Tuning a 1300 engine - Alfa Romeo Bulletin Board & Forums

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post #1 of 18 (permalink) Old 03-12-2017, 03:59 PM Thread Starter
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Tuning a 1300 engine

Hi

I am having the engine of my 750D, engine # 1315-43101 totally rebuilt. To improve the drivability I am thinking about some changes:

1. Boxing the Solex, installing a Weber 36 DCD.
2. Replacing the standard 101000320000 cams with a 105020320001 (Performance Rank 4) cams.
3. Replacing the distributor with a Bosch 123-Ignition.

Should I use old 1005020320001 cams or new ones from OKP - they should fit?

http://www.okp.de/xtc2/105/115-Berto...3200-01::15640.
html?language=en

I would appreciate some advice and opinions.

Thanks Roland
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post #2 of 18 (permalink) Old 03-12-2017, 05:52 PM
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Ask Alfar 7 here on the BB.


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post #3 of 18 (permalink) Old 03-13-2017, 07:21 AM
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RE: 750 cam change

Here is a response somebody sent me on this question long ago:
"Installing later cams is not a simple drop-in proposition. You will have to cut notches in the follower bores to clear those wider lobes or machine the cams to narrow the lobes. Doubt the lobes will hit the edge of the follower, but as Greg said, make sure they don't.

The 750 cams are also ground on a smaller base circle so all of your current valve shims will be too thick. I believe the 202 and later cams are ground on a 27.2 mm base circle and the 750 cam base circle is about 1 mm less. "
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post #4 of 18 (permalink) Old 03-13-2017, 08:31 AM
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If you are going with performance cams with a 750, you are best off having custom cams for this application. Again, check with Alfar7 on the BB for details.


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post #5 of 18 (permalink) Old 03-13-2017, 12:50 PM
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Single carbed engines.

I strongly suggest that you research the BB on the problems changing camshafts on Normale engines.

Cams designed for later engines use different base circles, lobe with and centering and higher overlap designs than those built for the 850 head (that as well has smaller cam followers)

The single carb whether Solex or Weber require higher running vacuum to pull fuel into the carb throats at low & mid RPM.
Using cams with high overlap as later stock cams will have very poor idling and drivibility.

The correct cam for your motor are the 10100 032000 00 with LCs specified at 111.5/111.5.
The 1600 Normale was fitted with 10502 03200 00 with a wider LC of 114 / 114 to negate some of the additional overlap, and might give you a little boost but they will have to be set at the same 114 lobe centers.

Best to accept that these motors are what they are.

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Last edited by Alfar7; 03-13-2017 at 12:52 PM.
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post #6 of 18 (permalink) Old 03-13-2017, 05:03 PM Thread Starter
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Thank you for all your comments, especially Alfar7.

That is what I did - read lots of threads about tuning 1300 engines - which just confused me more. Most of the threads were older dates, which is why I brought up the subject again, before I ask my mechanic.

He is highly recommended by Alfa enthusiasts, here in Switzerland and will make recommendations to improve the driveability of my Engine ore not.

I always thought (after reading) the main problem with the early 1300 engine was that the timing was wrong, that the valves were not open long enough to suck efficient amount of air/gas mix in the cylinders. Is this wrong?

Is the Bosch 123-Ignition a good idea and what about the 36 DCD?
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post #7 of 18 (permalink) Old 03-13-2017, 05:20 PM
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The car will drive perfectly well with it's original distributor as long as it is mechanically intact and correctly set up. Fitting the 123 distributor is certainly not a tuning measure if you mean tuning as in 'go faster' tuning.
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post #8 of 18 (permalink) Old 03-13-2017, 08:01 PM
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I like putting a 1400 kit in any 1300 engine. The increased torque produced by the kit is great. I also replaced the Solex carb with a Weber downdraft carb, used a Bosch distributor and used XK140 springs with the stock cam. The car was much better than stock and drove my 1957 Spider Normale for more than 70,000 miles without any problems. I also have a 101 Sprint Veloce with a ported head, 1400 kit, 101 1600 Veloce cams and had to use larger jets to make the car run better.
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post #9 of 18 (permalink) Old 03-14-2017, 01:08 AM Thread Starter
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I don't really want my 58 Spider Normal to run faster (OK a little wouldn't be a bad thing) it should just have more torque at low RPMs. The not original 5 speed transmission is staying.

A 1400 Kit always scared me - there are a lot of warnings out their. I just wanted to try a more modest approach.
The engine is getting new Pistons and liners (stock?).

I was never able to drive my car, so have no idea how it runs on the street with the setup that it had as I pulled the motor - just so much - after 20 Years of not running - the motor ran but the timing was way of. I would love to keep the DCOs (beautiful) but then comes the problems with slanting the motor / oil pump etc - ore should I?? Alfar7?
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post #10 of 18 (permalink) Old 03-14-2017, 01:14 AM Thread Starter
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Can anyone see, from which car / motor the Veloce parts came from?
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post #11 of 18 (permalink) Old 03-14-2017, 04:19 AM
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Roland

I start this reply by stating that according to Fusi's data, your 1315-43101 engine is from a 1957 build year chassis.
As such it is an early die cast block.
Your cylinder head appears to be of a similar age as it has the exhaust cam drive for the fuel pump and swedged or peened alloy plugs in the head's casting holes.
The cam cover is not a Veloce item and the nuts used to secure it are a mix of old and newer retainers.
Your exhaust manifold is not original for a 1300 750 Series engine.

Establishing an exact date for your Veloce parts is difficult .. can you provide the DCO3 serial numbers ?

One additional comment: what appears to be a rubber hose attached at the oil line that normally connects to the oil pressure gauge .. it is most peculiar and causes one to question: What was the previous owner thinking ???

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post #12 of 18 (permalink) Old 03-14-2017, 07:07 AM
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"I am having the engine of my 750D, engine # 1315-43101 totally rebuilt. To improve the drivability I am thinking about some changes:"

It seems like you have driven the car as it was in the photos? Is that correct?

If the previous owner (or you) installed the carbs your ace mechanic should give you a clear understanding why that investment has pitfalls if that alone was the change. He should also understand the 101 cam issues. Maybe he is only familiar with newer Alfas? My point is changing to twin Webers comes as only a starting point if you wish to improve "driveablity".. cams, timing, headers, oil pan, motor mounts, distributor will all have to be considered as part of the change to technically improve the drivability and changing only carbs has it's consequences.

Properly equipped and tuned, the stock engine should provide a pleasurable driving experience. If there are issues with smooth running, a Weber downdraft could be the only change necessary if you can trace the problem to fuel delivery,that would not lead to a chain-reaction of further changes and get better results . You might have issues with "altitude" in Suisse I am not aware of.

Last edited by divotandtralee; 03-14-2017 at 07:09 AM.
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post #13 of 18 (permalink) Old 03-14-2017, 08:52 AM Thread Starter
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Hi GTD

Production # 5382 the last number could be wrong because the Webers aren't by me (looking at Photos). What my Brother was thinking of (rubber hose) I have no idea at the time (some 30 years ago) I was not around to help him and now he is no longer around to ask.

Automobilismo Storico Alfa Romeo:

According to our documentation files, the chassis number AR 1495.03544 originally corresponds to an Alfa Romeo Giulietta Spider, manufactured on the 7th February 1958 and sold on the 5th March 1958 to Hoffman Motor Car Co., New York, U.S.A. The body colour is white, with black or red interiors.

The car has matching numbers.

What interests me is from which car model or motor (year, cc) the Veloce parts came from (if there is a dead giveaway)?

Thanks Roland
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post #14 of 18 (permalink) Old 03-14-2017, 09:30 AM Thread Starter
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My "ace mechanic" wants the Veloce parts for him self and he is only familiar with older Alfas. What he has in his shop would bring you to tears - Italian cars.
I think downdraft Weber sounds good to me too. We do have a few Mountains around here and they are fun!
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post #15 of 18 (permalink) Old 03-14-2017, 03:34 PM
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I assume you are aware of the value of these rare Veloce parts. If not, start with checking out the prices those Weber DCO 3 go for.
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