[Blob]

I am rebuilding a small block chevy, and i am ready to buy some motor parts. Do i need to buy new main bearing cap bolts and new rod bolts, or can I reuse the old bolts? If I have to use new bolts how do I get the rod studs off the rod?

[poncho62]

Depends on what is being done to the motor. A stock rebuild probably can get away with the old bolts. Of course, this being a hot rodders site, that probably isn't the case.

For the cost of them, I would get new ones. ARP (or is it ARP) makes quality fasteners for most engines. It's the old case of....here comes the cliche'...

"You get's what you pay's for"

or

"You can pay me now, or pay me later"

[scholman]

Blob,
You don't have to replace them. But if you are going to be doing any after market parts to raise the horsepower then it isn't all that much more for some new nuts and bolts. I think Summit has a kit you can buy.
As for replacing the connecting rod bolts you just need a vise and a brass hammer. Clamp the rod in the vise so as not to grab any machined surface and remove the cap. Hit the bolts with the brass hammer a few times and they should come right out. Then install the new ones using the same hammer until the head is "seated" against the rod. Be sure you have them in in the correct position. The head is sort of off set to one side so just be sure it is hitting the rod correctly. Now replace the cap and put a drop of thread lube that comes in the kit and torque the nuts with the cap in place. This will truly seat the bolt head. Take the cap back off and install the new bearings and start putting this thing together.
Have Fun
Scholman

[BOBCRMAN@aol.com]

Blob

ANYTIME you change the bolts or modify the big end of a rod you MUST get it resized!! There is no room for error here.

[k-star]

Something you need to look out for when replacing rod bolts is the chamfer on the top of the rod where the bolt head seats. I have seen rods with next to no chamfer there and if you use a arp style bolt you will need to chamfer the hole. Also it's a crap shoot if the rod size is going to change. I have done sets of rod (that were on size)as a test and 7 rods will be within .0002 of the original bore size and 1 will be out .001 or more. Sbc's only have .0005 tolerance on the big end size. To be sure that you don't have a failure you need to have the rod re-sized by a shop,unless you are really skilled at measuring the bore size of the rod.

You will be fine with the main bolts.

keith

[rifraf]

I often reuse the main bolts on moderately built motors,but always change the rod bolts,just my thing,but I would put resizing the rod way before the importance of new bolts,and to do that the bolts need to come out anyway. You can get a decent set of rod bolts for about $50.

[Cstraub]

Mains are okay to reuse but you need to just take the rods to a shop and have new bolts put in them and resized. You do not put rod bolts in yourself because housing bore will change.

CStraub

[11echo]

As already pointed out, if your "just" rebuilding a stock motor then reusing original bolts is fine (as long as they are in good shape). BUT if your trying to build something "hotter" and plan to get into the higher RPMs then I would suggest replace them with some better bolts ...ARP's would bet my first choice, Muldoons (SP?) my second. Stock rod cap bolts tend to abit "stretchy", which isn't so good at high RPMs. And if you do this you'll {B}NEED[/B] to have a machinist do it because he'll have to re-build the rod cap end (to make sure everything matches), so you can't just knock them out and replacement with the new ones. I like to replace the main bolts too. IF stock rod bolts aren't that great ...and stock main cap bolts are made of the same mat'l and grade, then after the market would be better. And as long as we're talking bolts here ...same goes with head bolts. There I try to get longer then "stock", it adds to the over all cost, but as soon as you start cutting corners you short yourself in the end, or so it's been my experience! ...Anybody disagree? Good Luck with your project! ...Mark

[rifraf]

No,not really,Ive just seen a lot more failures due to rod bolts than main bolts.

[deuce_454]

bolts are the only thing holding your engine together (literally) i would but a set of Milodon, ARP, or generic PAW bolts, anything is better than old questionable ones... paw sells OEM replacement rod bolts for 1.25$ each and a kit of main bolts for 16.95$ for the set.. a set op arp rod bolts sell for 42.95 for a set, and s set of main studs costs 45.95, without provisions for windage tray.. so for somewhere between 36.95 and around 90 bucks, you are insured against catastrophic engine failure... not somewhere to be cheap in my book

[machine shop tom]

Originally posted by scholman
Blob,
You don't have to replace them. But if you are going to be doing any after market parts to raise the horsepower then it isn't all that much more for some new nuts and bolts. I think Summit has a kit you can buy.
As for replacing the connecting rod bolts you just need a vise and a brass hammer. Clamp the rod in the vise so as not to grab any machined surface and remove the cap. Hit the bolts with the brass hammer a few times and they should come right out. Then install the new ones using the same hammer until the head is "seated" against the rod. Be sure you have them in in the correct position. The head is sort of off set to one side so just be sure it is hitting the rod correctly. Now replace the cap and put a drop of thread lube that comes in the kit and torque the nuts with the cap in place. This will truly seat the bolt head. Take the cap back off and install the new bearings and start putting this thing together.
Have Fun
Scholman

This my friends is a good recipe for a set of screwed-up, twisted rods. Better to take your rods to a competent machinist to have them done right than to try to save a few bucks and try to do it yourself.

For most stock or mildly upgraded engines, stock rod and main bolts are re-usable if in good shape and they haven't been re-used multiple times. Having said that, the extra money for new fasteners is like insurance money. You probably won't need it, but if something happens, you'll wish you had.

Be sure to follow the directions that come with any aftermarket fastener.

[seven1nova]

Hello all, first time posting but have been doing a lot of reading on this site. A lot of good info on here, and you guys have answered a lot of my question that I had, but one. First: I'm building a 71 Nova 400 SBC .040 over(409), stock crank/rods both journals cut .010, bowtie heads 2.02/1.60 (w/steam holes) Isky 232 @.050, .488 lift, 1:6:1 roller rockers (total lift .518), Vic jr, 750 Holley, TH350, 2500 stall, 411 gear.

Ok here is my question I'm installing new ARP bolts in the connecting rods and having them resize. If I change over to ARP main bolts, stock style, do I have to re-align-bore/hone the block, or can I just put in the new ARP bolts (main caps) w/original caps, stock bolts are ok, Block align is good now w stock main bolts.

edit for spelling

sorry for the hijacking


Thanks in advance

joe

[Guy Hiltz]

If you are just replacing the main bolts,or even replacing the bolts with a stud kit,assuming that the crank turned OK,there should be no need for align boring/honing,so long as you are re-using the original main caps in the location they came out of.

[RPM]

Originally Posted by BOBCRMAN@aol.com

Blob

ANYTIME you change the bolts or modify the big end of a rod you MUST get it resized!! There is no room for error here.

I agree 100 percent

[CNC BLOCKS NE]

Originally Posted by seven1nova

Ok here is my question I’m changing to ARP bolts in the connecting rods and having them resize but if I change, over to ARP main bolts (stock style) to I have to align-bore/hone the block or can I just the bolts (main cap). Block align is good now.


Thanks in advance

joe

Read the instructions in the ARP box as they requires the block to be align honed when installing there hardware and we have seen a differance from the stock bolts and going to the ARP hardware.

Every stock type GM block that goes through our shop gets a ARP bolt kit and we line hone it as it takes the guess work out when assembling the engine unless we install billet caps the we use studs down the center.

After 32 years building performance engines we have taken apart stock engines and have seen the head of a main bolt broke and laying in the pan and the 2 we have seen the engines were changed do to high mileage or using oil nothing to do with the broken main bolt.