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Discussion Starter #1
Good evening! I hope everyone has had a healthy and safe weekend!
Like everyone else, I have found some new free time due to the current outbreak. I have been fiddling with my car here and there checking out some of the quirks and fixing some things that had been shelved.

One thing the car has done the whole time I have had it is every so often, between 2500 and 3000 RPM the engine will almost cough. It'll make a chirp type of sound and lose power for a millisecond. It never does this at high speed or outside of 3K RPM, and it doesn't always do this at 2.5-3K rpm. Its sporadic.

I checked cam timing today, thinking maybe I was a little off when I set it up last year. The intake cam was a hair counterclockwise of the mark (looking towards the front of the car from the back). I loosened the big nut and took the 8mm bolt out, adjusted the cam over, and locked it all back together. Pushed the car a few times to make sure the marks stayed lined up after a few rotations, they looked right on.

I took it out for a test drive, it still did it. Is this a normal Alfa quirk? My engine has 180,180,180, 175 PSI compression. The carb floats are set at 29mm tested using a vernier, and the carbs are synced.
Usually after a drive there is a few drips of fuel on the bottom of the carb throats, is this normal? its not a significant amount and it does not have a raw fuel smell.

I took a pic of the fuel in the bottom of one of the carb throats, it doesn't show much but I thought I would share anyway.
 

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Super Moderator
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Try richening up your idle jets 1 step. If they are ( for example only!) 50F8, go to 55F8. That may do it. The issue may be a lean spot in transition fro low speed to high speed circuit.
 

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Premium Member
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Discussion Starter #3
Ok I think that is simple enough. Im running F11 emulsion tubes, 210 air correctors, 135 main jets, 35pump jets, and 50F17 Idle jets.
Dumb question, whats one step up from the 50F17 jets? 50F 18? or 50F 16?
 

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But Mad North-Northwest
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The idle jet F numbers are not sequential, they're totally random with regards to richer/leaner. F17 is an oddball jet and isn't in the standard idle jet sequence. I think those may be for the emissions carbs? In a DCOE 151 I suspect they'll be very lean, and that's probably your problem.

For a stock 2 liter 50F8 is much more typical. Any idea why you have F17 in there? How many turns out are they at lean best idle?

This chart has the stock Alfa jetting. You likely want to reference the 40 DCOE 32 line for a stock engine (the 72/73 are emissions carbs and use different jetting.)

 

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Discussion Starter #5
Correction.
I had thought I updated my notes on what jets were in my car, those numbers I gave were the jets on the car when I bought it. Not the current jets.

I just went out to my car and checked.
I have 50F8 idle jets, 130 main jets, and F9 emulsion tubes.
 

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Richard Jemison
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7,370 Posts
The correct E-tubes for your application are the F-16 tubes. They are richer than the F-11 or F9.
You didn`t give the "Timing mark" or cams being used?? What LCs are your timing marks?? What are the main jet and air corrector jets??
Don`t bother changing jets until you install a wide band O2 meter.
 

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Discussion Starter #7
Cams are both 10502032000.

Timing is set with the timing pointer and cam marks. I took pictures of the cam marks as they are today.
When I had the cylinder head over last year I calibrated the timing pointer on the pulley.
Main jets are 130, air correctors are 200.
I wasn't looking to tune the engine with a wide band O2 meter, I just dont want the car to cough

IMG_6646.JPG IMG_6643.JPG IMG_6645.JPG
 

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Super Moderator
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FIRST, simply go to 55F8 and see if that's a fix. If not, send me an e-mail and I'll be able to give you a good baseline for whatever engine / Weber combo you have. Keep it simple.
 

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Premium Member
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The cam timing marks on a US spec 1974 are 114/102 which is terrible for carbs. Your motor will behave better if you time it to 104/104 or maybe 101/107.

Also make sure that you have no air leaks between the carbs and the intake manifold.
 

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Discussion Starter #10
101/107, is that 101 intake and 107 exhaust or is that 101 exhaust and 107 intake.
 

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Intake number is first, that is the convention.
 

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Richard Jemison
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The cam mark on your intake is 114. That`s for a VVT intake cam. You cams appear to be stock Alfa USA cams. These cams have too much off the seat duration/overlap to use the settings that Ed suggested. At best they should be at 104/104. Do not just install a 55F8 idle jet. You need to correct the cam position before anything else.
 

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Your 74 Spider should not have VVT. 72 - 74 SPICA motors were timed at 114/102 to reduce CO & HC emissions. The timing got worse in 75 & 76 as they struggled to meet the NOx standard that was introduced in 75.
 

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Discussion Starter #14
Thats what I was about to say, my car is a 74 with a 74 head. No VVT. So are you thinking this cam cap came from a VVT head?

For a stock, SPICA to Weber conversion, I should set the cams at 104/104 correct? Is this the best option or the starting point?
I have the templates from centerline, but I don't want to mess with the cams until I go in knowing what they need to be set at.
They should be stock standard SPICA cams, I haven't changed them.
 

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Apologies that this is not a direct answer.
in 1999 I bought my 79 Spider that had stock SPICA cams, a SPICA manifold with a Shankle Weber conversion, Headers and foam filters on the intakes. I had the same symptoms as you. The cams were timed at 102/102.
I rebuilt the motor with 10548-01 Euro cams, a Euro manifold, plenum and air box. I installed the Webers without making any adjustments and I never again experienced the "sneezing". Whether it was due to installing cams that were designed to be used with carbs, eliminating leaks that I was never able to find or something else, I will never know. The stock US cams are useless except for passing an emissions test and the Weber conversion of the SPICA manifold can be a source of problems.
 

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Cams are both 10502032000.
is that not a 1600 cam?
are you talking the silver 2 litre spider in your avatar?

maybe have another look, you might find the number is more likely
105200320000
 

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maybe have another look, you might find the number is more likely
105200320000
Exactly. That is the US Spec SPICA cam referred to in the previous post.
 

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Discussion Starter #18
Ok so for sake of kicks and giggles, I thought I would do some digging. When I had to have the cylinder head rebuilt last summer I had two heads, the one that was on the car when I bought it and then the spare that came with it (supposedly original to the engine, in bad shape).
Long story short, which can be found in another thread, the original cylinder head was rebuilt and switched with the head that was on the car because the head that was on the car had damaged valve seats.
Both heads went to the shop together, they took the cams from one and put it on the refurbed head.
Head that is damaged and is now sitting in a box in my basement has a 2.0 in a circle on the front, the head on my car has a circle, with a square, with a line through it.
I took both sets of cam caps and set the centerline markers on them.

Heres my results. Which ones actually belong on my car and what marks do I actually need to follow.
The first pic with the 2.0 sticky note, are the cam caps off the damaged head.
The second pic with the less than pretty drawing, are whats on my car.
Third is the front of the damaged cylinder head that used to be on my car.
 

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Premium Member
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Discussion Starter #19
is that not a 1600 cam?
are you talking the silver 2 litre spider in your avatar?

maybe have another look, you might find the number is more likely
105200320000
Correct it is the SPICA cam, some numbers have been rubbed on. I posted a picture earlier where you can see the given numbers.

I believe the SPICA cams are the only SPICA pieces left on my car, the manifold is a weber manifold its not a SPICA manifold. I have a SPICA manifold sitting in a box and it most definitely isn't whats on my car
 

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Discussion Starter #20
Apologies that this is not a direct answer.
in 1999 I bought my 79 Spider that had stock SPICA cams, a SPICA manifold with a Shankle Weber conversion, Headers and foam filters on the intakes. I had the same symptoms as you. The cams were timed at 102/102.
I rebuilt the motor with 10548-01 Euro cams, a Euro manifold, plenum and air box. I installed the Webers without making any adjustments and I never again experienced the "sneezing". Whether it was due to installing cams that were designed to be used with carbs, eliminating leaks that I was never able to find or something else, I will never know. The stock US cams are useless except for passing an emissions test and the Weber conversion of the SPICA manifold can be a source of problems.
No worries, im attempting the measure twice cut once method here before I start moving cams around. Just trying to make sure I understand it all! Besides car talk is fun

I wonder if I need euro cams to fix the problem or if it is just a matter of setting timing right. In the future I wanted to mess around with cams a little to make the engine a little hotter, but truthfully right now is not the idea time :rolleyes:
 
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