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Engine Drilled for 1/2" headbolts

  • Thread starter Thread starter rockyracoon
  • Start date Start date Feb 7, 2022
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rockyracoon

10 Year Member
Nov 23, 2005
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margate NJ
Feb 7, 2022
#1
  • Feb 7, 2022
  • #1
I'm installing a set of ported E7s that are drilled for 1/2" inch on my 302. I'm running studs and I'm wondering if I'll need to use different washers or even bushings?
 

Willybill32

But at least it's tight!
5 Year Member
Jul 16, 2019
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Lexington, KY
Feb 7, 2022
#2
  • Feb 7, 2022
  • #2
rockyracoon said:
I'm installing a set of ported E7s that are drilled for 1/2" inch on my 302. I'm running studs and I'm wondering if I'll need to use different washers or even bushings?
Click to expand...
You’ve already got the studs in place, so this may not help. ARP makes head bolts with 1/2” shoulders for that application.

Bill
 

7991LXnSHO

wanna catch the space herp
10 Year Member
Sep 1, 2010
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Kearney, NE
Feb 7, 2022
#3
  • Feb 7, 2022
  • #3
If you do not use the bolts with the 1/2” shoulders like Bill suggests, I wonder if ARP has spacers (or tubes) for studs in this case.
Edit: Sleeve is the word I was looking for.
 
Last edited: Feb 7, 2022

Cheapskate207

The left one hangs a little lower
5 Year Member
Jan 12, 2020
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Feb 7, 2022
#4
  • Feb 7, 2022
  • #4
https://lmr.com/item/TFS-51400419/1979-95-Mustang-50L-Head-Bolt-Reducer-Bushings-Pack-Of-20

They may be cheaper elsewhere or maybe other manufacturers (like arp) but I think this is what you need.
 
Reactions: 7991LXnSHO
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rockyracoon

10 Year Member
Nov 23, 2005
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margate NJ
Feb 7, 2022
#5
  • Feb 7, 2022
  • #5
Thanks gents.
 

90sickfox

Wasn't a pretty sight...and I've got big hands
SN Certified Technician
Mar 2, 2015
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Feb 7, 2022
#6
  • Feb 7, 2022
  • #6
I always tapped my blocks for 1/2 studs. You would have to be really careful with shavings. Bushings work though. The 1/2 studs give more clamping force. All my blocks had them but my current engine builder left this one 7/16ths.

I had a set of ported e7 heads on my 306 and 347. They actually worked pretty good on the street. Didnt flow as well on the stroker. The exhaust side is where most of the power loss comes from. The heads were shaved a little bit to bring the compression up. I didn't have stock pistons.

If you turn the heads upside down, and use a baby medicine syringe, you can measure the chamber cc. Best to do it now while they are off. Just fill with water to the top cc line and fill the chamber until its level all the way around. Subtract the amount left in the syringe from the full number and you have a starting point to get a real compression number. Compression is important so you know what gas you need to run. You'll also need to bring the cylinder up to top dead center and measure piston bore depth. Then calculate ( or find ) your head gasket installed thickness.
 
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