stock blocks, main cap walk?

I was reading.
it said not to run studs on the main caps. To reuse the stock bolts.
also I read thatBBF s had or has main cap walk. I'm building a 521/545 soon.
Do will all with 2 bolt mains run a.main girddle. Do thay come with studs. Wondering cause iam going to have my BBF Aline honed so they will need to tq.all this down before doing it I would imagine. What's the best one to run and will it work with a 4.300 or 4.500 stroke, and will the oil pump bolt on or will I have to notch it?

Thanks .

Once again you will get many opinions on this subject.

Some will say any two bolt block is good to 750-800 hp with stock caps,stock bolts, no girdle but tuned safe to avoid detonation. There are many documented cases to support this. Even a couple of turbo deals that have gone north of 1000hp.

Others will say that you need to convert any serious effort stock block to four bolt mains. depending on where you get this done it sometimes ends up costing almost as much as a good A460 block.

While a few believe wholeheartedly that even if the girdle doesnt do much good at least it does no harm. The best and strongest ones that firmly clamp the cap will tend to interfere with oil pumps, pickups and windage trays.

General consensus seems to be that the biggest issue is detonation. If you keep that under control a lot of other problems cease to exist.

dkp

Thanks bosshosss. So is it safe.to just run ARP.main studs without the girddle? Or should I get ARP Bolts? 700/800 HP I want with 250.hit of.nitrous. nothing fancy 521-545 heads? Dunno to many to choose from.

What's the best price.on a A460 block.do they have a cheaper version.can you get them in stock bore size. And 4.500 -4.600.bore sizes. What the largest stroke to can fit? .if I get over 600 cubes wont I need a bigger than A single dominator Carb a 1450 single Carb wont work will it.If I go A 460.block I will.have to also get the Big fogger kit.
I.don't want.to.run 2x4's .what's that pro systems.Carb.I.seen with the big round plate and the 2 tubes running over it.I never weeknights that sort of.Carb before.what CFM is that?
Thanks have a great day

2fox wrote:Thanks bosshosss. So is it safe.to just run ARP.main studs without the girddle? Or should I get ARP Bolts? 700/800 HP I want with 250.hit of.nitrous. nothing fancy 521-545 heads? Dunno to many to choose from.

What's the best price.on a A460 block.do they have a cheaper version.can you get them in stock bore size. And 4.500 -4.600.bore sizes. What the largest stroke to can fit? .if I get over 600 cubes wont I need a bigger than A single dominator Carb a 1450 single Carb wont work will it.If I go A 460.block I will.have to also get the Big fogger kit.
I.don't want.to.run 2x4's .what's that pro systems.Carb.I.seen with the big round plate and the 2 tubes running over it.I never weeknights that sort of.Carb before.what CFM is that?
Thanks have a great day

No need to spend any money on a girdle, or studs. The factory Ford bolts are plenty strong.
There is only one A460 block, buy they can be had with a bore of just under 4.36" or just under 4.5", and they cost just under $3k
Phillip Oakley has done a few 1450QFX single carb deals with C heads that were 1150+ hp. So yes you can make some serious hp on a single carb.
That Pro Systems carb is the SV1.

i has some cap walk on my 521 , 2 bolt about 700-750 hp with a 200 hp in the plate ....... block half filled , windage/girdle ..... had hundreds of passes on that stock block and i was learnig how to use nitrous , so i had some bad tunes in there most of the time

Detonation will make any cap walk around regardless of how it is attached.
Even a pinned cap will show metal transfer from bouncing; just show less of it.

Do whatever you gotta do to keep the detonation away ... it is happening long before you actually hear it.

Is detonation the only cause of cap walk? Please help me understand detonation. It is my understanding that there are 2 possible causes, timing and compression. I've always run 110 race fuel (12.5 - 1 compression). My timing has been set at 29 degrees (MSD dizzy and digital 6, P-51 heads,) What other signs would I see if I have been detonating? My plugs look clean.

Also, I have the ARP main studs in my 2-bolt stock block. The diameter of the stud looks much thinner than the bolt (I haven't measured them). If this is really the case, would that allow the cap to move more. Would a cap move enough to allow the bearing to spin? I have a spun bearing on number 2 main and 1-4 caps show major signs of cap walk. Never seen nitrous (or any power adder), turned 6700 max. Block was line bored. Stock crank and rods. Balanced, 678 gram pistons.

More hp than the main caps can hold with out flexing, they tend to do it more with a big stroke deals also. But not limited to just that.

It's not a game killer until the cap moves in enough to actually make the bearing contact the crank. Or flexes enough over time to crack the cap.

Proper balancing,flexplate weight,condition of harmonic balancer,and basically the harmonics of an engine as a whole, is very important to keeping cap walk from becoming an issue.

61coon wrote:Proper balancing,flexplate weight,condition of harmonic balancer,and basically the harmonics of an engine as a whole, is very important to keeping cap walk from becoming an issue.

Very well said..............

Could cap walk alone be enough to cause a main bearing to spin?

460Dave wrote:Could cap walk alone be enough to cause a main bearing to spin?

Yes, if you do not have proper clearances for the block / cap flex or if the movement overcomes the amount of clearance.

460Dave wrote:Could cap walk alone be enough to cause a main bearing to spin?

Re: stock blocks, main cap walk?

Post IDT-572 Yesterday at 9:47 pm
More hp than the main caps can hold with out flexing, they tend to do it more with a big stroke deals also. But not limited to just that.

It's not a game killer until the cap moves in enough to actually make the bearing contact the crank. Or flexes enough over time to crack the cap.

460 Dave,you ask the question about other signs of detonation. One of the other signs would be light gray specks on the plugs and the piston tops. A bad tune causing detonation imo can also crack a block from the cam journal to the mains. I know from experience a long time ago.

61coon wrote:Proper balancing,flexplate weight,condition of harmonic balancer,and basically the harmonics of an engine as a whole, is very important to keeping cap walk from becoming an issue.

Is a lighter or heavier flexplate more likely to be an issue with cap walk?

Would aluminum rods help. With the cap walk?

Also. You recommend ARP main studs or bolts.?

On the flex plate, I was thinking more along the lines of an after market flex plate being balanced improperly. A factory ford plate shouldn't be a problem on balance.

2fox wrote:Would aluminum rods help. With the cap walk?

Also. You recommend ARP main studs or bolts.?

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

tune up is gonna be the biggest factor IMO.........

61coon wrote:

2fox wrote:Would aluminum rods help. With the cap walk?

Also. You recommend ARP main studs or bolts.?

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

OK thanks

richter69 wrote:tune up is gonna be the biggest factor IMO.........

would less.compression be better with a bigger shot of nitrous? No street use at all. Thinking of a. 060 over bore with a 4.3 or 4.5 stroke. I like the alum rods be of shock factor with the nitrous
I was thinking not. Going 14.1. More..like 11-1 with a pro shot fogger kit 400 -600 shot with..a 250 plate too.
I wont run this car much. What you.think.?

The factory caps are going to walk, especialy with big strokes and NO2...... your not going to get around it, unless you put 4 bolt caps on it.

Also I'd avoid boring it more than it needs and block hard it. the more cylinder wall you have the better.

Your money would be wisely spent on a A460 or Eliminator block if you want a big motor.

Ive seen major capwalk on a deal that made less than 400 hp, n/a and a bad tune....... streetcar.

I agree an eliminator or A460 block would be a wise investment.

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.