Engine donor selection question for rebuild?

[Bret]

Hey folks,

Ok in my collection process I have acquired two engines which will be the nucleus of my engine build. Guy offered me one for a $150 and ended up giving me two.

The first is out of a 71MGB with everything intact. It has the smog rail and from the looks of it has never been taken apart. The owner said he did hear a ticking noise and suspects it is either a crank or rod bearing. Won’t know for sure until I open her up to have a look see. Worst case I have a complete “big valve”(1.62”) head that will probably get put on Ebay to help recoup some expenses for some of my project.

The second engine is a bit of a mystery. No head & like the first motor there is no engine number tag. The only thing I know for sure is that it is a 5 main block with some parts. Doing a quick inventory it looks like most of the bottom end parts are there. Best I can tell it is missing one rod & piston. The engine has already been bored over +40. It has the crankshaft and a new camshaft of unknown specs? As well as a number of other useable components. Also the three remaining pistons are +40 over pistons.

But I ain’t quite sure what year it is. The identification tag is missing but the only clue I have is the rods are the old angled type. Assuming that they are the original rods – that makes the engine an early 5-main 65 thru 68 (18GB – 18GF). Anybody know of a way of knowing for sure?

Anyway I plan on tossing the pistons unless I can find a lone +40 over piston looking to join a foursome. As stated the rods are the old angled type so they will be tossed in favor of the sturdy strait type connecting rods. Just not sure if I want the press fit or the floating type.

As for what engine to go with right now I’m leaning towards the 71 as it is complete & not such a big question mark. I am going to go +40 over with whatever engine I go with for my project.

Wouldn’t mind some thoughts from the forum?

So what do ya think.

 

[Dozuki]

I wouldn't mind having the pistons that you are going to toss out. I'd pay shipping and what ever. As for the re-build I think I would go with the complete engine. What is the casting # on the head? From that you can look up the chamber size and the year of the head (as well as the valve sizes). Might not necessarily be a 71 head. There are 2 different size heads as far as chambers go. The early heads with larger chambers (and smaller domes in the pistons) and later heads with smaller chambers. Mixing and matching heads/blocks is possible, but you have to take into account compression ratios. I just checked out a head that I got off eBay and seems it was an earlier head than what the car was, so I;m kinda going through this process my self. Engine rebuild in the spring.

-Doug

 

[Bret]

Hey Doug,

The three +40 pistons will only be tossed if I can't fine a fourth one. If I can't they'll be yours.

Regarding the 71 head; I'll try'n look at the casting # number of the head tomarrow. Regardless I'm pretty sure I ain't going to use it but it'd be interesting to know what the chamber cc is in relation to the pistons.

Thanks,

 

[Bob Claffie]

Bret: Why 40 over?? Seems that won't allow for another rebore if something goes wrong later on. You won't feel the difference anyway , between 20 or 40 or even stock. Two or three C.I.s don't amount to a row of beans. Not worth the price of the machine work or parts unless you just want bragging rights. Bob

 

[Bret]

Actually going 40 over isn’t set in concrete just playing with the different numbers. However in Peter Burgess’ book “How To Power Tune MGB 4-Cylinders Engines” he recommends not going more than +60 over while the factory recommended not more than +40 over. In fact British Automotive recommends +20 for their setups. So as you can see lots of folks have differing options on what they feel is best.

But because I am planning on using a new alloy head, with a larger combustion chamber I need to do something. It just happens that the +40 numbers works best for the numbers I am currently looking at. Not going over at all with the larger volume chamber of the alloy head would drop the combustion ratio from 8:1 to about 7.6:1. That is not something I am willing to do. While I might not feel much of a difference going over, I am pretty sure I’d know the difference using the alloy head if I didn’t.

Another option keeping a standard bore would be to bring the "piston to deck clearance" down by decking it. Problem here is you need to make sure that I don't remove (or if I do add) the little relief cut-out for the exhaust valve on the side.

Perhaps some combination of the two (Bore & Decking) will give me the compression ratio I want.

 

[Dozuki]

Bret-

Do you know what the piston to deck clearance is? I though I remeber reading that it was only .040. If this is the case, and new recesses for the valves would have to be re-milled I might consider decking the head instead of the block. I would also consider doing/having porting done. The Aluminum head still benefits from porting from what I've read.

Speaking of reading, I have read the Burgess book. Good book, but definatley leaves me wanting more. Aside from the factory manuals here are some other things that I've found that have some good info:

mgbtunings.pdf - Wish I had a link, but I don't. It's a 28 page pdf file specifically about the naunces of the MGB engine in particular.

Triumph Preperation Handbook, by Kas Kastner - Trimph specific, but has some REALLY good general engine building material.

How to Modify Your Mini, by David Vizard - Again, non MGB specific, but as an added bonus it covers modification to Sprigets. And has much usefull info.

Still need to get:

Power tuning A series engines (Vizard)
Power tuning Cylander heads (Burgess)
Power tuning SUs (???)

I have the Power Tuning Sprite/Midget (Stapleton) - But not nearly as good as the Burgess/Vizard books I've read.

Sorry to interject that, I would love to hear more/discuss your plans for the re-build, like I said mine is due as soon as I can get to it (weather providing). I'm not planning on a re-bore, but definately head work as well as other bits. I don't have to pass emmissions here, so I have more le-way in that area.

-Doug

 

[Bret]

Hey Doug,

No I ain’t exactly sure what the piston to deck clearance normally is or should be. But I get the impression that it could vary a little from one set-up to the next. For now I just plugged in a random numbers (1mm to 1.5mm) along with random volume number (-11 to -16cc) for the piston dish that worked with the known numbers. I then stuck with those for my calculations. That allowed me to see what kind of affect different piston/bore combinations had on the compression ratio. First with the standard 38.9cc combustion chamber then with the larger 42.5cc chamber of the aluminum head.

Thus far the +40 thou over pistons seem to work best with what I have planned to keep the compression ratio in the 8 to 8.7:1 range.

As for your other source recommendations I’ll look into them. Still have a lot of stuff to do before I start the build-up phase. However I am going to have to make some hard decisions soon once I have the engine torn down and a machine shop looks at what I have. Probably going to have to commit one way or the other with my internal components by mid November.

Regarding my Engine build:
Here is a little more on what I have planned. The bottom end is where I am going to make my largest investment. Once I acquire all of the normal rebuild components – pistons & rods etc. I plan on having the crankshaft cleaned up and balanced along with the rods & pistons as a complete unit with an aluminum flywheel. In an effort to help this emissions legal engine revving smooth, fast & freely I am also going to use a set of up-rated valve train components double springs and have a set of roller 1.5:1 rockers to top it off with the aluminum head. Current plans call for a stock early camshaft and use a set double of fully adjustable timing gears. This should allow me better dial the engine in.

Externally to help the engine breath easier I plan on using Moss’s (hopefully soon to be released) EFI kit as a direct replacement for the Zenith Stromberg carburetor, along with a “cleaned up” and hopefully free’er flowing, stock single carb intake/exhaust manifold.

Next I will install & relocate a better inline catalytic converter. Mainly to get it away from the side covers but also to facilitate the use of a bung for a wide band 02 sensors between the manifold & the cat. This should allow me to better tune the air/fuel mixture and should be much better than using a Gunson 02% Analyzer.

Once I’ve completed the engine I plan on installing a 5-speed transmission to allow for a more comfortable ride & road manners at freeway speeds

 

[Dozuki]

Your alloy head has a similar combustion chamber size as the earlier head (~43cc). So, you will have to work out the compression ration in one way or another. European spec cars run 9:1 and do not have a dished out piston in order to get this ratio(?) (hence Burgess refering to 9:1 for a standard engine). This might be a way to bring the ratio up using the head on a later 18V block. However, if you are planning on using the 71 Block I would check the casting # on the head and the dish in the pistons to see if it appears to actually be a 71 since you said that the tag is missing. From the chart, the 71 used a 12H2709 casting # head on an 18V block . Now that is assuming that the engine wasn't swapped for an earlier engine (71 being the first 18V). The 18GB-GK engines used a piston with a 6.2mm dish and a 43cc combustion chamber for a ratio of 8.8:1. The 18V engine used a 39cc chamber and a dish of 16.2 mm for a compression ratio of 8:1. I don't have any specs on a euorpean model, only that the compression ratio was 9:1. Here's the link for the mgbtunings:

www.sterlingbritishmotoringsociety.org/files/mgbtunings.pdf

The head that I have came out of a 71 car, but is not the 12H2709, rather it is a head from an 18G engine, with the larger chamber. I wasn't too happy to find this out as I have an 18V engine. Hence your rebuild interests me. I planned on porting this head myself (and this will increase the chamber some) but it will definately need decking if I don't go to earlier pistons (wasn't planning on new pistons unless necessary). It's not in the greatest shape, the #4 cylander is rough, looks like in got over heated and blew out the piston, crap everywhere in the chamer.... but I digress.
Seems like piston choice would also be a valid way of getting the ratio you want without messing with all the decking, and I may consider this as well if I decide to use this head.

On another note... The single manifold for the B sucks. The design sucks. The Austin Marina also had a single inlet/exhaust manifold. However this was more of a marriage of the single MGB exhaust manifold with the dual pipe hookup and an inlet manifold. Fits a Stomberg 175 or SU HS6 carb. This would seem to be a better manifold, if nothing else than for the exhaust side. I havn't really compared the intakes versus the standard RB B manifold but shouldn't be worse, as the RB B manifold isn't all that great. One minor difference with the marina manifold is that the engine in the Marina actually tilts upward a bit, while the B is parrallel to the ground. Thus the Marina manifold's carb mounting is slightly turned to accomidate this. Not sure what the effect of this would be to a Stromberg or HIF6, would kind of mess with an HS6 tho... And for FI shouldn't matter at all. FI should just have a throttle body to control the air, and the injector for the fuel. No float. Hence this could be a consideration as a manifold. It would almost be like headers. Food for thought =)

-Doug

 

[Bret]

[ QUOTE ]

On another note... The single manifold for the B sucks. The design sucks. The Austin Marina also had a single inlet/exhaust manifold. However this was more of a marriage of the single MGB exhaust manifold with the dual pipe hookup and an inlet manifold. Fits a Stomberg 175 or SU HS6 carb. This would seem to be a better manifold, if nothing else than for the exhaust side. I havn't really compared the intakes versus the standard RB B manifold but shouldn't be worse, as the RB B manifold isn't all that great. One minor difference with the marina manifold is that the engine in the Marina actually tilts upward a bit, while the B is parrallel to the ground. Thus the Marina manifold's carb mounting is slightly turned to accomidate this. Not sure what the effect of this would be to a Stromberg or HIF6, would kind of mess with an HS6 tho... And for FI shouldn't matter at all. FI should just have a throttle body to control the air, and the injector for the fuel. No float. Hence this could be a consideration as a manifold. It would almost be like headers. Food for thought =)

-Doug

[/ QUOTE ].

Ok now you’re talk’in! Yes I know the late B single carb manifold sucks. But while I have some ideas for working with it, I would much rather try to locate one of these Austin Marina manifolds if you think it would work with a 18V engine. By the sound of it, you have some experience with this particular manifold. Where do you think I could find one?

Who knows this might be just this ticket. But the only way to know for sure is to try & bolt it up to a 18V engine and see what happens. Worst case I could always have a adaptor shim made to adapt the ZS 175cd. Should Moss delay in it release of the EFI kit.

I’ll start scoping out ebay for one of these Austin Marina manifolds but if you know where I might find one - do let me know will ya?

 

[Dozuki]

Actually, I have one =) they are not easy to find in the states. Never saw one on e-bay. But, the Marina used the B series engine. It will bolt on. People have used the B exhaust manifolds on Marinas. I'm not currently using it, and I'm not sure if I would in the future, as I've also aquired a dual HS4 setup. It's rusty and would need tanked. Also I can't remeber what fitting there are on the manifold as far as brake servo/vacuum etc. But those aren't that difficult to retrofit (I'll check tomorrow). Not sure how much of a DIY/Experimenter you are, but have you looked into MegaSquirt ECU and a DIY FI conversion. I've thought of this (maybe for My next LBC). If you are interested in this manifold, I can take some pics. And I'd be willing to trade for it or something.

-Doug

P.S. when is the release date for the FI supposedly?

 

[Bob Claffie]

Bret: I didn't mean to rain on your parade. I am usually looking for the most bang for the buck, but seeing you plan on an alum head and flywheel obviously $$ is no object. I agree with the fellow above on the merits of the flat top pistons vs rebore. Admittedly I am much more familiar with Spits but have done some "B" stock rebuilds with pretty good success but not performance orientated. My goal would be to make the engine as responsive as possible while using regular gas. If you make enough 2% improvements you should end up with a bullet. Bob

 

[Bret]

Hey Doug,

Great suggestion for the other EFI setups? However I’ve looked into the MegaSquirt conversion, but I haven’t looked at the DIY EI conversion. In the case of the MegaSquirt all I know is that for the money ($$$) there sure seems to be a lot of work involved to adapt it to the B system. But the hugest issue for me is that it hasn’t been CARB (California Air Resources Board) certified. While Moss has already gotten their kit certified and been awarded their CARB # number for the late model MGB application.

While the EFI is the most logical choice for a late model emissions regulated engine, without that CARB certificate it wouldn’t be legal to run on late model emissions tested MGBs. That said - I don’t really want to waste time or money on something that might cause me more trouble than its worth.

Regarding the Austin Marina manifold? A little rust is fine, but I am defiantly interested if you don’t think you’re going to use it. So yes, if it’s no problem – I’d like to see some pictures if you don’t mind? BTW I guess I should asked this earlier but does the Marina manifold uses an EGR valve.

As for the Moss EFI kit release date? Well they are currently about two years behind from the original release date quoted back in 2003. But I’ve been talking to the guys working on the kit off & on sense then. In fact I just talked to one of the Moss guys yesterday via email and it is still in the works – they’re just shaking out some last minute issues. So I look for some good news on a new release date very soon.

 

[Bret]

[ QUOTE ]
Bret: I didn't mean to rain on your parade.

[/ QUOTE ]
Hey no worries Bob,

I asked for input and you gave it. I was merely pointing out why I was considering a +40 over-bore. But just so you know I am on a budget. I’ve just been collecting parts & ideas for some time now and watching for the best deals. In fact I’ve had a lot of luck on ebay.

I may love my B – but as a Scotsmen money & me don’t part easily. /ubbthreads/images/graemlins/wink.gif

 

[Dozuki]

Brett -

Not sure on the EGR valve. The Marina was only shipped over here in the mid 70s. But, I will take some decent pics (hopefully) tomorrow. I'll even do measurements as well as check it against a manifold gasket I have.

I forgot about the whole CARB thing. That's a bummer. BTW where did you find if specific to the B for MegaSquirt. I havn't looked into it yet, just tossed the idea around in my head.

-D.

 

[Bret]

[ QUOTE ]
Brett -

Not sure on the EGR valve. The Marina was only shipped over here in the mid 70s. But, I will take some decent pics (hopefully) tomorrow. I'll even do measurements as well as check it against a manifold gasket I have.

I forgot about the whole CARB thing. That's a bummer. BTW where did you find if specific to the B for MegaSquirt. I haven’t looked into it yet, just tossed the idea around in my head.

-D.

[/ QUOTE ]

Yep the CARB thing is a bear. As for the MegaSquirt – I never found anything B specific but I did talk to one of the folks over their and they basically said they’d be happy to help me adapt their system to whatever setup I had. In other words – I spend a lot of my money for their universal kit & do all the work and at the end of the day I still ain’t emissions legal. Truthfully they have a great system but it just won’t work for an emissions tested car.

As for the Marina only being shipped over here in the mid seventies. At that time they should have had the to meet some of the US emissions standards as the MGBs did. If you look at the MGBs they sported the single carb Zenith Stromberg setup from 1974.5 onwards. Hopefully the Marina’s had to deal with the same concerns or Bs did back then too.

 

[Morris]

Hey Bret,

You may wish to chat with the guys at Moss before investing in the Marina manifold, alloy heads, etc. As I understand it, the Moss kit does not include an O2 sensor, which may mean that it is only set up to run on a bone stock engine. Changing the head, manifold, and compression will radically change the VE (volumetric effiency) of your engine. Without an O2 sensor, it will be difficult to tune your EFI system to work properly for your modified engine. Also, the brief description of the Moss system I read did not mention anything about its programablity. If the ECU is not easliy reprogrammable, the changes you make to the engine could really work against you.

 

[Mark Jones]

[ QUOTE ]
Here's the link for the mgbtunings:


-Doug

[/ QUOTE ]

I have a much more up to date copy of the document. If anyone is interested in a copy, just send me an email (it's a Word document).

 

[Bret]

[ QUOTE ]
Hey Bret,

You may wish to chat with the guys at Moss before investing in the Marina manifold, alloy heads, etc. As I understand it, the Moss kit does not include an O2 sensor, which may mean that it is only set up to run on a bone stock engine. Changing the head, manifold, and compression will radically change the VE (volumetric effiency) of your engine. Without an O2 sensor, it will be difficult to tune your EFI system to work properly for your modified engine. Also, the brief description of the Moss system I read did not mention anything about its programablity. If the ECU is not easliy reprogrammable, the changes you make to the engine could really work against you.

[/ QUOTE ]

Thus far I don’t think I am going overboard on the engine build – just using more robust components, balancing & freeing up the breathing a bit in an effor to build an engine to a “better than stock” condition. Not really planning on exceeding the basic setup – just pushing the envelope out some. With EFI because of its reliability & stability, I should be get a lot closer to the edge of that envelope.

To be safe however I did ask the folks at Moss if I had anything to be concerned about with the EFI kit for my application (alloy head & +40 pistons). They basically told me that I should ok as it sounds like I'll still be within the initial tune. At this point we'll have to wait & see when the kit is finally released.

While the system is a black box (ie. No adjustments allowed) to meet CARB regulations. I’ve been told that they have taken into account that many of the late model B’s the unit is intended for will not be in pristine condition and various levels of tune. So it’s probably a fair guess that lots of folks have made modifications (both good & bad), and swapped out heads over the years.

I figure as long as I don’t go crazy with my camshaft selection I should be fine.

 

[Nunyas]

Hey Bret, in my quest to find information on relocating EGR valves I came across a site that detailed installing a super charger into a Crown Vic/Gran Marq ( https://www.allenengine.com/cvinstall3.html ). During the installation they have to relocate the EGR valve. In the process of moving it they had to change the exhaust feeder tube. There's only a few steps detailing the relocation of the EGR valve, but seems to be enough information to carry the technique over to a different car. They basically replaced the hard exhaust feeder tube with a flexible stainless steel tube, and cinched the fittings onto the tube with "brass crush collars". The use of a flexible stainless steel tube in this application ought to reduce the complexity of engineering a new intake manifold with EGR fittings. You could probably even go to a cross flow head and still maintain emissions equipment (assuming the fitment of air rails isn't a problem with cross-flow heads).

After reading how "the best supercharger kit on the market" does the EGR relocation bit and what materials the parts are made from, it doesn't seem like to difficult of a thing to do. It seems like it just comes down to having the fittings added to the parts you want to add. At any rate, I feel more confident that I'll be able to do it when finally get around to upgrading my manifolds... Rather, I'm less hesitant to eventually do the upgrades... /ubbthreads/images/graemlins/smile.gif