This is why a main cap girdle is important !!!

[@robertwood3970]

Building a 351W now, measured the clearance of the the main cap bolt holes to the bolts. Main cap holes measure .530" the bolts are .490 right below the head for about .750" below that they are .450" My main stud girdle will keep the bigger part of the bolt from engaging the main cap. That will allow the cap to walk all over the place. I am thinking about making my own studs so they are big enough in diameter to eliminate the clearance in this area. The girdle I have will not help much with the problem I am seeing.

[@HowardJrFord]

Small block mopars have more beef in the main webbing, bigger main cap bolts, beefier caps, and more robust rods. They easily handle 600hp on the stock main caps with a stud kit.

[@charleslowe522]

^^ This is how a Buick 3800 v6 series II and III is designed and it is much stronger than the 109 block found in Grand Nationals, T-Types and Turbo T's. The 3800 v6 series II and III can handle around 600whp with stock components, up to a 1000whp with rods and pistons. The mains are very beefy and the stock crank is nodular iron, which has never failed from just making power.

[@DobermansRock]

Its funny people saying girdles are nothing more than a band air. They make the bottom end more riggid. Manufacturers today incorporate a girdle into the caps. So I guess they like band aids a lot too. Makes no sense to go splayed 4 bolt. Some blocks don't have the material to hold the extra bolts. So a girdle is the way to go. Just going to ARP studs is a good choice for a longer life engine. A girdle is just an addition to make the bottom end stronger.

[@chippyjohn1]

My little Suzuki M13A has 4 bolt mains from factory with interference fit and it is only 66kw stock, lol. They are billet steel, planning on making some from 7075. Technology. I am only pushing 165KW now at 5000. You could eliminate the walk by having a tighter fitting stud or a dowel in it.

[@griffsrearmountturbothemod1623]

Nice one, since running a girdle on the main caps its really helped keep the caps and resisters in good tight condition👍

[@charleslowe522]

Is a girdle necessary on a deep skirt engine block. I've heard no, but if an engine only has two bolt mains then regardless a girdle may be necessary. There is a debate in the turbo Buick community and the 109 block, to girdle or not to girdle. The stock Grand National block is a 109 block with 2 bolt mains and the girdle is mounted to the oil bolt holes and the 2-bolt main bolts are all tied together. Some guys do and some guys just use ARP main studs with billet 2 bolts mains. The thousand horse power stock Grand National blocks are all girdled and the blocks cooling passages are filled to harden the block.

[@HoweDoYouDo1999]

Charles Lowe the more I know with these buick techs 😂😂😂

[@whiplashmachine]

Maincaps are stretched downwards and pulled in at the sides. That main bore is no longer round. Extreme conditions and/or bad tuning are causes for this. The small block Chevy has this happen often also. I have about a dozen of them here that need fixing. The thin cap and 7/16" bolt doesn't help. There are a handfull of repairs for this and the most common I have seen is to mill one end of the cap where it mates with the registers, weld it up and mill down to gain correct fitment. Then proceed to line honing operations. In the case the repair did not line up real close, we would bore said housing bore first to insure no steps between cap and block that could damage our honing mandrel in any way. A girdle will help, espesially one fitted to support the center of the cap but in the end it is still a small bolt or stud holding it together. I am a machinist but have spent many years in engine shops also. One of which was a very high performance engine shop. We did a lot of circle track engines and small Chevys dominated the work orders. Our super late models engines were hot sellers and averaged just over 600hp in the 8000rpm range from 353ci without girdles. These engines were well built and tuned and never had cap issues like this. Even the ones we would use the thin factory main caps had no issues. It seems it's always the daily beater or home brew street machine that come in full of dark oil that are the ones that have the cap issues.

[@imarooster3548]

I make my living as a full time engine builder and your wrong. The caps don't walk in the registry slots, the mains become out of round due to downward force. This is a common problem with small blocks. The solution is to remove the stress from the cap, cut the cap and reduce the center line, then align hone the mains. Surprisingly it's more common on the 4 bolt mains than the 2 bolt.

[@a-75n5lee4]

I agree with you I'd convert it a splayed 4 bolt and line hone

[@e36racer44]

Jim Phillips *you’re Spelling is wrong too

[@hotrods4x4s18]

E36 Racer a machinist called you out so I guess “you’re “ an English teacher

[@shannan1561]

Hey Rooster, Your method of cutting mains caps is also Wrong if applied to a Straight 6 with a Crankshaft Driven oil pump. As "if" offsetting the crankshaft during line boring in the block will damage the pin located crankshaft oil pump resulting in Engine Failure. Actual Center must be maintained..

[@racerd3801]

The caps are pinched , a stud girdle will not fix this at all and will not even prevent this. The strenght of your engine is in the tune up . Your engine is detonating , this is what has streach out the middle of the cap. Bolting on a plate to the oil pan rail will do nothing, nothing. 2 dowl pins on the outside of the main bolts will be better than a girdle . Do you really think the 1/4 20 oil pan bolts can fix this.Dyno your engine with a good dyno shop, get the tun up right , this will stop this also.

[@charleslowe522]

I've heard something similar to this.

[@craphittingthefan9445]

very common for the GM 350 that's why they made a 4 bolt block, the 3 middle caps do that.

[@griffsrearmountturbothemod1623]

Im actually using this block, the way it is, but with main studs and a girdle.. 4 bolt is the ultimate..

[@UsefulEntertainment]

CrapHitting TheFan when you say "GM 350" I assume you're referring to the Chevy. Too many people forget that Pontiac, olds, and buick all made their own 350s as Well. The oldsmobile engine are cast with a very high nickel content and do not require 4 bolt mains. Chevy engines are cheap and dime a dozen, kind of like nasty McDonald's burgers.

[@mikeskidmore6754]

@@UsefulEntertainment Millions of small block Chevys being hot rodded.. Why did he have to say it's a 350 Chevy are you blind? Actually he should have said Holden ..

[@micheal321456]

i just put a low end girdle on my 6.5L TD its a 4 bolt main but you can never be too safe

[@griffsrearmountturbothemod1623]

Doppler girdles are a good thing, and work well..

[@HoweDoYouDo1999]

I wouldn’t even think about not shit just for safety shit I’d be doing it every time I get the chance to 😂

[@charleslowe522]

No first hand experience but, since your block doesn’t have a deep skirt a girdle should be used. I have a series II 3800 block which has two main bolts and then cross bolts that run into each side of the main cap. It’s also a deep skirt block. So I’m essence a 4 bolt main cap, with an additional feature the main caps are press fit. For my block a girdle is pointless because the design of the block and main caps eliminate cap walk. Good luck. Remember the 2jzed only has two bolt mains and can make 1500hp without a girdle.

[@borismcfinnigan3430]

How can this be fixed in terms of taking that slop away?? as soon as i saw this 20 minutes ago quickly ran outside and cracked the main bolts on an engine i just bought yesterday and it has some of that rock. Not as bad as what you are illustrating here but bad enough!! am i screwed??

[@griffsrearmountturbothemod1623]

I ran that engine for a couple more years only changes i did was arp main studs with a girdle and had no issues with bottom end.. I still have it and plan on using again one day 👍

[@borismcfinnigan3430]

@@griffsrearmountturbothemod1623 Hey man thanks a lot for the reply. I just quizzed somwone on facebook land and apparently it is common practice in a machine shop when line honing these that they need to be whacked on the sueface adjacent to the register with a ground down, flat faced chisel to close them up again. Makes me think that the register is mainly there for assembly purpose? I planned on (hoped on) leaving this engine 2 bolted and using arp studs, its going to be an ok performer, dash 3s and a 288 solid flat tappet, but i just wanted to do it kind of cost effective. Maybe i am stupid and should go a 4 bolt but i dunno man.

[@juliuscullum6596]

I was just wondering myself. I have a 90s model 350 one piece rear main but it a 2 bolt main and was wondering if I used one of those girdles if I could build it to put out more power and it being able to handle over 500 hp or would I be better off getting 4 bolt main cap and sending it to a machinist and have them do what they do. Not to mention I've got a budget. 😔

[@griffsrearmountturbothemod1623]

Four bolt is better than a two bolt, But saying that I'm ten years in on a two bolt with girdle around 700 hp flywheel and still holding up👍

[@juliuscullum6596]

@@griffsrearmountturbothemod1623 thank you.

[@sandamgroup]

Jason your pretty much on the money as to why girdles are needed. usually they are doweled but the dowels can wear with high horsepower applications and stretching of cap bolts with the reciprocating mass on the power stroke can be a catastrophic disaster. Your engine was a ticking time bomb and lucky it didn't puck up a bearing. Nissan RB engines have main caps and girdle combined in one and have made power over 1200 hp and 8500 to 10,000rpm or even an LSX engine that has 6 bold mains wedged into the block to stop the walk and can make upwards on 1000+ hp with standard internals. that just proves why engine manufacturers spend much time trying to stop the crank from walking. It would be interesting to see what your center bearing looks like or how much crank movement it has in it now compared to factory spec.

[@griffsrearmountturbothemod1623]

+damian b the bearing is not to bad considering. Your right though it was only a matter of time. thanks for the extra info nice too know cheers Damian

[@shrekwest8587]

Replace your bearings that's the issue and maybe chevy see if you need new main caps try that sir.

[@naui_diver9290]

Thats not cap walk. Cap walk is when the engine is running so hard it causes a 2 bolt main cap to walk or rock back and forth.

[@michaelmerrill589]

Start with shit end with shit . Not meaning that your choice is not what I mean by saying that it means start with problems end with problems.

[@OldSkoolF]

That block is junk.... Needs more work than its worth.. Someone ground the caps... Also WHY NO STUDS???

[@williammitchell5678]

TIME FOR LS MOTOR 4 and 2