I am not a tech... just did my 84 V-8... for what its worth as long as you have it that far I would replace the chain... not that expensive of a part... I think mine was $55 or $60 last summer. I also would not remove the motor to remove the heads.

good luck on your project.

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dloveless

1984 500 SEL [131K]-
1991 GMC Sierra 4X4 XC [162K]- War Pony.
2004 Jeep Liberty Limited [8k]- wife's sled- Belle.