GTD40 Restoration

[Randy V]

Quite honestly Andy, I've never balanced the timing gearset.. I suppose if the engine were to spend any significant time at max RPM, I might be concerned - but that's not likely..
Remember that the cam sprocket spins at half the speed of the crankshaft.

 

[Andy]

Thanks for the confirmation.
I continued the assembly of the engine.
Checked the geometry of the rockers and need to buy a longer set pushrods.
The rollers on the rockers were at not in the middle of the valve stems during the travel. The pushrods which came with the engine were 6.75 inch and after some trials, found out they should be 7 inch.

Now heading to the biggest challenge in my view.
Trying to align 4 pulleys...hate this part of the build :evil:

The adjustable bracket which came with the nostalgic air AC set is no good for our gt40's. It puts the compressor very high at the cylinder head level. With the old engine, a simple bracket was fitted which fits quite nice. Hope the small bolts of the mechanical fuel pump cover will hold the compressor. There is no room for any adjustment at this stage. Perhaps I can use the nostalgic air bracket and rebuild it to be able to fit it in the lower position.

The new harmonic balancer seems to be smaller comparing to the old balancer so need to source a spacer for the crank pulley.

Noticed the waterpump pulley is wobbling like crazy so need to replace it aswell.

(Dont't look to the waterpump bolts, I added temporary some spacers since missing the right lengths). And the March bracket is not fitting either...

 

[Andy]

Have one concern with the gear on the camshaft.
I noticed that the pin in the new camshaft is snug but not snug in the gear so the gear has now some play with regards to the camshaft.
Since the gear is bolted to the cam, this fixes the gear towards the cam but it can be temporary to my feeling. I can recall this happened with my previous builds so is my worry correct ? The gear was used in a 351w.

 

[Randy V]

It should be a snug fit on the pin, but not an interference fit. I have lain the pin on an anvil and given it a slight tap with a hammer to deform it sightly in the past and no ill effects...

 

[Jac Mac]

I read where you have been swapping gears... early 221/260/289/302 cams used a longer dowel pin that extends thru the gear and into the fuel pump eccentric and the bolt washer prevents the dowel pin from moving forward. Look at pics 2 & 3 in your post #171, you have a later version gearset and a later version cam/dowel pin without the eccentric to retain the pin. Later 302/351 cams use a shorter dowel pin that only extends approx 50% thru the gear and the fuel pump eccentric is two piece with a tang/tab that fits into the remaining portion of the dowel hole in the gear to prevent it moving forward.

If you have used an early gear set designed for the longer dowel on a camshaft with a short dowel you must replace the dowel and use the appropriate fuel pump eccentric or the dowel could move fwd in use. When using the later two piece eccentric you need the gear set to match that, simple when your conversant with both methods, but confusing if you have been given a mixed set of parts.. ask Ron Earp, he threw all the toys out of the cot when trying to get his set up years ago! Since the early gear sets are relieved at the camshaft side a short pin cam might exhibit play at that point.

 

[Andy]

Attached a movie, it is not really clear since it is reduced and converted to be able to upload it. Also attached a high res picture.

The dowel pin will not be able to come loose, checked that but the diameter of the dowelpin should be bigger on the gear side...in the camshaft, the dowel pin was snug.

In the movie, both camshaft and crankshaft are not moving...
you can see also a rotational movement on the lower gear.
Looks like the wedge is smaller and leaves a gap for the notch in the gear.

So anxious to finish the build but my feeling told me its wrong since it will mess up the timing aswell.
This gear set came out of a turnkey 393w stroker engine...the engine lived only 1000 miles and stopped running due to the camshaft gear was eaten by the distributor gear. From that moment, I decided to build my own engines...and the first one is still running strong, done 10000 miles and big smiles :happy: (crossing fingers)

Looks like I have to order also a new gearset and some new gaskets :furious:

 

[Andy]

Any suggestion with regards which gear set to buy ?
There are hundreds to choose from :huh:
Looks this one fits a 302 (my block is from 1968).
COMP Cams Magnum Double Roller Timing Sets 2120

 

[Jac Mac]

As you mention, several to choose from, of the chains there are some with full rollers and heavier straight side links that do seem to last longer and not stretch as much in service... the one in your pic has likely got split bushs and as seen the links are slightly figure 8 style.
BTW there is absolutely nothing wrong with the original morse type chain when used with metal type gears sprockets rather than the factory nylon tooth cam gear. When you think of them doing 100k miles in the factory application... you do not see many roller chains doing that sort of mileage!

 

[Andy]

Decided to continue assemble everything since the devil is in the details and perhaps other items encounter. Trial fitted the engine today, always rewarding to see the engine back in the car ;O)
But found an issue with the clutch, the lever is stuck and can't be removed from its position.

It is a new AP racing clutch set.
CP2394-14
CP2346-42
CP3457-2
Flywheel from Southern GT.

Perhaps the AP racing bearing is too thick ?

 

[Andy]

Quick update,
I removed the gearbox and measured the distance to the adapter plate.
There should be 1 mm slack when the lever is at its max so should be okay.
Assembled it again and now the lever is not stuck anymore and at the top just not hitting the frontside of the bellhouse. To me this feels okay now.

 

[Jac Mac]

As the clutch lining wears the diaphragm fingers move toward the release bearing, your 1mm freeboard might not be enough long term.

 

[Andy]

I see...
or it can make constant contact staying at rpm.
How much slack is recommended, 3 to 5 mm ?

 

[Andy]

Electrical system hooked up. Needed to fix quite some issues but it is now all working fine except the hazard buttons gives crazy effects on the blinkers.
The rear end of the car is not on, perhaps the absent of the rear blinkers is making it crazy so gonna wait untill the rear blinkers are connected.
Heading the right way but still no engine fire up since fighting to get the coolant water system holding its pressure.
When pressurizing the coolant water system, the aluminium reservoir is bubbling along its welds....very strange. visually the welds look fine but perhaps the aluminium itself became too brittle due to its age ?
Looks like it is ready for the scrapyuard.

My idea is to have it made according to my drawing.
But locally here in Belgium, they quoted me 100 euro for a 20 mm weld when I asked to weld some brackets to the one I have :shout:
For sure not asking a quote for a complete reservoir, probably they will ask 1000 euro for it...
On Ebay you can find new polished reservoirs for 40 pounds, this is the other extreme.

Perhaps I am looking in the wrong corners, any advise where to look for an affordable custom reservoir or a similar used one ?

 

[Mike Pass]

Hi Andy,
When I did my clutch I removed the pin that goes through the end of the clutch release arm and replaced it with an HT bolt. The pushrod can then be easily changed. You can then make up different length rods with rounded ends from some cut down HT bolts or make an adjustable push rod. I believe Mick Sollis does an adjustable one but they would be easy to make.
When setting up the free play I try to keep it as small as possible to ensure that all the movement from the slave cylinder gets transferred to the release bearing. I check it regularly to make sure that there is some free play but as little as possible. Make sure that the slave cylinder piston is fully pushed back when you check the free play. I keep a few spare pushrods in the car just in case but I haven't needed any of them yet after a fair amount of use - maybe I am too gentle on the clutch!
Cheers
Mike

 

[Andy]

Attached the drawing of my coolant reservoir.

Hi Mike,
There is some slack on the lever (when pushing back the slave).
The gearbox outputs can be rotated (both at the same time) and I feel no drag from the release bearing so to my view it is okay now.
In case the pushrod is too long,
I can reweld it indeed or make an adjustable as you suggested.
Thanks for the input.

 

[Andy]

Big milestone today.
Fireup the engine epper:

Besides a small water leak still to pinpoint, nothing major.
It runs silk smooth so the engine balancing really paid off.
It picks up very well on the throttle.
After 5 minutes I noticed the water temperature rising rapidly and started to boil coolant at the reservoir while I felt the radiator was still cold. So shut it off immediately.
The only thing I can think off is that the new thermostat is not opening properly.
The waterpump is an Edelbrock Victor 8843 standard rotation.
Other suggestions always welcome,
I heard a lot of people remove the thermostat with their Gt40's ...;O)
Could it be that the resistance from the radiator together with the too long pipes causes a very weak flow...not enough to dissapate the heat and get some circulation.
When I was draining the system, I noticed how slow the water goes through the hoses and radiator so a lot of resistance is in the water system.
My 2 cents..

 

[Bill Musarra]

Andy,
I would go with the thermostat or the wrong rotation. Pull the thermostat and drop it into some hot water and see if it opens. If it does then I would suspect the wrong rotation, as the cold water hitting the thermostat would snap it shut and you would get little if any flow through it. Did you put the thermostat in facing the right direction?? That brings up another problem. Was the original belt setup a serpentine unit??? With V belts you don't have the option of reversing the pump. If you do find the pump is the problem then I would think you need to go electric pump. Just make sure you put the outflow of the pump toward the block. My 30 gal/min. pump keeps my cooling temps in the 150-16- range without a thermostat. I may add a pwm unit to control it, but the slow warm up is not a problem I worry about. Could it be something strange like a blocked line???

Bill

 

[Andy]

Hi Bill,
The pump is the standard rotation one so that root cause is eliminated.

Coming days, I will remove the thermostat housing to check it.
The thermostat direction should be correct since I couldn't fit it they other way around.
Another reason could be that the "burping" was not yet 100%...I consumed 25 liter coolant, the reservoir was topped but perhaps it burped, water level dropped and perhaps too low...still after 25 liters...but for sure, feeling the tubes, the hot water didn't reached the radiator. I felt the tubes next to the fuel tank and only one was warm around the center of the car. Could it be that the impeller is not turning anymore inside the waterpump ? (perhaps a crazy idea).
When I mounted the pump, for sure the impellers worked with the front of the pump.

 

[Andy]

Removed thermostat, tested it, it opens okay just before boiling water.
Drilled a hole in the thermostat.
Burped the system and topped the reservoir.
Restarted the engine for 5 minutes.
Got to 70ºC, radiator is getting warm this time but the reservoir started to spill water again through the pressure cap.
Perhaps the cap has a too low setting, need to verify this.
After 10 minutes allowing the coolant water to cool down and releasing the pressure, the reservoir was still topped to the max.
So next run, I will let the engine run and allow it spilling its water.
I guess it needs to expand and get rid of the excess water.

 

[Bill Musarra]

Andy,
What is the pressure setting or your reservoir cap?? I have a Stant racing cap and it is rated 28-32 lbs. of pressure. You may need one of higher pressure,,,, or you may need an expansion tank. A lot like what is in your standard automobile. There should be a small tube on the back of your fill neck, where the reservoir cap mounts. You add a hose from that to the expansion tank. When hot, water from expansion will leave the reservoir and go to the expansion tank. When it cools the water will contract and pull the water back into the system. There are some nice catch/expansion tanks out there if you look. Most aftermarket places carry them. Do a general search. Believe I found mine at Summit:
Overflow Tanks & Catch Cans - Free Shipping on Orders Over $99 at Summit Racing
Here is mine.