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Discussion Starter #1
I bought my first 105, a GT Junior 1600, at the beginning of the Summer and have enjoyed it a lot but the itch for more power has to be scratched!

I've just bought a 2.0L Alfetta engine.

I've read Jim Ks' book as a starting point and I'll probably follow his route as a guide.
My overall plan is pretty standard I think....

HC pistons
Balancing bottom end (installing bush into Alfetta crank also)
Higher lift cams
Maybe Weber 45s budget depending (I have 40s at the moment)
Upgraded valve springs
And then porting and polishing the head.
I've sourced a 105 sump and I'll get a new oil pump to match.

Car at the moment has....

Alfaholics fast road suspension
Alfaholics stainless exhaust
1300 gearbox
Gripper LSD
123 ignition
Weber 40 DCOEs

Ultimate goal is 170 bhp whilst remaining streetable. Is that a reasonable figure, and realistic prospect?

2 subjects that I'm finding tons of info on is valve port sizes and cams.
I'm thinking 45 or 46mm inlet and 38 mm exhaust. And cams I have no idea!

I know there's been a ton of posts on this subject but I suppose every build/rebuild is different.

I'll no doubt post again with more questions as I go along. In the meantime if anyone has any pearls of wisdom, dos/don'ts, pitfalls etc. I'd be grateful to hear. Especially from someone with a similar set up.

Don.
 

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Sounds like you're moving in the right direction. One of the most enjoyable things about the BB is that it's ok ask questions as you go along. Once you get your Alfetta engine apart you should check and see if it has a pilot bushing hole in the rear of the crank. Although I'm told some Alfetta 2 liters were drilled for the bushing, I've never seen one myself. Most likely you'll have to find a machine shop to drill it for you. It's best to find a shop that has experience with Alfa cranks because 2 liter cranks are nitrided and are a lot harder to drill than normal crankshaft.
 

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You don;t need 45's. See my thread about my Spider on the dyno. It not only makes the power that you want, it has wide torque and power bands and is very driveable.
 

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Discussion Starter #4
Sounds like you're moving in the right direction. One of the most enjoyable things about the BB is that it's ok ask questions as you go along.

Thanks. I always enjoy following someone's progress on a project so I thought I'd do the same with mine.

... Once you get your Alfetta engine apart you should check and see if it has a pilot bushing hole in the rear of the crank.
It doesn't have the bushing. So when I find a machine shop (which I haven't yet done, it's harder than I thought where I live) I'll get them to do it at the same time as balancing etc.


You don;t need 45's. See my thread about my Spider on the dyno. It not only makes the power that you want, it has wide torque and power bands and is very driveable.
That's been the one thing I've been uncertain about. The only reason I decided on 45s is that my 40s are not in the best of health. They've been cleaned and serviced but one of them I think may have a damaged mixture needle seat. I've been posting here about it and thanks for your help with that Ed. They're fine at WOT but the progression and idle are ropey.
So I thought to do this properly I'll either need to get my 40s fixed and rejetted, new venturis etc.. Or for just a bit more expense get some new 45s.

So basically it's buy new 40s, fix mine, or new 45s. I know 40s will do just as well for what I want but will 45s do the job as well? And maybe the one advantage they have is they'll give me room for further improvements if I decide later to go that route?
 

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Some people report that 40's give better throttle response but I don't have personal experience of swapping carb sizes. I have 40's because they were less expensive when I bought them and they do the job. There is no doubt that 45's would be better if I was trying to get close to 200HP @ higher rpm and they may give a bit more with my current motor. Alfar7 has encouraged me to try them.
 

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Discussion Starter #6
I think given my options I'll bite the bullet and buy a pair of 45s. At least they're something that will keep their value relatively well.

One more question - as you know 95 RON fuel is the norm here (I think it's the equivalent of 90 in the US) and 98 RON is easy to come by so I assume I can run a reasonably high CR. What figure would you suggest in order to achieve my goal?
 

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It depends upon what cams you are using. I have RJ cams which have good duration at high lift combined with moderate duration at low lift. They are torque cams and they result in high combustion pressures so they are used with moderate compression ratio - 10.6 to 1 in my case. I believe that I have some safety margin with 93 octane and 34 degrees of max advance. I think that I could run a slightly higher CR if I were using "old fashioned" cams such as C&B. I was pleasantly surprised by how easy it is to get this kind of horsepower and torque. The cams and head preparation seem to have the biggest influence on power. I had several different types of cams in the previous engine and I got a big improvement in performance when I switched from C&B to RJ cams.
 

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You do not need bigger valves or 45 carbs to get 170 hp. You do need however good cams and a decent CR to cope.
 

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Discussion Starter #10
What sort of CR are we talking? I'm thinking of getting these pistons....HC pistons

It says they're 10.4:1, does that mean that's the maximum or can they be used up to 11:1 for instance?
And are RJ cams Richard Jennison cams?
 

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Those pistons are claimed 10.4 with a head of standard thickness that has not been decked. I would treat it as a nominal number. I measured my combustion volumes and had the pistons machined to get the required CR. This is important if you are getting close to the limit. The cams are Richard Jemison cams. I think that I have detailed much of this in the dyno thread.

I also suggest that you read through the spare engine rebuild thread to see some of the potential pitfalls in building a high output engine. It looks like his pistons and liners are not properly matched.
 

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Discussion Starter #13
Yes I think I have a lot of reading ahead. Is Richard happy to deal with amateurs like me? If I send him an email with what I'm trying to do.
 

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Richard Jemison
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Engine build

If I were going to build an engine to get no more than 170 crank HP from a basically standard 2 liter and an Alfetta block at that, I would save the effort of machining the Alfetta cranl and just source a good Spider crank to go in it.

If the pistons you want to use are "really" 10.4 to 1 (and they generally are not as high a CR as advertised) I would start by building a head to properly ger the CR to where it needs to be. Mill the head .020 and you should be in the ball park of 10.6.

You can easily run a CR of 10.6 on any pump fuel over 91 octane as measured here in the USA. Just be attentive to the ignition advance curve.
So as a start here`s how I suggest you build the head.
Stock valve sizes with the seats opened as I have shown on the BB. Large valves are a detriment to flow unless you are installing larger intake seats which you are not going to do. ( as that requires welding up the spark plug hole and moving the plug to one side.)
Using smaller exh valves is a waste of money and effort. Again open the seats correctly.

For this level of power, port the inner area of each port. not the outer area.
Use short guides on intake and exh. (V6 12V 3.0 exhaust guides , set 11mm max above spring pan floor and green Viton seals.
Then you can use any cam lift you want after notching the cam follower bores to clear. Don`t start cutting until you have your cams so you cut as little as needed.

Cams are the brain of the engine and control the Valve events which have to me optimized to make any power. Never consider using the same camshaft design on both intake and exh. There are intake cams and exhaust cams. They are designed and paired based on engine build and how it is to be used.

Note, you will need a custom machined 2 liter flywheel that will take the 105 tooth ringgear from the 1600. ( I have one on the shelf lightened & balanced) The early flywheels are a different size and bolt pattern.

I strongly suggest you avoid the bling and excesses pushed by Alfaholics and Jk in his book as they are basically non productive unless you are building the ultimate high RPM race motor, and then only marginally ...
 

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Discussion Starter #16
Thanks for your advice Richard.
Just to clarify something, I was initially aiming for 170bhp at the wheels not the crank. Is this too ambitious without a crazy amount of head work, race spec con rods, sky high RPMs, etc., and then ending up with a potential hand grenade?

Maybe I should get the following straight first...Am I approaching this from the wrong direction? Is it better to have a HP figure in your head you're trying to achieve and then adjust the budget to suit, or to have a set of steps/parts you want to implement within the budget and just see what HP you end up with?

I'm willing to do quite a bit of work to the head but not moving the plugs. Can the intake seats not be enlarged a couple of mm without moving plugs? leaving exhaust valves standard is easy :)
I'll port as much as I can.

I assume I can run a higher CR than 10.4 as I'm happy to use 98 Ron fuel, and I have 123 ignition.

And with regard to cams, I assume you can recommend some of your cams that would be appropriate? Is there a long lead time on these or do you carry stock?

Thanks.
 

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Don

I have had three 2 L motors with RJR cams.

One thinks of great drivability with lots of torque over a wide band.

For whatever reason the one in my Spider really pulled. The one in the Sprint was not fully tuned.

By spring, the one in my Super will be fully tuned, with the intake and exhaust improved.

:cool2::cool2:
 

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170 at the wheels is 200 at the flywheel. That is a race engine.
 

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Discussion Starter #19
170 at the wheels is 200 at the flywheel. That is a race engine.

Yes and that's not what I want so I think I need to temper my expectations a bit.
I'm going to build it to the best I can within my budget and aim for as high power as I can that still keeps it drivable. So sacrificing top end for torque I suppose.

What's a realistic expectation within those parameters?
 

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Richard Jemison
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engine

a good running 2 liter as Alfa built them is lucky to see 90-95 HP at the rear wheels You won`t find a decent drivable Nord or TS making 200 HP regardless of the claims made.

You can answer your own question by just looking at the valve seats (intake) and it`s proximity to the spark plug bore. No room!

Cam choices are dependant on the head build. Build the head for clearances for 12.7mm intake cam and 12.2mm exhaust cams and you can make any level of HP you shoot for as long as you are willing to buy the fuel to support higher compression.
Send me an email re cam choices.
Rj
[email protected]
 
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