1949 Buick Super Lacks power

[Buick36-49]

Hello,

My 1949 Buick Super 248 straight eight (Dynaflow) recently started lacking power…a lot of power. For example going up slight grades at only 35-40mph. I’ve rebuilt the carburetor, put in new plugs, wires, coil, points, condenser, checked the fuel filter and pump. Even hooked up an aux 6volt electric pump…NO CHANGE. Still has lost most of it’s power. Runs fine at idle no miss or erratic idle.

When driving it cruses a long fine, but when you put the peddle down to the floor, the engine bogs down and if you take you foot up a little, it seems to get more power. I drive this car about 50mph on a level highway and when I encounter a small hill, I lose so much power. Any ideas? I’ve even checked the values to make sure they were not hanging up.

I do want to add though, that at idle, the engine starts develop blue smoke and when you race it, there is a cloud. Does not smoke when driving.

Thanks

Robert

Edited February 19, 2011 by Buick36-49 (see edit history)

[Guest Jim_Edwards]

More or less guessing, but from what you wrote it sounds like the engine may have ring problems. But it could also be carburetor issues. Did the problem exist before the carburetor rebuild?

Jim

[Buick36-49]

Hello Jim,

Thanks for your reply. What we thought was the carburetor, we deceived to rebuilt it. Then we bought another one that was rebuilt. So, I believe it’s not the carb. We did do a compression test and found that the first 2 cylinders were down around 6lbs. The third cylinder was down around 4lbs. And the rest were fine. Engine has great oil pressure even at hot idle. But the engine seem to have a lot of power even when those symptoms existed.

Robert

[The Old Guy]

Check your fuel pressure. It may be the fuel pump ,or a clogged filter.

[Ben Bruce aka First Born]

Agree with The Old Guy. Sounds like filter. Or partially plugged gas line from tank.

Ben

[Buick36-49]

Would you guys think it might have something to do with the valves. I changed the fuel filter...but engine has almost no power with throttle wide open.

[JohnD1956]

I'm guessing but it sounds like you have a poor fuel /air mix.

Have you checked the bolts holding the carb on? Also I'd look for an intake manifold crack.

And on a different note, I might consider replacing the coil.

[Buick36-49]

Thanks JohnD1956,

We've replaced the coil as well with a new one (6volt). I am thinking too that it has something to do with the fuel and air mix. When we took the manifolds off a few years ago, they were frozen together, so we had to drill out the froze bolts to separate them from each other. We then had a machine shop (try) to grind down and drill new bolt holes. To this day the manifolds do not line up correctly. But we were almost sure that the intake did not leak. (Exhaust does leak and blackened the valve cover). We try spraying starting fluid around the intake to detect a leak (idle does not go up). Carb bolts are tight new heat insulator

Robert

[JohnD1956]

have you checked your mechanical advance and vacuum advance?

[Pete Phillips]

I was going to make the same suggestion as John just did: Distributor advance. If it was rings you would have lots of smoke, if it was valves, the idle would not be smooth

Pete Phillips, BCA #7338

[Guest 38cadillacjack]

with 3 cyl not working,i'd guess that could be the problem.

[old-tank]

After you are sure you have your fuel and ignition sorted out, check for an exhaust restriction.

Willie

[buick man]

My vote is a Vacuum advance problem. This can be checked with a vacuum meter. If it runs fine under minimal torque conditions but bogs down under torque that would be the first place I would go to since your fuel system is OK. Your compression is OK since only off by a few lbs of each other. Again a vacuum gauge can confirm leaking valves as well at Top Dead Center of each cylinder. Lean mixture will cause pops and white smoke and too rich will cause black smoking. Blue black smoke is oil.

Vacuum test the intake manifold system as well even if you have to take the carb off the top and plate it shut to test.

[critterpainter]

Restricted exhaust? If a baffle comes loose in the muffler it can cause the problem you are having. Runs ok at lower RPM but runs out of power and RPM when you try to rev the engine. Low intake vacumn is one syptom.

Bill

[60FlatTop]

If you take the breaker plate off the distributor you will find a cork pad that is supposed to be oil soaked. Most are dry from some long period of setting during the car's life.

Delicately work new oil into the cork and you should see a big difference.

Being dry the cork will make the advance drag and just never be in the right place for correct timing.

Bernie

[Guest sherlok]

FUEL PUMP. Had the same problem.

Don't change a bunch of stuff before making this simple replacement.

Sherlok

[NTX5467]

I concur with Old-Tank . . . exhaust restriction. Remember the post a while back from a member with a late-model Buick Century that suddenly lost power? Everything else checked out well, but when the catalytic converter was replaced, it ran fine again. I KNOW this vehicle has no catalytic converter, but the principle is the same . . . exhaust restrictions allow less exhaust gas flow which gives the engine LOTS of "internal, residual EGR" from such restriction, which leaves too much inert gas which kills power and performance once the flow limitations of the exhaust system (be it muffler or an internally-collapsed double-wall pipe!) are reached . . . just puts out the fire regardless of how well things might be happening upstream from the restriction. Things are fine at lower rpms, but hit the brick wall at moderately-higher rpms.

Vacuum advance is there for part-throttle fuel economy, so ensuring the mechanical advance is working can be important -- mechanical advance is the "default mode" of sorts as the vacuum advance can come and go with throttle input. Compression being different by 5 or 6 psi is no big deal, either, but 25psi difference can be, cylinder to cylinder.

Best way to check for the exhaust restriction is to take the pipe loose from the exhaust manifold and see how the engine responds. Might take some penetratin' oil on the studs/bolts and a new gasket, but that'll pinpoint if exhaust restriction is an issue.

Regards,

NTX5467