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Old 08-10-2010, 04:37 PM
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Default Troubleshooting 350 engine problems on '69

I recently bought a '69 camaro with a questionable 350 installed. Initially it ran so so and got worse over the next two months. I'm still trying to get it running properly and hope others can give me some advice. Here are the specs on the motor.

Engine code - T1013HD - V8 small block 350
Carburetor - Holley (4160) 80457-5 D676 600CFM
Intake manifold - Edelbrock Performer EPS
Ignition Coil - Accel 8140C 12 Volt
electronic ignition replaced points
original mechanical fuel pump
Unknown whether cam is original or aftermarket

I did some troubleshooting and did the following:

Rebuilt the carburetor
replaced the spark plugs (now E3), distributor cap and rotor (stock replacement)

The problem is that it still runs very rough and almost sounds like it's not firing on all cylinders or not quite right. It stutters when I accelerate as well.

With all of that said, three questions:

What should the intake vacuum reading be? I show 15 at idle. It looks like it drops for a second and then goes up to 20 at 1500 RPMs.

How do I check the fuel pressure reading and what should it be?

I bought a compression test kit as well. What should the compression be on each cylinder?

Any advice on other tests would be appreciated.
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Old 08-11-2010, 03:27 PM
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On the compression tests... anything over 170 should be good.

Is it mechanical or hydraulic lifters? When was the lash set on them last?

Vacuum depends on the cam and its duration. The higher the duration the lower the vacuum at idle. So that's a shifting variable depending on engine setup.

You can buy a fuel/vacuum pressure gauge at any auto parts store for under 20 bucks. It will come with a junction t-fitting that you can put in the fuel line. It will tell you fuel pressure. For a carb'd application anywhere around 6 psi is good. Over 7.5 - 8 and you're looking at flooding the floats in the carb. Anything lower than 5 and you're looking at starving the engine at higher RPM's. Since you said you had a vacuum gauge then there's a chance it's also a fuel gauge.

Sounds like it could be a burnt valve though. Is the vacuum gauge fluttering a lot when you have it on the intake taking readings?
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Old 08-12-2010, 08:58 AM
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I'll check the compression this weekend to see what I get. Hopefully they will all be good.

I'm not sure about the lifters, and I would be surprised if the lashings have been set in years considering the general state of the motor when I got the car. I've only had the car about 3 months and have not gotten that far into the engine yet. I've seen some shows about doing that, but I'm not really sure of the process. Is it something I can do, or should I take it to a mechanic?

The vacuum gauge I bought does fuel as well. I wasn't sure if the pressure needed to be read with a T or could just be attached as the termination for testing purposes. I don't think the T that came with it is large enough to fit the fuel line though. I'll probably need to get another and extra line.

I'm not really sure what a "lot" is for vacuum fluctuation, but it doesn't go back and forth more than 1 or 2 in either direction when idling.
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Old 08-12-2010, 01:54 PM
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A compression reading between 150~160 would still be considered very good for your engine. What's also important is the uniformity between all the cylinders. A difference of +/- 10% from highest to lowest is considered to be in the acceptable range.
Here's a good procedure for doing a static "adjust & run" valve lash adjustment: http://www.chevyhiperformance.com/te...nfo/index.html
Oh and by the way, E3 plugs are crap. I know more than one person who tried them and they made the engine run worse. Take that for what it's worth.
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Old 08-12-2010, 03:12 PM
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do you know how many miles/hours on the motor? timing chain could be streched out too.
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Old 08-13-2010, 12:22 PM
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Thanks a lot for the article on valve lashings. I'll see if I can work through that in the next week or so when I can make a little time.

As for the E3 plugs, they did make an improvement on the motor, but that could very well just be getting rid of the rusty plugs that were in the car. I can't imagine they make any significant difference from properly gapped new plugs, but they do at least work.

As for the age of the motor, I have no idea. I can't even say if it's the original because the spot where the VIN code should be is blank or at least was rusted enough at one time to obscure the numbers. It has obviously been pulled at one time because it has been repainted, poorly I might add, yellow. With the other visible modifications, intake, valve covers, etc, it's impossible to say what the true condition of the motor is without pulling it and completely tearing it down. The odometer does read about 156,000 miles for the car at least.
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Old 08-13-2010, 04:46 PM
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why **** with someone else old junk crap ?? why not spend the money and buy a descent replacement sb anything from a 327-400 you should be able to find a shop nearby that builds engines get to know them and the quality of work done etc.. once you find a place you like talk to them about a descent sb with a hp range you want should be 1500-4000 depending on what you want.
and any real shop will warranty their work performance items or not!!!!
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Old 08-13-2010, 04:48 PM
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where are you located ? if near illinois and you dont know how to swap a motor let me know i can help you!!
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Old 08-14-2010, 04:17 PM
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I do plan to swap the motor eventually, but $1500 or more for a working replacement motor isn't in the short term budget. I am saving up for it, but there are other things that need attention on the car as well, such as getting the suspension replaced. I have a busted spring and need to fix that and plan to convert the brakes from drum to disk while I'm at it. As long as I can get the motor running reasonably for the next 6 months to year, that will give me enough time to save up for an engine swap. I know someone who has a few 350 long blocks in good condition and hope to get one of those once I have the money.

BTW, I live in the DC area. Anyone nearby who wants to wrench on an old Camaro is welcome to come by.
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Old 08-15-2010, 04:34 PM
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I did some more tests on the car this weekend and found that it seems to run fine when it's still cold. Once it warms up, it starts to stutter when I rev the engine. It idles fine cold or warm.

I checked the fuel pressure today, and it's running a steady 10+ PSI from the mechanical fuel pump.

I checked the vacuum advance to see if it is advancing the timing. When I apply manual vacuum to it, I can see it moving the timing. It holds vacuum as well.

I am unable to check the cylinder pressure at this time as I don't have someone to bump the motor to run the tests. The same goes for checking the valve lashings.

Unless someone can think of some other tests I can run at this time, I think I'm just going to have to break down and take it to a mechanic. Everyone I know has run out of ideas for things to test.
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Old 08-15-2010, 04:34 PM
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327, 350, 69, 804575, carb, chevy, engine, fluctuation, fuelpresser, holley, idle, motor, problems, sbc, troubleshooting, vacuum

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