gbarmore

I recently tore down my 383 stroker with just 6K miles on it due to some poor valve train geometry that destroyed my valves, etc. I pulled the pistons to make sure everything was cleaned out and no debris remained from the valve tips fracking up.

Prior to doing that, I figured I'd just clean up the pistons, inspect the bearings, buy some new rod bolts and slap it all back together. Then I started doing some research and found a lot of discussion about needing to resize the rods when using new high strength bolts like ARP 2000 series or 8740 Steel. This is apparently due to the additional clamping force they can apply and resulting distortion of the rods vs. 'stock bolts'.

Since I don't have the tools to determine correct clearances, I'm now thinking I need to take my motor to an engine builder and have them determine what needs to be done and have them assemble the bottom end for me.

I'm also changing out my cam, heads, rockers, etc., and wonder if I might be better off just dropping off my parts and having a builder put it all together, warrant the build, and get it dyno'd while its there. Not what I wanted to do, but if I have to worry about the bearing clearance issue, I feel like I don't have much of a choice. Failure there is not an option.

Anyone have any input on this? Is this something I need to worry about or can I just slap this thing back together (using the proper methods of course) like I planned.

Appreciate any input.

cv67

Just reuse what you have youll be fine
If the valve tips are beat up make sure your retainer to guide clearance has enough clearance and seat/open pressures are on the money

What cam?
Sometimes valve float or not enough spring and a steep ramp can cause that too.

Least you caught it in time.

gbarmore

I bought fully assembled AFR 195 competition heads and a new Howard's CAM with 237 int./237exh. @.050 with .560 lift. Valve control should not be an issue with this set-up.

Another reason I decided to pull the pistons was that this build will put me over 500hp, and I don't know the quality of the bolts that came with the original crate motor. So, figured I would replace with some known quality bolts. This has also been a challenge since I also don't know the mfg of the rods, and the bolts I'm finding on Summit Racing seem to be mfg specific. All I know is they were described as 'extreme-duty' and are H Beam.....

So you'd still say just reuse the original bolts given the above??

hotrodnick

Although my experience as a counter person is mostly with diesel engines. It is not recommended using rod bolts over. Those bolts have already been torqued which stretches the bolt. I am assuming gas would be the same,

427Hotrod

I'd say if it has H- beam rods...just re-use what you have. The trick is going to be finding out what TQ/stretch spec to use. Are the bolts marked ARP? If so...you can do some searching to determine which ones might be knock offs...there was some counterfeit stuff going on with some folks' parts. Can you contact whomever built the crate motor to see what they use?

Still need to verify the correct springs for the cam.....I'm assuming it's a HR cam? Will take more than a flat tappet.

What pistons are in it? Forged? Hyper? Cast? They worry me on a higher HP unit than the rod bolts. If cast or hyper...make sure your tune is good and don't let it get into detonation. Many crate engines are built with cheaper "claimer" hyper pistons and they aren't good.

Who's going to verify the valvetrain geometry this time and get right length pushrods?

JIM

TimAT

You can buy the tools and measure the bearings yourself for about $150. Dial Bore Gauge and a 2-3" micrometer.

gbarmore

Thanks Jim. The rod bolts simply have 8640 stamped in them which makes them kind of look like ARP, but no ARP stamp. I verified with Howard's Cams that the valve springs that come with the AFR Comp heads are appropriate for my Hyd. Roller. The pistons are Probe forged units, should be good there. I plan on setting up the valve train myself depending on whether or not I end up using an engine builder to put the bottom end back together, if I do, I might as well have them do that as well.

There seem to be some here that think reusing the old rod bolts is OK, and others that believe they should be replaced... I figured that would be the case.. Are the torque specs determined by the Rod manufacturer, or by the fastener manufacturer? Not sure how to determine torque specs for an unknown bolt, but I guess I will have to contact the original builder and see if they can help me.

73racevette

If you are looking to check rod clearances on the crank, etc, a purchase of a stick of plastigage for probably less than $10 is all you really need (other than the normal install tools). Buy whatever tools you need and do it yourself. You will save $$ in the long run and you will have more knowledge of how it went together than someone else. Also no one cares more about your car than you, so go for it.

jimvette999

If it was me, and it was, I used Oliver rods and ARP rod bolts. Tightened using dial indicator measuring and recording the bolt length prior to torque and stretch of each bolt during torque using ARP specs. The bolts have a dimple for setting up the gauge. Upon teardown in the future, I can remeasure the length of bolt to check its integrity and if unchanged, reuse the bolts again stretching to achieve the proper clamping force. If ANY of your bolts were inferior, over stretched from RPM or improper torque loads upon assembly, you risk throwing a rod IMO. Why risk it? Give yourself peace of mind when your zinging up at 6-8k? I also invested in dial bore gauges for measuring bearing clearances, cylinder bores but many do use the plastigage...I just don't feel it's adequate for anything more than a daily driver or a gambler. Pretty sure you should see "ARP" on the fasteners head if they're ARP BTW.

gbarmore

So i'm struggling to understand something here.... If (as some have said) rod bolts are only good for one 'torquing', how then do you check bearing clearances? I assume you have to bolt the big end of your rods together at full torque, then use a caliper to check size, and compare to your measurements on the crank and make sure your in spec, correct? If you do this, then aren't your bolts already stretched and no good anymore? What am i missing here? If I use my old bolts when I measure for clearance, then use new, stronger, ARP 2000 bolts (for example), will my tolerances not change? This is the question I originally started this thread about because I read some horror stories about things going south quickly on guys that did nothing but change rod bolts and ended up burning bearings, cranks, etc. Again, maybe this is just being over-thought, I tend to do that, but I'm a bit of a perfectionist. OH, and here is a pic of my bolts. Anyone recognize and know the mfg??

73racevette

If you are a perfectionist, then this is up your alley.


Some rod bolts are good for "one torqueing" not all. Truly, what you are worried about is the change in bolt tension/length. As long as the bolt does not go past yield strength it should be fine to torque, remove then retorque. If you over torque them past their yield strength, then they need to be replaced. If they are run a long time in an engine, they may (but not always) be stressed passed their yield strength.


This is common practice and not a problem.

terrys6t8roadster

My engine redline is 7400RPM. I have an engine builder assemble the short blocks, mainly for peace of mind. All fasteners are always ARP. With the cam and heads you purchased it sounds like your are looking for high RPM, the pros have the proper tooling to do the job right. T

gbarmore

Thanks 73, as has been the case since buying this car, I'm getting a case of the 'while-you're-at-it' striking again..... I'm now considering a new crank and rods so I can get a complete forged bottom end and get away from the unknowns, as I have no idea what rods are in the motor and therefore no real understanding of their limits with respect to power and RPM, and that's not a good feeling, nor worth the risk. I think my Scat 9000 series crank is up to the task of the HP I'm going after, but maybe not the RPM. Decisions, decisions. Thanks for the input.

73racevette

If you are doing that, a stroker kit is where it is at.


Don't assume your rods are junk though. Most cases they are fine and just need to be reconditioned. If however you are going with a forged crank and forged pistons, a stroker kit has all the parts you need and is not much more if you are buying a crank anyway by the time you recondition rods, bearings, etc.

USAFVeteran

I know that you're just asking for opinions, and that's what I think this place is all about.


If you have the money to do this build again, use what you have. If you'd like to have a reliable engine, and not have to do this for a while, go for the ARP bolts and nuts. Use ARP on your mains and head bolts too.


I don't own a shop, and I haven't been around this forum that long for people to know who I am, but I've done a little motor work a few times.

jimvette999

There's a rod clamping fixture I bought that you use to do as you described.... fully tighten rod bolts in caps with bearings installed in rod, measure, compare, adjust tolerances with bearings as needed. As long as you do NOT exceed the ARP specs for tightening/stretching bolts....as far as I know you can use it over and over again. Use ARP Moly lube follow their spec./directions to the letter. You'll need a stretch gauge, clamping fixture. I too am a perfectionist, I just never get there. These guys are right, plastikgauge is OK, just not exact enough for my preference. I want that bottom end to stay together because an oil slick under your tires at 110 through the traps will not be pretty. You can have rods magnifluxed along with crank or any questionable ferrous metal parts at a good machine shop. Use your new bolts for measuring clearances...only one use bolts I've heard of are some head bolts and some intake bolts...not Gen I SBC though. I also like to use ARP head studs fwiw. Here's the pics of tools mentioned.

record measurements, make a chart, before length and after length...creep up on torque value

00fxd

The engine shops here say that when a rod bolt is installed it is a a slight interference fit in the bolt hole which likely will slightly distort the big end hole. When rod bolts are installed they are torqued to 95% and the big end hole is re-sized. They are adamant on this. Race engine guys believe that rod bolts can only be re-torqued 2-3 times before changing bolts and re-sizing. High end guys measure bolt stretch instead of torquing. I believe that if you have removed a bolt, you will need to resize that hole after re-installing the bolt. It looks to me like you have high end bolts and would have just re- installed them. But if they have been disturbed I would buy new bolts and have the big ends re-sized. For peace of mind you you should call ARP tech line and have a conversation. Let us know what you find out, it has been many years since I dealt with this stuff.

OldCarBum

For many years I conducted engineering environmental stress testing on military gun and missile systems. Standard procedure was to torque any fastener one time, if removed, throw it away and replace with a new one. Even in our test hardware. A fasteners torque specification is rated by the fasteners material, diameter, length and thread pitch. The torque specs are the maximum torque that can be applied to the fastener before the material yields or breaks. If you go to home depot and buy a 1/2" grade 5 bolt used for assembling a work bench you can twist them with a 3/8" drive socket, while a 1/2" grade 10 bolt can be torqued to 180-200 ft. lbs. of torque without it yielding. If you cannot verify your rod bolts material and look up the torque specification on a chart, (or specified in an assembly instruction sheet) don't use them, let alone re-use them. Even though they may appear to be in perfect condition to your naked eye, they may have been yielded and may fail. I would never reuse any fastener that has been torqued. An easy test is, if you have a good dye set, you can thread the fastener through the proper diameter and thread pitch dye with your finger tips. If you have to apply much more force to run the threads through the dye, then the threads are probably stretched and or the fastener has yielded. Just my .02 cents.

00fxd

Good advise based on real experience OCB but what say you to a re ring and bearing job as is and has been practiced for many years reusing torqued rod, main and head bolts?

OldCarBum

I'm not saying the fasteners "will fail", what I'm saying is that once the fastener is torqued it's integrity is compromised. If it were on my build, whether its the rotating assembly, top end, suspension or any other fastener on my car, I will replace the fasteners. **** that I am. Even more so with any of the original fasteners.