what is the ideal bearing/ring/shortblock clearances for 109 block?

threerail

Member
Joined
May 26, 2006
lets hear from the engine builders on what has worked the best for them....looking to set up a serious 234 cube, steel crank, floating rod, je piston, roller cam 109 motor running 25 psi or so, thanks in advance guys.....,
1 rods and mains
2 crank and rod end play
3 piston to wall with je pistons, anyone going tighter than 4.5 thou ?
4 ring gap preferences for total seal moly rings..., seems that many prefer different variations here? depending on boost?
5 also, a high volume oil pump/frt cover? Or stock with oil pump mods and clearancing tricks?/booster plate?
6 any other recommendations also welcome
 
These are guidelines rather than ideals since my experience with the V6 Buick platform is limited. Hopefully this is a starting point for others to give advice.

Rod and main bearing vertical clearance: Clevite says .00075" to .0010" per inch of shaft diameter. Then add .0005" for performance applications.

Source:
http://www.mahle-aftermarket.com/C1...5AD100AC1257A79006F8720/$FILE/CL77-1-205R.pdf

Connecting rod side clearance: hopefully it is tight, near the factory service manual's minimum of .004". Usually that's not the case. It will end up being somewhere closer to .010". I wonder if new forged cranks tighten up the connecting rod side clearance?

Crankshaft end play (thrust surfaces): .003" to .009" is what the factory service manual calls for. Cranks run in automatic transmission cars usually end up with about .005" of crank end play. That has worked fine for me.

I believe proper measuring equipment, repeatable and accurate measuring techniques, and quality machine work are the keys to success.
 
.0015 --.0020 thou on the mains, .0018-.0022 on the rods., side clearance ends up being whatever--unless you have a pile of rods to pick from somewhere around .010 -.014 seem to work and endplay at .005-.008. piston clearance go on what the maker says I have seen .004 --.007 work fine stay to the tight side of their recomendation. rings--standard moly .016-.020 top .014-.016 second depending on boost up to 22 pounds use the lower number up to 30 pounds use the higher number, over 30 well good luck. What cam and rods do you have in mind?
 
Thanks for replies guys, keep em coming. My own thoughts were to target .0018 on rods and mains, .0045 on pistons per je info, cam I'm thinking a custom spec with about 212 to 214 duration and about 520 lift. Leaning towards 112-114 lobe seperation angle with morrels hyd rollers
Open to recommendations on cam, especially the LSA and if I should install 2-4 degrees advanced or not...opinions here please would be great, thanks
 
I don't know if you've considered this but people on here pay engine builders a lot of money to assemble these short blocks and custom cams. Do you think Nick, Chris, Dan, Bobby, Don, Lou, Bill, and the other Bad Ass Buick Builders are going to offer this information to a public forum for free? I have a blueprint of the 109 Russ Merritt built me and the 109 Brian at Speed Service built me. I wont share their knowledge/secrets, just isn't right. Sorry! But this could be why your thread is so dry.
 
I can spec a custom cam that will make more power and have more cylinder pressure at low rpm and to the right of peak power than the commonly used stuff thats out there if interested. You will need more spring pressure and possibly 3/8 pushrods and 885 lifters. Or a custom solid cam with a shielded roller. Either way your thinking is on track for the lobe separation if you are going to run a high backpressure setup. If youre looking to just run a mild setup the off the shelf stuff will work great and not give up much if any versus some of the more aggressive stuff that could be used and it will cost about half as much to completely install.
 
jasjamz.... yes i know i wont have responses from some experts because they dont want to share all their knowledge....... even though many helped them along yhe way......but there are also many that i see that will help others learn and share their knowledge, i see this from many good members here, thats what makes us all come here to learn and share their experience with one another.......guys like nick, bison, fastblackracing, dan/DLS, weber, etc are always helping to spread some good info, like many i am thankful for the info. its always the right thing to do to pay it forward to help someone.....we all can learn something from everyone. i see alot of the trans experts do this alot as well.

Bison....would like to hear what you would spec a hyd roller for my 235, and see if its close to my less experienced ideas, especially when it comes to lobe seperation and lobe profile characteristics, and if i should install 2-4 degrees advanced and why? also thoughts on single or dual pattern cam favoring longer intake vs longer exhaust and whats your experience with them

my goal is to find a good comprimise cam that will have good street manners and torque, with top end pull to about 6000, with 140lb pac 1201 springs on aluminum champs ported to 1200 gaasket, champ intake, art carr 3400 n/l converter and 6765 billet jb turbo. about 8.7 compression, atr headers,3.4 steel crank, girdle,2 caps,scat rods, je pistons, all the other usual stuff with about 25 psi boost, hoping to get about 600 hp to the wheels

i was thinking this, 214/212 hyd iron roller about 520 lift, 114 degree lobe seperation, maybe 2-4 degrees advanced...thoughts on this cam ? whats a better option in your experience?
thanks to all replies guys
 
.016-.020 on the top and .014-.016 on the second in case you did not see it in my oy other post. Do you feel you need something out of the normal for this?
 
fastblack...have read its common for engine builders to run more top and 2nd ring gap on turbo engines especially when running high boost..and high cylinder temps/ psi,.but wondering what is the sweet spot for our engines when running 25/30 psi boost? im sure alot of buick builders have their secret numbers and wont line up to share but hoping a few will step up and give some advice, have read about some opinions/ articles on other engines but havent seen how it works out on v6 buicks, the fastest guys know but will they share?? we will see
 
bison.... would be great to hear your thoughts on a hyd roller cam, especially one i could use with morrels if possible. read my thoughts a few posts above and see if im on the right track or not??
what lobe profiles do you like? would pac 1201 springs be enough to keep the valvetrain stable? not looking for ultimate power here just a strong low 10 streetable engine with enjoyable drivability
 
As an engine builder...Buick V6s don't like any of the same tolerances / combinations that the more mainstream "performance" engines do....from bearing clearances to cam bearing selection....ring end gaps to piston / wall clearance....and the list goes on. Your questions are valid...but so dependent on actual component selection...expected power levels...and desired durability. My suggestion is to not over-complicate your build. I have seen it time and time again....dump money and time into a complicated combo and it shits the crank out on the first hit.

All engine guys have their tricks....and as mentioned, that info comes with a price....BUT, its all tied to your particular combination. Cookie cutter "recipes" don't work the same on every car....and it doesn't matter if its a BBC or a 4.6 Ford. At the end of the day all engines are air pumps....and you have to figure out what you want to accomplish with a given budget. That ultimately is the road map to answers for all of your questions.
 
HO Speed....care to share any high boost ring gap preferences on the 3.820 je pistons, and how you came to your conclusions/experience on what works for you, thanks for your reply
 
Threerail....have been an engine builder / tuner for 25 years, grew up in a machine shop and have taught the theory and application at SAM here in Houston. My Buick experience is pretty deep...worked for the Conleys in the late 90s...lots of 109 and Stage builds in my pocket....including my own stuff over the years.

My preference for a high boost application (not really a street setup) on that piston....6.5 thou per inch of bore on the top and 7 thou per inch of bore on the second. So, for the specific bore in your example..... .025 on the top and .027 on the second. For the record, on 109s with JEs or Wisecos I use a C&A ring pack that I pick the tensions on based on application. For Stage stuff it really depends on the total package and the power level what ring pack I use.

Sidenote....you can drop that down a thou and a half per inch of bore on lower (street) boost applications.
 
threerail said:
bison.... would be great to hear your thoughts on a hyd roller cam, especially one i could use with morrels if possible. read my thoughts a few posts above and see if im on the right track or not??
what lobe profiles do you like? would pac 1201 springs be enough to keep the valvetrain stable? not looking for ultimate power here just a strong low 10 streetable engine with enjoyable drivability

You're pretty much at most limited to off the shelf XER grinds with 1.55 rockers with your low lift requirement. 140 on the seat. The really fast ramp high lift lobes need more spring which require an anti-pump limited travel lifter. I've got a soft 212/212 that has .495 lift Witt 1.65's. Cheap if you want it. 112LS. I went 10.61 with a cast 60-1 and junk heads using it. Only needs 120-130lbs on the seat and will rev to 5800@30psi no problem.
 
Now that's what I'm talkin bout....some good experienced advice right there!!! Thanks for posting up!! What u just said is like the advice I've read in articles on high dollar turbo motor builds, non Buick though. Very similar ring info to yours, thanks
 
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