64 Monza low on power

[Ron64Convertible]

I'll try not to make this too long. I have a project car (hasn't run in 20 years) that I have been working on for about 1 year. New 30 over pistons, rings, bearings, lifters. Valves adjusted 3/8 turn. Carbs rebuilt, new coil, wires and all tune up parts. Engine starts right up, accelerates and idles smoothly in the garage. When I take it on the road I get some slight missing when accelerating and very low power climbing any type hill. I've checked all settings and it appears everything is okay. Compression between 110-125 with only about 20 minutes running time on the new rings, vacuum steady about 13lbs, timing at 14-BTDC. 63 102-hp engine.
Does this sound like a mechanical, electrical or fuel issue? If you need anymore info please let me know. Thanks

[Jerry Whitt]

Lack of power is sometimes due to improper timing. Not sure which crank damper you have, but some of the dampers have an outer metal ring, that in turn attaches to a rubber inner ring. Sometimes, the rubber ring allows the outer metal ring (with the timing mark) to move. A fairly easy test would be to just advance the timing some more and see if the power increases. If the power is a lot better, may have found the issue.

[bbodie52]

Were there any modifications to the distributor? Or is it a stock unit with points and condenser? Vacuum advance connected and working? Did you check the function of the centrifugal advance by observing with a timing light while increasing the engine speed (vacuum advance disconnected)?

What type/model of coil was installed?

[Ron64Convertible]

I believe I have the stock damper. I did try to advance the timing, which did increase the vacuum reading but didn't seem to increase the power. The mechanical advance weights are moving freely and give about 8 degrees advance. I installed a new vacuum advance, which appears to be working properly. The distributor is original with points, no modifications that I am aware of. I am getting frustrated not knowing how to proceed. I am not a mechanic, but do enjoy working on old cars. I think I get some missing when I accelerate, timing shouldn't cause a miss should it? Thanks for the feedback.

[terribleted]

Is the accelerator linkage adjusted properly? When the pedal is pushed to the floor does it give full throttle at the engine? Check and adjust so that when the pedal is on the floor, the carbs are all the way to wide open throttle. You could indeed have a carb or ignition problem as well causing the "slight missing". Who rebuilt the carbs? They could be flooding they could be lean as well. Is the spark strong at the plugs? Is this miss a stumbling miss where you feel vibration and bucking in the engine or is it perhaps just detonation which would sound like a slight rattle with some loss of power? detonation is usually from timing advanced too far or a lean condition where you are not getting enough fuel for the current throttle opening. How is the fuel delivery and fuel system? have you checked the fuel deliver volume? Has the tank been replaced and lines cleaned? A fouled fuel system will not deliver gas on demand like it should.

[bbodie52]

What type/model of coil was installed?

Not yet answered. If your new coil is a 3.0 ohm primary resistance coil, and you still have the standard, non-modified Corvair wiring harness (that has an embedded 1.8 ohm ballast resistor wire in the harness that powers the coil) the total resistance in the primary ignition coil circuit may be too much (3.0 ohms from the coil plus 1.8 ohms from the resistor wire). The original stock Corvair ignition coil has a primary resistance of a nominal 1.5 ohms (1.28-1.42 ohms specification). Substituting a 3.0 ohm coil could weaken the spark at each spark plug, which could result in a misfire under load when accelerating.

Can you check the documentation that came with the new coil you purchased, and provide the make/model and primary resistance specification? (Should be a nominal 1.5 ohms or 3.0 ohms, which are two common coil types).

A weak ignition system (if that is what is causing your performance problem) can have several causes, but since you mentioned that you installed a new coil, verifying the coil specification and proper installation would be a first step in troubleshooting and fault isolation. Also check the polarity of the wire connections (Positive (+) to the wiring harness, and Negative (-) to the wire leading to the distributor ignition points). If you suspect an incorrect coil is the problem, you could try reinstalling the original coil and see if the performance problem goes away. Also confirm the condition of the points contacts (not burned or pitted). The point gap should be 0.019" (New) or 0.016" (used), which should produce a Dwell reading on a Dwell meter of 31-35 degrees (33 degrees preferred). If you have to readjust the point gap to correct the dwell setting, the timing will have to be rechecked after getting the correct Dwell reading.

Aging harmonic balancers are subject to develop slippage between the fixed center section and the outer ring as the rubber component that holds the two sections together ages. Any slippage will affect the accuracy of the timing mark on the outer ring, so be sure to check the slip check reference marks on the harmonic balancer. If the harmonic balancer shows any signs that slippage has occurred the harmonic balancer should be replaced with a new one before the harmonic balancer fails completely.



Watching the video presentations below helps to provide insight and understanding about proper sequencing of the tuneup steps and procedures. Skipping around can insert obstacles and problems with getting the engine properly tuned.

The portion of the first video segment toward the end (Part 1, 5:10) and at the beginning of the second segment discusses throttle linkage adjustments and carburetor synchronization.

Tuning the Corvair Engine — Part 1



Tuning The Corvair Engine — Part 2






I hope the above material helps. Please let us know what you find as you work to resolve your performance problem.

[Ron64Convertible]

I do not have the info on the coil, but it was purchased for a 1963 Corvair. (on the coil it has "External Resister Required" #1303 and on the bottom is #0116) the wires are connected properly and I have a new condenser/resistor on the side purchased from Corvair Ranch. Is there a way to check the ohms with a meter? The wiring harness is original. I did take the harness out and replaced a couple burnt wires while restoring it.

The Damper is the riveted type, I don't see any markings on the front other than a hole near the center bolt. The spark looks to be pretty strong. Yes, the throttle appears to be opening all the way. I have a new fuel pump (have not checked the pressure) and the points are also new, gap at 19.

I rebuilt the carbs myself, so cannot guarantee they are done right. I also adjusted the balance according to directions I found using a vacuum gauge. They are adjusted within 1-2 lbs pressure, but this is one area I may not have done totally right. The car starts right up, but runs very rough when first started cold for about 1 minute then smooths out once the chokes open.

[Ron64Convertible]

One other thing. The diagram you attached for the carbs show the two gaskets recommended for both sides of the insulator. The insulator has two small cutouts in the center that conform to the base of the carbs however the gaskets do not? Since the gaskets didn't appear to match the carbs i only used one gasket against the manifold and not against the base of the carb. I checked for any leakage by spraying starter fluid while running and got not variation in the RPM.

[Wagon Master]

Have you ever advanced the ignition timing to the point that it causes pinging on acceleration?

[bbodie52]

At this point I'm sure you want to remain focused on your performance problem to get it resolved. But for future reference here is some harmonic balancer information...



The presence or absence of a harmonic balancer on a 164 CI crankshaft can also potentially impact the stresses a given crankshaft has to absorb over years of operation. GM engineers were forced to compromise by GM accountants in 1964 when the engineers specified the use of an [expensive] harmonic balancer on the long stroke (164 CI) crankshafts. A compromise was established where a solid cast pulley was permitted only on the low horsepower (95 hp) engines, with 110 hp and 150 hp engines receiving the desired harmonic balancer to prolong the life of the crankshafts that were assuned to be exposed to greater stress factors. In 1965, as engine stresses increased even more, nitrided crankshafts were specified on the 140 hp and 180 hp engines. We must assume that GM engineers concluded that there was potentially some stress weaknesses in the top 164 CI engines that might bring on possible crankshaft failures in these street engines that were not likely to occur in low revving, lightly driven "grocery-getters" fitted in 95 hp Corvairs driven by little old ladies nursing their Powerglides.

Of course GM only expected the average Corvair to see about 10 years of use before it hit the scrapyard. I don't think they anticipated 50+ years of use -- much less these engines migrating into race cars, dune buggies, air boats, aircraft etc.

Over the years some owners substitute inexpensive solid crankshaft pulleys (steel or cast) when their pricey harmonic balancers age out and suffer separation. Doing so could possibly introduce small stress fractures or cracks into aging crankshafts. Any machine shop work on the crankshaft journals on nitrided crankshafts would also remove this nitrided surface. When performing an engine rebuild, it might be wise to consider all of these factors when having the crankshaft inspected -- including a check for cracks.

Is it certain that the engine in your 1964 Corvair is a 1964 or later (164 CI) engine? If it is, you should try to replace what sounds like a 1960-1963 riveted pulley at some point with a new harmonic balancer. If your engine is a 1963 102-hp engine, the riveted steel pulley is fine.

http://www.corvair.com/user-cgi/catalog ... ge=OTTO-23


Part number C9871A: HARMONIC BALANCER-REPRO ORIGINAL STYLE *SUGGEST SEAL C483/C483V

Weight: 6 lbs 0 oz
Catalog Pages(s): 11(43),OT-23
Price: $ 236.25

[Ron64Convertible]

No, I didn't get pinging when I advance the timing. I did advance it until the engine RPM started to slow and the vacuum started to decrease, I don't recall how much I advanced it.

I believe I have a 1963 102-HP engine in my 64 with the 60-63 riveted pulley.

[bbodie52]

Even a new coil can be faulty. If you still have the old coil and believe it to be serviceable, you could try swapping coils just to be certain. Also, the 10-pin multi-connector in the engine compartment that connects the main harness to the vehicle is a common problem area. Check for corrosion or a possible internal faulty high-resistance connection inside the plastic case, if your voltage is low at the coil.




The voltage feed to your ignition coil is important. With the engine off and the key ON, you should measure battery voltage (Nominal 12 VDC) with the points OPEN. With the points CLOSED and the coil primary therefore conducting electrical current to GROUND, the ballast resistor wire in the wiring harness and the coil primary resistance will reduce the measured voltage. You should read a Nominal 4½-6½ VDC with the key ON and the points CLOSED (Voltmeter V-2 in the diagram below).

LEFT-CLICK THE IMAGE ONCE TO ENLARGE THE IMAGE. LEFT-CLICK A SECOND TIME FOR MAXIMUM ENLARGEMENT FOR BETTER VIEWING...

Below is a complete, combined wiring schematic for a 1964 Corvair passenger car...

LEFT-CLICK THE IMAGE ONCE TO ENLARGE THE IMAGE. LEFT-CLICK A SECOND TIME FOR MAXIMUM ENLARGEMENT FOR BETTER VIEWING...

1964 Corvair Passenger Car Combined Schematic

[Ron64Convertible]

I am reading 12.5 with points open and 5.0 with points closed.

[Ron64Convertible]

I also took an ohm reading (1.9 low side and 8.9 high side).

[64powerglide]

Are you getting gasoline to both carbs?? Do you have a new gas tank?

[Ron64Convertible]

New tank, sending unit, fuel lines and plump. Both carbs are getting gas. The plugs from the left bank appear to be getting a richer mixture than the right although both carbs are adjusted the same.