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Need some help getting this piece running!


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So here's the low down... 79 brat with the Webber carb. We have replaced the voltage regulator, fuel pump, dist cap and rotor, plugs and wires, and cleaned out the gas tank and put fresh fuel in it.

 

Where we stand... She turns over but the fuel pump never even seems to get power nor will it start with starting fluid in the carb. When it is turned over I get some pops and flames from various points in the intake manifold or out the top of the carb. I know we are getting sparks to the plugs but I don't know much else.

 

What's the next step? I can grab some pics and maybe even a video later tonight if that helps anyone but were stumped right now. I've gotta get this running so we can start on brat no. 2!

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I've been helping the OP, so I'll provide some additional info.

 

We tested the alternator (it performs within spec) and installed a new voltage regulator after the original failed some of the resistance tests. Everything on the electrical side seems to check out now.

 

As for the distributor, we're fairly confident the firing order is right. The timing is another issue. We haven't messed with that, so it may need to be reset to the factory specs and tweaked from there.

 

I also wonder if there are vacuum issues. Could that cause the engine to not start? I think the only vacuum line currently connected is the one from the right side of the intake manifold to the brake booster. All the others are disconnected. On the Weber carb, is there supposed to be a vacuum line plugged into the front side of the carb? Also, the valve thing (I'll try to post pictures later) on the side of the distributor that has some vacuum lines going in and out, should that be connected to anything?

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That 'valve thing' is the vacuum advance canister and it would certainly come into play when the engine is idling but you should still be able to start the engine without it connected. Afterall, when you set the timing with a light you disconnect the vac advance anyway.

 

As noted by imposter, could the distributor be out? When installed correctly the rotor in the distributor needs to be lined up with TDC, which in turn, means it faces the number one spark plug wire on the cap (this is the one closest to the carburettor,at the back when looking from the front). To check remove the number one spark plug, place a finger over the hole and turn the engine clockwise. You will feel air pushing past your finger, which indicates the engine is at TDC for that cylinder.

 

Just some thoughts, if I have only stated the 'bleeding obvious' I apologise!

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I'm going from where the OP states "fuel pump not filling chamber etc".

 

Otherwise remove plug number one , using finger over hole locate TDC compression stroke , set the distributor with the result causing the rotor head to be pointing where the number one wire would be. Then when all buttoned up check with timing gun and rotate the distributor until all sounds and looks as best as can be , lock the distributor down with the 10mm bolt.

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First confirm your getting spark at all. Pull plug #1, plug it in to its boot, hold the end against the block and turn the motor over (confirm TDC while #1 plug is out). If you are getting spark, start from scratch and confirm your timing, fireing order 1-3-2-4. If you are not getting spark, you know what your problem is, just not why. My guess would be coil or disty pickup. These motors are super simple, spark, fuel, compression, is all you need. If you were getting spark, and your timing was close, the motor would at least try to start w/ starting fluid.

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  • 2 weeks later...

Thank you guys for the advice! We finally got around to really working the timing over, and we're getting close. Firing order and spark has been checked on all cylinders. Timing was reset per the factory service manual and all your advice. The fuel pump is finally delivering fuel to the carb. Since it's a Weber carb, I don't see where there is a float chamber porthole (someone correct me if there is one).

 

At this point we're stumped, and think it may be a carb tuning issue. OP and I are both idiots when it comes to carbs. The carb came with zero instructions, so we found this guide http://www.redlineweber.com/html/Tech/carburetor_set_up_and_lean_best_.htm

and assumed the 1 to 1-1/2 turns for the speed screw and 2 turns for the mixture screw mean scree them in all the way and back them out by that much. Right or wrong?

 

Here's a video of what it's currently doing.

It seems really close, but just won't quite start. The "puffs" you see out of the far side of the carb are fuel. It seems to be jetting fuel up out of the carb, which doesn't seem right to me.

 

Any advice from here?

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Update:

 

A friend suggested that the timing might be off 180°. We went to follow the advice Moosens and Leeroy gave about setting the timing, and ran into an issue. We never felt pressure on the spark plug hole for cylinder #1. So, we got a compression tester. Cylinders 1 and 3 don't get a reading. Cylinders 2 and 4 get about 120psi. So, I was prepared to accept that one cylinder might have a stuck valve. But is there any simple reason that both cylinders 1 and 3 wouldn't be getting any compression? It just seems to coincidental that it's the two cylinders in the same side.

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  • 2 weeks later...

The intake valves being stuck open on 1 and 3 seems possible but unlikely. You can remove the valve cover on that bank then crank it over while observing the valves to determine that.  Perhaps the head gasket is blown out between those two cylinders?

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Darsdoug, thanks for the input! That was my thought as well. The chances of valves in both cylinders being stuck seems unlikely. I've also watched the video I posted a few more times, and the amount of hissing might point to a gasket issue (or at least I'm hoping that's the problem). This weekend, the valve cover is coming off for sure, and probably the head as well. Whether it's a gasket or valves, the head has to come off, so we'll get to the bottom of it.

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Ordered a whole felpro gasket kit from rock auto... figure i might as well do everything. Any tips on cleaning valves and pistons? Also the head studs are very very grimy. Do people typically replace them on these motors? If not any recommendations for cleaning?

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  • 5 months later...

It finally started, but we could still use some advice! The Brat will turn over, eventually start, but dies after a matter of seconds. It won't just sit and idle, it takes some babying to keep it going. Here's a YouTube video of what it does

 

Any pointers on what might be going on?

Edited by RZ16
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