dynamically Balanced
Flywheel Dynamically Balanced

Very Quick, quite tractable, and surprisingly reliable. Worth the money? It is to me. You decide if it's right for you.
Steve S.

For a chrome bumpered car, considering the mods need for the V-8, I would give the Moss Motors supercharger kit a good look. It is claimed to add about 40 hp to a stock, unmodified 1.8L engine. It is supposed to take about 5 hours to install, and can be removed and used (or sold) on another car, unlike most conversions or performane equipment. Not cheap, howvever, at US$2,800 or so.
Andrew Blackley

<<<snip>>>
improving performance
<<<snip>>>
According to all the spam I get, there's a pill out there that will help.
Bullwinkle

Gary,

I replaced the tired engine in my '67 Roadster last year using an 18v block with a fast road cam and a flowed head. The carbs and bore are standard, but the exhaust has a straight pipe where the middle box would be. I am hugely pleased with the results. The car feels fast, and the engine is lively and loves to rev, in great contrast to its previous temperament. The relatively quick and simple mods have made it twice as enjoyable to drive for me. The downside is that fuel economy has taken a beating but that's largely because of wanting to gun to the redline in every gear.

I would guess that the biggest gain comes from the flowed head, as the cam is not very radical. V8s sound fun but I've seen enough "unfinished projects" advertised to know what an undertaking they are, and I'm not sure what they are like as a daily drive.

Steve
Steve Postins

For maximum bang for buck, so to speak, stick to your current engine, but follow the Burgess book on modifications.
Firstly, ensure the bottom end is up to the job. That is, good compression and oil pressure etc. A tired, or almost tired engine, will not welcome extra compression from a new head etc.
I considered both options but for the cost, (approx £400 more than a standard rebuilt engine) I went for a stage 2 head, 715 cam and 1860cc unit. Although still running in, it is noticeably better!
You're obviously not looking at 1860cc as you upgrading your existing block, and a cam change may or may not be an option. However, start with the basics like K&N filters, a flowed head, and a decent exhaust system. Possibly consider electronic iginition. These will improve the driveability in terms of response with the addition of a noticeable power increase, but it still won't blow the 'bloody' doors off, if you get my meaning! Also, for what it's worth use a fuel like Shell Optimax and then have the engine set up on a rolling road after a few tankfuls of Optimax. Phil UK swears by this as it has the highest Octane (98) compared to the super u/l at 97. My experience is the same with Optimax.
Don't forget of course that the suspension and brakes may need upgrading (definitely for V8) but minimal cost changes like a 3/4" anti roll bar (£30 approx) and maybe better pads etc (what price safety even on the standard set-up?)

OK, having said all that, Geoff King took me for a spin in his Roadster with a V8 (3.9L IIRC) and electronic iginition and faster cam (probably about >200bhp) and it was incredible, particularly the sound, never mind the seat crushing acceleration, enough to make me wish I had gone that road.
But remember, a V8 conversion will cost:
extra insurance
extra fuel costs
extra effort compared to upgrading standard B
It will be off the road for a long time whereas the B upgrades are weekend jobs

If the B is your daily driver and your only car, why not consider selling it and buying a factory B GT V8. They seem to be reasonably priced (cheaper than a recent conversion), and will cost less than building your own, possibly less to insure than a conversion and will hold its value better than a conversion IMHO.
Martin

thanks folks for your comments especially both Steves. I think i'm going to go the way of improving my engine. Do the checks are suggested and if all is well go for the Burgess head & 270 cam with the peco exhaust.
If that works out well when the engine is tired rebore a little larger balance etc.etc. That way as you suggest I'm on the road within a couple of days. Have already sorted the dizzy out with new springs, electronic ignition, K&N pancakes, 3/4 anti roll bar, sorted or changed all the front suspension, and in the next couple of weeks will replace rear springs and fit spax shocks, so after that on with the engine..... Thanks /gary
G Roberts

Steve

I have a 1971 B and a 1974 V8 GT. B is great in this lovely weather but is so slow! V8 is a wonderful tourer and sounds great but the fuel consumption is eye watering.

I think you are doing the right thing. There are plenty of V8 conversions for sale, but it is a challenge carry out.

Please let me know how you get on with your upgrade, both in terms of performance and handling.

Regards

Iain Hallifax
Iain Hallifax

G- Good to have you ask for personal over theoretical experience testimonials. Over 3 recent complete rebuilds I have done, the Burgess head continues to be best bang/buck period Vic PS- I'd vote Doug Jackson's 1.55:1 ratio roller rockers on the Piper 270 in the #2 slot.
vem myers

While we're on the subject......I've got:

1798 3main std cam
crank, pistons, rods balanced
lightened flywheel

moderate diy head (18V BIG VALVE)
3 angle grind, bronze guides
dual valve spgs
port matched to mga manifold
throttle shaft flowed
9.5/1 compression
pertronix ign
MGA exh manifold and std pipes

The engine runs great but it seems like it should have more power. It's quicker, but not a great deal faster than a friends 1600. I've tried various different timing set-ups.

Questiions: Could I have too much air going in? I've read that the big valves are more suited for big bore and/or high rpms. I've got a small valve head I could use.

Do I need a different cam?

Is a sport coil going to make much difference?

Thanks in advance.



Fred H

Fred-
Your engine sounds pretty good, but I don't think I would have gone to the bigger valve with the 1798. I have a 1868 and did put in the bigger valve, but not sure it helped much. What is nice is the Piper BP270 cam (which I got from Brit-tek). I also ground out the exhaust ports per Burgess' recommendations. It seems to me that the original design is what slows down the engine more than anything. Unshrouding this really allows it to rev very nicely. I have 9.7/1 and buy the highest octane I can find. No pinging. I also lightened my flywheel to 16# which also helps the revs. I'm going to do an 1800 transplant into an A next so will do something pretty similar. Haven't decided if I will stay with the 1798 or go up to the 1868. Will for sure do similar head mods. To sum up, I would open the exhaust port (especially with large intakes) and go to a 270 cam in your case. How much advance do you run?
Tom
Tom Lennon

Tom, I did take the exh ports out to 35mm or the Burgess ralley spec. I also took out much of the exh valve guide boss. I was amazed at how restrictive the exh ports were! I unshrouded the chambers and - oh yeah - I had the shop equalize the volumes of the chambers.

I'll go out and check the advance today, but I think it's at 28* total advance.

What is your engines highest useable rpm? Mine completely poops-out at 5,000rpm.
Fred H

Fred-
I can add a little more...my advance is quite a bit more, if I understand you correctly. My total advance, (running at 4000 rpm) is more like 40 BTD. My idle is lower of course, but I didn't really check it with vacuum on and off. I figure more is better, as long as you don't get pinging. The BP270 I think makes a real difference. I don't know my top end yet, as 1) the tach is poorly calibrated (have to fix that), and 2)I'm still running in the engine. All I can tell you is it's hard not to push the revs, because it sure wants to go there. Other than the cam, it sounds like we chose similar mods. I was aiming at a 9.5 CR, but my machine shop decked the block more than I reckoned. Tom
Tom Lennon

This thread was discussed between 07/08/2003 and 13/08/2003

MG MGB Technical index

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