Can I/should I Replace My Rod Bolts - W/ Engine In Car?!?

oz · Nov 7, 2012

Greetings,
Long story short, I added a blower to my modified 5.0. The bottom end (block, crank, rods, pistons) are stock.... My combo made 488.5 RWHP.
I know this is too much for the stock bottom end if I want it to live long and I was thinking that the rod bolts were probably the weakest link.

My questions are:
1. Is it possible to change the rod bolts while the engine is in the car - assuming I've lifted it high enough to remove the pan? Are the bolts pressed into the rods or can they be removed?
2. Would replacing the rod bolts w/ ARP bolts be the best way to reinforce my bottom end - short of getting a sportsman or dart block w/ upgraded rotating assembly?

Thansk!

91TwighlightGT · Nov 7, 2012

I still think you will break the rods themselves or the block will crack, so it is probably not worth the effort. It is probably easier to change the blower pulley and back the power off if you want it to live longer with those components.

oz · Nov 7, 2012

Yea, I thought the same thing and suggested it to the tuner. They said that as long as I keep my rev limiter where it is (5750) and stay off the 1/4 mile that it should be fine for quite a while. I was just thinking that it bolts would be cheap insurance.
I belive they're pressed in but how tightly, I don't know.

Thanks!

Noobz347 · Nov 7, 2012

oz said:
Yea, I thought the same thing and suggested it to the tuner. They said that as long as I keep my rev limiter where it is (5750) and stay off the 1/4 mile that it should be fine for quite a while. I was just thinking that it bolts would be cheap insurance.
I belive they're pressed in but how tightly, I don't know.

Thanks!

Your mains and lifter valley (the block) are the weakest links. I dunno that I'd be that concerned about rod bolts.

I think I still have a main bolt girdle lying around somewhere. PM me if that's a consideration for you.

oz · Nov 7, 2012

Thanks Nobz347 - PM sent.

RangerJoe · Nov 7, 2012

The rod bolts are pressed in, not easily removed. I am fairly sure that the ends of your rods should be rebuilt, or resized, as well after installing arp bolts. Or so i was told when i looked into this idea. Joe

85_SS_302_Coupe · Nov 7, 2012

Have to agree...the rod bolts are weak, but at that power level the block is going to let go before anything else does.

tannerc91gt · Nov 7, 2012

it takes about 20 minutes to pull an engine in a fox. Hell ive gotten one out and on a stand and it was still hot from driving it into the shop. So this isnt really a reasonable question. why make it 20x harder than it needs to be?

91TwighlightGT · Nov 7, 2012

tannerc91gt said:
it takes about 20 minutes to pull an engine in a fox. Hell ive gotten one out and on a stand and it was still hot from driving it into the shop. So this isnt really a reasonable question. why make it 20x harder than it needs to be?

It takes me 20 minutes to get the car into the garage and up on stands

oz · Nov 7, 2012

91TwighlightGT said:
It takes me 20 minutes to get the car into the garage and up on stands

Yea, me too... lowered car, can't drive up on anything and can't get a floor jack under it makes the job pretty tough...

Noobz347 · Nov 8, 2012

Wilfred Edwards said:
I agree with the author's point of view! I learned a lot. Thank you!

... and I agree with drop kicking china-bots.

NIKwoaC · Nov 8, 2012

Just so we're clear, there is no way to change rod bolts with the engine in the car (that's not a completely hack method).

Failure of rod bolts are more related to RPM than anything else (assuming the engine is working the way it should). The faster you spin the engine, the faster you're pulling the pistons away from TDC, which puts the rod in tension, and the rod assembly has to work harder and harder to make this happen. Considering that guys run stock bottom end 302s to 6500 RPM and beyond with fairly regular success (myself included), I would think that your rod bolts are probably fine with 5750.

Remember, power comes from the combustion event, which compresses the rod. Unless you have bearing failure and the rod tries to turn with the crank, the bolts don't really see any of that load.

90lxcoupe · Nov 8, 2012

Noobz347 said:
Your mains and lifter valley (the block) are the weakest links. I dunno that I'd be that concerned about rod bolts.

I think I still have a main bolt girdle lying around somewhere. PM me if that's a consideration for you.

The main support need to be installed when the block is honed and main supports wont make the block any stronger, it'll just hold the pieces together when it breaks.

Gearbanger 101 · Nov 8, 2012

tannerc91gt said:
it takes about 20 minutes to pull an engine in a fox.

I'd love to see that. You should be working for NASCAR.

Noobz347 · Nov 8, 2012

90lxcoupe said:
The main support need to be installed when the block is honed and main supports wont make the block any stronger, it'll just hold the pieces together when it breaks.

Exactly... Greatly increases the chance to salvage internal parts and does help spread deflection a bit.

tannerc91gt · Nov 8, 2012

Gearbanger 101 said:
I'd love to see that. You should be working for NASCAR.

It's really not that impressive nor was it meant to be boasting. Obviously not including pulling in the car and putting it up on stands. Consider the amount of bolts that actually secure the motor in the car...there aren't but a few

Gearbanger 101 · Nov 8, 2012

tannerc91gt said:
It's really not that impressive nor was it meant to be boasting. Obviously not including pulling in the car and putting it up on stands. Consider the amount of bolts that actually secure the motor in the car...there aren't but a few

Dude, I spend that much time getting it on the hoise and another 20-min searching for tools. I supose in an ideal situation, with all of the tools laid out in front of you, with no complications (broken bolts, rounded bolt heads, rusted whatever, no pee breaks, etc) it could be possible....but for the rest of us, it's a good 2-hour job.

In any case...my hats off to you if you've actually done it in 20.

mikestang63 · Nov 8, 2012

it takes about 20 minutes to pull an engine in a fox. Hell ive gotten one out and on a stand and it was still hot from driving it into the shop. So this isnt really a reasonable question. why make it 20x harder than it needs to be?

I've been working on cars for 30 years and can't say I've ever seen that done EXCEPT at the boneyard where they cut every hose, wire, etc. off. I must be getting old cause it takes me 20 minutes to get the car on jackstands, raise the hood, and then remember why I put the car on jackstands in the first place.

Care to come help me with the intake and header swap this weekend? That should take you about 10 minutes I guess.

tannerc91gt · Nov 8, 2012

Haha it wasn't meant to be an amazing feat. And it was done with a buddy who's been around the fox block more than most. With it sitting on a hoist and the tool box next to us, it was out and on the stand in about 20-30 min. Still warm when we bolted it to the stand. If you think about it it's much less labor intensive than most work you'll do.

To each their own

Btw, head swap shouldn't take you more than 6 minutes if you're changing the oil as well.

90lxcoupe · Nov 10, 2012

Noobz347 said:
Exactly... Greatly increases the chance to salvage internal parts and does help spread deflection a bit.

So why would you want to do that with a stock bottom end?

Can I/should I Replace My Rod Bolts - W/ Engine In Car?!?

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