1.7 Rebuild First Start Up Advice, 1.7 Start Up on stand Options

[Robroe]

Have 73 1.7 bought in pieces. Engine has been rebuilt and ‘souped up’ however I don’t know what internals were installed. New crank, cam, pistons, rods and heads. but I don’t know which ones. Weber 44 idf carbs. Never had oil in it and been stored unstarted for 10 yrs in climate control. I’ve added oil by slow dripping 2 quarts through the oil pressure sensor hole. Oil dripped out of the rockers so I’m pretty sure it got some oil as pre lube. It’s on a home built test stand with the transmission mounted with the starter.

I’m trying to turn the engine over by hand with the plugs out. Have squirted oil in each plug hole. I’m able to turn the engine by hand about 45 degrees and it gets harder to spin so can’t go any further. Would it be a good idea to pull the rocker arms to see if the builder installed some wild cam without checking valve/piston clearance? It doesn’t feel like internals are hitting each other but who knows? Would hate to pull the heads if I don’t have to. Any thoughts before I break something?

Rob Roe
Newbie

[technicalninja]

95.95mm in a 96mm bore equals .05mm PTW clearance or .002".

This is a clearance for cast pistons...

It's a TIGHT clearance for cast pistons in an air-cooled application!

Not really. 0.03 mm was initial clearance when 914 engines were built. Per the Tech bulletin for the Bus engines the clearance was later opened to 0.05mm

Here are OEM 914 shallow dish pistons for a 2.0L 94mm - marked 93.97


Here’s is the excerpt from the bus bulletin that has later been applied genetically by the aftermarket to Type 4 pistons and cylinders


Bus would have had more susceptibility to seizing due to the brick in the wind aerodynamic loads plus the cargo loads that are way, way higher than the load imposed on a 914. So 0.05mm of clearance is more than adequate for a 914.

I believe Raby has run Nickies with as low as .00075” (0.019mm) piston to cylinder clearance somewhere along the line. I can’t find the source for that so take it as unverified. That of course would be possible because the piston is running in an aluminum cylinder that is expanding as fast as the piston as it heats up.

Side topic @technicalninja
Comparison of HAM head to OEM (2.0L)

Thanks for the pics SH!
Answered some questions I had.
That has minimal chamber re-shaping.

I'm betting your Nickies will not fit in your HAM heads as is...

You're going to have to have those fly cut to the larger diameter and then re-ceramic coated due to the loss of coatings on the flat sections.

Got the heads BEFORE the Nickies did you?

That would piss me off!