Just put my '68 383 (274H Hyd. Comp Cam, 9.8:1 comp, Edelbrock E-Street heads) back together after getting a different block from the '65 383 being cracked. I had 45 miles on everything & lots of fire ups/idle/tuning, drove great, lots of power & just put the '65 rotating assy in this '68 block. I put it together, primed it on the stand & got oil in both heads & started it in the car. First 3 fire ups it was out of time and didn't start & when it did bust off once in time it was making some racket so I killed it immediate. Fired it back up to see if there was oil pressure & there was, 50 & climbing so killed it again. Checked firing order & just looked it over. Fired it up again, revved it to 2500 to see if maybe the lifters were making all the noise, it was a consistent racket, it didn't quit once it came back to idle so I killed it. Pulled the valve covers & the rockers are tight/lifters are pumped up. Went to fire again & it's like the starter is at 6v but I've got 12.7 & a Napa rebuilt Chrysler Late Model Mini Starter. Cranked it several times & it's just really slow. I have a new fresh battery & a full size starter so I threw that on thinking maybe the starter is shot & it's the same deal, really slow. It builds up to 30 psi of oil pressure while cranking so I don't think a main is spun or giving issue. I pulled the spark plugs & stuck a torque wrench on the crank with no belts on, just the rotating assy & flex plate is still hooked to the tranny & it clicks at 57 & turns it over at 58 ft/lbs.

How many ft/lbs should that take to turn over. Is something possibly bound up? It doesn't feel like it's hard to turn over & it's smooth thru turning it. Really at a loss for what's going on here.

Voltage drop test it. Hook the voltmeter from battery positive to starter positive. Then crank and read the voltmeter. It should read less than 1 volt. What you are reading is what is lost between the battery and starter. Same on the ground side, starter case to negative post. If either reading is high, trace back one connection at a time until you find where it is losing voltage. The test is only valid if checked while cranking.
Doug

That's a bunch. Shouldn't be that tight. Try taking the converter bolts out to isolate the engine from the trans first. Still tight? Start looking at the filter and the oil for metal.

Just took the converter bolts out & it's the same.

Unplug the dist pick up, and see if it cranks faster. If so, back down the timing.

Yes do this.

Noise and hard cranking ? look for where a bolt or bolts could be to long or it pull it back out and check the bearings.

57 lbs rotating torque?! Should be a fourth of that amount. Something doesn't seem right.

How long are the bolts holding the front pulley on? I've made that mistake once, bolts were rubbing the timing cover

Agreed, we missed the (stated) obvious, sumpin ain't right inside (noise/hitting).

You kept the rod ends with the rods they came off, correct? They are machined as assembled rods so the cap is married to the rod. This could also cause the motor to bind up and possibly spin a bearing

Rotating toque is very Valve spring driven. My 18.5-1 diesel turns easily. My 15-1 572 can have the rotating assy turned by hand at the crankshaft snout, with no valve train or plugs. In the car you can barely turn it with a breaker bar, I'll bet close to 100 ft/lbs on breakaway.
Doug

Do not run the motor again until you find this problem

I had done this as soon as it started cranking slow thinking the timing was making it slow.



They are the bolts that came with the pulley from Bouchillon, they don't protrude thru the balancer.



Yes, I was making sure to never take or mess with more than 1 rod assy at a time to not have a mix up.

If you put regular length conv bolts in they
could be dragging on the block.. if they are
you should see marks on the block

Convertor bolts should be audible when they hit the block. They will not be in contact with the block at all times, meaning you should 'feel' each of the 4 bolts catching the block edge.

The engine turns hard at all times so I think the problem is elsewhere.
I think I would want to pull a few bearing caps and have a look.

If you can get the oilpan out in the car, I would probably start with checking the mains, after you inspected the oil of course.

Maybe even quicker, take off and cut open the oilfilter and have a peek inside.


edit:
Just reread everything and it got clear this rotating assembly has been running fine for 45 miles in your previous, '65 engine block.
You just changed the engine block and the problems started.

Does the '68 block have the exact same cylinder bore diameters as the '65 block?
I'm now thinking of pistons maybe starting to skuff on the cylinder walls.

That's really got me thinking now. When the machinist first did the '65 block he had the pistons to press them on the rods. Not sure if he measured them when to get the exact size boring but with the '68 block he said I didn't need me to bring the pistons for him to bore it. Originally he did say on the '65 he would be boring loose because I was using forged pistons but not really sure what that consists of.

I pulled it tonight, pulled the pan & didn't really see anything. The bottoms of the cylinder walls looked fine. I'll be pulling the heads & disassembling the rotating assembly tomorrow night.

When in doubt, double check it out
Way better to be safe than sorry

If nothing obvious is found as you pull it apart,Check rotating assembly torque before putting the top end back on. I would check the crank by itself, then each pair of pistons. The total torque on my 528 assembled shortblock with race rings is 15 ft lbs or less. Not sure what your 383 ought to be or less,guessing less than 20?

Well I learned a lesson on this one. The block still had the stamping on the deck & I thought it was just a stock block. I had done all my measurements when I first built the 65 block, put light weight springs in & checked the clearance. I didn't measure anything in this '68 because I was under the impression they were the same deck height. The 65 was the first one I've put together & this is the 2nd. I should have went thru all the steps in the big block rebuild book I bought when sticking this 2nd one together.

The original set-up was 0.024 below the deck with forged flat tops
The new set-up now is 0.009 below the deck with forged flat tops now with dents from the valves.

So the damage - the push rods are bent, various valves are slightly down when you stick a straight edge along them & the pistons have dings & aren't flat in the holes, 0.003 variance from front of the piston to the back, higher in the front of the piston/lower on the back of some(0.009 front / 0.012 back)

I was running the Fel-Pro performance head gasket @ 0.039 compressed thickness.

I'm going to take the heads to the machine shop to see what valves are going to cost.

Need to get a pair of solid lifters & check exactly what the clearance is. What is an acceptable clearance with forged pistons & how do you go about getting lifters the exact height to replicate the hyd. lifters?

Maybe I can use this to bump my compression up from the original set-up.

So you went from .024 down to .009 down - a difference of .015. With the same reciprocating assembly if I'm reading correctly. And now all the intake valves are crashing into the pistons? I don't think that .015 of difference is the cause. I think you should look at the cam timing, especially given that it was so hard to get to run. Or adjustable rockers set up way tight.