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MG MGB Technical - Sequel to 'engine teardown after 3000 miles'

I posted a thread about 2 months ago about my engine which had been rebuilt 2 years (3000 miles) ago with a crack in the head becoming evident upon first startup. I had just removed the head for replacement, and had some questions since the engine had been consuming large quantities of oil also. The rebuilder said that the rings didn't seat, and that we should simply re-ring it. I had questions about the bores etc about which I received several replies. I thought I would post an update now of what has happened.

I ended up removing the block, and had the bores honed with a machine that does the correct cross hatch pattern. I suspect, as others had, that this didn't happen during the initial rebuild. I reassembled the block with Hastings rings, new tappets (the originals had been refaced and had pits already), and a Payen head gasket. I used Aviation gasket sealant on all oil-tight junctions, and black RTV on all coolant-tight juntions. I made cork gaskets for the front and rear main bearing caps out of an unused valve cover gasket as the ones supplied with the lower gasket set were absolutely the wrong dimensions. I made mine about 1mm larger in each dimension than the space they belong in. I rebuilt the adsorption canister as described in the archives of this forum. I installed the engine into the car, filled with equal parts coolant and water, as well as Rotella 15-40 for oil, and ran the engine for 25 mins at 2500 rpm. Noticed a small coolant leak where the upper rad hose joins the thermostat housing, tightened the clamp and all was OK. Stopped the engine, drained and refilled the oil and put on a new filter (for a Volvo 4-cyl). Retorqued the head studs, and readjusted the valves. Began driving, ran from 35 mph to 55mph in 3rd overdrive with throttle on the floor 10-12 times to bed in the rings as recommended on the Hastings box. Timing was set at 10 BTDC Static, and gave no pinging on Supreme gas. Over the last 100 miles, I advanced the timing little by little, and backed it off at the first sign of pinging. Now have 40 advance at 4000 RPM with vacuum disconnected. No pinging ever.

After 110 miles, the oil level is still right on full (would have been near the low mark by now before the recent rebuild). No oil leaks noted. So it seems like success!

I plan to change the oil/filter/torque head/adjust valves at 500 miles. I do have an autocross on June 1st which I expect will be before 500 miles are done, maybe I should change the oil/filter/torque head/adjust valves the night before?

Thanks to all who responded to the original post. I was starting to wonder whether all the work would pay off, but the car is a pleasure to drive and oil consumption so far is nil.

Erick
Erick Vesterback

Erick

Sounds like things are going well. I would change the oil/filter and other items a few days prior to you autocross and run the car a bit. That way, if by chance you do have a leak or filter problem, it will not ruin your day at the autocross.
Bruce-C

Erik,

Nice to hear the follow up on your success. I do remember the original post.

If you used the diesel motor oil because of the zddp, I think that the newer Rotella and Delo have also cut or removed the zddp. If that was your reason, you might consider Valvoline racing oil, or a new oil that Castrol came out with to address the issue.

Charley
C R Huff

Your local GM dealer has a product to use during breakin. It is called EOS engine oil supplement. I have used it with good success on many XPAG engines without galling at all.
Rotella has been reformulated.
Sandy
Sandy Sanders

Congradulations on your success. Bet you feel much better knowing exactly whats inside your motor and how the work was done.
J Heisenfeldt

Good to hear you got things sorted out with your engine, Erick. Well wear!

Charley, would you mind elaborating on this zddp you speak of, and the advantages of using diesel engine oil? If there's merit in it, next time I change my oil I might use 15w40. It will mean I can readily pick up oil in the local garage if Im low instead of having to wait until I can find 20w50.
Ross Kelly

Ross,

ZDDP (zinc dialkyl dithiophosphate) is an extreme pressure (EP) additive for motor oils that is being removed because of problems it causes with shortening the life of catalytic converters. Currently (Stateside anyway) emission control systems must be under warranty for 5 yrs or 50,000 miles. I believe there is a push to extend that period. This may have already happened. Apparently the ZDDP was causing a problem with meeting the extended warranty provisions, so it is being removed or significantly reduced.

A lot of people believe its removal is causing premature failure of cams and lifters on flat tappet push rod engines (like our MGB engines). Some people believe it is a serious problem, and some believe it is nonsense.

I don't have the wherewithal to make a scientifically based decision for myself, so I decided to error on the side of caution and buy oils that still claim to have zddp. I'm currently running Valvoline racing oils, which claim on the label to have zddp, though they do not state the quantity. Some of the containers state that they are not to be used in highway engines, and some do not. That may be a timing issue with new and old stock.

There was a short window of opportunity when you could by oil for diesel engines that still had the zddp, but as far as I know, those days are now over unless you find old stock.

There is plenty to be found on the subject, some of which has been discussed on this board under the subject heading of motor oil or zddp. You could also do a google search. If you can't find enough info to satisfy yourself, send me your e-mail address and I can send you some info that I downloaded and saved.

However, keep in mind that I don't know if any of this is an issue in the UK.

Charley
C R Huff

Erick,
It is great to know you are back on the road and things are running well in your car.

Thank you for the follow up and letting us all know the results of your investigations and how the problems were traced and solved.

It would be fantastic if more people did this both to help those having similar problems in the future as well as giving some feedback to those offering possible solutions at the start.

Pete.
Peter Thomas

Erick
Hi Mate I have just read through your thread here and it's good to see you up and running again , but i'm really worried about the amount of ignition timing and the effect that is going to have on the life of your new engine. 40 degrees total is too mutch and it will kill your bigend bearings and probably detonate and wreck pistons and rings if driven hard for any length of time on full throttle. 30 deg full advanve is the recommended setting. 32-34deg absolute maximum total advance should be your limit . Any thing over this is trouble with a capital T
Hope this helps Gary
Gary

What comp.ratio and camshaft are you using. Gary
Gary

Wow - the oil thing is hard to keep on top of. Thanks Charlie for keeping me aprised. Thanks also for the pointers on the GM supplement, Sandy.
Gary - when I went online and looked at distributor curves for 1973, it showed 39 to 41 degrees advance at 4000. I believe I got the data from Paul Hunts website. There is no pinging on high octane pump gas. I plotted the curve, and there is 32 degrees at 3000, like others have suggested. Its just that the advance seems to continue above 3000. I had my cam reground to a fast road profile, and the CR is 9.5:1 calculated. Really running nice at this point. With the lower advance that I started with, there was much less power. Of course, I don't want to ruin my new engine!

Erick
Erick Vesterback

Erick,

I wondered a bit about your timing figures too, but I have not run mine up to the point of preignition. So, I only know what I have read, which I thought was about 32 degrees max at 4k. I have heard about preignition occurring without it being audible, though that may have been related to aircraft engines.

One other thing I thought I would mention is that you said you were using a Volvo oil filter. I know that they will fit, but is your filter sitting upside down? That is, would the oil drain out of it when you shut the engine down? If so, you would be better off with a filter that has a good check valve to keep the filter from draining on shut down. I suspect the Volvo filter may not have that, which would result in a delay in building oil pressure on start up.

Charley
C R Huff

Charley. If the "Volvo" filter is the Mann W917 filter, there is no problem. I have used it for a number of years on four cars without any problems.

Les
Les Bengtson

Erick
With your fast road camshaft I guess it has approx. 280deg duration and with that I agree that a higher initial timing is an advantage to enhance bottom end running without any ill effects. But with 9.5 compression I still think 40deg total is too high. On an engine with that compression and a cam of approx that grind I run a distributor with 18deg initial that runs out to 32-34deg full advance and all finished by 3000-3200. This is a really good curve for road or track work and if your cam is a wilder grind than 290 deg the same total advance of 32-34 can be in earlier like 27-2800 I would really give some thought to blocking off the travel at the top end of your distributor' I don't want to sound like Mr doom&gloom just trying to help. Maybee you could ask around at your upcoming autocross to see what others are running , I think i've said enough--too much maybee
Gary
Gary

Hey Gary - no, I don't think you've said too much - I truly appreciate your input. What I read alot on this board is similar to what you say ie 32 deg at 3000 RPM. The cam profile I am running reads like this:

Intake Duration is 220@0.50(270 Adv.), with lobe separation of 108 deg.
Exhaust Duration is 224@0.50 (274 Adv.)
All valve lift is .378.
By contrast, he shows the following for a stock 1971 and up:
Intake Duration is 199@0.50(230 Adv.), with lobe separation of 108 deg, valve lift .378,
Exhaust Duration is 213@0.50 (252 Adv.)

I am not sure what is meant by "Adv." - is that the duration at proper valve gap settings?

I have another distributor - maybe I will see what the curves in it are like. I had Jeff Schlemmer make up the distributor in am using based on my engines specs. I carry the old one around in case the Pertonix on the new one gives up suddenly. The 2 vacuum capsules are different, I ended up using the original because I had pinging with the newer one. I felt that the setup I am using was working quite well, but I don't want to damage my new engine. Come to think of it, with the switching around of pertronix, capsules etc, I wonder if I may not have Jeffs distributor in there right now.

Les and Charley - I thought that the Volvo filters had the valve in them, but I could be wrong. My understanding is that the Volvos have them oriented such that oil drips out as soon as it is unscrewed, as is the case on my engine. I do notice almost immediate oil pressure when I turn the key. The longer the car sits IE 2+ days, the more cranks it takes to get pressure, but at most its 2 or 3 seconds. With the FRAMs I was using before the first rebuild, it took alot longer even if the engine was off for only an hour. Not to mention the other quality issues people have been describing about these filters. Maybe I need to check Ebay and buy a flat of the Mann filters.
Erick Vesterback

Erick,

Adv is short for advertised duration, or degrees that the valve is actually off its seat (regardless of lift) and typically becomes part of the identifying number of the camshaft. Industry seems to have settled on the duration at 0.050 in. lift as a standard method of comparison and it is a good indicator (with other specs) of the performance you can expect from that grind.

Wayne
Wayne Pearson

So when Gary refers to a cam with 280 deg duration, I would think that refers to advertised, because 280 is so far different than the .050 lift number.
Erick Vesterback

Quit true. And not all cams are designed equally, i.e., depending on lobe design, you may "waste" a lot of degrees duration just getting to the .050 in. lift points. So a smaller advertised duration cam can actually be a "bigger" cam (to the engine) if it has more duration at .050 in.

Wayne
Wayne Pearson

Erick
How are things going there. Wayne is spot on with his info. and as he says two camshafts can be advertised with the same advertised duration but the profile of the lobe can be very different. I was talking about advertised duration as that is how most retailers here seem to advertise their cams but as Wayne suggests the 50th lift measurements are more accurate for comparing grinds. For advertised duration I know some manufacturers use seat to seat figures while others use .005in lift to determine their adv. figures. Just looking at the figures of your cam it is a slightly milder grind (but not much milder) than I thought it to be, and it really surprises me that you can run 20deg initial timing without pinging problems. I'm not sure of the octane rating of your Supreme fuel but from what i've read elswhere I take it to be 94 or 95 which should be spot on for 9.5 comp. At that I would have expected an initial timing of 12-13 or maybee 14 would be it without pinging. I'm really puzzled by it all. Just standing back and looking at it in general the whole timing looks about 8-10deg out to what I would expect.--It might just be that your timing marks are out. I have seen harmonic balancers slip on their rubber insert before throwing the timing marks out maybee this could be what's happening. To check your timing marks remove no.1 spark plug and get a screwdriver or similar weapon to feel the top of the piston and slowly turn the engine till you are sure the piston is in it's uppermost position--be as accurate as possible then check the timing marks on the balancer and timing cover, they should be at TDC. It's difficult to get it dead accurate just by feel but should be within a couple of deg. enough to show if there is a problem there or not.
Gary
Gary

After I checked out my advance at various rpms (having advanced to first sign of pinging, then retarded slightly) I rechecked the static value again, and measured it to be at about 14 degrees BTDC. So it appears to me that my distributor provides 26 degrees of centrifugal advance. I have checked the TDC point when the engine was out of the car and it was exactly correct. After running down to the E on the fuel gauge, I put in a half tank of mid-octane gas, and now I notice that at around 2000 rpm, if I open the throttle alot, I get some pinging again. So, I think I really need the premium stuff. Some people here are using regular gas but adding an octane booster to the fuel to save on gas costs. Maybe I'll do that also, but for the fiddling with it, the extra couple of dollars it might cost to just use supreme pump gas might be worth the convenience. Esso shows their premium gas as 91 octane, mid-grade is 89, and regular is 87. But I think in Canada they use a different grading system - I can't ever remember seeing 94 or 95 octane in Ontario or BC. I think Shell offers 93 at some but not all stations.
Bottom line, I think I will run premium fuel, and to be safe, retard the timing a couple of degrees more. Apparently detonation is difficult to hear, whereas pinging although milder on the engine, is easy to hear. I don't want to take a chance that there is detonation occuring without me knowing it. Thanks Gary and Wayne for your help - I have learned a lot of valuable information in this process.

Erick
Erick Vesterback

Erick
Hi Just one little thing that I found on Google Wiki. You are quite right on the different octane ratings of fuel.It appears that the octane rating of fuel here in Aust. is measured differently to US- Can. Australia uses the Ron measurement while you use a combo of Ron and Mon the result of which is a difference of 4 to 5 points for the same fuel. As a result of that the 95 octane fuel that we would use in an engine like yours here is in fact 90-91 in your part of the world. Fuel prices have gone sky high here with Regular91 (86-87 US)being $1.60/litre and Premium 95 (90-91 US)at $1.64/litre. Anyway it's been good talking to you, cheers for now Gary
Gary

Our 87 fuel is $1.339/litre, and 91 is like $1.45ish/litre. The 87 fuel will reach $1.50/litre this summer they say, don't know what the 91 will reach as a result. But I gather Europe has had prices like these for years, so here in North America we've had it good for quite awhile. Athough the US is consistently about 30% or more lower than Canada for fuel prices.
Erick Vesterback

UK prices in Sterling currently approaching the same as dollar prices in America, i.e. about double! I wish we *did* still have prices like yours! I'm old enough to remember buying four gallons for a pound, now it is significantly more than four pounds per gallon.

95RON is standard here in the UK. I found that both pinked badly and ran-on badly after switching from 99+RON 4-star leaded some years ago. The recommendation was to retard the timing, but that increases running temps and badly affects performance *and* economy. I tried Castrol Valvemaster with the octane booster but found it made no difference so now use the Valvemaster without booster (only on the roadster, the V8 has valves and seats suitable for unleaded anyway). Running on super unleaded at 97/98/99RON depending on supplier definitely improves things, although still not as good as the old 4-star, and I have had to fit an anti-runon valve.
Paul Hunt

This thread was discussed between 15/05/2008 and 27/05/2008

MG MGB Technical index

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