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Subject: "Boosted 420A head lifting? Any tips to keep head planted ? " Previous topic | Next topic
driverx08Jul-14-25 09:09 AM
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#138760, "Boosted 420A head lifting? Any tips to keep head planted ? "




          

Question to those with boosted 420a

Running a fairly built engine now for several years. I've lifted the head once before but blamed it on detonation when a fuel pump was slowly failing.

I'm back to the same issue now. I used a cometic MLS gasket and arp studs. I'm at about 18-20psi on around 14deg timing (93pump) and I'm pretty sure I'm lifting the head again. I get small amounts of compression in the cooling system. Turn the power down to 15ish psi and no more combustion pressure.

I've seen some old forum guys running close to 24ish psi before having to go to 1/2in head studs. Any other tricks to keep the head planted? I'd rather not take the block out to take to the machine shop.

I'll try to upload some pics if I can remember how lol

  

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Global Ruler Of All ThingsDarkOneJul-14-25 09:37 AM
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#138761, "RE: Boosted 420A head lifting? Any tips to keep head planted ? "
In response to Reply # 0




          

How high are you torquing the studs? It's been a long time, but I always went up to at least 90ft/lbs and never had too much trouble with either the 2.0 or the 2.4.

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'95 Eclipse TurboGS (garage deco)
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driverx08Jul-14-25 10:09 AM
Member since Jul 24th 639557
11 posts,
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#138762, "RE: Boosted 420A head lifting? Any tips to keep head planted ? "
In response to Reply # 1




          

I think I just followed what the ARP instructions were.

I did forget to add.

8.5 com pistons
11.5-11.8 afr
14deg timing at the top.

  

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Global Ruler Of All ThingsDarkOneJul-14-25 10:15 AM
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#138763, "RE: Boosted 420A head lifting? Any tips to keep head planted ? "
In response to Reply # 2




          

You can always pull the valve cover and throw another 15 to 20ft/lbs of torque on them. Just be careful with the corner studs, they are not as robust as the others.

______________________________
If a sentence found online has 35% misspellings or greater and includes at least two racially charged expletives, chances are it is a YouTube comment.

'95 Eclipse TurboGS (garage deco)
'95 TSi AWD (restoring a survivor)
'97 Talon ESi-T (poor impulse control)
'99 Eclipse RS-T (daily beater)
'13 Evo X (mostly stock)
'17 Sienna (Middle Aged Dad Mobile)



Factory Service Manuals: http://nawdu.de/files/

  

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