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Build Thread - 2L Nord with Twin Spark Head for Track Day/Street Use

22K views 57 replies 16 participants last post by  amb.lawfirm 
#1 ·
All -

My 72 GT is all show and no go at this point. It has a stock rebuild on a 2L Nord.





However, I plan to change that in the near future -- I have a spare 2L Nord block (casting 512 - 1972 or so), crank, and I have a twin spark head on the way here from Europe. I don't plan to do anything exotic here; just want a strong N/A motor for track days and a bit of street driving.

My basic plan -- balanced bottom end, aftermarket rods (MaxSpeeding?), quality forged pistons (recommendations?) with about 10.5:1 or 11:1 compression (something that will live with 93 pump premium if I back off timing, but will usually have some race fuel mixed in), aftermarket camshafts (recommendations?), aftermarket ignition (MSD 6AL box + 8 plug distributor?), and I'm guessing Weber 45's.

I plan to have the head ported. Will tackle it myself if I can't find anyone to do it.

Questions -

1. Recommended block and crank mods - drilling the oil passage in the block, staking the plugs in the crank, right?

2. Recommended pistons and compression ratio? How far can I go on an overbore?

3. Recommendation on camshafts and valvetrain?

4. Recommendation on ignition?

5. Recommendation on carbs and intake?

6. I know the TS head is thicker, so I'll need to either mill the bosses where the studs go through or remove the shorter Nord studs and install TS studs. Will probably leave this to the machine shop. Any other needed mods that I'm forgetting?

7. If you have any recommendations on someone to port the head, please post here or send me a message. I'll do the engine assembly myself.

Almost forgot -- I don't necessarily have a hp goal; just want to make as much as reasonably possible without exotic components and/or twisting it to 9,000 rpm. Having said that, I think 200+ at the crank sounds reasonable.

Thanks in advance for any info!

Scott
 
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#2 ·
6. I know the TS head is thicker, so I'll need to either mill the bosses where the studs go through or remove the shorter Nord studs and install TS studs. Will probably leave this to the machine shop. Any other needed mods that I'm forgetting?
Yes. Fitting a TS head on a Nord block requires in total 17 different mods to make it work.

Oil passages in block vs. oil passages in head, chain gear mods (sprocket position of crank relatively to cam sprockets) and head studs/nuts (including sealing against water!) are the most important.

It's not a plug and play job!
 
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#6 ·
Yes, I know there are a few threads on the subject that I need to review. thanks

Are you using a 75 or a 155 head? There is a good thread covering the differences with you should review.

If a 155 you'll need a manifold block and associated plumbing to bring the radiator upper hose up front. PM me if you need help with that.
Thanks, I'm going with a 75 head.

Its from a 75 TS,I´m selling him the head, Scott, look asap in your mail, I need something from you to ship the head.
Ok, I'll check. thanks

My 8V Nord makes 190 HP on pump gas with good driveability and I am confident that it would make 200 HP at about 6800 rpm with 38 mm Venturis. PM me if you want to talk about it.
I'm familiar with your Nord; impressive research and results. I'm going with a TS, but I'll send a message anyway; I'm sure most of the lessons learned are applicable to both. Thanks
 
#3 ·
Are you using a 75 or a 155 head? There is a good thread covering the differences with you should review.

If a 155 you'll need a manifold block and associated plumbing to bring the radiator upper hose up front. PM me if you need help with that.
 

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#58 ·
question. On a 2 liter nord with 11:1 compression can you run 93 octane. Im looking to buy a new engine for a 67guilia gta build I’m doing and I came across one for sale but concerned that I will need to run race fuel only which would be cost prohibitive. Can you enlighten me on this point. I could send you the specs if your willing to help me out. Thanks. Tony
 
#8 · (Edited)
No, there is absolutely no reason. And a TS is stronger than a 0512 block as well. TS blocks have several differences in casting leading to a much stronger block.

The only reason is you want to spend several hours on extra work for realizing the mentioned and required mods . No advantage, only extra work. Less structural and torsional rigidity included as well.

Drop me a PM if you like.

I've built 3 engines w/TS heads on Nord blocks. 2x 75, 1x 155. Only because the customers wanted that for homologation/historical basic reasons.

I never would do that if I could come across a 75 block easily. Never.
 
#12 ·
#14 ·
This Nord information relates to your prospective TS build.
Jim Steck recently dyno'd a race motor with cams from Paul Spruell. He then swapped out the exhaust cam for an RJ785 from Richard Jemison and made no other changes. The RJ785 made a little more peak HP but it made almost 25 HP more at 5000 rpm. The Spruell cam has longer duration. So beware of long duration cams!
 
#16 ·
#18 ·
Hello!

Quick (dummy?) question:

I've got an Alfa 164 2L Twin Spark (8v) (1995), that I recently messed up the timing chain and bent a couple of valves. I'd like to know if the intake & exhaust valves and valve guides are the same on the Alfa nord 2L TS (Alfa 75) and the newer Twin Spark engines?? I know that the head gaskets are not the same. But the intake and exhaust valves seem to be the exact same thing? I came to that conclusion after comparing part numbers online. I'd appreciate if someone could kindly confirm that for me :D

Thank you!!
 
#19 ·
Hello!

I'd like to know if the intake & exhaust valves and valve guides are the same on the Alfa 2L TS (Alfa 75) and the newer Twin Spark engines?? I know that the head gaskets are not the same.
Yes, they are. Valves are interchangeable.

Head gasket's different by rear length and 1 different bolt hole pattern at the chain cover side.
 
#21 ·
Any progress on the modded head? curious hows it going
Also what spark plug do you find works best for a 75 2L twinspark?
Im running on in my Berlina and feel they are due
 
#23 ·
Steve Hannaford in Washington State is experienced in twinspark head work, including porting. I've found him good to work with.

Progressive Automotive
3036 68th Avenue West # H
University Place, WA 98466
Phone: (253) 565-3633

Lawrence
 
#26 ·
I think Wes uses---or at least used to use---Hanniford for his cylinder head work. I've seen a couple of his heads and he does nice work. Cylinder head porting is definitely a cottage industy, about half science and half art. What's cool about putting a well-ported head on an Alfa is finding that you suddenly have a fatter torque curve and more power throughout the range. It's sorta like getting free hp . . . only it ain't exactly free . . .
 
#28 ·
Not sure if this is the right place to ask. Has anyone fitted the Jim Evans 11.2mm Nord cams from Classicalfa in conjunction with the 2 Litre CA 10.4.1 high compression pistons. I have, via an engine builder in the UK and am having problems getting it set up ( fuel standoff, miss fire and generally gutless to 2500rpm, surges a bit to 4000rpm, then flies to the 7000 rev limit on a 123 usb tune ignition. It been suggested the the 10.4.1 compression isn’t enough for the 11.2 cams. Any advise anyone please.
 
#29 · (Edited)
It been suggested the the 10.4.1 compression isn’t enough for the 11.2 cams. Any advise anyone please.
You need to set up your LCA's different to get a bigger LSA, I guess you're running now way to much overlap.

With 10.4 pistons (in reality less static CR) you're loosing dynamic CR by excessive overlap. Which LCA's are now set?

That's the key to get it run properly, as well as your ignition curve and carb set must be adjusted to different cams than stock.

Those 'Jim Evans' cams are stock CatCams cams, properly set up your engine will run fine and provide WOT from 1.800rpm on with a nice, wide torque band.
 
#30 ·
It been suggested the the 10.4.1 compression isn’t enough for the 11.2 cams. Any advise anyone please.
[/QUOTE]

I doubt your compression ratio is a problem since there are lots of performance Alfa builds running 10-10.4 (more or less) compression ratios. Do you know the lobe centers at which your cams are set? Timing curve and/or max advance? It might be a good idea to talk to Classic ALfa and get their recommendations for cam timing. Even better you could contact Jim Evans and/or CatCams for timing information. Then talk to he guy who built your engine as ask how he set things up. Lots of unknown variables here.

Something else to consider. Are you using the same camshaft design on both the intake and the exhaust side? If so you might consider using a milder cam the exhaust side.
 
#31 ·
This may sound stupid of me but what is LCA and LSA and WOT = torque I guess. Yes lots of overlap. It’s been to two rolling rd firms both are struggling to set it up. I’m talking to a third RR firm who sound as though they are good with old Alfa’s. Thanks for the reply.
 
#34 · (Edited)
As long as you don't know how cam timing has been set it's time and money wasting to consider a 3rd RR. Like Jim and I suspect, you need to know that first.

And when terms like LCA, LSA and WOT are unknown it points exactly to that. Lobe center angle, lobe separation angle and wide open throttle.

Cam timing is all about before you even should consider to try 3rd RR.
 
#32 ·
180OUT. Thanks, yes they’re a matched pair as recommended by CA who sold them to me/ engine builder along with the pistons. Iv just e mailed Cat Cams for info. Unfortunately Jim Evans is quite hard to get hold of as he’s retired but a third RR firm I’ve just spoken to maybe able to contact him. Yes lots of variables, I’m hoping this third firm who do sound as though they know Alfa nords will be able to sort it out. The biggest problem is I’m out of my engineering depth!
 
#33 · (Edited)
If you've been to a rr firm then they will have produced a performance print-out showing how your ignition timing is set up. Let's start there. Once we have an idea of what exactly your running, there is a lot of informed opinion available here on the bb to help get you running right. I wouldn't recommend spending any more money on rolling-road/dyno tuning until you know what you have.

For raference, I'm running an engine that is similar to yours---10:1 (more or less) compression, Centerline 11.1 mm lift x 254 @ .050 duration intake cam combined with a very mild stock 2 liter exhaust cam---9.6 mm lift x 222 degrees at .050. My ignition timing is set at 36 degrees and is "all in" at about 3400 rpm. We used this combination more as an expedient since we didn't have another exhaust cam available and we wanted to get my car out of my friend's shop. This combination gave a whopping 32 degree difference in duration between the intake and exhaust cams. The result, however, was quite surprising providing both very satisfying torque and power across a much wider power band.

Attn: mods. Since this is Scot's TS head thread, maybe we should move this to RJ's thread?
 
#35 ·
Thanks all.

180OUT. is your engine a 2L on Weber 40’s or Dellorto’s. Mine is Dellorto 40’s with 34mm chokes, 50 idle jets, 7772.5 main jets. The chokes where 32mm. Not sure about the idles. Which idle jets and chokes do you have? There isn’t any timing info that I can see on the print out from the RR but I’m reasonably sure it’s 35 degrees. It peaks at 5862rpm 145 bhp and 133 lbs. The cam sheet says lash ramp .20mm. Duration @ 0.1mm 284 degrees. Duration @ 1.0mm 252 degrees. Valve lift / cam lift 11.40 mm. Centreline 108 degrees. Timing @ 1.0mm 18/54 degrees. Valve lift @ TDC 3.65mm. Overlap looks like 18degrees but not sure if that’s 18degrees x 2. If I could work out how to get a picture of the Cam spec sheet on the BB I’d post it.

I spoke to Cat Cams tech dept today who said these cams should start to work at 3000 (ish) rpm, which is what is happening. Maybe I need different cams?
 
#37 ·
I spoke to Cat Cams tech dept today who said these cams should start to work at 3000 (ish) rpm, which is what is happening. Maybe I need different cams?
You don't need to post the data sheet. You do need to know how they are set!!

And yes, the combination of a milder exh cam with an inlet cam works as well better.

As long as you don't know which LCA's have been set in your application (or, even which lift at TDC?) you will only waste time and money.

But what do I know having built a minimum of 30 engines with CatCams in the past decade.....
 
#36 ·
My engine is a 2 liter with Motronic style 10:1 (relative) pistons, mildly ported head (intakes only), Alfaholics exhaust. It has 40mm Webers with 33mm chokes. I don't remember offhand how my jets are set up. I'll have it all written down. . . somewhere. As mentioned my distributor (MarelliPlex) goes to full 36 degrees advance at about 3400. Basically this is a fairly conventional engine build only with a surprisingly good camshaft combination. I've already mentioned the cams we used. I don't think that I mentioned that we timed both cams at 102 degrees. I'll leave any further comments about your hardware to others who are better informed than I am.
 
#39 ·
The carbs are DHLA40, the idle jets are 50 set in emulsion tubes 7850.1 the carb tags say 5233.P rear and 5234.A front, which I believe makes them correct for the engine and year. I’m going to speak to Eurocarbs UK and find out what jetting was standard for the 2L engine when new and see if they have any suggestions on jetting it now.
 
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