1971 Datsun Truck - Need Help

[1971tantruck]

I have a 1971 Datsun truck and I'm having trouble adjusting the valves, they won't adjust. The truck also keeps backfiring. Recently put new timing chain and gear and a new distribtor. 

 

Any help and advice you can offer would be much appreciated.

 

Thank you,

[laotsu]

what do you mean "they wont adjust"? are you able to loosen the locking nut on the valve?

[datzenmike]

New distributor???? Check your wires. The order is 1342 counter clockwise on the distributor. Sometimes it's the simple things.

 

 

Valve lash? In.0.0010" and Ex 0.012" on a hot engine

 

Turn engine until TDC #1. The first cam lobe should be at 2 o'clock and the second lobe at 10 o'clock. You can now safely adjust...

 

In and Ex on #1

In. #2

Ex. #3

 

Rotate the engine exactly ONE turn and now you can safely adjust...

 

Ex. #2

In. #3

In. and Ex. #4

[1971tantruck]

@laotsu Yes I'm able to loosen the nut. The lifter wants to stay tight against the lobe after I loosen the nuts.

 

 

@datzenmike The wires are in the correct place.

 

Would you recommended a valve job or rebuild the carburetor?

[HRH]

Sounds to me like you have the cam lobes in the wrong position.  Are you on the underside of the lobe, not on the lobe when you're trying to adjust?

[1971tantruck]

@HRH Yes they are in the correct spot. I am on the underside of the lobe.

[HRH]

The nut you're loosening, which way are you going?  It's reverse IIRC.  Tighten the 14mm adjusting nut to get more clearance between the cam follower pad and the cam.

[1971tantruck]

@HRH When I loosen the big nut I do it in reverse and then I tighten the 14mm nut.

[HRH]

The big 17mm nut is the jam nut.  Loosen that to turn the pedestal (14mm) nut up or down, increasing or decreasing the distance from the cam follower to the cam.  Sounds like it's just way out of adjustment.

[DanielC]

If you have the original engine, the valve seats slowly sink into the cylinder head, or the valves sink into the seats.  In 1971 we had gasoline with lead in it, and it reduced this problem a lot.  But lead is not good to be expelled out of car engine exhaust, so, no more lead.

When the valves sink into the head, the adjustment on the valve clearance gets used up.

 

A lot of shops that do cylinder head work do not understand how critical the amount the valve stem heights is on Datsun's overhead cam engines.  After you get a valve job done on a Datsun head, before putting it on an engine, make sure you have two to three turns of clearance on the valve adjustment.

[1971tantruck]

@DanielC That sound exactly like the problem. Any idea where I should take it to get a valved job in Oregon?

[DanielC]

The last cylinder head I had gone through, I took to Rick's cylinder head, in Milwaukie, on SE River Road.

 

Be sure to block the can chain tensioner before removing the cam chain.

[1971tantruck]

I took a head to them in the past and they did a good job. However, someone said they have a new manager and got ripped off. Thank you for your help, I appreciate it!

[HRH]

That would make sense.  I've never had that happen on an L series, but I could see where it could be a problem.

[ggzilla]

1971 L16 is a lead-free engine with hardened valve seats.

 

When you loosen the nut it is not supposed to loosen the follower. You have to turn the adjuster to loosen it.

[1971tantruck]

why does the truck miss blackfire  stalls 

[ggzilla]

Maybe because the valves are not correctly adjusted. Get er done.

[banzai510(hainz)]

look up on u tube for Datsun valve adjustment.

if the rocker arm is tight with cam lobe pointed up this means the valve is sinking. Bet its the exhaust valve as this mostly happens.

Since your in Washington there are a lot of L16 heads lying around and you could just bolt one on.for cheap. I gave one away recently.

[banzai510(hainz)]

olddatsuns.com the tech section has good infor

[mklotz70]

these might help.....