Girdle...Again

[Gary]

I'm sure everybody is sick of discussing the "girdle" vs. steel caps. But I can't make my mind up, so I hope it's okay for another go around. I recently heard that the original purpose of the girdle was to not strengthen the block, but to keep the caps from moving and eventually breaking. The steel caps came along and now there is no need for the girdle. Having looked at the girdle, it appears to me that the girdle ties the front of the block to the back and the sides to each other. How can this not then, strengthen the block. I guess I'm just looking for reassurances.

Gary

 

[Intercooler]

Yes,

Girdle= better, reinforces caps, ties block together.
Caps= good, will prevent a cracked cap. Will not prevent walking.


How fast are you?

 

[jetmech]

Im kind of in the same boat as you. A reputable engine shop (buick) told me to just do caps and that all that is needed. I think geno went 9's with just caps. and others are in the 10's with just caps. I believe it all comes down to detonation. Keep it to a mininum if not any and you will be ok. but detonate it and thats where the caps and girdle help. I think im just going to do the center caps.

 

[Intercooler]

I had a girdle on my 11.52 pump gas motor. I don't think I really needed it at that level but it was there. It took more assembly time doing it. My current 3.8 and 4.1 builds just got caps and studs and will see the high 10's but not all the time. Mid to low 11's caps work fine and less hassles. Running faster than 11.0 all the time spend the money on the girdle.


Pictures of me ole motor with the girdle:http://www.gnttype.org/techarea/pictureguides/blocks/8687SG.html

 

[EightSecV6]

Gary Gary Gary.....
How about 6 bolt mains and 14 head bolts per side?

 

[NICKG]

what if the rear main leaks with a girdle?

big problems, that is what steered me away from a girdle, (i use my car every day, 120 miles)realisticly, you have to set a goal and then go with it, while it would be nice to have a girdle, if you use the car frequently(or not) you may run into this repair, and that is gonna be a big one if you use the girdle. just something to think about

 

[Gary]

Originally posted by EightSecV6
Gary Gary Gary.....
How about 6 bolt mains and 14 head bolts per side?

Bill Bill Bill....$15,000 $15,000 $15,000
Uh, I did get some very, very good tax return news from the little lady tonight, so we need to talk soon.

Gary

 

[Gary]

Re: what if the rear main leaks with a girdle?

Originally posted by NICKG
big problems, that is what steered me away from a girdle, (i use my car every day, 120 miles)realisticly, you have to set a goal and then go with it, while it would be nice to have a girdle, if you use the car frequently(or not) you may run into this repair, and that is gonna be a big one if you use the girdle. just something to think about

Now this is something to really, really think about. Very good point that I will have to consider.

Gary

 

[750H.P.V6]

Girdle vs caps

Guy's,

This subject has been beaten to death so I figure I'll put in my 2 cents to make sure it's good and dead. Steel main caps work fine but at some point you can make enough H.P. to break the main webs in the block. Gene did this. Can you run really fast with just steel main caps? The answer is "yes" but you better keep a eye on things. Gene was a fanatic on maintenance, cutting open filters after every outing to the track etc. and caught the problem before it became catastrophic.

If you opt for a girdle then caps are unecessary. The girdle can become a problem if you have to replace a main seal but if the seal is installed correctly to start with that shouldn't be a common occurance. The nice thing about the girdle is that it ties the whole bottom end structure together and minimizes block distortion and undue stress on the crankshaft.

Depending on the H.P. level you want to achieve both options are viable. I would say caps alone are good for a low 11 to high 10 second full weight car. A girgle should be used at higher H.P. levels. If you want to go faster than low 10's and don't want to be fixing your car all the time it's time to spend some bucks and go for a Stage motor.

Just one opinion and you know what they say about opinions...

Neal

 

[EightSecV6]

I am not going to slam the girdle, I think it is a good piece. I personally choose not to use them. On a stock block with stock cast caps, no matter what you do with a girdle, you still CANNOT get the cast caps to index tight enough into the block for reliability sake.While the block will be structurally stronger, there is still an issue with deflection due to the inability of the cast cap to maintain its "roundness". Take the bolts out of a used factory cap, turn the block upside down and jiggle it a little, it will fall right out (with the exception of the rear cap). You can knurl it to make it fit a little tighter but it is still not good enough for me to put the HEAT to it. A girdle cannot prevent that cap from wiggling unless it has TIGHT fitting dowels into the saddle where it sits.Put a set of billet caps in with a fresh align bore and they practically have to be beaten out wit a deadblow.I know people have gone fast with it and held up reasonably well.
I have really never heard of someone that has been able to get it to seal completely.
I personally choose to use 4 steel caps on the high horsepower engines (Just as the Buick engineers did on the stage 2 block, no girdle). I put together an average of 10-12 full race type GN engines per year using this method and as of right now have zero failures on the main brgs/steel caps (stock rods are a different story... I dont want this to turn into a P*****g contest, just stating my reasons for doing things the way I do. The choice is yours make it wisely.
Bill

 

[Gary]

Eight sec., Would you and the other guys on this board stop saying intelligent things, you're confusing me.

Gary

 

[49-blues]

What power levels are the stock rods able to stay together to when using four billet steel main caps?

 

[rking]

When adding a girdle, does it have to line bored??

 

[49-blues]

i believe it does.

 

[tazgn]

Line Bored

Adding a girdle usually does NOT require line boring. This was put out by Jason Cramer too. I have not bored mine at all. I had them honed on the last rebuild for assurances, but I was running the girdle before that with no problems.

As for the rear main seal with a girdle. The girdle adds about 2 hours worth of work to the job TOTAL. It can be done completely in the car, although it's obviously a bit more difficult (I've done it more than once). The hardest part about doing it in the car is getting a good seal around the girdle to stop leaks. But it has been done.

Oh, and I don't really think I'm the exception, but I've had my girdle off at least 4 times and it's only leaked oil ONCE (which is the reason for one of the 4 times I had it off). I don't think it's really that difficult to get it to seal. Oh, and 3 of those times I had it off it was with the motor in the car. Don't get me wrong though. It is a million times easier to do it with the motor on a stand.

Derrick

 

[J-Rod]

I guess I am in the minority here.

I put on billet caps, and I installed a girdle. The biggest thing on preventing leaks was in the machining (which was quite extensive to get everything true and flat).

 

[TheNovaMan]

When I looked into aftermarket Chevy big blocks, I asked the casting companies whether I should get billet caps or regular nodular iron caps. They said if you're going to drive it on the street at all, stick with the nodular iron caps since they have the same coefficient of expansion as the block.

So if the billet caps don't expand at the same rate as the block, wouldn't the main bores become non-circular and tend to squeegee oil off the crank's main journals?

Seems like theoretically, the setup for the street would be a girdle, and billet caps would be race-only. So where does my logic fall apart?

 

[EightSecV6]

Originally posted by TheNovaMan
Seems like theoretically, the setup for the street would be a girdle, and billet caps would be race-only. So where does my logic fall apart?

If you want to get into the expansion thing..... The billet girdle attached (indexed by studs)to your cast caps will expand at a different rate than the rest of the block which it is attached to, hence distorting the entire engine.... Correct? We are not talking about Iron vs. Aluminum.
I do not know the differential rate of expansion between billet steel vs iron but the bottom end the engine block (webbing,caps, etc.), probably doesnt exceed 200degf. after a full pass so I dont believe distortion from differential expansion comes into play with either set up. Now if a bearing spins for whatever reason, the heat permanantly distorts the block and cap if it is billet or cast, requiring the block to be align bored.
Again this is my preference and I stated why that is as such. I am not saying the girdle is wrong, it is just not what I prefer.

 

[750H.P.V6]

Expansion coefficients

Bill,

I agree with you in the fact that the difference in expansion rates between Iron ans Steel at the operating temps we're talking about is so negligible as to not be a factor at all.

I have to contradict you on one of your earlier statements that all Stage II blocks came with 4 Steel main caps. This is incorrect. All Stage II block produced after 1985 did. Earlier blocks were a combination of cast iron caps and steel caps. The earliest blocks had only 2 Steel caps in the middle.

Obviously the factory didn't think much about the diference in expansion rates. Also there are many blocks both OEM and aftermarket which are Aluminum with either cast iron or steel caps and they seem to work fine.

Neal

 

[EightSecV6]

That is correct Neal, however,I didnt post ALL. The point I was trying to make was that The engineers designing the block used 4 steel caps for stregth, just as the later blocks were changed to oncenter for strength. They never made an on center block with cast front and rear caps as the early Off center blocks were. The early On center blocks used all steel caps even though some of them were not cross bloted. I guess I was just trying to say in a round about way, Buick never engineered any type of girdle system for their racing blocks, even the aluminum On Center Indy blocks, with 4 billet caps but they also didnt do alot of things (improvements) we do now as well. They evolved with their improvements to the block as needed until the program was ended.
Bill