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Discussion Starter #1
Hi all,

I thought I’d start a separate engine thread as I’m rebuilding the engine from the GTV.

The engine had been rebuilt by the PO, (camshafts are marked up) compression was good but the few times I had it running it was pretty rough. This was undiagnosed but I wanted to check everything for piece of mind before I put it back in.

As for the fast road side of things, my other cars have all been standard and great as they are in standard form I just fancy tweaking this a bit. I’m not after a race car, it won’t be tracked or raced it’s just for fun blasts around the Peak District. I do want it to idle properly and be able to drive it normally though.

The build started with an eBay purchase of some 12mm C&B cams but reading Jim K’s book and some advice from Steve I’m realising that there’s a lot of work and not to mention expense in head work and other bits and things are already out of my comfort zone despite reading and rereading Jim’s book!

Other planned items that need replacing anyway will be a ClassicAlfa sports exhaust, lightened flywheel and piston rings and bearings if needed.

So my initial questions are:

1. Are 12mm cams overkill for what I’m after. If so what do people recommend?

2. If I do stick with the 12’s does anyone have a ball park as to the cost of the head work as per Jim’s book.

3. With an eye on the budget, with the 12’s are there any other things I’d need to change to get the most out of the head. I know if I’m changing pistons and rods then it’s going to get very expensive.

4. Camshaft specifics aside, are there any layman friendly build sheets/ step by step ‘fast road’ guides that I could follow?

Please feel free to assume my engineering knowledge is very limited so I won’t be offended if you keep things very very simple 😃

Thanks

Simon
 

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Hi all,

I thought I’d start a separate engine thread as I’m rebuilding the engine from the GTV.

The engine had been rebuilt by the PO, (camshafts are marked up) compression was good but the few times I had it running it was pretty rough. This was undiagnosed but I wanted to check everything for piece of mind before I put it back in.

As for the fast road side of things, my other cars have all been standard and great as they are in standard form I just fancy tweaking this a bit. I’m not after a race car, it won’t be tracked or raced it’s just for fun blasts around the Peak District. I do want it to idle properly and be able to drive it normally though.

The build started with an eBay purchase of some 12mm C&B cams but reading Jim K’s book and some advice from Steve I’m realising that there’s a lot of work and not to mention expense in head work and other bits and things are already out of my comfort zone despite reading and rereading Jim’s book!

Other planned items that need replacing anyway will be a ClassicAlfa sports exhaust, lightened flywheel and piston rings and bearings if needed.

So my initial questions are:

1. Are 12mm cams overkill for what I’m after. If so what do people recommend?

2. If I do stick with the 12’s does anyone have a ball park as to the cost of the head work as per Jim’s book.

3. With an eye on the budget, with the 12’s are there any other things I’d need to change to get the most out of the head. I know if I’m changing pistons and rods then it’s going to get very expensive.

4. Camshaft specifics aside, are there any layman friendly build sheets/ step by step ‘fast road’ guides that I could follow?

Please feel free to assume my engineering knowledge is very limited so I won’t be offended if you keep things very very simple 😃

Thanks

Simon
If you don't change your pistons, the original ones will require modifying to give clearance for the valves due to extra lift and duration of the cams
 

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Discussion Starter #3
Ok thanks, that’s pretty much a deal breaker then as I can see the costs really starting to spiral.

Is there a size camshaft thats would give a good balance between performance gains and keeping the bottom end fairly standard and hopefully limiting the head work?

CA list 10.8, 10.9, 11.2, 11.6 then 12.

What sort of gains would I expect from a good medium one and at what point does the head work start getting serious and expensive?

Thanks
 

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Discussion Starter #4
Just read on CA that anything bigger than 10.8 will require modification of the head around the camshaft follower to allow the camshaft lobe to turn freely.
 

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Overlap

Hi Simon

Most discussions about performance quickly turn to new pistons/liners/camshafts/valve springs/flywheels etc – but there’s a lot you can do without spending much money at all.

For a start, the classic Alfanord twin-cam has vernier-adjustable cam timing. By advancing the inlet cam (so the inlet valves open a little earlier in the combustion cycle) and perhaps retarding the exhaust cam very slightly, you end up with more ‘overlap’. This is the period towards the end of the exhaust stroke when both valves are open. At higher engine speeds a bigger overlap allows a greater air/fuel charge to enter the combustion chamber and a generally better gas-flow, increasing power.

A larger overlap gives higher peak power, but at slightly higher revs than before. A lower overlap gives better low-speed torque but the engine runs out of ‘puff’ at slightly lower revs than before. So you can set the standard cams to give the balance you want, between ‘torquey tow car’ and ‘peaky race car’. If you want to retain driveability but add a little bit of extra punch at higher revs, this might be just what’s needed.

The default ‘factory’ cam timing marks provide a compromise midway between the two, and I run mine with just a little bit of extra overlap.

Use new nuts and bolts on the cam sprockets verniers and a new tab washer (picture attached), and torque everything up correctly. Make small adjustments and - afterwards - always turn the engine over by hand (at least four turns of the crankshaft pulley, to be certain) with the spark plugs removed, to be sure you’ve got piston-to-valve clearance at the top of both the compression and exhaust strokes.

If you're not after a race or track-day car but just a bit of extra 'sparkle' in a well-mannered road car, then maybe worth trying this first, before committing to more expensive, time-consuming and invasive options? The big advantage is that it costs almost nothing to do, is instructive and interesting, and is easily reversed if you choose to.

Advice offered freely, but anything you choose to do to your own engine is (of course) at your own risk!
 

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Discussion Starter #6
Spoke to a recommended engineer/engine builder this afternoon who was very helpful. He said the head work, porting, polishing and setting up would be about £800 plus vat with any parts on top which was about what I’d hoped for.

He give some very good advise about the law of diminishing return though in that the more money you spend the smaller the gains.

I’m going to take the head in, he’ll check it then we’ll discuss options and how far to go within budget.

I’d be interested to hear people’s opinions on the different camshaft sizes though to help me make up my mind.
 

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Discussion Starter #7
Thanks Rob,

Thankfully that was the stance the engine builder took, advising that a lot of noticeable gains can be had for a modest expenditure.
 

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If you want some cam knowledge, look here and scroll down.

Scuderia Giallo-How-To

# Camshaft identification - Lift - Description - Perf. rank.

1 105020320000 factory cam 9.10 mm Early 105 type, 1600cc 2
2 105020320001 factory cam 9.60 mm Std 1300 & 1600 cam 4
3 105480320001 factory cam 10.06 mm Euro 2000 & late 1750 cam 5
4 101210320000 factory cam 9.47 mm Std TI Super & Veloce cam 7
5 115010320032 Alfa Grp. 1 10.92 mm Same as CB 47 8L
6 CB47 Colombo & Bariani 11.00 mm Stamped "II". Body tuned 8L
7 CB48 Colombo & Bariani 11.93 mm Stamped "I2". Body tuned 9
8 101210320001 factory cam 10.52 mm Racing 1600 & 1750. Opt. for TI Super 10
9 Alquati A35 11.03 mm Racing 1750, 1800 & 2000. 10L
10 JK 303 Kent Cams 11.96 mm 2000 use with special valve springs 11L
11 Kent Cams ZL1 11.97 mm High rpm 2000 application 11
12 Colombo & Bariani CB 54 11C3 11.30 mm Stamped 11.3. High rpm circuit racing 12
13 Colombo & Bariani 11.3A 11.32 mm Original GTAm cam 12
14 Alquati A35-1 10.95 mm Flat lobe noses for xtra valve high-lift duration 12
And above doesn’t include Richard Jemisons cams, which given the choice I would rather have.....but are £700 a pair.

However, you do appear to be a complete novice with limited funds. So I think you need to be practical with what a) you can afford, b) that you need someone who knows what they are doing, rather than combining skills of various engineers and people c) an understanding of what you will get with what, for what.

Given all that, you should leave your mods to head etc well alone, stick with, exhaust, carbs, and spend decent money on Dyno time with a good carb guy.

I’ve been down the road of mods, and all the rest. And the costs and time do ramp up. So you either dive in or not. Or get someone to give you a hassle free solution, but then you will end up spending 2-3 times more for their skills n services.

So if I were you. Know your limits and stay with the easy gains.
 

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Discussion Starter #9
Thanks, I'll have a read of the article.
 

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The biggest driving difference I found on my car was a big front ARB, no rear bar and an LSD out of a 2000. I managed to get used parts so the cost wasn't huge, but they really improved the drive.

I later had the bottom end lightened and balanced, fitted an Alfaholics manifold and exhaust plus a LHD air intake. Embarrasingly I can't remember what my cams are as they were already in the car when I got it. It was showing 135bhp on Alwyn Kershaw's rolling road so it's a healthy 1750 and revs really nicely.

All these changes were nice to have, but none made the profound difference the anti roll bar and LSD did so if you are watching the budget I would start there rather than expensive engine bits.
 

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Discussion Starter #11 (Edited)
Thanks Richard, that’s good to know.

Thankfully being a 2000 it should have an LSD and I will be fitting a fast road kit together with a full suspension rebuild. Other bits planned are the full sports exhaust, lightened flywheel, sports brake kit, 123 dizzy and I’ve also got a refurbed set of Webers. I’m planning on fibreglass bonnet and boot and possibly plexiglass to save some extra weight. Not decided on the interior yet but i’ll be saving weight where I can.

My budget is £20k but that’s got to stretch to everything. The shell is in the body shop at the moment and will be blasted within a couple of weeks. Depending on what they find under the paint will give me a better idea of how much the body is going to cost then i’ll know how much is left for the engine and other bits, fingers crossed!
 

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Discussion Starter #12
Strip down has gone well tonight, everything came apart easily and all looks in good condition with no obvious concerns. Timing chain was tight and no scoring on the underside of the cover. All the timing marks lined up as expected. Oil was pretty clear with no debris on the plug or bottom of pan. No scoring at all on the clear piston liners, top of pistons look fine.

I’ll get the crank out next time.
 

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The biggest driving difference I found on my car was a big front ARB, no rear bar and an LSD...
+1 for that.

Interestingly, I used to know a former Alfa Course (works race team) engineer, who told me that that's exactly how they ran the track car versions: thicker front rollbar, no rear rollbar. A fast road car is arguably much more about dependable handling and full-range driveability than it is to do with top speed, peak power, 0-60 times or fancy flywheels....so these suspension improvements are indeed very worthwhile - and relatively cheap too.

Removing the rear ARB increases the rear grip, but gives a more abrupt breakaway at the limit of adhesion - so you'll need to have your wits about you! :)
 

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Discussion Starter #14
Some progress on this after speaking to the engineer and CA;

We've decided that the 12mm cams are a bit ott for what I'm after. CA advised that they are a bit outdated now and though there should be enough piston clearance (provided the head hasn't been skimmed before) they don't perform as well with 40's and I'd need 45's. Even with the bigger carbs fuelling can be an issue and performance at lower rev range can be compromised.

After discussing a few options the head build that sounds the best compromise is 11.2 exhaust and 11.6 inlet, 1mm oversized inlet valves with standard exhaust valves. This won't necessitate any serious head work other that matching the ports or additional bottom end work and together with the sports exhaust will give 150bhp for a relatively modest outlay.

I'll strip the bottom end and provided all's well it will be a standard rebuild with new bearings and piston rings. Everything will be balanced beforehand. If the pistons or liners need replacing then CA mentioned this being an opportunity to upgrade to high compression pistons which will take things up to 165bhp.
 

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150 bhp sounds great 165 even better. I know you have a budget and what most people have mentioned is sensible, but your only stripping that engine once, hint hint
 

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Discussion Starter #16
150 bhp sounds great 165 even better. I know you have a budget and what most people have mentioned is sensible, but your only stripping that engine once, hint hint
Haha, don’t you worry I’ve already done the man maths and you’re right it’d be churlish not too!
 

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Haha, don’t you worry I’ve already done the man maths and you’re right it’d be churlish not too!
SimonGTV, I’ve just found your post. I’m very interested to hear how it’s going / gone. I’ve had my 1974 2000 Spider engine rebuilt using CA 11.2mm Jim Evans cams on the inlet and exhaust, 7.2 kgs flywheel, high comp pistons, 123 usb tune ignition, head gas flowed, standard valves, rejected Dellorto 40’s, sport exhaust system. I wanted to keep the intake noise down so haven’t fitted trumpets etc but have altered the inside of the standard airbox. It’s showing 145 hp and 133 lbs torque but has a lot of stand off in the airbox and miss fires when under load below 2500 rpm. The tuning chap says it needs trumpets and ideally longer carb mounts. The overlap on the cams when set to the marks is 18 degrees which seems a lot and will be causing the stand off I expect.
 

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Discussion Starter #20
Hi James,

Sorry but cam overlaps and any associated effects is beyond my knowledge.

Mine is a very similar build so I’d be interested if you do find any information.

My head is back from the shop I just need to put all the bits back together!
 
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