Manifold bolts change - Harrop single plane manifold

[Scatman696]

Hello All,

I have a 355 in my Vk. However, I have rusty bolts on my harrop single plane manifold (from previous owner) and I would like to change the bolts to new bolts. Do these manifold bolts require a torque wrench? If so can anybody tell me what the setting should be? Should I be concerned about removing these bolts? Is there any tips or tricks to changing them?

Thanks and any advice would be great

cheers

 

[shane_3800]

Technically yes, they are "meant to be torqued" in reality no just don't go crazy tight.

 

[shane_3800]

Also now there will be a chorus of keyboard warriors saying the opposite, ignore them because if I or someone else said they need to be torqued the same idiots would respond opposite, the two or three people know who they are, I'll leave it at that.

 

[Scatman696]

Technically yes, they are "meant to be torqued" in reality no just don't go crazy tight.

I’m just looking for the replacement bolts. They seem generic almost. My motor is a 304 VN HEADS with a harrop manifold. Rare spare sell these bolts (kit) for $30. Seems right. I checked the harrop website - they don’t seem to sell the bolts. Any recommendations?

 

[shane_3800]

I’m just looking for the replacement bolts. They seem generic almost. My motor is a 304 VN HEADS with a harrop manifold. Rare spare sell these bolts (kit) for $30. Seems right. I checked the harrop website - they don’t seem to sell the bolts. Any recommendations?

Yes they are just generic, I can't remember the size but I think it's 5/16 unf off the top of my head, i might be wrong, you can get fancy 12 point bolts or cap screws or bolts.

 

[Immortality]

If you are just replacing the bolts, remove one and replace, torque to spec and then do the next one. Don't take all the bolts out at once so you don't disturb the gasket, last thing you want is it leaking around the coolant passages.

Also now there will be a chorus of keyboard warriors saying the opposite, ignore them because if I or someone else said they need to be torqued the same idiots would respond opposite, the two or three people know who they are, I'll leave it at that.

And what about the order to torque up the bolts or is that not important either? No, the bolts don't have to be torqued to spec but it is good practice, especially when you are working on customer cars.

Factory specs attached for reference.

 

[Smitty]

Hello All,

I have a 355 in my Vk. However, I have rusty bolts on my harrop single plane manifold (from previous owner) and I would like to change the bolts to new bolts. Do these manifold bolts require a torque wrench? If so can anybody tell me what the setting should be? Should I be concerned about removing these bolts? Is there any tips or tricks to changing them?

Thanks and any advice would be great

cheers

yes... you can replace them

use ARP 6 or 12 pt, or factory style if you prefer (and in stainless steel if you can afford that... they are much more exxie)
on each side, do ONE at a time .. starting in the MIDDLE of the manifold and work out towards each end from there

torque setting is 35-40nm and torque wrench? yes.. beg,borrow or hire one. Thye do need to be tight and the last thing you want to do is snap one

 

[shane_3800]

If you are just replacing the bolts, remove one and replace, torque to spec and then do the next one. Don't take all the bolts out at once so you don't disturb the gasket, last thing you want is it leaking around the coolant passages.




And what about the order to torque up the bolts or is that not important either? No, the bolts don't have to be torqued to spec but it is good practice, especially when you are working on customer cars.

Factory specs attached for reference.

You weren't in the two or three I was referring to FYI.

 

[Immortality]

I know, I think you should add certain people to your ignore list and if they did the same everyone else will be happy

Not every home mechanic has a torque wrench, but if you have one, use it (they aren't to expensive these days )

 

[Ginger Beer]

Take a bolt out and go to your local fastener business/shop (not Bunnings, not Ebay, not Rare Spares), they can match whatever thread/pitch/length you have, plus you can pick whatever material and head you want

I needed new longer bolts after fitting thermal spacers, I ended up getting hex/cap head stainless bolts in the correct size that cost about 50 cents each

Buying fasteners from anywhere other than a fastener shop is pissing money away, you would surprised at the mark up that people put on fasteners

Typically a box of 100 M5 x 50mm 304 stainless cap heads cost "around" $60

https://www.allfasteners.com.au/cap-head-socket-screw-gr304-stainless-steel-metric

Google "fastener shop near me" and look at their range