Quick Mark V BBC valve question

[boz42]

I was going to do a tune up on my '91 CC. It has a 454. 2 simple questions:

1. Are the valves adjustable? or do you just tighten them down & let them go. Mine has bolts through the rockers & no way to keep them thight unless you tighten them all the way up.

2. What do I need to do to set the timing. I am thinking there is something I need to do to keep the ECM from advancing it so I can set it. Am I close to being right.


Sorry I am sure this has been cov ered before, but I am in a hurry. This is my first TBI truck to. Thanks in advance.

 

[nvrenuf]

There is a wire by the master cylinder that needs to be disconnected. At the front of the truck looking toward the firewall, it's at about a 5 o'clock position. Iirc, it's tan with a black stripe and it has a connector to make it easy to unhook. My 350 was supposed to be set at 0* but everything I read said 4* helped a little.

As for the valves, Mark V's should be nonadjustable. Are you sure it's a Mark V? I would have assumed a Mark IV. Then again, I'm a little vague on when the 2nd gen motor started.

 

[boz42]

Thanks, John

Pretty sure it is a Mark V. It has Mark V stamped all aver the valve train parts.

What is a sure way to tell it is a Mark V? The casting number?

 

[nvrenuf]

See if it's got a usuable mech fuel pump boss on it, that's a for sure sign as a Mark V does not (I believe it's smooth right there).

 

[boz42]

I went back out & looked, It doesn't have a fuel pump boss at all. It looked so funny I had to go look at the old BBC in my '69 to make sure I wasn't going crazy.

It has bolts to hold the rockers down. Under the rocker & the pivot ball there is an aprox. 1" tall spacer it all sits on.

Tryed to look for the cast number but there is too much crap on the engine to see it. I hate to pull all that off just to get it.

 

[nvrenuf]

The fuel pump boss is the red flag, Mark IV & VI have them but a V does not.

Afaik, the valves are nonadjustable so you just torque them to spec and let it fly. Unless there's a real problem I wouldn't mess with them.

Any luck finding the timing wire?

 

[boz42]

Well the truck has about 125,000 on it now & I just figureed I would run through the valves to make sure they were right. I was surprised to see bolt heads instead of nuts. Guess I'll put the covers on & call it good.

I found the wire thanks again, John.

 

[4X4HIGH]

All Gen V and VI use non adjustable rockers. You will find what you already have, a bolt instead of a stud and nut.