Opinions on Pre assembly

[80schstragedy]

Opinions needed.

This might be a touchy subject but have a question for you engine builders out there. Let me start out by saying, I don't want to sounds like a guy trying to squeak by or take a short cut but I know that very well may be how it comes off. Looking for experience in which I'm lacking on this engine. Currently in the process of building my 1980 911sc. Pistons and Cylinders are mounted and have checked for deck height via the acid core solder method. Everything there checks out well (1.3-1.5mm) with .25mm cylinder base shims. In Wayne's book, he recommends pre-assembling everything and checking for valve clearance, disassembling everything, and then doing a final assembly. He also goes on to say that unless major modifications were made, this usually results in good numbers/clearance and is primarily a making sure your efforts are not dashed l. So here where you all come in... I have had cams reground to 964 specs, heads have all been rebuilt with OEM parts but resurfaced with .22mm cut, pistons were replaced with new Mahle euro spec 9.8.1 pistons. No machine work to the cam boxes or case halves. Bottom end was not split, so original crank and rods. Think I'd be an idiot for not preassembling? Im not apposed too but if I'm being a bit overly cautious I'd like to not waste my time(I know it's not a waste of time per say to know its good, but you know what I mean). So give it to me, what you think?

Thanks for the input!

[PeteKz]

How many of these engines have you built? If this is the first or second, I recommend you do the test assembly. If you have done this a dozen times, you wouldn't be asking.

[targa72e]

Lets see, new cams, pistons and machining. I would test assemble and check for clearance. Its not that hard.

john

[vl5150]

I preassembled everything on mine and checked the valve clearance. I also picked up a burette and measured my chamber volume and piston dome height while I was at it to calculate my compression ratio.

[nospiners]

I would be very leery goin through all that work and not having checked oil pump , replacing # 8 oring and resealing all fresh .. Just a piece of mind..

[Dpmulvan]

Originally Posted by targa72e

Lets see, new cams, pistons and machining. I would test assemble and check for clearance. Its not that hard.

john

Not hard just a major pain in the butt.

[targa72e]

Not hard just a major pain in the butt.

I kind of like it

john

[Dpmulvan]

Originally Posted by targa72e

Not hard just a major pain in the butt.

I kind of like it

john

Next your going to tell me you like mowing the lawn (sober).

[targa72e]

I don't like mowing the lawn sober (or with a cold beverage either)

I do like measuring, CCing, checking clearances, machining etc. I find it relaxing.
It also allows me to do component matching. I can put the biggest piston with the biggest cylinder, tallest head with shortest cylinder, etc. none of these items are identical (especially if used and/or machined).
I have gotten items back from the machine shop and on measuring found them to be out of spec and had to have them redone (they were spot on the second time).
Also, this way I know what I actually have vs assuming things will be ok.

john

[Dpmulvan]

Originally Posted by targa72e

I don't like mowing the lawn sober (or with a cold beverage either)

I do like measuring, CCing, checking clearances, machining etc. I find it relaxing.
It also allows me to do component matching. I can put the biggest piston with the biggest cylinder, tallest head with shortest cylinder, etc. none of these items are identical (especially if used and/or machined).
I have gotten items back from the machine shop and on measuring found them to be out of spec and had to have them redone (they were spot on the second time).
Also, this way I know what I actually have vs assuming things will be ok.

john

I’m just busting on you, Had plenty of issues with local machine shops that’s why I switched to Craig. At the cost of building an engine you’d have to be a fool to make assumptions and not measure, recheck your measurements.