Has anyone run into this problem?
Its a 73 455 block with two bolt main caps. I installed ARP #194-5401 studs, hand tight as per the instructions, they went all the way in untill the unthreaded portion of the stud entered the block, then I put the caps on to check the fit/alignment. I want to measure the main bearing bores. #1 thru #4 everything fits/aligns good, the studs are just above the ends of the nuts/washers (proper thresd engagement). Rear main cap (#5) studs are too short, the studs are only about half way through the nuts. The course thread end if the studs go very deep into the block, the instructions do not mention backing the studs out to get proper thread engagement of the nut. This is the first time I have used studs vice bolts. Is this normal or did I get improper length studs?

Has anyone run into this problem?
Its a 73 455 block with two bolt main caps. I installed ARP #194-5401 studs, hand tight as per the instructions, they went all the way in untill the unthreaded portion of the stud entered the block, then I put the caps on to check the fit/alignment. I want to measure the main bearing bores. #1 thru #4 everything fits/aligns good, the studs are just above the ends of the nuts/washers (proper thresd engagement). Rear main cap (#5) studs are too short, the studs are only about half way through the nuts. The course thread end if the studs go very deep into the block, the instructions do not mention backing the studs out to get proper thread engagement of the nut. This is the first time I have used studs vice bolts. Is this normal or did I get improper length studs?

I talked to my machinist today, he says no big deal, just back them out enough to get the required thread engagenent for the nut. As long as the course end has six to eight threads in the block its OK, thats kinda what I was thinking. I just thought someone on this board might remember if there #5 studs were short, or if I recieved the wrong ones? Is anyone going to help help me, or did I piss off the board?

The proper bolt engagement is 1 1/2 x the dia. of the bolt for bolt depth. So if you have 1/2 - 13 threads it would need 3/4" depth threaded in the block min. for proper torque. This can be found in the machinist hand book for 75% thread engagement.

Thanks Bob,

I was planing on taking them out to measure/ count threads. Your reply specificly addresses bolts, do studs fall into the same catagory as bolts in your machinist handbook? All I have is an old NAVAIR 1-1A-8 structural hardware manual, it does not address stud tread engagement.

I just pulled both of them out, they both go into the block 14 threads. The one on the left I put it into the block 10 threads, the one on the right I put it all the way in, 14 threads. As you can see, the nut does not have proper thread engagement when threaded in 14 threads. Has anyone seen this before? or did I get the wrong studs????

I forgot to attach the pic...

i had the same problem just back them out till you have proper length for the nut. as long as you have 3/4 depth of thread like bob said. mine have been in for 3 years running high 10s and 3 low 10s passes.

mike m.

I agree with that line of thought. I just wanted to here from someone else who noticed the #5 studs should be longer to match the #1 thru #4 studs...
Thanks...
Now, its on to balancing the mess...

If it is short don't use it. This is simple to solve. Example: 13 threads per inch = .500 X 1.5 = .750 = or 9.75 threads min. Remember the more the better.

Studs and bolts use the same formula for thread engagment.

You must use ARP assembly lube to get the proper torque on the nut. Use it on the threads and under the washers too. You do not need to put it on the threads that are in the block because you are not turning the stud, you are pulling on the stud. Torqueing the nut causes the stud to stretch. This stretching is compression that will hold the cap in place.

You can do two things when torque is needed on a rod cap. 1. Torque to the amount needed. 2. Measure the amount of stretch of the bolt that is specified by the manufacture.

All of the IA II blocks are torque before line boring. We use ARP studs in all five caps.

I bet if you cal ARP they'll send you some correct length studs.

My block wouldn;t take all the correct length head bolt for my E heads in one spot. $6.00 for 2 new ones

The #5 cap uses larger diam, 9/16" I think, so using TA Bob's formula, thread depth for the #5 studs should be a minimum of 0.85"

WOW I just now run into the SAME thing! They are head studs only. I am using .074 Cometics to lower compression on a Procharger blown 9.5 462 with ARP studs and they too come up way short when threaded in the block all the way like ARP says. http://forums.performanceyears.com/g...s/icon_mad.gif
When I back them out to show enough threads,and I tightem em the stud itself turns along with the nut, making it....well a bolt basically! Then what the hell is the purpose of stud then?? What to do??http://img.photobucket.com/albums/v2...n/P1010038.jpg http://img.photobucket.com/albums/v2...n/P1010036.jpg

I bought a set of ARP head studs from Spotts Performance. When the box arrived, I noticed it had been opened & the plastic bag that the studs were in was also torn open.
The first thought I had was that maybe some of the studs were missing.
However, they were 'all present & accounted for' & all were the correct length.
After reading the above posts, it seems likely that Spotts Performance, due to incorrect length studs being supplied, opened the package to check the lengths before shipping them.

Geoff, my set was from Paul Spotts too. And it had been opened also. On the box it says #190-4002. Pontiac '67 and previous 400-428, which is not my application.Are these shorter than the 455's? But my guess was that Paul had put them in another box as he's known to check for these things??? They are still too short.I'll email him.

have had same problem call arp they will send longer studs

What to do when installing studs that turn when tighted. Simple fix is to use a thread locking compound. Clean with Brake Clean first on both the hole and stud. Wait 30 minutes and then retry the nut.

Bob,I thought of that too but I highly doubt a threadlocker can withstand (sit still)so much torque and if it can it will be a pain to get them out when needed. I need to know first if I have the right part #. If it is then ARP should have tested them on more then one Pontiac block to check thread depht in a block, why not make them a little longer anyway??? It's not like they will block anything?

Dutch, Ho, yes it can, 970 locktite can withstand the twisting motion of the nut. And, yes you can get them out by using a double nut on the stud and back them out. ARP is like any company with employees. Mistakes can and will happen. They make a great grade 8 bolt. The final quality control is always the builder’s job.

Making a longer bolt cost more and in most cases it is not needed.

Remember, if it dose not sound good, look good or smell good, it probable isn’t good. So don’t use any bolt that is to short.

Geoff,

You are right about the diameter, I just measured them.