1275 Motor Overhaul from Atlanta

Got a little more done on WillieB's engine project today......I got the transmission cleaned out and all the old gaskets scraped off - I don't know what kind of gasket sealer he used before but it was some TOUGH stuff to scrape off!

I installed the rings on the pistons and but before I did I put the top ring in each respective bore and checked the ring gap. they were all in tolerance so I slid piston one into it's bore.




Then I installed the crank, and used plastigauge to check the clearance Clarance. Everything checked out fine. I also checked the crankshaft end play using my dial indicator.



With that all set I torqued the main caps and the cylinder one rod caps and checked to make sure it all turned smoothly, which it does.

Before I installed the front plate I put the oil gallery plugs in.

Next up I put the lifters and cam in, then filled the oil pump with oil and installed it to hold the cam in the right depth so I could do the front end.

Then it was time to figure out how to install that slick cam belt drive....I looked at it a while before I figured out I had it upside down - once turned around it fit perfectly!



I had to make some small modifications to the front plate - same as you do if you're going to run a dual chain - you have to chamfer the holes for the two bottom screws then you have to use allen head screws instead of bolts. With that done and all the parts cleaned up it was ready to go together.



Lastly I had to clean off the end of the crankshaft, they tend to get a raised edge that keeps the lower pulley from sliding on easily. A little bit of work with a file and some 1200 cleaned it up . I also had to rework the woodruff key so the new pulley would slide on. It was interesting to find that the cam had a 3* offset key in it.

That's where I stopped for tonight, I'll install the cam drive and set the cam timing next....

 

Some more progress on this motor.

I installed the trick adjustable, belt driven cam drive kit and spent this afternoon getting the timing set right - 106* ATDC intake valve fully open. It took a while to get the set up right, then it's super easy to adjust the cam timing.



With that set I buttoned it up.

Next I'll go ahead and install the other pistons and torque everything up.

I also was lucky to find a couple gaskets for the center oil pickup in my spares stash. I don't think I'll be able to install the pick up unless I take the layshaft out first - with the screen on the end it's too long to bend around and fit in the opening with the layshaft installed.



With these things done the rest of the build will go much more quickly.....the head is done and ready to go on. with any luck by next weekend it will be headed back to Atlanta.

 

I've never installed one before, so there was a learning process but it sure looks slick!

 

Agreed. This engine had a 3* offset key in the cam gear as it was.

The pistons are about 10 thou proud of the deck height, and I wasn't able to borrow my friends CC'ing kit, so I'm just going to buy one for myself. I want to calculate the compression ratio of this set up so I know where we're at. It won't be a problem if it's higher than the 10.3 I normally prefer, but it affects how far you can go with the timing among other things.

It also won't be a problem with the pistons hitting the head as the head gasket is much thicker than 10 thou.....

Edit: preliminary calculations make it look like this engine is running 11:1 compression - that's too high for a street motor on even top octane gas, it would need race gas at 100 octane or an octane improver to keep from detonating - now we know why it banged up the bearings so badly.

 

We've been discussing what to do about the compression - it's too high at 11:1, but I want to make sure so I have a burrette and plate coming so I can CC the heads, then we can get an accurate calculation.

In the meantime....

Making small progress on the engine build while I wait for the burette and cover plate to come in....

In cleaning up the thermostat housing I noticed that one of the bolts only had about three threads going into the head, rather than find another bolt with a different head I decided to put studs back in - they're stronger anyway.




I also put the new studs in the bottom of the exhaust manifold - one interesting point, those studs are metric! 8X1.25 for those counting.....



I'm also waiting for the gasket to put the trans cover on, one of the pot joints was leaking engine oil into the joint - it's a common problem on these - the easiest way to fix it is just put some JB Weld over the cap on the inside so I cleaned it up good, blew some carb cleaner into the joint and blew it out with air then sanded the surface a little to give it some tooth for the JB to stick to. I also replaced the axle seals and shift shaft seal and installed the new center oil pickup to replace the one that lost its screen. To do that I had to pull that end cover so I could remove the laygear.



That done I went ahead and mounted the engine onto the transmichigan....then I mocked up the exhaust and intake manifolds to make sure my intake would work with that exhaust - only to remember I'll be using my header in the test stand! Oh well....




Next up I'll mount the rear cover, flywheel and clutch and button up the back end as much as I can. Once the last bits come in either I'll be reworking the head to have larger combustion chambers to take the compression ratio down or waiting for a thicker head gasket or what ever the owner wants to do.

I was hoping to have it in the engine stand this coming weekend, but I don't know if we'll make that now.

 

Back end is pretty much buttoned up - clutch, flywheel and release bearing installed and adjusted.

 

After some discussion, we decided that I would go ahead and resize the combustion chambers to get the compression ratio more in line....our calculations indicate we need to go from the current approx 21.5CC to 24 to get compression down from 11-1 to 10.3-1.



I copied a pic out of Vizard's book to get an idea of the best place to remove metal, and decided if I could get enough off from the exhaust valve area that would work the best (Areas marked C and Din the pic) . In these pics, the green area is inside the fire ring, so at the edges I did not want to remove any metal if I could help it, just enough to blend in the new area (areas marked XXXXX).



I marked a small area off in red and took my burr in my die grinder to it - going really slow and carefully so it would blend at the bottom and not leave any sharp edges that could evolve into hot spots that could cause detonation or trap carbon. You don't want a polished surface, but rather a slightly imperfect one and smooth surfaces cause the fuel droplets to condense and you don't get as good and complete of a burn.


After the first go around I had only gained about 1 cc, so I marked off a larger area and went at it again. After blending and polishing I rechecked it and had my 24 cc. I did the second chamber in one go and measured it and bingo - right on the money!









I had to cut away and take the bride to dinner and do some other honey do's so I only got two cylinders done today, I won't get back to it till tomorrow.

Die grinders use a lot of air - especially my 35 year old and well used one - so it was nice to be able to have the new air compressor which not only could keep up but would shut off for quite a bit even when I was going at it pretty long and hard....not to mention the grindier stayed at full speed unlike with my old compressor where I'd get about 30 sec of full speed then it would begin to slow down.....then I'd have to stop and wait 5 min or so for it to catch back up.

 

I did the same on a Fiat 124 head in 69, in conjunction with a Judson supercharger it really opened up the high RPM power, and I didn't really lose any low end.
Then my buddy overhauled the transmission - it was scrunching going into 2nd - and when he got done the 5 speed was now a 4 speed! somehow he's lost 5th gear - no idea how he did that! Kids!

I laughed at your idea of me doing my own knee!

 

I finished up the head and today I bolted it on and torqued it down.



I still need to set the valve lash and button up the front end - the gaskets came in late this afternoon, I'll do that tomorrow.

I also need to install the distributor drive and set the initial timing.

If things go well I'll get it loaded into the test stand tomorrow and by Wed with any luck it should be making some good noises!

I'll video the startup, but I know after about the first minute or so it doesn't make for compelling watching as I run the cam in.

 

Buttoned up a few more things, set the valve clearances and closed up the front of the motor, then I installed the radiator and got the engine loaded into the stand and mostly wired up.



Took quite a bit of fiddling to get the yellow fan blade not to hit, also the water pump pulley hit the cam belt cover, so I had to add a spacer inside the pulley between it and the pump. Then everything finally cleared ok.



Just a few more bits to hook up. Add oil, water and gasoline, then I'll crank up oil pressure and see if it will make some good noises.

I also need to weld the 02 bung into the muffler, then move a few things around and clean up a bit so I can get it to the back door for the exhaust to go out....

I have an exhaust hose but I don't think it's big enough to fit over the chrome end on the muffler - if I can get that sorted I can run with the back door mostly closed when it's really cold out.