Pre-Assembly Engine Build-up

[jluetjen]

I'm going to be doing a pre-assembly build-up of my race motor project to check all of the clearances and stuff. For hardward that is single use (like rod bolts), do people use the old bolts for the pre-assembly and save the new bolts for the final build, or do they use the new bolts? If they use the new bolts, do they fully torque them? Finally, if they use the new bolts and fully torque them, do they still use them for the final build up, or scrap them and get new ones for the final build-up?

[andrew15]

Use your old rod bolts - keep the good stuff for the real build

AM

[88-diamondblue]

For a race motor wouldn't you want to use ARP or another brand of high strength rod bolt? The ARP and other aftermarket bolts can be reused numerous times plus are much stronger than oem single use bolts. Don't know of any other bolts that are single use. Same question for the head studs on a race motor, Supertech, ARP instead of factory. JMHO

[304065]

John,

Good for you. Since it's not a stock engine it's a great idea to double-check all the clearances.

Without question the factory rod bolts are a single-use-only item. Even with an aftermarket bolt like an ARP, there is a stretch specification that must be adhered to. I assume you will be using a micrometer or dial indicator stretch gauge to verify the correct preload. As long as the bolts aren't stretched beyond spec following the dry runs, you should be OK, and the burnishing of the threads in the dry runs should reduce friction for subsequent assemblies.

Next: Bearing shells. Wayne claims that a "well known engine builder" whose anonymity ensures that no credibility will be attached to his recommendation, says that bearing shells deform when torqued and will go oval when re-used. It seems to me that this ovality is susceptible to measurement, perhaps with a simple outside micrometer around the bearing shell, tightened with the mic's ratchet clutch so you don't inadvertently bend the shell oval by measuring it. If you do a dry assembly, some before-and-after measurements would helpful to validate this and then YOU can be the expert we cite to!

Next: Clearances. How thick is a layer of Loctite 574? If the case halves are assembled without this glue in place, how will you verify the correct geometry? Maybe somebody could put a depth mic on an unglued case.

Next: cylinder base gaskets. I assume you will be starting with .25mm standard gaskets. When these are coated with Curil-T, how thick is the layer and what does it do to cylinder height? I don't doubt that some people goop it on which could increase deck height.

Next: when a layer of 574 is used between the heads and the cam box, valve lift at the head is changed, but that can be compensated for with the valve adjustment, I would not think the geometry effect could be measured at home.

Next: will you use ANY assembly lube to prevent wear on the moving parts when the engine is rotated by hand to verify clearances and correct operation?

Those are the only things I could think of off the top of my head, I'm sure others with more experience will comment.

Good luck and I can't wait to see photos!

[dtw]

Note regarding one of Cramer's points above. When I dry-assembled my 2.4, I put cam lube on the cams/rocker faces. Eventually I traced the fact that I could not produce repeatable dial gauge measurements (cam timing) to the cam lube. I cleaned it off and used a light application of fresh motor oil and instantly had repeatable measurements. The variances with cam lube weren't huge, but I was running the ragged edge of piston/valve clearance with an aggressive cam, so I wanted as much accuracy as possible. On the other hand, the 2.7CIS I'm building now, I would have just said 'close enough' and gotten on with it.

Rod bolts - I've done both. If you have old bolts lying around - use those. If not, use new ones - just torque them a few ft-lbs past finger tight.

[Determined]

Hello there,

I used a small (3") cheap paint roller and rolled on my 574 onto a single side of my case half. My understanding is that you don't need a thick layer of this material, instead put the emphasis on a very clean mating surface. Once both halfs come together it will begin to cure and squeeze most of it out leaving only a very thin layer to form the seal.
During my preassemble I started with .25 mm gaskets with no sealant of course then realized in needed about .75mm for my 3.2 Euro. When it comes time to sealing, like everything else....surfaces must be very clean to properly seal. I plan to put a small amount of curil-t on my finger and lightly coat the gaskets on each side. After torqueing I expect that some will extrude out.
I don't believe the amount of cam lift between the heads and the cam towers is significant or important due to the 574, the clearances will be set later anyway. I'm not the expert on this so I hope others jump in.
I did use assembly lube on just about everything recommended in Wayne's book and had no problems with anything. Use good judgement on the quantity, I used only a thin coat.
Lastly, I installed ARP rod bolts and head studs. For the rod bolts use a stretch gauge and carefully adjust to within recommended specifications. The torque method is not as accurate. I believe the rod bolts if stretched properly can be reused as well.

Good luck,

Alex

[jluetjen]

BTW, for general purpose assembly lube (as opposed to the cams and rockers) I've got some swepco in a little hand-oiler. I've also got the real "assembly lube" for doing cams rockers and all of the critical stuff.

- As far as the head studs, this is a 2.2 so they are "reusable" steel studs.

- As far as the rod bolts, I'll double check because I'm pretty sure that I've got stock bolts because I'm using the heavier 2.2 rods, and if I remember correctly, the only bolts available are the stock one. In which case I think I'll reuse the old ones.

[Rob 930]

John,

I'm wondering why you feel it's necessary to do this. Note: I don't mean this as criticism, just as a question. I would think that if all the necessary machine work is done (to your satisfaction) to the bottom end components, you could confidently assemble the crank, rods, and case in (expected) final form, do some checks, and be done. If it's not right, you can still disassemble and fix it. But if you do a "final" assembly, all the lubes, sealants, and torques are unquestionably correct. I can understand why the top end might be good to assemble "dry," to set deck height and check piston/valve clearance, but what is going to be discovered during the bottom end assembly (that couldn't be discovered earlier) that causes you to want to assemble it dry?

Rob

[jluetjen]

Originally posted by Rob 930
John,

I'm wondering why you feel it's necessary to do this.

Rob

Rob; the engine is a full-out race , hi-comp, race fuel engine. The pistons are hi-comp, the cams are high-lift, long duration cams and the valve springs are race springs. For example, I wouldn't be surprised (knowing me) that when I get it together that I'll find that I want to shift the rods around to get the absolutely least variation in combustion chamber size. I'm just trying to make sure that I do a good job on this engine so that I don't have to open it again for a couple of seasons.

[Rob 930]

John,

I understand that it's an engine you want to do the best possible job assembling. It's just that I think that for the bottom end, it would be more effective to make the important measurements on the components before assembly, rather than after a "dry run" assembly. You should be able to measure (or have measured) crank throws, rod lengths, spigot heights, and all the things in the bottom end that would matter. Or at least I think you can. Do you know about some variations that can only be determined after assembly? Of course, you can always check it after assembly, and if it isn't right, you can redo. But I would think that with the right measurments done by the right person, you shouldn't need to do a dry run for that part of the job. And I would be concerned that the dry run may cause issues for the reasons you and others mentioned above.

Rob

[Eagledriver]

IMHO, stock rod bolts are fine in this application. I would use new ones however. I doubt that the small amounts of sealant will make a difference in measurements. And if they do then perhaps the tolerance was too tight anyway.

-Andy

[YTNUKLR]

As long as your rods are all balanced, and everything is new/fresh/machined/the way you want it, you should have no issues with at least the bottom end. There should be no statistically significant variation between combustion chamber volume, especially related to the rods. There is variation in head cc, a little anyway, but why don't you just get an acrylic disc and measure the cc in each of the heads, and see what each one is?

The stock 10mm rod bolts are fine for your application. That said, most rod failures are not the rod, but the bolt, and I would use the lighter (weaker) 2.0 rod with the ARP bolts, especially on an engine that has relatively lightweight pistons, like a 2.0/2.2. On a 2.5-2.8 short stroke engine, 2.2 rods machined for use with 2.4/2.7/3.0 ARP bolts are the bulletproof combination (albeit heavier).

The only real area that I see as cause for concern, and which I've had to deal with, are custom pistons. If they are not made correctly, you may need to remachine the rod bushings to suit, unless you get new pistons made. If you are using Mahle factory pistons there should be no issues whatsoever. Otherwise: make sure your oil pump turns freely, make sure your intermediate shaft is straight and in-spec., check your rod length, wristpin bushing bore, big-end bore and crank journal measurements prior to assembly, check your cylinder heights, and confirm correct case-->cam distance regarding both a) head surface depth and b) chain box distance. Also, make sure your case was machined correctly; if it was not line-bored, make sure it was inspected correctly. Get the measurements from your machine shop if you don't have the tools.

I understand your desire to be cautious in getting everything perfect. But, I think you could find a better way to spend 20-30 hours than building your engine a 2nd time over. That is JMHO, however.

Cheers
Scott

[304065]

John, do you really expect that the rod lengths will be different enough to allow you to use the variations to equalize compression ratio? This is not my typical smartass question in which I know the answer and I am being socratic, I genuinely wonder whether this is a technique that is used. I know you can swap the pistons with the heads and you can put the higher compression ratios in the "hot" cylinders to smooth things out, but shouldn't the rod length be exactly 130.000mm center to center?

[jluetjen]

John, While I'm long on the analytical analysis, my engine building experience is limited. So I'm just being cautious because I don't want to mess it up and ruin the motor. That would easily set me back a year or two to fix given my time and budget. I'm not sure if I have enough zen to take that long with this project!

[ChrisBennet]

John,
Let me know if you need to borrow any tools for measuring your motor (micrometers, burette's, etc).
-Chris