Time for a Long block?

-
AValiant69

AValiant69

Member
Joined
Jun 11, 2012
Messages
12
Reaction score
0
Location
Sacramento
Hey everyone I was hoping you could help me come to a decision; but first some background.

The Car: 1969 Plymouth Valiant I bought from a junk yard a few years ago. It has a 225 I upgraded to a Super Six with a 2 ¼ exhaust and a HEI. Still runs; I driven it most every day since the upgrades.

The Problem: The car starts fine, cold or hot, but lacks power and stalls if I give it too much gas from a stop. Now I can turn a wrench pretty good but I couldn’t diagnose my way out of a paper bag, so I finally broke down and took it to a mechanic someone recommended. Well the diagnosis is in; no compression on cylinders 1, 2 and 3; valve leakage and crank case leakage.

Questions
1. How much trouble am I in?
2. Could the trouble be in the block or might I get away with replacing the rings and rebuilding the head?
3.What else should I replace once I have it open?

Any advice would be helpful.
 
get the timing set correctly...and check the accelerator pump in the car....as soon as you move the throttle it should squirt gas.
 
First thing is to do some serious diagnostics. Especially since these girls are "so old" you could be "anywhere" on this

Engine wear in general, rings, valves

Valve seals leaking

Carburetor problems

Ignition problems including but not limited to a stuck advance mechanism, and some amount of wear, generally, in the distributor.

If you don't have, stop by MyMopar where you can download (some) free factory service manuals. By the way, some of those came from the guys here on FABO

http://www.mymopar.com/index.php?pid=31

what I would do, "just so you know" where you are

Run a compression check and cylinder leakdown test.

Read the engine section (9) of the manual, re: the cam and cam drive. Determine the wear on the timing chain, and whether it's slipped. The procedure is in there

Set the valve lash if they are adjustable.

Examine plugs for carbon, fouling, oil, etc, and wear

Test the plug wires for continuity, examine the cap and rotor for grease, moisture, dirt, carbon tracking

Inspect the distributor. Read section 8 of the manual, electrical, theres a section on there about distributors. IN THE rear of that chapter is "specifications" which detail vacuum and mechanical advance in the distributor. Set and check the timing, and attempt to determine if the advance is working correctly.

By the way much of what I detailed above is simply "a major tune up"

Once you get done with compression tests,valve lash, and ignition, NOW you can pay attention to carburetion / intake

Along the way are OTHER "gotchas" EG is the heat riser butterfly stuck / rusted, which can become a partial blockage in the exhaust, and speaking of which INSPECT the exhaust. It's not unheard of that someone "drags" the car over a curb, log, or "errant sand bar" and mashes part of the tail pipe shut!!!
 
"The car starts fine, cold or hot, but lacks power and stalls if I give it too much gas from a stop. Now I can turn a wrench pretty good but I couldn’t diagnose my way out of a paper bag, so I finally broke down and took it to a mechanic someone recommended. Well the diagnosis is in; no compression on cylinders 1, 2 and 3; valve leakage and crank case leakage."

Does anybody spot a contradiction here?
I don't understand how your slanty, with 3 cylinders at zero compression, starts fine, cold or hot............
Lacks power ; I get that!
Ima thinkin it's time for a valve adjustment, a quick check of the seat pressure, and a leakdown test. Make sure to knock the carbon off the valve sealing face,before the adjustment. I do this with the piston going down on the power stroke.
The quick check is to attempt to spin the intake spring, with the valve on the seat.If one or more is considerably looser than the others, or worse flops around,then it's time for a valvejob. With high mileage pre 70/71 engines,comes valve seat recession, as well as seat wear, and a loss of seat pressure is a sure tell.
 
^^^
This!
But, if it does come to needing major work, fear not.
I've found that the /6 pretty much "falls apart" and "falls together". I recently rebuilt mine and I gotta tell ya, that was the simplest rebuild I've ever done in my life.
I got a "running" slant from a guy, I decided I was going to reseal it, and the next thing I know I'm down to a bare block. Glad I did too! My rings were super brittle, this thing would have been a smoker for sure if I hadn't done the rebuild.
I replaced everything, and sent the head to a machine shop I trust.
In the end, I have about $500 in the build. keep in mind, I did put it back stock, and my wife works at O'Reilly's so parts were cheap!
 
I wouldn't jump into a long block based on what one mechanic said. Ditto post #4, things don't quite add up. Free test - turn the engine over by hand by tugging on the fan belt (key in your pocket, pull plug wire off coil to be safe). If you feel 3 strong "air springs" resist you per crank revolution (chalk mark) and hear them hiss down, the "no compression" data is bogus. Kick over a motorcycle and you will understand.

Bad rings cause blue smoke out the exhaust under full throttle (have someone follow you), plus excessive oil consumption. Bad valves is a "head job", not a new long-block. Bad valve guides or seals is much smoke as you drive away after sitting at a stop light for 5 min. Often just replacing worn rubber umbrellas on the valves fixes it, which you can do w/ the head on the engine.

Stuttering from a stop has little to do w/ bad compression and more to do w/ fuel. My 1969 slant ran like that for decades, particularly when hot, and I feared stalling at every red light so often had to goose the throttle. I suspected fuel, but 3 rebuilt Holley carbs didn't change it, nor did several valve jobs, and no mechanic could diagnose it. Finally, after it still did it after a complete rebuilt long block, I bought a 4th 1920 and it purred like a kitten. Unbelievable change. If you have a Holley 1920, there are many bad rebuilt ones. The sealed metering blocks clog and most rebuilders don't touch that part.
 
Check the valve clearances first, and then on to the next possibility.

There is a lot of good advice above, and that would be the first thing I would check.
Or maybe a cold comp test of my own first, and then valve clearances.
After that I would decide how big of a deal it could be.
 
Do a wet and dry compression test and go from there...
 
Its not time for a long block....Its time for a small block.:burnout: :D
 
You must log in or register to reply here.
-

Back
Top