Pre Assembling Heads to Camshaft Towers, Cams, Rockers

[MyFlat6]

My P&C’s are going to be delayed for what looks like could be months, I am debating putting the heads and cam tower assemblies together while I wait. I have read it can be easier than the traditional method of installing piece by piece from the cylinders out except the weight of the assemblies when you go to mount them to the cylinders can be challenging. Any experience with this?

How about checking the valve to piston clearance - would this approach make this process more challenging?

[dannobee]

It's easier to assemble the heads on the bench, then put the whole shebang on the short block. And if it's going to be awhile before you get the short block assembled, your chances of misplacing stuff is less if you have two assemblies rather than a jumble of parts.

Checking VTP clearance difficulty depends on your method. If you're using clay, then yeah, you'll need to lift the head assembly off a couple of times. If you're using the valve drop method, and your clearances check good, you can just continue with the assembly.

[MyFlat6]

^thanks! For the VTP check, any concerns with installing all of the rockers as part of the pre assembly if doing the valve drop method? I have read that you only install on #1 and #4 cylinders for the test but would rather install all of them together on the bench. Didn’t know if I would have to undo any or if this would cause any other unexpected issues.

[Jeff Alton]

Have never installed heads and cam towers together on the bench. Not saying it is a bad idea, but also very unclear how it is "easier"... I see at it as more difficult to get proper torque, but YMMV.

What motor, cam spec, piston spec are we discussing here??

What is the delay in your P/C set?

If you wait to install the heads first, then the cam towers, the total time will be less than an hour per bank, some of which you will spend trying to cobble it together on the bench anyways. Do you have the spare time?

If you are checking piston to valve clearance you are going to do that dry anyways, so you are not final assembling anything at this point. Also, depending on the cam choice some are easy with only 1/4 installed and some it doesn't matter. Let us know what you are building and why you are asking the question and we can give you better guidance...

Cheers

[MyFlat6]

I am taking my stock 2.4T motor and building the following:

Bumping to 2.5 using a P/C set from LN Engineering. This is a set of their Nickies and JE Pistons designed for the 2.4 as a slip in. Using DC-30 cams.

Unfortunately I found that this set from LN is back ordered and will take a couple months. I am doing a complete restoration of my ‘72 and balance this with a lot of hours with my job so I am just trying to keep things moving on this project when I have time.

I went ahead and assembled the heads to the towers today. I have not installed the rockers yet though.

[brighton911]

Another consideration, as you are not using the original cylinders, if their heights are not exactly the same, you could run into cam binding issues. To ensure the cams turn smoothly, best to assemble heads & cam cases (dry) on the cylinders and torque to spec. Then insert the cams to determine if they turn freely. If all OK, then disassemble & assemble with appropriate sealer of your choice. Sure, it takes some extra time but you will be confident in the job done right.

[MyFlat6]

Good point about cam binding. This is another reason I may not install all of the rockers. I will do a trial fit before I install them. I found this thread which gave me some confidence in the approach. It is tough having my short block all ready to go on the engine stand and these towers with heads now waiting on my bench. All waiting for P/C’s. This was after it took 7 months for my machine work to be completed.

http://forums.pelicanparts.com/911-engine-rebuilding-forum/1065093-installing-heads-cam-tower.html

[Neil Harvey]

If you measured the case halves and the deck heights were the same and parallel, measure the cylinder heights and heads before assembly and they are the same, go ahead and assemble the heads to the cam decks.

The only reason not to would be if you are going to check the P/V distances. Its probably easier to handle the parts singularly than as a whole assembly.

[MyFlat6]

Thanks,Neal. Yes, the heads and case measure out after Ollie’s spent a considerable amount of machine work. They supplied me with 1mm base shims for the cylinders to get it back to spec. I hope the cylinders measure out when I get them. LN is supposed to be of good quality. If they don’t, it would seem the best course of action would be to have LN make corrections? Same with the P/V clearance if there are issues, isn’t the answer to machine the valve cutouts on the pistons? Sorry for the amateur motor building questions but I guess what I am saying is that even if the heads and towers are all assembled, I am not sure how it would change the best solutions to issues encountered with P/C’s?