Over last Summer I rebuilt my 312ci Y.

Why is my car so painfully slow? I have no power on tap.

Ive read that Y blocks are pretty darn tasty and quick off the mark.

My Mercury has a 2 barrell intake with Holley 2 barrel carb. Is this the reason?

If I stamp my foot on the gas, I get a major flat spot as it seems the carb starves the engine of the fuel required for any decent acceleration.

The carb has been fully rebuilt. Would a 4 barrel carb & 4 barrel intake solve this?

  Picture taken in 1960. Funnily enough it still looks like this!

1959 Mercury Monterey 312 Y Block.   NORFOLK, ENGLAND, UK.

I wonder if it's the timing chain.



When I was assembling a 292, I got a degree wheel to check the timing chain. I checked two new chains and neither were close. I ended up buying a RollMaster from Mummert to get the chain degreed in.

Best regards,



Paul Menten

Meridian, Idaho

Comrade Paul:

A four barrel wouldn't be much help under about 3000 rpm, so if it is lazy off the line, that's not it.  Was it that way before you rebuilt it?  Maybe the front damper has slipped and your timing marks are wrong.  It's difficult to diagnose a problem from far away, we need some input from you so we can suggest solutions.

John - "The Hoosier Hurricane"

Sounds like timing to me, ignition or maybe valve. Did you degree the cam when you assembled?  Do you know for sure where TDC is on your damper? Things to check. If it is your ignition you may be able to fix it with a little diagnosis work. If it is your valve timing it is going to take more, like pulling the front cover.

   God Bless.   Tim                           http://yblockguy.com/

350ci Y-Block FED "Elwood", 301ci Y-Block Unibody LSR "Jake", 312ci Y-Block '58 F-100, 338ci Y-Block powered Model A Tudor

tim@yblockguy.com  Visalia, California    Just west of the Sequoias

I’ll suggest checking out the distributor first.  Assuming the electrical part of the distributor is in good condition, then use a timing light to check out both the mechanical and vacuum advance portions.  With the timing light hooked up and reading the TDC mark on the damper, simply rev the engine up and observe the TDC mark with the vacuum advance line to the distributor both connected and disconnected.  You should see significant movement of the TDC mark in both instances but even more with the hose hooked up.  If you see no movement of the timing mark on the damper with the distributor hose unhooked when bringing up the rpms, then the distributor will need to be disassembled so that the mechanical advance portion of the distributor can be freed up.  If there is movement of the TDC mark when reving the engine with the hose unhooked but it doesn’t change when hooking up the hose, then the vacuum advance chamber or the hose itself is faulty.  If there is no movement of the TDC mark with the hose either hooked up or not while speeding up the engine, then both the mechanical and vacuum advance portions of the distributor need attention.

 

If the distributor checks out and isn’t the source of the problem, then other things to check and report on would include manifold vacuum readings and the results from doing a cranking compression test.

Lorena, Texas (South of Waco)

Thanks for replies.

I know the timing is A1 perfect as is the distributor.

The car hums along nicely, I just have a flat spot on pull away, so I have to feather the throttle and pull away gently.

Once moving I can bowl along beautifully. Just the acceleration is gradual rather than rapid due to my flat spot.

See this video of a run we did on December 28th.

http://www.youtube.com/watch?v=mOICudPGjAw

About 15 seconds in you will see me pull away behind a red 55/56 Ford.

He shoots out, I move off slowly. The gold & white 59 Ranchero really pulls away fast & thats a Y.

  Picture taken in 1960. Funnily enough it still looks like this!

1959 Mercury Monterey 312 Y Block.   NORFOLK, ENGLAND, UK.

I hope the club plate on that red 55 was a "Y-Blocks Forever" plate! Great looking run. Thanks for posting it. Chuck in NH

Y's guys rule!
Looking for McCullouch VS57 brackets and parts. Also looking for 28 Chrysler series 72 parts. And early Hemi parts.

MoonShadow, 292 w/McCulloch, 28 Chrysler Roadster, 354 Hemi)
Manchester, New Hampshire

Is your "flat spot" momentary as if the carb accelerator pump is weak? A weak accelerator pump and a vacuum advance not working optimally as Ted said can cause a need to feather the throttle. How is the vacuum advance connected- manifold or ported? What is the initial and total advance in the distributor anyway?



Steve

Sounds like you might have a vacuum leak.

Best regards,



Paul Menten

Meridian, Idaho

As Paul mentions, a vacuum leak is a possibility and a vacuum gauge can help to determine this.

 

But assuming that checks out, is the accelerator pump pumping fuel when working the linkage?  Is the accelerator pump linkage adjusted correctly at the carb?  If there is free play in the accelerator pump arm in the idle position, then readjust the accelerator pump linkage so there is only 0.015” additional travel in the arm at full throttle.  Essentially, the pump diaphragm should be almost at the point of being bottomed out at full throttle when properly adjusted.

Lorena, Texas (South of Waco)