1964 GMC Model 1002 build journal

[tbucketnut]

Well I find out not all 305 blocks are created equal. This bit of info might be useful for others and should be a sticky. I thought the only difference in the 305C engine were beefier rods but I find my main bearings do not fit the main webs and cabs. It turns out my 305C replacement engine I found was casted in 1974 and the main caps and webs are different. It takes a bigger main bearing. So I now have a fully machined .020/.020 crank and main and rod bearings I cant use.

When I checked the casting date it had a year 4 which I assumed "64" but it is indeed "74" based on block casting. I got lucky and found main bearings only in .010 undersize so I had to machine another crank. Note I belive the last two years of production 1973-74 305 engines have the bigger mains. Why did they change for two years and then discontinue the engine? Things that make you go Hmmm.

[lizziemeister'sV6]

Just a guess but I bet it was do to an excess of excess inventory that fit the bigger V6's and corporate bean counters.

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[tbucketnut]

Moving right along on the V6 assembly. Block ended up .040 over on the cylinders, crank turned .010/.010 on the mains and rod journals. Cam freshened up at Delta cams along with the lifters were resurfaced. Mains came in at .0025 oil clearance, rods were in at .003 oil clearance. These pistons have the three compression rings, gaps are in at .020. Skirts were a little tighter than I liked but the machinist said it will be fine .003.
Notice the picture of the chain hoist used to lower the crank into the main bearings, these cranks are so friggen heavy.

[snazzypig]

Looks like a first class engine build Steve. Any tips on installing the rope seal, and did you put it in dry, or soak it in oil as some people have done?

[tbucketnut]

Hi Rolland, I did not use the rope seal that was in the FelPro kit. For the last three stovebolt inline six engine I have assembled I went with Best Gasket rear main seals. The later blocks 1955 and later I used their rubber lip seals, which are the best out there IMHO. The earlier blocks I used a rope seal provided by Olson Gasket here in Port Orchard, WA. They build obsolete gasket kits for farm tractors and obsolete vehicles of all makes and models. They advised against the newer rope seals available. The asbestos ropes are all long gone unless you have an old gasket kit, So I had them provide me with their own version of rope seal available for the 305. They advised to install dry, I used a little of "permatex 2" along the outside edge of the three sides of the bearing cap surface/block, and they also included the two skinny side bearing seals for the rear main cap to go with. I used very lightly permatex 2 on these too. Like all rear mains installs, take a deep breath and hold it and wait for the first engine run cycle. For some odd reason I don't have too much anguish over it this time. Probably just my ignorance. I'll have some pictures of your wonderful pistons shortly.

[snazzypig]

Thanks for the great information Steve!

[tbucketnut]

Few more hours spent in the shop. Cam, lifters/timing gear and chain installed.
Opened up the oil pump to inspect and clean. I fully expected to do this and reassemble it but found significant scoring to the rotary gears so I will replace. You would think a pair of gears immersed in oil would not wear but it is shot. I usually replace the oil pump on all rebuilds as a rule but I saw a machinist inspect his and regasket it and run it. I'll get some pics up tomorrow on that one.
Steve

[tbucketnut]

Man, I got three days in a row in the shop.
Today was a long day, Bolted down the heads, rocker shafts, adjusted the valves and installed the valve covers. Degree wheel helps with rotation of the crank through the firing order. So far no hiccups with the exception of the AC plugs I bought from Rock Auto. 5 were AC-4 and the sixth AC R455XLS. What the heck?

[LEWISMATKIN]

your build looks great!!! keep up the good work.

[tbucketnut]

Not much work getting done on the GMC through the holidays, but did get an engine dolly built to get this heavy big block off the engine stand. I have a 4 wheel engine stand but all the time the 305 was on it getting assembled, I was constantly worried about dumping it over. Especially after the heads and huge front cover got bolted down. The dolly I built will allow the entire engine bell housing clutch and sm420 to rest easy until I'm ready to drop it in. If anyone is interested in the dolly specs pm me and I'll give you the dimensions. Cost me $50 with nice cast iron wheels rated at 300lbs each. Also, I sent my motor mounts to Steel Rubber and had new rubber vulcanized to the mounts. They do really good work for anyone wanting to know. Other than that about the only other thing was I put a kit into the stromberg WW and freshened it up, bent a new pump to carb line as well.
Cheers
Thanks in advance guys

Steve