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Engine Rebuild Recommendations

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I have a '76 2002 that I am rebuilding the engine on due to bad piston rings. While I have it taken apart I figured in addition to replacing the rings and gaskets I should do some machining on the engine and replace some of the internals. I want to add some power to the engine without sacrificing too much by way of longevity, so I figured I would ask people on here what they thought of my plans, and if people have any recommendations on things I should/shouldn't bother buying. As for parts I am planning on going with an MLS performance head gasket, ARP head studs and forged pistons (haven't figured out where I'll be getting them from), I am going to replace all gaskets and seals etc. Eventually I plan to upgrade to sidedraft carburetors, a larger exhaust and a 5-speed transmission. Does anyone recommend a place to buy pistons from? Ideally I'd spend less than $800 on them. As for machining I will level out the block and head with a mill, hone the cylinders, and port the head. These are all things I can accomplish on my own but is there anything else that anyone would recommend doing? I am willing to pay a machinist to do something more complicated if the work is worth the money. I will start a project blog sometime soon, but I am just now starting to disassemble the engine. I appreciate anyone's input and suggestions!

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  I'm in the same boat as McKenzie.

How about some of the members sharing their combined wisdom on a Street build. I have a 72 with stock motor, 121 head and 32/36 weber. Looking to rebuild motor in the Mid 9 compression range with 292 - 300 cam and dual sidedraft 40 webers. Planning on 91+ pump gas. Drivers car... What would everyone suggested parts list / needs be? Also any other suggestions while we are in there? Better oil flow etc. I know this topic has been covered in pieces before but how about one place for this common upgrade. Whos pistons, rings, cam, intake, linkage would you use? Which head 121 or E21?  And maybe a little of the why too. Thanks from both of us...


Pls no motor swap or EFI. I like old school analog not digital.


Cheers Girt


Lets build this motor up and give her some twin carb balls.....






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My intentions are exactly the same as Girt, running 92 octane in mid 9 compression range to be a driver's car but still capable of decent performance. I too have a great appreciation for the old school and want to steer away from EFI or an engine swap (saving that for the e28.. eventually).

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There are simply too many variables and opinions to make one ideal setup.  Current engine condition, budget, time line etc.


As for performance parts vendors (who actually make parts and not just resell parts) there are a couple to choose from.  Full disclosure, I am somewhat bias since I work at Ireland Engineering (andrewadams@iemotorsport.com).  But like IE, there are others whose primary function is to supply performance parts like Korman, Metric Mechanic, for example.  There are other performance parts suppliers like us like VAC, BavAuto, Turner, Bimmerworld, etc. who do supply parts, but these old cars tend not their main source of revenue and focus.  We make it our jobs to hotrod and race these cars.  Then there are the garage guys who are working out of their garage tinkering and making small runs.  Then there’s a host of passionate mechanics and race prep shops across the country.  Lastly there’s this wonderful online community.  The best thing about the FAQ is that everyone has an opinion, unfortunately it is also sometimes the worst thing.


My primary advice would be to contact one of us and start a bit of a relationship.  You’ll be getting input from the source, and as it is, we’ve all been tinkering on these cars for well over 25 years.




This list is assuming you've already decided to stick with a carb setup as opposed to an engine swap or fuel injection.

My OPINION is based off of street usability and 91ish octane whose optimum power band would be between 2.5 and 5.5 rpm.   You can go up and down the performance scale, but this setup is a good middle ground for a streetable hotrod. The parts I am listing are the performance parts, a full rebuild would also consist of all the auxiliary replacement parts (gaskets, rocker shafts, etc.).  You would also need to find a shop to handle the assembly and outsourcing of the machine work.  OR if you plan on doing the assembly yourself, then you’d still need to source a competent machine shop.



-292 Camshaft

-Heavy duty cast rocker arms, or polished rocker at a minimum

-Slightly uprated single Valve Springs

-Gasket-Matched porting of the intake and exhaust

-Late Style (09/79 320i and later) Valve Guides and Seals



-9.5:1 Cast Pistons

-NEW rod bolts (or aftermarket rods)


Factors on Carb choice for street hotrod.


Weber 38/38 downdraft:  Streetable, easier to tune, cheaper, provides just as much power as DCOE’s through the street-range powerband


Weber DCOE40 sidedrafts: Higher Cost, more parts, Sounds great, great throttle response, looks great, more difficult to tune, more power at top end.




-Lightened factory flywheel





-Shorty style headers (1.5" piping)

-Long tube headers (1.5" piping)

-2.25" Exhaust system

Edited by AceAndrew
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Thank you! I have looked at the pistons Ireland sells and was considering buying from them. That set up sounds like it would be pretty perfect. You  As for machining I was hoping to do as much of it myself as possible to keep costs down etc. the engine only has 70,000 miles so I don't think it's going to need much machining. The most complicated thing I expect is going to be the porting of the head I have access to a shop with professional grade tools and an experienced machinist. However, if the machining is too complicated I have no problem taking it into a shop and paying to have it done.

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Curious why do you plan to deck the block and surface the head. If they are flat there is no need to do this. Better to keep the meat and achieve compression via pistons. Also, why bore the block if the cylinders walls are OK? Incremental displacement is small, perhaps can just break glaze and re-ring. Or just increase bore by 0.025" for the new pistons, that is what I did on a recent rebuild.


Have you done porting before and do you have access to a flow bench? I did a lot of research and spoke with race engine builder friends before deciding to do some mild porting on my own without a flow bench. The most work was on the short side turns, the stock head had significant ridges there. The rest was light bowl cleanup. While some say "port and polish," you likely know the intake ports should not be polished. They need to be a little rough to energize the boundary layer and avoid net fallout (pooling) of fuel from the air/fuel mixture. Grinding rolls of 60-80 grit are good for the intake. I did polish my combustion chambers and exhaust ports to 320 grit (80-->120-->240-->320). If you are not familiar with porting, read the books by David Vizard and others.


For pump gas paying careful attention to compression/cam combo is key. Mild build would be 9.5:1 and a 292. Others can say if a 300 cam and 10:1 compression would be OK. As said above, depends on where you want the power band. For a bit more torque you could consider stroking with an S14 2.3L crank. Even if sticking with stock 2.0 crank, consider getting the longer 144mm rods for a better rod/stroke ratio than the stock 135 mm rods. [EDIT--you'll need custom pistons with raised pins if using the 144mm rods with a 2.0L crank. No extra cost from IE so that is what I did]


I am not an expert by any means, but I have now spent about five years of research and many $$$ getting my 2.2L race engine built (slide throttle, dry sump, 336 cam, 13.8:1), and I am now building my 2.0 L race engine myself (11.5:1, 316 cam, 45 DCOE). The funny thing is that I am now building the engine that five years ago I was going to have Eric Kerman build for me. He retired, I went with the more ambitious 2.2L project, and now I am learning how to do it myself. I've recently done quite a bit of measurement on valve-piston clearance and will post that at some point.



Fred '73tii (to be 2.2L) & '69 "1602ti" (to be 2.0L)

Edited by FB73tii
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Thank you for all of the suggestions. I am not positive the block/head will need decking/resurfacing, I'm simply worried they may have become a bit warped. And I have not done porting before but I know a few people who have and are willing to help me, and I will spend a lot of time researching it before I go through with it. I would be doing it without a flow bench, and yes! I am aware that a slightly rough surface on your ports helps for evaporation of fuel that sort of thing.  I did not really want to bore the block, just re-ringing would be fine. 9.5:1 and 292 seems like the way I should go, I was also hoping to keep the stock crank as the s14 one runs about $500 if I'm not mistaken? Is the torque increase significant to warrant spending that kind of money?

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The IE cast pistons are a 90mm bore (+1mm) so a rebore would be necessary.


The S14 cranks, 144mm rods would also indicate you would be running forged pistons and some other things. You will have a more grunty engine, but asking if it's "significant enough to warrant spending that kind of money" is relative.

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I got my used S14 crank in great shape for $300, and have seen others for this price as well. Some additional cost to machine the front cover for the larger front main seal and a little bit of block clearancing for the crank. Going from 2.0L to 2.2 L is a 10% increase in displacement, so a rough ballpark would by 10% increase in HP and torque. So if 9.5 and a 292 gave you 130 crank HP, a stroker would give you 143 HP (numbers for example only).


If you are looking for more performance you can also go to a higher diff ratio (though not so good for street with a 4-speed, but a 3.91 with a 5-speed is likely good).


Or, you can take weight out  of the car with lighter seats, lighter S14 starter, lightweight battery, fiberglass hood and trunk, etc. For example, say your car weighs 2500 lbs now. Using the HP numbers above, with 130 HP the weight/power ratio is 19.23. With 143 HP the weight/power ratio would be 17.48. BUT, if you could take 227 lbs out of your car, with 130 HP you would be at 17.48. So, is the cost, time and effort better spent on a stroker or on lightweight components? 


Or course, you might as well do both (***scope creep alert***), along with bigger valves, tube header, crank fire ignition, etc. Then it is a slippery slope to ending up like me--two trailered 2002 track cars, and only a truck for the street!



Edited by FB73tii
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Thx So far for all the comments.

    I like Mackenzie have access to a local shop that will be guiding me thru the port and polish of the heads and will be doing the build with me. If not planning on boring the block what pistons have you guys run? Should I stay with the 121 head or source another for the build? Budget is about 7500$ with great shop rates due to a long relationship with my builder. So what components are worth the investment??? She will get a 5speed and 3.91 LSD once I can find one. Looking at JE Pistons and No gap rings, lightwt connecting rods and pins, 292 IE cam new billet and IE Top end. Possibly IE intake and linkage assembly with 40 dcoes. I have a tii exhaust manifold with IE stainless exhaust. Header better idea? Need suggestions for ignition? Right Distrubitor to look for Tii? or other. Crank fire?  Full balance and blue print by shop. Keep the info coming I'm starting to drool.  Thx Guys.

Edited by GirtAllerton
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I am unfamiliar with the various heads on this engine. Did all of the non tii 2002's come with the 121 head? I think mine says e12 on it. It seems like all of the heads are pretty similar though, I think I'm going to stick with the one I have, the difference still seems rather minimal.

Edited by mackenzie242
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I am unfamiliar with the various heads on this engine. Did all of the non tii 2002's come with the 121 head? I think mine says e12 on it. It seems like all of the heads are pretty similar though, I think I'm going to stick with the one I have, the difference still seems rather minimal.

Search on "121 E12 E21". It may not change your decision, but it might make the decision more informed. It seems you're very interested in getting this engine rebuild right, so why not at least understand where your E12 head stands?


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  • 1 year later...

Where did you end up going for your machine work and how far along is your build? Just read through this as I'm in the same situation as you (and the same city) and doing a little more research while I'm waiting to hear back from the machinist. When I hear if everything checks I can make the final decision on parts, but I'm guessing it'll be very similar to what was suggested by Andrew above. What direction did you decide to go in?

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