pinogg

Hi all I have just rebuilt my engine and put 3.8 Pistons and Cylinders in it, had the case bored out and replaced the cams with mechanical lifters with a super-cup grind. new valves etc. the whole nine yards. Here is my problem when I manually turn the engine through it's 360 degree turn it seems to get stuck at around the top dead center mark. I used the timing tools so I know it's not the timing. I really don't think it's the pistons hitting the Valves so here's my question what could it be. I'm ready to put the engine back in the car but I am afraid something is going to go wrong and I just spent a ton of money to rebuild this engine
Could someone shead some light or maybe explain why it seems to get stuck and this point. Just to clarify when it gets stuck with a litlle force it does rotate fully around the complete 360 degrees but at this one point it become hard to turn. Thanks in advance for your feedback.

trophy

Is the engine spinning reasonably freely upto that point?

pinogg

yes

bobt993

If this happens with no plugs in then you should look things over. If you have plugs in the engine will get hard to turn when it is on a compression stroke. Did you check clearance with a small bit of solder or soft material placed on top of a piston? New rods? (Carrillo can hit the oil pump). You indicate you used timing tools. Are you saying you used the factory tools to setup on the key slots for the stock cams/hydraulic lifter package or did you actually use a timing chart given with the cams and a dial gauge. I would always second guess even triple check it all before dropping it in the car. Even get an experienced independent mechanic to look it over.

doublecabmel

Valves too tight?

pinogg

I did not do the solder or clay checking of the pistons. And no they are not new rods. The cam tools are the factory tools which seem to do a better job than I did when I used the dial guage. The cams were reground to super-cup specs and I used solid lifters. And to my ignorance I've never learned how to degree a cam.

trophy

Did something get dropped into #1 cylinder? This could prevent it to turn past TDC

NP993

Sounds to me like the plugs are in and this is perfectly normal. With the plugs out it should rotate smoothly.

pinogg

Only top plugs are in not the bottom - I performed a compresion test and I get 120 out of all cylinders by hand cranking

NP993

When you installed the camshafts, did you rotate them while you torqued the cam housings to the heads to ensure there was no binding as you tightened everything up?

race911

1. If you have any concern, you don't install the engine and hope for the best. At worst, you'll lose 3-4 hours satisfying yourself all is well.

2. How many of these have you assembled before?

3. Remove all the rocker arms. Rotate until you're satisfied you don't have a bind in the reciprocating bottom end components.

4. Install the #1 and #4 intakes. Recheck cam timing. No matter what you say about using the timing tools, oversights happen. (What is TDC overlap for a Supercup grind, anyway?)

5. If things still don't bind after being dead solid sure the cam timing is correct, install rockers one cylinder at a time. Rotate. Hell, install them one valve at a time and rotate 720.

If you go through all this, and the engine is buttoned up but still binds............well, time for some serious disassembly rechecking.

pinogg

when I installed the cams they turned freely. Then I locked everything down and tightened the bolts. I guess the question I would have is why does it do it only when the engine is at TDC . The only Valve that's open, looking through the exhaust ports is Piston number 3 and the valve seems to be open all the way but I don't feel the pistons near the Valve by sticking a peice of wire in the hole.

race911

You mean why does there appear to be plenty of clearance at #3 when it's fully open? Because the piston is at/nearly at the end of its intake stroke. Inches of clearance at that point. (~3" stroke on these engines.)

Where things get all gummed up IS at TDC overlap. The intake is opening just before the piston comes to TDC, so you're often working in fractions to make sure it all works freely. We all have a pretty good idea with factory tried-and-true combinations. I can't speak to what you have from personal experience, but maybe some actual checking for clearance is in order.

NP993

That might be your problem. You gotta spin the cam **while you're torquing** to ensure there's no binding.

race911

While you're torquing what? I never have. 250+ sets of cams successfully set up............