Used Billet Caps
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artrenee10
Older...wiser...and broker...
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Just my own opinion...
I would definitely have concerns, not necessarily because of the compromised strength of the caps, but rather the caps being honed for THAT specific engine block. I would just up the coin (for my own peace of mind) for new ones for each rebuild...
I would definitely have concerns, not necessarily because of the compromised strength of the caps, but rather the caps being honed for THAT specific engine block. I would just up the coin (for my own peace of mind) for new ones for each rebuild...
I was thinking the same thing, that's why I posted. I didn't know if once installed on a different block if having them rehoned would correct or create other concerns.
Still would like to hear other opinions or from those who have tried it.
turbodave231
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Used caps can safely be reused on another block:
The caps must fit tight in the register of the block or they will walk and cause crank and bearing problems. If the used cap is already too small, it can be knurled or welded up.
At a bare minimum, the block will need to be align honed, more than likely align bored.
But all this holds true for brand new caps too. The new caps come wide and the registers machined to fit the block, then align bored/honed.
Dave
The caps must fit tight in the register of the block or they will walk and cause crank and bearing problems. If the used cap is already too small, it can be knurled or welded up.
At a bare minimum, the block will need to be align honed, more than likely align bored.
But all this holds true for brand new caps too. The new caps come wide and the registers machined to fit the block, then align bored/honed.
Dave
turbofabricator
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I agree with Dave. It's just steel. ANY main cap installation job NEEDS to be performed by a competent machinst. Key word is "competent' a.k.a. highly skilled. You just cna;t remove them and bolt them onto another block. Even new, the steel caps need alot of hand fitting/machining to do them right.
while you guys are talking about steel caps i have a question------i haven't really done too many of these--------any time i felt the need for something like this i have always gone the girdle route------- i am working on an engine for someone that had a set of these caps installed------there was terrible fretting at the junction of the cap/block-------the registration appears to be done correctly-----ie fits tight like a stock cap and has to be lightly driven in with a dead blow hammer-------my question is whats with the oversized holes-------whats the sense of making a hole for a 1/2 inch bolt thats nearly 9/16 ?????------really puzzled me so i machined sleeves, pressed them in place and reamed them to .503" in hopes that it might prevent some of the "walking"--------is there more than one company making these things and perhaps this is a crummy set or are they all this way?????.............RC
turbofabricator
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The oversized holes are due to the required fitting of the caps. They are NOT a bolt on deal. Most of the caps I have seen installed had the holes in the cap elongated to get the registers to align. (especially the thrust cap) I, too, prefere the girdle approach. DLS likes steel caps. He says the girdle approach prevents the caps from walking, but hasn't found the girdle to be alot better. I feel that if the girdle stops fretting, it's doing it's job, and I can use the stock caps. (after machining them flat) Anything that strengthens the bottom of these engines is a good thing. I think the time (labor) to install a girdle is more than just adding steel caps. Especially during assembly of the short block. The steel caps require no more time to assemble than a factory cap block. BUT.......the machining required to install the steel main caps is SIGNIFICANT! You have to machine the actual cap holes, so they align correctly, machine the cap registers in the block and on the cap, align bore, and align hone to proper size.
To install a girdle, you only need to machine the caps flat, face the caps .002" (to allow material removal during line hone) and verify pan rail to girdle dimensions via laminated shims. To do it PERFECTLY, some machining of the pan rail may be in order. I will sometimes hand sand a 109 blocks pan rail to get a near perfect .005" gap all the way around the pan rail. Stage blocks are a bit too hard to sand easily, though. A 109 block sands real easily with a flat sanding block and 100 grit. I have the caps machined flat by a competent machinist (non-automotive), and have them grind .002" off of the parting surface to clean them up, and give the automotive machinist something to remove when align honing. I then fit the girdle in place and torque it all up, and drop it off at the machine shop, and pick it up a few days later. All the machinist has to do is take a light pass through the block with his hone, and hand it over to me.
Honing is not enough. The hone will follow the shape of the bore. If the bore is not straight honing wont correct it. This goes for any time you switch caps on any block. A line bore must be performed.
The pan rail doesnt need to be machined. You could mill the tight side of the girdle to get the clearance the same all around. Its easier than trying to mill the pan rail.
DLS likes steel caps. He says the girdle approach prevents the caps from walking, but hasn't found the girdle to be alot better.
I don't know when we had this conversation but if we did you totally
misunderstood my explaination. I not going to even get into this because
as usual this topic as gone so far off course it's insane. Yes you can make
caps work from another block but usually the work required to make it
right exceeds the saving from buying new caps. Also you must be a far
more experienced machinist that taking only .002 off the caps ,changing
the fasteners and torque values allows for a straight round hole.
I don't know when we had this conversation but if we did you totally
misunderstood my explaination. I not going to even get into this because
as usual this topic as gone so far off course it's insane. Yes you can make
caps work from another block but usually the work required to make it
right exceeds the saving from buying new caps. Also you must be a far
more experienced machinist that taking only .002 off the caps ,changing
the fasteners and torque values allows for a straight round hole.
ken---------i certainly realize that the caps have to be fitted, bored and honed---------but the main bolt holes are always the same distance apart and the bolts are always 1/2 inch--------i see absolutely no need for the holes to be so oversize--------any competent machinist should be able to fit the register of the caps to the block and not need such oversized holes to do it-------with the holes so large there is just too much variation for placement of the cap in the front/back direction------it just doesn't seem like a good design to me--------to me precision is a hallmark of quality and manufacturing a critical engine part with oversize holes just doesn't seem the way to go--------here is a picture of the sleeve i am talking about---------the cap fits over this without any wiggle and slid into place just like a stock cap-------just seems like the right way to do it to me..........RC
Attachments
Richard,
I guess that maybe you got lucky on that block but the stock machining
is a crap shoot at best. I have had plenty of blocks with bulkhead core
shift so bad that I had to slot the holes. I have also experienced many
blocks with the bolt holes so far off that the studs wouldn't even start in the
threads. It is more important to have the caps in a relaxed state and sit flat
on the block then to have them side loaded from poor factory machining.I
think that the fact of the block bulkheads being so thin plus a casting joint
running through it doesn't help either. I have see plenty of aluminium blocks
with locating dowels and serious fretting ,it's the nature of the beast . When
trying to make 1000 + HP out of a block that wasn't designed to do such
you make do with the best you can. When Dave Bamford took his stage 2
twin turbo car to the Hot Rod power tour dyno challange a few years back
and put down 970 at the rear wheel on 5 cylinders (broke a rocker during the pull)
there happen too be a retired GM engineer observing he walked over to the
car shaking his head in disbelief when he saw that it truely was a V6 he had just witnessed.
I think he walked away mumbling something about that being impossible it just couldn't be.
I guess that maybe you got lucky on that block but the stock machining
is a crap shoot at best. I have had plenty of blocks with bulkhead core
shift so bad that I had to slot the holes. I have also experienced many
blocks with the bolt holes so far off that the studs wouldn't even start in the
threads. It is more important to have the caps in a relaxed state and sit flat
on the block then to have them side loaded from poor factory machining.I
think that the fact of the block bulkheads being so thin plus a casting joint
running through it doesn't help either. I have see plenty of aluminium blocks
with locating dowels and serious fretting ,it's the nature of the beast . When
trying to make 1000 + HP out of a block that wasn't designed to do such
you make do with the best you can. When Dave Bamford took his stage 2
twin turbo car to the Hot Rod power tour dyno challange a few years back
and put down 970 at the rear wheel on 5 cylinders (broke a rocker during the pull)
there happen too be a retired GM engineer observing he walked over to the
car shaking his head in disbelief when he saw that it truely was a V6 he had just witnessed.
I think he walked away mumbling something about that being impossible it just couldn't be.
thanks for the comments------perhaps this is why we see so many of them always in the shop being repaired-------i guess so far i have been lucky------if i came across a block that i couldn't even get the cap bolts to start in the threads i would put it aside and move on..............RC
