Re: stock blocks, main cap walk?

cool40 February 11th 2013, 2:07 am

Dave De wrote:My personal experience with a lower hp 521 motor pump gas 4.3 stroke had no cap walk but probably just under 600 HP. The other engine was a 547 4.5 stroke E85 13.5 compression at around 800 HP and it had extreme cap walk similar to Nicks. Both were D9 blocks.
Let's face it even with a good tune that crank wants out of there. What I find strange is that the experts say that cap walk damage is less with main bolts instead of studs. Could the bolts be more forgiving when the cap crashes into the block?
I wont use a 2 bolt block with a 4.5 crank again. 2 bolt blocks are cheap but after they get remachined then you use them to see that the bottom is getting beat up you wished you'd have spent the money on a 4 bolt.

i have studs in my 526 and had some cap walk.last time it was down i used oil on them and tq'd them to 105. confused

maybe it helped Laughing

dfree383 February 11th 2013, 2:50 am

cool40 wrote:
Dave De wrote:My personal experience with a lower hp 521 motor pump gas 4.3 stroke had no cap walk but probably just under 600 HP. The other engine was a 547 4.5 stroke E85 13.5 compression at around 800 HP and it had extreme cap walk similar to Nicks. Both were D9 blocks.
Let's face it even with a good tune that crank wants out of there. What I find strange is that the experts say that cap walk damage is less with main bolts instead of studs. Could the bolts be more forgiving when the cap crashes into the block?
I wont use a 2 bolt block with a 4.5 crank again. 2 bolt blocks are cheap but after they get remachined then you use them to see that the bottom is getting beat up you wished you'd have spent the money on a 4 bolt.
i have studs in my 526 and had some cap walk.last time it was down i used oil on them and tq'd them to 105. maybe it helped

Antisieze between the block and the cap help ease the pain a little.

Rich Osmond March 13th 2013, 4:21 pm

Agree, the girdle doesn't hurt, but not sure that it helps either (maybe to make us feel better about it). Tune-up is the key.

Mustang-junky March 13th 2013, 8:23 pm

If you find cap walk what should you do? Does the cap need to be cut and the motor align honed? Or would smoothing out the areas scuffed up by cap walk be OK? I found some signs of walk on my 351w when I took it apart to change some stuff.

Jess

Frank Merkl March 14th 2013, 12:26 am

back when I ran stock blocks and there was fretting from the walk the bores never changed so I just ran them figured the fretting would keep the main cap aligned better! Hell I was running a 545 and out running big dollar Chev 572's and 632's , and never hurt a bearing!and for the price of machining a stock block - bore , deck and align hone run it 2-3 years and put the rotating assembly in an other used block
Frank

jm March 14th 2013, 5:30 pm

i believe using a steel crank and arp studs torqued down to 115lbs with a line hone, i have seen 2 bolt blocks hold up fine at 800hp. the less of the crank flexing using a steel crank over a cast is a big issue to what i have seen. jmho Smile

IDT-572 March 14th 2013, 5:56 pm

I have always thought the torque value was low for that size fastener. If your line boring, how much more torque could you add and not have problems. The threads are deep enough to go more I would think to handle the extra torque.

Might help cap walk if enough was added. If the foot doesn't move the cap would have reduced flex.

Lem Evans March 14th 2013, 8:31 pm

Fretting between the cap and the block are fact of life with high HP and 2 bolt blocks. The caps are bending, bouncing or both.

What could happen is that the block could crack from one of the main bolt holes to the cam bearing tunnel....if so the #1 suspect would be the # 2 main saddle.

It is my opinion that using a better fastner and jacking up the tq. will load the suspect area more = more likely to fail.

TravisRice March 14th 2013, 8:58 pm

One other thing for the OP to consider ........... If you are going to line bore / hone the mains , use the fastner you intend on using at that time. If you are going to use the bolts then bolts it should be ....... if its the studs then studs it should be at the time of the line bore/hone. Don't take for granted you can just swap them out because you think its the thing to do. Both have different clamping forces and will effect bearing tolerances differently. JMO

the Coug March 14th 2013, 9:20 pm

shave the caps level with the bolt perches and install a 3/4 or 1 inch strap will fix the cap walk in 99% of the cases. the main caps stretch from the middle outward causing fretting or cap walk...Girdles do nothing because the do not support the cap in the middle where it is bowing....

Nevs March 14th 2013, 9:20 pm

Nevs March 14th 2013, 9:22 pm

the Coug wrote:shave the caps level with the bolt perches and install a 3/4 or 1 inch strap will fix the cap walk in 99% of the cases. the main caps stretch from the middle outward causing fretting or cap walk...Girdles do nothing because the do not support the cap in the middle where it is bowing....

Nevs wrote:
TravisRice wrote:One other thing for the OP to consider ........... If you are going to line bore / hone the mains , use the fastner you intend on using at that time. If you are going to use the bolts then bolts it should be ....... if its the studs then studs it should be at the time of the line bore/hone. Don't take for granted you can just swap them out because you think its the thing to do. Both have different clamping forces and will effect bearing tolerances differently. JMO

X2, that's excellent advise and I've done both

Frank Merkl March 14th 2013, 11:24 pm

Okay ,I figured I'd better spend some time checking before I opened my mouth and maybe put my foot in it !! I just spent an hour pissing around mic'ing , as I've always called bull$$it that if you change from bolts to studs you'll need a new linebore well as they say the proof is in the pudding . I'm using Mitutoyo Dial bore gauge a mitutoyo mics for zeroing the dial bore is accurate to .0001 , this block is an old D1VE-A2B block that I ran 15 years ago and has been collecting dust in the shop , this motor was run as a 521 yeas ago until the crank broke on the front throw . #2 main shows the most fretting so this is the one I checked
stock blocks, main cap walk? - Page 2 Dive-a001_zps329406fb

stock blocks, main cap walk? - Page 2 Dive-a001_zps329406fb

with bolts torqued to 105 ft/lbs
stock blocks, main cap walk? - Page 2 Dive-a003_zps4bada58d

with studs torqued to 105 ft/lbs
stock blocks, main cap walk? - Page 2 Dive-a004_zpsa5f92499

and the results!
with bolts measured at 12 O'clock 2 o'clock and 10 oclock front and back
12" 3.1933
3.1934
2" 3.1934
3.1934
10" 3.1935
with studs at 12 2 and 10 front to back
12" 3.1934
3.1934
2" 3.1934
3.1935
10" 3.1934
3.1935
by the numbers I'd call the bore still round even with the fretting and the difference between the bolts and the studs I'd call it " 0" and difference here I call minuscule
Frank

Lem Evans March 14th 2013, 11:33 pm

" #2 main shows the most fretting so this is the one I checked"

Interesting.....given my observations about #2 main saddle.

Frank Merkl March 14th 2013, 11:40 pm

probably not the best camera for the job !
Frank

rmcomprandy March 15th 2013, 12:08 am

the Coug wrote:shave the caps level with the bolt perches and install a 3/4 or 1 inch strap will fix the cap walk in 99% of the cases. the main caps stretch from the middle outward causing fretting or cap walk...Girdles do nothing because the do not support the cap in the middle where it is bowing....

The main cap girdles from years ago REQUIRED the caps to be machined flat and did support them all the way across however, in the interest of sales and making the girdles easier to install, things changed. Rolling Eyes

TravisRice March 15th 2013, 4:50 pm

Frank no way I can argue the numbers you have posted on the 460 production block. My basis for my comments were from a high end N/A small block that competed in the Hot Street Class in the NMRA. Engine was a 400 inch with an aftermarket block and the measuring technique was recorded the same as you have done. Lets say the lesson was learned the hard way and the bearings were junk after not even 10 passes. He had the hard data from the engine builder documented on paper and the differences were from .0006 --- .0008 Again a small block and not a BBF production peice. Good info to know and thanks for the research.

Paul Kane March 17th 2013, 11:18 am

61coon wrote:
2fox wrote:...Also. You recommend ARP main studs or bolts.?

If it were mine,yes, I would run arp studs.

Yes, I agree that if you wish to increase the amount of cap walk, be sure to use the ARP main studs. Laughing

We've built a number of 4.3 stroke engines with 2-bolt blocks, many of them between 700-800 hp. Of those we've serviced, we haven't seen any cap walk. They all use OEM main bolts.

At this moment, a customer of ours is going through his 700+/- hp 500-inch engine in the off season and called to tell me he has found evidence of cap walk (his short block build) and asked me what to do.

"Are you using main studs?" I asked
"Yes."
"Take them out and throw them in the trash. Reinstall the OEM main bolts and remeasure the main bore diameters. Align hone if necessary."

We'll see how his main cap registers look next year; I'm expecting a big improvement (ie, little-to-no cap walk).

______________________________________________________

Lem Evans wrote:Fretting between the cap and the block are fact of life with high HP and 2 bolt blocks.
What could happen is that the block could crack from one of the main bolt holes to the cam bearing tunnel....if so the #1 suspect would be the # 2 main saddle.

It is my opinion that using a better fastner and jacking up the tq. will load the suspect area more = more likely to fail.

This is another good reason to stick with the OEM fasteners--the strength level of the OEM main bolt matches the cylinder block in which they are used. Stronger fasteners send more of the shock loads to the cylinder block casting instead of being absorbed more.

This may not be the case in every example but of all the OEM 2-bolt blocks with yanked main webbing that I know about had aftermarket fasteners in them.

Paul

rmcomprandy March 17th 2013, 11:30 am

Paul, It is almost funny, (not humorous but maybe weird), that with the main girdles of 30 years ago where you had to machine the caps flat on a 429/460, it was recommended to use the 351W head bolts for the fasteners.
scratch

Paul Kane March 17th 2013, 11:44 am

rmcomprandy wrote:Paul, It is almost funny, (not humorous but maybe weird), that with the main girdles of 30 years ago where you had to machine the caps flat on a 429/460, it was recommended to use the 351W head bolts for the fasteners.

That is interesting. One could only guess why, what do you think? Maybe because the OEM 351W is of the correct (read: SAME) strength and also correct length (with the addition of the girdle)? Or maybe because SPS didn't offer a 460-specific fastener back then--but then again "a bolt is a bolt" and so an aftermarket fastener of the correct dimension should have been readily available but not selected...which brings us back to the girdle manufacturers opting for the OEM-strength fastener.

I'm speculating, of course. In the very least I admire the ingenuity of utilizing the the head bolts for their alternate (but suitable) application.

460bronco March 17th 2013, 12:40 pm

I know this has been hit before, but just to add to the thread; How much of an advantage do factory 4-bolt blocks give over their 2-bolt brothers if any? Also, how does the non-splayed bolt design play into the mix?

460bronco March 19th 2013, 12:03 am

Anybody got a factory four bolt opinion?

schmitty March 19th 2013, 9:43 am

The factory DOVE 4 bolt blocks are an upgrade, but they are a far cry from the splayed 4 bolt of an A460 block. You can also do a splayed 4 bolt conversion to a DOVE block, and it will help to a certain extent.

460Dave March 19th 2013, 1:46 pm

https://picasaweb.google.com/117409403657915074198/20130204?authuser=0&authkey=Gv1sRgCJ6Fja_8lqaW_QE&feat=directlink

I thought I would try to post a couple of pics of my cap walk issue. (at least links to them). I believe my original cap walk was exacerbated by the use of some Pioneer main studs. They are designed with a cut down shank. As a result, there is very little lateral support for the cap. They didn't break, but allowed the cap to move quite a bit. My initial issue was a spun main bearng (#2) and a spun rod journal w/ bent connecting rod (stock rod w/ ARP 2000 bolts.) When I unbolted the M84HV pump, it came apart in 2 pieces at the base. I'm sure that had something to do with my oil pressure challenges and led to my bearing issues. The cap walk may have been a secondary issue. It's really hard to tell which was the destructive factor for the bearings. Maybe a combination.

Anyway, I have moved on to a splayed cap, 4-bolted D0VE block (Thanks to Paul Kane) that has been filled. I have learned my lesson with the cap walk issue. It's 4-bolt for me from now on.

Let me know if the pics don't work. P.S. How can I put the pics directly into this message?

Lem Evans March 19th 2013, 2:45 pm

stock blocks, main cap walk? - Page 2 547001Medium

This the 4 bolt SCJ block...my 547". The outer bolts are 7/16" and there is a solid dowel between the inner and outer bolts. They are a lot of comfort over and above the 2 bolts blocks but, like Rob said they are not in the league with the A460 race blocks.

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