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Discussion Starter #1
I did a compression check on my 2 liter, and got 120psi on all 4 cylinders. Is this good or bad, or just barly hanging in there?

What's should a stock 2 liter's compression be?

Thanks
 

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Sniady said:
I did a compression check on my 2 liter, and got 120psi on all 4 cylinders. Is this good or bad, or just barly hanging in there?
Thanks
Depends. Was the comp test done with a hot engine, all four plugs removed and wide open throttles? Hi-po cams and altered cam timing can also lower the readings. The key is that all the cylinders are within about 10% of each other.
 

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Discussion Starter #4
Re: Re: Good or Bad compression

papajam said:
Depends. Was the comp test done with a hot engine, all four plugs removed and wide open throttles?
I knew I was forgetting something. WIDE OPEN THROTTLE!!!

I did do it with a hot engine. But I didn't know about all the plugs having to be out? So all the plugs must be out (just to clarify)?
 

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Yes, with all the plugs out, the starter will spin the engine at the blistering pace of 300rpm giving a higher reading.
 

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My stock 74 has 93k on the engine and has 140-150 compression, measured with engine hot, and dry (vice wet with oil to help seal the rings).

Before you run the compression check, you should check valve clearances to make sure none are too tight.

Be sure to run your test with engine warm, and wide-open throttle. (You can disconnect the long link from the FI pump to minimize the fuel injected into the intakes).

When you remove the spark plugs it's possible that you'll dislodge some flecs of carbon that may foul the valve seating surfaces. If you get a low cylinder, put everything back and drive a while to clean up the valve surface and retest.

1. How did the compression come "up?" Did you get a good pump on the first stroke of the piston or did it come up incrementally over the 6-7 strokes of the piston?

2. Do a wet compression test by dropping a teaspoon of oil in each cylinder and see if that make a big difference in how the compression builds and the top reading. A big increase probably indicates worn rings. If there's no increase it's probably worn valves.

3. What is your oil burn rate?

4. Have someone drive behind you and note the smokiness of the exhaust under hard acceleration and when decelling from speed, throttle closed. Bluish smoke is oil. Black smoke is overrich mixture. Bluish smoke on hard accel is rings. Bluish smoke on hard decel indicates valve guides/seals.

You can also see part of the valve sealing surface through the spark plug hole (albeit a small portion), but it's worth rotating the engine and at least checking the part you can see for anything really obvious. Although, if it was really bad, you'd probably have a low cylinder.
 

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Discussion Starter #7
...back with results

Ok, things are looking good.

I did what was instructed.

(I don't know which is cylinder #1, but I assume it's the closest one to the radiator)

#1 - 165
#2 - 162
#3 - 160 ish
#4 - 152

So what's my verdict guys?

Little History on my GTV -

The previous owner, owned the car for 15 years, and told me not once had the motor been OPENED. He only put 35-40k miles on the car, as receipts gave me proof.
As some know, it's my daily driver. I drive it very hard! I hit redline everyday. I've been driving it for 10 months, with a total of 10k on the odometer, and only experienced very minor issues. I think I've pushed this car to it's absoulute limit's. For a period of time, I wanted to see if the engine would croke. Was'nt happening. The canyon roads cannot defeated this GTV. Not yet at least.

My point -
I'm a happy guy, with a great GTV, sure I complain about wanting more power, but the future is waiting for that.

I'll keep knocking on wood.

p.s. I picked that sucker up for 3200 dollars. I want to call the owner and say Thank You again! But I lost his number.
 

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Looks very healthy and about what a 50k engine should be showing dry. Was that compression wet or dry? Did you get a good pump on the first stroke with a measured build after that?

Running an Alfa engine hard regularly is good for it, I think. Every time I take mine out, I run the RPMs to at least 5000 a couple of time. ONLY after it's FULLY heated up, however.

Be sure to check your valve clearance, too. It's easy and quick and may ensure you don't burn a valve from too little clearance. At the same time you can check your cam lobes for normal wear patterns.

Also, document everything you do and check. If you're like me, you'll forget a year from now what the compression reading was yesterday. That way you can perhaps spot trends.
 

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I was going to write a little program for this kind of work, memorize what had been done to my GTV, until I found this little 30bucks program -

CarCare from

http://www.carcaresoftware.com/

I've been trying it for a few days, it let you SCAN in your receipts and create a report. Pretty customizable for what we need for our Alfas.

Too bad it's PC only. :(


Roadtrip said:
Also, document everything you do and check. If you're like me, you'll forget a year from now what the compression reading was yesterday. That way you can perhaps spot trends.
 

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Re: ...back with results

Sniady said:

(I don't know which is cylinder #1, but I assume it's the closest one to the radiator)
You assume correctly - unless it's a Saab.:D
 

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Roadtrip said:

Also, document everything you do and check. If you're like me, you'll forget a year from now what the compression reading was yesterday. That way you can perhaps spot trends.
Absolutely!! In ISO speak, this is called predictive maintenance and is mandatory in helping to identify a problem before it breaks.
I document everything on a spreadsheet including symptoms, diagnosis, before and after readings and results. Things like valve clearances with the shim sizes, suspension height, alignment settings, carb jetting, etc. The following is a snapshot of a spreadsheet with date, mileage in km and hours spent on each procedure.


22 Oct 00 - - Slight engine miss under hard acceleration. Idle to part throttle transition fairly poor.
28 Oct 00 28,090 1.5 Retorque cyl. head. Replace long throttle linkage rod. Adjust throttle linkage geometry. Readjust float levels. Replace brake booster vacuum hose.
18 Nov 00 - - Major engine miss under hard acceleration (3500-4500RPM). Spark plugs 1&2 lean: plugs 3&4 slightly rich. Change to F11 E-tubes and 45 accel. jets. Road test. Same engine miss and very poor transition. Diagnose bad ignition wires or carb mounts.
28,150 0.5 Replace ignition wires. mileage=10.25 gal/260km 15.75MPG
- - Same symptoms.
18-19 Nov 00 28,245 6.0 Overhaul (2) Weber 40 DCOE 32 carbs (SN#6748 & 7699) for future installation.
23 Nov 00 28,245 4.0 R & R intake manifold. Replace (4) carb mounts. Install overhauled carbs with stock jetting (F9 E-tube, 125 mains, 200 air, 35 accel.).
24 Nov 00 - - Road test. Engine miss and transition problems eliminated. Gets rubber in 3 gears. Spark plugs normal.

Keeping records also serves as the service history of the vehicle so you can up the selling price - assuming that you ever want to part with it!
 
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