RussJagoau

On my 51 and the 53 the Idler arm was the major culprit , or to be more specific the threaded section of it that rotates approx 90 deg or more. Im referring to the component on the passenger side opposite side to the Steering box / Pitman arm where it attaches to the chassis rail. Typically these threaded pivots wear over time - just as the upper and lower control arm threaded pivots are also prone to do especially if the sealing rubber has failed. Whilst you are there you may want to check the adjustable socket ends on the tie rod as they are also adjustable for wear or the spring tension can wane over time leading to excess movement. Even though the steering box and pitman may be in fine order with minimal slop , a lot of rotational movement from the box/ arm can be lost in the linkages on these pivot points if they are worn or requiring adjustment. Particulary on vehicles that have been driven a lot on country roads that are then subject to dirt ingress over the years. The lubricant combined with the dirt and dust turns to valve grind paste and gradually wears it away. Tie rod ends are similar thieves for loss of movement from the input from the steering wheel to the king pins... If you leave the car on the deck, then have an assistant move the steering wheel, it will be soon obvious where the worn components are if you observe the linkage.

Hi Bob So on re-reading your text ( If I have interpreted it correctly ) your plan is to put the spacer/s on the new mounts to abutt to the the transmission ( not the cross member ?) thereby to space the new mounts backwards so that the threaded holes will align to the original bolt holes in the cross member. Given the condition that you found your original mounts in ( broken -as I did mine ) then most likely the transmission will have "sagged' under its weight as being supported by only 1 sound mount at the rear. Would be interesting exercise to measure your driveshaft angles before and after the replacement of the old mounts. I also struggled to find new rear mounts and after a few years of searching was fortunate enough to locate some N.O.S GM units on Ebay from within the States - so i purchased those - hence the measuring of the driveline angles before and after. Prior to the changeout the angles as found were significantly different at either end. The new mounts restored it back somewhat but there was still 2 degrees difference - hence I fabricated some spacer plates to go under the mounts on the cross member location to raise the rear of the transmission even higher to equalise the angles. it certainly smoothed out the dynamic vibration in the shaft even further as I also had the shaft at balanced at Hardy Spicer as it was also out of balance prior to the mount changeout. Hope its a good result for you.

Keith Lugging the engine under heavy load load with WOT will give you almost zero manifold vacuum, as there is minimal pressure differential between atmospheric and manifold vacuum due to the WOT. With the engine under heavy load, spark advance is not required or desired due to detonation / engine damage potential as indicated by pinging or ignition knock. Once the engine load is lessened and the throttle closed somewhat, then the vacuum advance can kick in again as the potential threat of Detonation is reduced. To much total advance is way more detrimental than not enough, not so much on older vehicles with lower compression ratios but definitely on later models with CR's above the 8.5 :1 ratio....

Gents Just something to be aware of as a precaution, if you place the spacers on the rear engine mounts to the supportive crossmember, you will / may well change the angle of the transmission / driveshaft to the final drive. I would suggest that you measure the current angle of the transmission / driveshaft before you change the mounts and add the spacers. Then once you install the new components measure the angles again. On my chieftain the angles are now -6 deg on the driveshaft unijoint and -5.5 deg at the diff pinion flange, as the operating angles were un-equal before hand. If the mounts are broken , bent or sagged then you may well have to compensate with different thickness shims to get them somewhere near equal again. Driveline vibration can result if the operating angles are different at either end of the driveshaft. the vibration was substantially reduced when i equalised the operating angles . Just a suggestion thats all.

Hello I did my Mechanics apprenticeship on those old slants and the timing gear failure is a common problem. So i would suggest you pull the sump off and clean the oil pump pickup as well - reason being 9 times out of 10 the fibre gear remnants will block or partially block the oil pickup. Holden 6 cyl Red Motors used to suffer the same fate also. More than one suffered catastrophic failure due to the blocked oil pump pickup not long after the timing gear failure had been repaired as to replace the gear itself is only half the job done !!!.

The steel fuel lines subject to the high temps were sheathed in rubber fuel line of approx 7/16ths I.D and then wrapped over in good old Silver cooking foil that was removed from the kitchen under the cover of darkness.........It worked a treat as its a great heat shield........ I have an old style AC Glass bowl sediment / filter at the carb inlet and the fuel never boiled in there after the discharge line from the fuel pump was insulated. Being in the northern state of Aus, heat transfer / operating temps are a constant challenge but i have it pretty well mastered now..

Gents Here is a couple of pics that show the angle of the heat deflector shields. The red engine is a spare i picked up a few years back and its almost at 90 degs as you can see, but thats how i purchased it. All the other Pontiac cars / engines i have seen in this model run are all similar angles like the first pic of the engine in situ. In a warm climate it seems to work well, my '51 didnt have one when i first found it, and it suffered dramatically with fuel vaporisation at slows speeds and traffic lights in the summer months, ......It has one now as well as fuel line wrapping / shielding the fuel pump discharge to the carburettor and the problem hasn't returned to bother me again....

Great job there with a great looking result, highly informative info over the duration. I'm looking to do a similar task next year on the '53 for exactly the same reason as the original headliner is showing signs of age. Appreciate the time you took to capture the story.

Agree with Charles. You may wish to try the bench bleed method to confirm the master cylinder operation. If you are concerned as to the brake fluid making a mess, just use fresh water when you have it on the bench, this will confirm that the internal components are configured correctly and it will displace fluid again when you have it installed and full of brake fluid. Drain the reservoir of water and displace it with brake fluid when you have confirmed the master cylinder operation. It will soon displace when you bleed the rest of the system to the lines. its one of the advantages of displacing to the shortest line first also. I bench bleed all of the master cylinders I overhaul / fit as I did on the 51 and the 53 to ensure it will work before its fitted to the vehicle. just confirms the functionality of the component before its fitted . On the discharge port I used a tapered adapter plug that you find in the handvac pump systems to plug into the port and then run a short hose back up to the reservoir so effectively you are just recycling the fluid internally and using the reservoir as a separator to allow the air to migrate out of the fluid. These small single acting master cylinder's usually only take 5-10 strokes to fill and bleed the air from the internal bore. See how you go

Re the bent blade, I have successfully used a digital protractor to set / adjust the altered fan blade pitches that were a result of making contact with an unwelcome long thick serpent like visitor in the fan cowling during the winter monthes. The readings are in half degree's so you alter the pitch and the balance to almost perfect conditions given time and perseverance. I also used these for adjustable blade pitch angles on gas compressors fin coolers in the offshore gas cooler fin fans and earth moving equipment with variable pitch cooler fans. These digital protractors / angle meters also come in handy for setting drive line angles for driveshafts, universal joints etc . The one I purchased has a magnetic base, so once you set the zero baseline, then attach it to the fan blade for the pitch angle, they are an ideal tool for checking that angle with a high degree of accuracy.

So heres hoping that the six bade fan and the efforts in your remedial works goes some way to cure the high temp issues as described in your original posts. Would be interested in to see the results that you witness. You may well have checked it but if not then the total ignition advance is another area that you might find some gains in especially if the mechanical advance springs have weakened over time or the advance mechanism is worn on the spring posts. One of my vehicles original distributors was gaining way too much advance early on in the rpm range due to the weakened springs and worn mechanism. The initial advance was always ok at =- 5 deg BTDC at idle speed, but the toal advance when checked with a strobe light was approx. 48deg BTDC. Generally in low compression engines this isn't too much a concern with detonation but if the advance is too great then the engine is effectively working against itself and higher het loads results. Any worth a check f you have access to an adjustable strobe timing light. The headlight shrouds were purchased about 6 years ago when I completed the resto on the '51. They were purchased via ebay and came from the USA ( $47) , but Im sorry I don't recall the vendor. They were good quality and the chrome finish is excellent. You shouldn't have to much trouble in locating a supplier over there as the classic car accessory supplies are way more plentiful than here in Aust for older US models. They certainly add some appeal to classic look Rgds

Suggest you fill the master cylinder and crack the closest bleed valve to start with then work towards the next closest bleed valve. Finally do the back wheel cylinders last as they are the longest run of pipe to displace of air. If you have overhauled the master cylinder, suggest you fill / bleed it on the bench first before you install it onto the chassis, that will considerably speed the removal of air from the system. If you are doing the bleed operation on your own, suggest you purchase a check valve type bleeder that will make the bleeding operation a success. Lastly if you have troubles with getting the last of the air out of the system piping and the pedal gets spongy overnight after sitting, utilise a tyre lever or such to hold the pedal down hard overnight and hold the fluid under pressure for quite a few hours. Then open the furthest bleed valve . Or use a hand operated vacuum pump from the bleeders. I have had success with all of the above methods in various times and older models in the past. Good luck

The Delta T across the radiators varied with the airflow rate across the core, however at idle speeds after the engine was at normalised operating temp, it was approx. ~40 deg F for memory when I checked it with the I.R temp gun. Im away from the vehicles at present for the next 5 weeks but can check for you when I return back to home base. I work in Deg C so will need to confirm the readings and reply back for you. Re the blanking panels in the radiator support, have the 2 round blanking panels removed? ? Not that it will help greatly at idle and slow speeds but I have the removed both blanking panels on my vehicles to assist the air flow at highway speeds and higher heat loads on the radiators. When my Dad had the '53 it was located in a southern state which is a lot colder than where I reside, so we had the blanking plates installed to assist with engine temps. I have since removed them when the car came to Queensland so both the 51 and 53 both have the blanking panels removed now.

Hello Gents, Given I live in a hot climate and have a couple of the 50's Pontiacs I consider myself well versed in the heat transfer challenge. In my experience one of the best indicators if you have a partial restriction in the radiator that reduces heat transfer is to view the lower radiator hose when you increase the engine speed. Many of the vehicles don't run an inner support spring in the lower hose nowadays due to cost. If you have the engine at normal operating temp and then increase the engine speed, see what the lower hose does . If you witness that the lower hose reduces diameter then its a clear sign of a restricted radiator as its effectively reducing suction pressure to the water pump. This obviously causes cavitation and reduced water flow / heat transfer. The comment earlier in the post that the lower hose was mildly warm when the Temperature gauge was showing hot is a bit of a giveway . The delta T across the heat exchanger radiator using the Infra red temp gun is also one of the best diagnostic parameters you can obtain. Both my Pontiacs now run 170 deg F thermostats and 7 psig radiator caps, and I live in the north of Australia whereby high jacket water temps and fuel atomisation in the summer monthes is a challenge. To which I have covered the fuel lines and fuel glass bowls with silver foil to prevent fuel boil which has proved succesfull to date . Still run the OEM 4 bladed fan on both cars. Both of the cars have benefitted from an air /water blast through the block / radiator to remove any crud / scale buildup accumulated over the years. worthy to note that Minimal amount of scale will limit heat transfer as in my time anything over 0.010" of scale reduced heat transfer by approx. 50%. Combine that with rust and reduced water flows and its an uphill battle to continuously transfer the heat using air as the cooling medium. One other item I have utilised is the fitment of a catch sock into the top radiator hose to the inlet of the radiator that catches any junk that becomes dislodged over time , this effectively filters what goes into the radiator core and prevents sludge and solids buildup in the inner tubes. Since I have fitted these I clean them every year and there is always some sediment and junk to be had there. The coolant used is de-min water and the long life TEctalloy concentrate mixed at 50 % ratios, so far so good as its prevented corrosion. Given the cast iron bocks - water distribution tubes and freeze plugs are all dissimilar metals then galvanic action is best avoided with the de-min water and coolant for corrosion control. Hoping this may go some way to identify your rot causes of the higher temps. Russ

Hi Gents Re the bracket next to # 5 plug as mentioned is for the throttle linkage as obviously we are on the opposite side to you guys over there. The gearcase is not the same for Right hand as compared to LH drive vehicles as the linkages to connect the column shift rods are on the opposite side. The internal cross shafts exit on the RH side of the gear case to suit the RH column linkages. Bellhousing is also different as the clutch throwout fork etc are all Right handed where they exit the housing. For the carburettors - I have an Ultra-sonic cleaner that works well for Fuel system components , used a water based fluid with some degreaser and Bi-Carb of soda, some soak time first with a few runs through the Ultra Sonic cleaner at max temp and it brings up components well. The carb in the picture was done a few years ago so its not as bright as it once was though.

Hello again, Finished Product for the Manifold Studs / Nuts combination .

Hello, Ive had the manifolds off my '51 and 53 a couple of times now over the years, mainly for valve lash checks and other times to replace the manifold stud set as the rear most one was broken on the 53. I machined a full set of studs to replace the originals as they have obviously seen a large number of thermal cycles over the years. Replaced all the nuts with Brass manifold 3/8 UNF nuts specifically as for 2 reasons: no antiseize required as being non-ferrous it wont corrode to the stud thread, 2- the brass thread will give up easier than the steel stud if for an unknown reason it does pickup over time. Also replaced the flange gasket studs and used brass nuts at the same time for the same reasons. Final torque values were 25 ft/lbs with No sealer on the manifold gasket. As the manifolds are not water cooled I could see no reason to apply the sealant and as such have used the same joint gasket numerous times now when doing routine maintenance on the 2 Chieftains. To torque the nuts especially the difficult access ones I use a 1/2 universal socket ( ie one that has the unijoint built in to the socket) That's the only tool I can find to get an accurate grab on the nut to allow the torque value to be applied. So far the fix has been ideal in that the manifolds are easy to remove as the nuts come off the studs readily , the manifolds haven't cracked so enough lateral movement on the studs to prevent stress and none of the new stud set has cracked or parted. The gasket comes off cleanly every time and as such I have re-used them on at least 2 occasions now after scheduled maintenance. Worked well for me.

As an owner of a 51 in a hot climate, I also suffer with the vaporisation of the modern fuels in the summer monthes. My 51 and 53 Chieftains have 170 degree thermostat's installed and the radiator is in good condition with good heat transfer, good temperature differential measured across inlet and outlet. As a suggestion you may wish to try wrapping your metal fuel lines in silver foil paper, as this acts a heat shield and will prevent heat transfer from inside the engine bay. It will also determine if your issue is indeed fuel vaporisation or another problem with similar symptoms. It cured the cause on my old girl particulary after driving in warn days and then idling or parked for a while when the heat transfer takes place into the carburettor fuel bowl and fuel lines. I originally had it around the fuel bowl and it cured the problem, I have since removed it from the bowl and manufactured a more professional looking heat shield that is mounted to the original heat shield between carb and intake manifold. Suggest you try it and see what the outcome is, if it cures your vaporisation issue then that's a start. Then you can investigate the higher than normal temp profile across your radiator as it does seem quite warm given the operating temps you stated.

Howdy I have a 51 and a 53 Pontiac and know the difficulty in locating the Spats. It took me quite a few years to get the reasonable sets for my vehicles , especially in Australia as I had to purchase from overseas. Best of luck with your search. If you need any pics or dimensions of the Spats, I can surely measure them for you. Rgds

Sometimes if you get a balancer thats been in place for a lot of years, these require some force to be removed from the crank snout.... and these balancers can be pulled off with a large gear puller, with the jaw hooks set to inside the belt sheave sides on the pulley. That being the case make sure the pulley / sheave sides are protected from the steel jaw hooks. I find Aluminium Vee bar / angle is a good protection method that prevents damaging the belt runs when you wind on the puller draw bolt !

The way that I have installed these seals in the past is as Summershandy states, ie the cork seal is the stationary element of the seal so it should be glued or cemented to the timing cover , the pressed steel shroud thats keyed to the crank is the rotating face , hence the contact face between the 2 elements is where one sealing surface is, the second one is the hub O.D on the harmonic balancer to the I.D of the cork inner face. You wouldnt want the cork face rotating against the timing cover ?? but between the inner face of the cork ring and the pressed steel shroud that rotates with the crank. Non hardening Permatex on these corks when cemented or glued to the timing cover seems to work well so far.

So the crank pinion looks to be at TDC given the orientation of the key. But the cam gear looks to be 180 degrees out... ..a full turn of the crank should see the correct marks line up together. I would think given the current crank angle thats indicated then that engine is on the exhaust stroke of the No 1 cylinder.... the Inlets on these engines have a 224 degree duration whereas the exhaust is 230 degree and minimal overlap so they are quite simple to valve time... To check that with the head on is quite simple, remove the plugs and install a piece of tissue into the #1 plug hole. Rotate the engine in the normal CW direction, if the tissue is drawn in its intake , conversely if its blown out its compression. this combined with the position of the rotor in the distributor should be a giveaway as to the what stroke in the cycle that the cylinder is on. As the engine has been running ok, then its also a simple matter of re-placing the chain with the same number of link s / pins of the timing chain from the timing marks used. You dont have to use the factory timing marks, as long as the phasing of the cam to the crank goes back in exactly the same position that you removed it. So if the car was a runner prior, replace the chain and ensure the timing marks are in exactly the same location before you pulled the chain.....

I have seen in some cases the clutch disc is installed backwards ( ie long side of the splined disc hub to the flywheel side as opposed to short side to the flywheel side ) this then pushed the pressure plate back towards the gearbox front and prevent the clutch from operating. Generally when the engine is started the long splined hub will clash with the spigot / pilot bearing and the resulting noise is quite obvious. Plus the clutch will not disengage. Maybe this is the reason for the spacers being installed ? Clutch assy.pdf

Hi 46 Poncho This may help you. Im north of Brisbane and have a few other pics and dimensions if that's of any help and a service manual that this pic came from. Lets know how you get on. Clutch assy.pdf

Hi All, Just enquiring if any of the members have ever balanced the 6 cylinder Side Valve engine during a rebuild ? My 51 has a critical speed vibration in it at about 2500 rpm, both loaded and under no-load. Its has good compression across all the cylinders and the Leak down test is less than 30% on all the pots, so the cylinder balance should be fine. It runs sweet but has a vibration at one particular rev range..... The harmonic balancer appears to be in good condition as by visual inspection there is no distortion evident and the timing marks line up with a degree wheel so no slippage there on the outher pulley from the hub. Borescope inspection is all normal in each cylinder so ..... I have the equipement to balance the piston / rod assemblies but will need to have the crank, flywheel, pressure plate and harmonic balancer dynamically balanced if its time to look inside. Any experiences from other engine builders on these 50's engines ? Thanks