Race Engine Forum UK

Hi Guy,

I am looking at buying a set of adjustable cam pulleys for my 1974 124 spider. It has a 2 litre engine with twin 40mm DCOE Weber carburetors. The cams are from a Mk1 Superbrava and the pistons are hi compression Mahle brand. Could you please provide me with the details to set up and adjust the cams to get the best out of my engine?

I also have another question. What is your opinion of the electronic block mounted Bosch distributor from the Lancia Beta? I have one fitted to my car and haven't had any problems with it. Some say the Marelli version is better. Any advice you can give me will be greatly appreciated.

Best Regards
Angelo

I would keep this as simple as can-be. I would copy the cam timing off the original pulleys. It will be perfectly suitable and likely 110 deg inlet and ex. There is no such thing as 'perfect cam timing' by the way. Engines will run with anything from 100 to 113 deg full-lift timing. With OE (Fiat standard) cams there is little to be gained by changing it to something, er,'more radical'.

Fit the original camwheels on the end of the cams - with the dowels located in the pulleys - and with the bolts just tightened a little. Use them to set the cams on their TDC positions - they have holes in them which should align with the steel pointer on the cambelt cover bracket at TDC (cyls 1&4). On an engine of that year the inlet camwheel may be marked 'A' and the ex 'S'. If they are not then let me know because there is another way to ID the right pulleys.

**** Make sure you don't bend a valve doing this - have a look at where the valves are in relation to each other before turning the cams*****

Mark the cams relative to the camboxes as you can see below. These are the positions the cams should be at TDC cyls 1&4 when the cambelt is fitted. Once you have marked them you can fit the adjustable camwheels and bolt them up hard to 83lbf ft. Thep purpose of adjustable camwheels is simply to allow the belt teeth to line up with the pulleys at TDC.

Timing by this degree method does not require the cams to be 'shimmed' ie: the timing is not affected by running clearance. What you do need is a TDC pointer that tells you reasonably accurately when pistons 1&4 are at TDC (top dead center) and there is an article in the GC Virtual Workshop section of this site on that at:

http://guy-croft.com/viewtopic.php?f=3&t=104

The cam timing method I have described is used by me sometimes though only if the cams are being set at OE standard timing. There is a more 'complicated' way of 'dialling-in' cams and you can read the attached GC 'How To' for more detail - a time-consuming method I have to use several times a week.

As for the ignition system the Bosch is the more reliable of two, apart from cable fracture I have never heard of one breaking down. That said one must have the right coil and the ballast resistor.

Hope this helps and feel free to ask for more help if you need it.

G

Hi Guy,

This will be the perfect job to do this winter down under! It looks like I'll be sourcing another head to do the job now that I know the head has to come off the block to do the cams properly. I'd rather not risk bending a valve with the head on. It also gives me the opportunity to build another higher specification head.This way I can keep on driving until the new one is ready to go on.
In my first post on your forum I asked about the modified 130TC cams I acquired some time ago. I'll use these these cams to build a head with the adjustable cam pulleys.When it's done, I'll have have a look at the jet sizes etc on the DCOE Webers and let you know what I have so the carburetors can then be sorted to suit the new cams.

Best Regards
Angelo

Hi Guy,

I have a few more questions. Now that I've decided to build a new head for my spider, I need to source another head so I can use the new parts I've acquired over the last year or so. I'll be keeping the one on it now as a spare. Here in Australia, the most common are the 2 litre heads from the 131,132 models. You can still find decent 1.8 litre heads well. Is there much difference between the 2 litre and 1.8 litre heads?
I do have a complete 1800 engine that I blew up in an AC 124 Sport years ago but haven't pulled apart to access the damage. The head might be usuable if there is no damage.I've been told by people in the trade that the 1.6 litre head from the Regata is a good one to use as the ports are bigger than the 2 litre versions. Is this true or false? At the end of the day which head would you recommend to use for the build?

Here is a list of the new parts I have in addition to the 130TC cams we have already spoken about.
Abarth exhaust valves part number 0513259
Abarth intake valves part number 0413217
Federal Mogul TRW valve springs part number 120-06194
Guarnitauto head bolts part number 700506-1010

I'm sure the Abarth valves are fine to use but I'm not sure about the rest of the parts. I use the car on weekends for drives into the countryside with the occasional blast on the freeway so there is some hard driving but nothing too unacceptable. It runs twin DCOE 40mm Webers and Abarth replica headers.
Can you please advise me on the parts I already have for the build and if some components are questionable I'll put them on an internet auction site and acquire the parts you recommend. Also information about a good head gasket, valve stem seals, spark plugs etc will also be appreciated.

Best Regards
Angelo

I'll get back to you on this but in the first instance please be aware I do not advise on 'shop & swap' where heads (and many other parts) are concerned. It is partly a function of how this firm operates (we very much specialise in alterations to heads to get the spec we need) and partly to do with my ethic of encouraging folk to 'have a go' - certainly with some of the more basic ops.

Our regime for prep on heads is typically:

1. Pick the head most easy to work with
or
2. Make the best of what we have to hand (may be client propery or a donor)
3. Pre-clean, pressure & crack test
4. Guides out, deburr
5. Port gasflow/mod and cc pre-prep. Sizes & shapes according to GC spec.
6. Race guides installation
7. Valve overhaul or replacement
8. Big - or new - valve seat installation
9. Seat ops & lapping/seal test
10. Reface, deburr and final clean.

For the interest of readers in generalI will simply say that an attempt to simply fit 'another head' without engaging in even the most basic ops to assure fit-for-duty (not assuming this is what you will do - but many go that route) given that this stuff is up to 40 years old - is no more than a 'bodge' likely to yield satisfaction in the short term - if that.

The examples below are an illustration of how we tackle this kind of stuff to get what we need. The old dirty head shown is GC supply donor destined for a Lancia Beta 1800 competition motor (for an Australian client FWW..) and is a 4371507 head from a Fiat 131 (not sure which engine - could be a 1600 or a 2 liter) with early confined combustion chamber and 42/36 valves. The inlet ports are 34mm dia at face and 32mm at port controlling section. It will have those ports enlarged to 36-34mm and the ex ports enlarged around the guide boss too, (it is going to get a 43.5mm inlet valve conversion though that's not strictly relevant to your topic). The chamber is restrictive even for 42mm valves and will get extensive deshrouding. It will end up like the one also shown. The 11.236 head is a short demo of how that head will get modified to the new spec.

As for the other parts can't see any problems there with the parts themselves - I will get back to you when I have time.

Hope this is useful guidance,

G

It all makes perfect sense to me Guy. My car was originally a USA specification 1974 model and it had the head with the air pump driven off the exhaust cam. I still have it and inspected it last weekend and noticed the extra castings into the head for the pollution epuipment. I think I'll be better off looking else where for a non pollution donor head. I'll be removing that head from the blown 1.8 litre engine to have a look at its condition.

I also completely forgot that I might a few suitable donor heads lying around in my former business partners garage from our days around 15 years ago when we used to run a part time Italian parts business supplying new and used spares. We accumulated a lot of spares (mostly junk) and I do remember seeing a few bare heads the last time I was in there over 5 years ago.

You've got me all excited now that I can't wait to get back to that garage to have a another look. Unfortunately I can't do that till the weekend. Hopefully I'll have a suitable donor head very soon. I'm eagerly awaiting your next post.

Thank you
Angelo

Re your parts my reply bold

Abarth exhaust valves part number 0513259 - OK
Abarth intake valves part number 0413217 - OK
Federal Mogul TRW valve springs part number 120-06194 - OK
Guarnitauto head bolts part number 700506-1010 - OK but will need late pattern washers as the underhead radius may foul the early wsr.

(Also information about a good head gasket, valve stem seals, spark plugs etc will also be appreciated.)

In case you did not know I try to avoid being overly-commercial on this site please pick other parts from the price list that I will email you if you wish to order, just mark them in bold

GC

Hi Guy

In my quest to find a good donor head, I finally got around to have a look at the 1800cc engine that's been sitting in the mud under my mothers grape vine since 1994. I blew up it in a yellow 124 AC I had all those years ago. It looks like it's only fit to be used for a boat anchor! I didn't have high hopes when I removed it from the block.

The first thing I saw when taking the head off was that one piston in the block had completely disintergrated but on turning the head over I was amazed at its condition. It doesn't look too bad at all. You did say that all TC heads are valuable to us, I just didn't think I'd find a decent one in a garden!

I'll have it pre-cleaned, pressure and crack tested before I really celebrate but for now things are looking promising. If it all works out, I've saved money and the hassle going on the hunt for a suitable donor head to use for the build. Another bonus is that I noticed what seems to be the correct rear flanged plastic auxilary shaft pulley for the 1" belt conversion fitted to the block. On closer inspection I can see that the teeth step up on the flange side. Is this the pulley that I'm looking for?

Regards
Angelo

YES,THAT IS THE PULLEY.


G

Guy Croft wrote:YES,THAT IS THE PULLEY.


G

Does it mean that every plastic pulley is suitable for 1" belt conversion or it must be of some specific model 124, 131, 132... ?

from every 8v TC yes..

G

Guy Croft wrote:from every 8v TC yes..

G

Thanks, appreciate it!