Using ARP Mains Bolts

[Ogre]

Just wanting to know, if when using ARP main bolts and rod bolts in a 4g63 do i have to get it line honed or will everything still be sweet when not using the standard bolts?As am only thinking of using the ARPs as an extra precaution, but if i have to go to the hassle of line honing/boring then i will just roll standard as it will still be plenty strong enough.

[eskymsport]

why on earth would you need to line bore it, you are only changing bolts.

[dwlee]

If you change the rod bolts the rod should be re-sized.

[cletus]

i built an engine years ago that broke one of the rod bolts when torquing it up- the last one. couldnt be bothered stripping it all so just whacked in a new set of arp bolts and it survived years of abuse and revs

Getting the rods resized is one of those things thats recommended to do when rebuilding engines anyway but you might get away with not doing it. cant see why it would make any difference on mains, as the caps are located by a tight fit in the block or dowels and the mains are usually bolts which you have to remove anyway

[RUNAMUCK]

I've read that having the line hone done is important with ARP's.

They actually give increased clamping force on the main cap once they're tightened. (More clamping than would be acheived with the OEM bolts at the same torque) So the shape can alter. As Clint said, you may well get away with it, but it's your call. I don't see why you'd spend the money on the bolts and not have it done.

[Lunacy]

I just had mine done in my engine and my builder said line boring was definitely something that should be done. Costs a bit more but for the peace of mind in an engine thats gonna see some abuse - well worth it.

[dwlee]

You can get away without resizing the rods if the rod cap is located by means other than the rod bolts such as dowels etc. In the case of 4g63 rods the caps are located by the rod bolts.

[Testament]

also depending on the engine you may find the cost of new bolts + line boring/honing is not very different to new forged rods.

[Unclejake]

why on earth would you need to line bore it, you are only changing bolts.

^ Because the journal will go oval

Caboon, if you go to an aftermarket big end or main cap bolt and associated increase in clamping pressure you need to re-size the conrod or main cap. It is a simple and cheap job.

You can, of course, just run what you brung and it will probably be OK, but if you are spending the money on a 22,000psi bolt a little more time spent ensuring the roundness of the parent componen(s) are not compromised is probably worth the effort. An oval main cap is a shit.

Having said this: If you can only afford the bolts, and can't afford the machining - then one will be better than none.

[Ogre]

Thanks guys, i was thinking that it may make things oval due to the increased clamping force and since i am thinking of using the ARPs as a peice of mind thing then it would be pointless not to do it right in the first place

.Im effectivly using a VR4 bottom end, and non turbo head,cams etc with r1 carbs.So the bottom end should be able to handle a fair thrash in standard form,although in saying that i would like it to handle 8000rpm all day.Do you think the ARPs are over kill and worth it or nah?

Cheers

[Unclejake]

I guess you should try to find out what breaks on these motors.

We used ARP stuff in the Cortina motor but that was an easy choice given that the original fastners were all 40 year old mass produced Ford items. Modernish Japanese fastners are beautiful. Perhaps the factory VR4 ones are perfectly adequate?

The Ford Kent motors will still snap off a chunk of the block where the ARP studded maincap threads in though........