Case Closed-through bolt and CR question

[Purkinjefibre]

Hi Guys, found the time to close my beautiful crank inside it's new home. Everything seemed to come together OK, i got the Loctite 574 to spooge out nicely- crank moves smoothly. I was a bit frantic, trying to get everything done in 45 mins and then i realised my through bolts are round the opposite way To Wayne's book. Is this a problem? Also my compression ratio is 10.3 with .75mm cylinder base gaskets, i am looking to get 10.0:1- can i use 1mm? how does this affect chain housing/cam sealing?

thanks
Brett

[sand_man]

Actually, that is the correct way (from the factory). My engine had never been apart before and I have pictures clearly showing the through-bolt acorn nuts on the drivers side (before I split the case). The only acorn nuts that weren't were the ones located behind the egine oil cooler (they obviously have to be on the passenger side). In Wayne's book, he has the acorn nuts all on the same side...the passenger side of the case. I got worried about this, but others told me that it doesn't make any difference.

[Purkinjefibre]

Thanks Sand_man. That is good to know, i didn't take my 3.0 apart so never saw it Factory style,
cheers
Brett

[kenikh]

First, what is your measured deck height? Are you planning on using twin plug ignition? Isn't this a 98mm P/C engine? Even 10:1 on pistons that big is dangerous.

[Purkinjefibre]

Hi Kenik, yes this is 98mm and will have twin plugs. Deck height is 0.0475. These pistons are a little more radical than i thought. Can i try 1mm's worth of shims?

cheers
Brett

[kenikh]

Why not just keep the CR at 10.3:1? Twin plugs make that eminently doable, especially with hot cams. If you really want to do this, I seem to recall 1mm shims are fine, but have never done this myself. I believe Henry Schmidt said that is about the maximum you should use, but I won't speak for him. Perhaps he'll come along and confirm or deny this...

Can you post pics of the pistons?

[Purkinjefibre]

Thanks Kenik, I might just do that. I thought that the West Coasters would be awake for by now. Henry are you there?

Brett

[ChrisBennet]

Originally posted by Purkinjefibre
Hi Kenik, yes this is 98mm and will have twin plugs. Deck height is 0.0475. These pistons are a little more radical than i thought. Can i try 1mm's worth of shims?

cheers
Brett

Your deck height (1.2mm) is already higher than ideal (but similar to what I've seen on a 964 motor) so I wouldn't increase the deck height. Increasing the deck height will reduce the compression some but it will increase the tendency to knock (pre-ignite).

I've machined JE 98mm 10.5:1 pistons down to 9.5:1. I'd go that route rather than using a thicker base shim.

I hope I'm wrong, but it looks like you've got a lot of squezed out 574. The last time I put it on that thick the case leaked...
-Chris

[viejopatron]

"The last time I put it on that thick the case leaked... "

Jeez, Chris, make us DIY'er feel confident.

However, I can't resist. Please tell the story re: thick goo = case leak.

[tctnd]

Originally posted by ChrisBennet
Your deck height (1.2mm) is already higher than ideal (but similar to what I've seen on a 964 motor) so I wouldn't increase the deck height. Increasing the deck height will reduce the compression some but it will increase the tendency to knock (pre-ignite).

I've machined JE 98mm 10.5:1 pistons down to 9.5:1. I'd go that route rather than using a thicker base shim.

I hope I'm wrong, but it looks like you've got a lot of squezed out 574. The last time I put it on that thick the case leaked...
-Chris

Chris,
I'm curious to know how lowering the compression by raising the deck height could increase the tendency to detonate. I could see this possibly in an engine with a squish area that needs to be carefully maintained but that is not the case here.
regards,
Phil

[kenikh]

Everything I've read says squish IS imprtant int ehse engines. Because of the pent domes, I can see errant gases hanfing out in the outer regions of the combsution chamber just waititng to ping...

[ChrisBennet]

Originally posted by tctnd
Chris,
I'm curious to know how lowering the compression by raising the deck height could increase the tendency to detonate. I could see this possibly in an engine with a squish area that needs to be carefully maintained but that is not the case here.
regards,
Phil

As it was explained to me, ideally you want between 35 and 40 thousands (.035-.040" / .89-1.01mm) deck height. A larger deck height leaves a "pocket" out at the edge of the piston that can increase the chances of predetonation.
-Chris

[ChrisBennet]

Originally posted by viejopatron
"The last time I put it on that thick the case leaked... "

Jeez, Chris, make us DIY'er feel confident.

However, I can't resist. Please tell the story re: thick goo = case leak.

It was back in 2001. Back then all I had was had Bruce Anderson's book and the factory manual to go on.
In my ignorance I (incorrectly) thought:
A: "If a little 574 is good, more is better"
B: "Better torque those important though bolts first, then the perimeter bolts"


Here are the truths:
A: "If a little 574 is good, more is better"
Wrong: 574 should be put on thin - like suntan lotion. Remember, if the case is prepped right it will almost seal without sealant.

B: "Better torque those important though bolts first, then the perimeter bolts"
Wrong: As soon as you put the case halves together snug up the perimeter bolts and get the sealant squeezed out before it skims making it impossible to tighten properly. Loctite's spec sheet for 574 states "Flanges should be tightened as soon as possible after assembly to avoid shimming." I will forever grateful to Steve Weiner for telling me this trick.

-Chris

[David]

I used Copper Coat on my base gaskets, I haven't run it yet but I heard good things about the stuff.

I agree on not increasing the squish any more than it is. What cams are you running?

[sand_man]

I can't really comment on the deck height and squish stuff (I let my machinist, Neil Harvey measure and deal with those aspects), but when I first saw the pictures, it did look like the 574 was a bit thick! Maybe it's just a photo thing. I used the ThreeBond 1104 on mine. Keep in mind that what you see squeezing out of the outside case perimeter is often squeezing on the inside!!!! I guess this 574 stuff can be "washed" away inside with the oil flow, but I sure couldn't/wouldn't gamble with it.

I went VERY, VERY thin with 1104 and had hardly any squeeze-out. I also tightened my perimeter nuts first, then did the through-bolts.

Please don't misunderstand, I'm by no means attempting to cause you worry...I agonized over the case sealing like a lunatic before I finally jumped in. Just be aware, that's all!

[Purkinjefibre]

Hi guys, all of your input is appreciated. First off those images are close ups. I tried putting the sealant on as a smooth layer all around as fast as possible. It actually looked similar to the pic in Wayne's book page 133. I had it together within 30 minutes and i don't think the 574 was skinning at all. With hindsight i probably could have used less- but it didn't spooge out until being properly torqued up.

I will certainly let everyone know it it leaks or not.

Easy
Brett

[Purkinjefibre]

Hi all lots of progress to report. P and C's are in place and cam housings on. I'll start with some pics...

[Purkinjefibre]

cams are in and timed...

[rs-vic]

Looks nice. I hope those mechanical chain tensioners are just for setting cam timing.

[cgarr]

Looks very nice!! One case half has a chanfer at the thru bolt, this is the side the nut goes on, (helps seal around the bolt thread) I put mine all in and tite without the o-rings then removed one at a time and put the o-rings on each, old 912 engine trick to keep the o-rings from grinding up when going tite, mine were also opposite the cooler too.