Author Topic: 454 dome pistons/718 head or flat top/closed chamber head?  (Read 3480 times)

Offline Sg3

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454 dome pistons/718 head or flat top/closed chamber head?
« on: June 21, 2017, 08:24:19 AM »
86 k10. What's up guys, so here's the deal got a pretty good deal on rebuilt 454 the throw in my 86 on 42 in tires. The motor I got has the 781 heads 2.19 in 1.88 ex, but flattop pistons. Now should I go with dome pistons and the 781 heads, or stick with the flattop and find a closed chamber head. I don't have the cam specs at the moment but it's a comp mild street/strip cam. The truck might see some mud bogs 3-4 times a year and other than that just some joyriding. Thanks

Offline VileZambonie

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Re: 454 dome pistons/718 head or flat top/closed chamber head?
« Reply #1 on: June 21, 2017, 08:36:33 AM »
I would run the domed pistons if you are cracking it open.
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74 GMC, 75 K5, 84 GMC, 85 K20, 86 k20, 79 K10

Offline Engineer

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Re: 454 dome pistons/718 head or flat top/closed chamber head?
« Reply #2 on: June 26, 2017, 07:56:31 PM »
Closed chamber heads shroud the valves.

Even with the bump in compression you'll not notice a bump in performance because of the lost airflow.

Put 2.19in 1.88ex valves in your 781s and bowl port to match the bigger valve. Sealed Power hyperutectic H426P pistons (H426P dome gives approximately 9.1:1 with 781s). A hydraulic cam in the 230° (@.050) range. Hooker headers to match your chassis. Set the timing 36°@3000rpm. Then get ready to start breaking parts.
2002 Chevy 2500HD 4x4 8.1/ZF6sp RC/LB
2001 Chevy 2500HD 4x4 6.0/4L85E EC/SB
1997 Chevy Blazer 4x4
1994 Chevy K-2500 4x4 C6P 5.7/4L80E
1979 Chevy K-30 4x4 4sp 4.10
1977 Chevy K-30 4x4 4sp 4.10 454

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Offline Engineer

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Re: 454 dome pistons/718 head or flat top/closed chamber head?
« Reply #3 on: August 06, 2017, 05:15:59 PM »
I hope nothing bad has happened to the OP.


Just the same I am going to use this thread as an opportunity to voice a gripe I have.

I really don't want to deny any new users to this board the chance to ask questions. However, understand those of us who have spent cubic dollars for the experience and knowledge we have of these topics and have enough going in our lives that time is a precious commodity would appreciate that the OP at least have the courtesy to drop back in and acknowledge the contribution of the forum members.

One other thing is the fact that the OP's feedback is valuable to those of us who are trying to help resolve their initial questions.

This makes more than one thread I have responded to where the OP has one all time post on the forum never to return.
2002 Chevy 2500HD 4x4 8.1/ZF6sp RC/LB
2001 Chevy 2500HD 4x4 6.0/4L85E EC/SB
1997 Chevy Blazer 4x4
1994 Chevy K-2500 4x4 C6P 5.7/4L80E
1979 Chevy K-30 4x4 4sp 4.10
1977 Chevy K-30 4x4 4sp 4.10 454

Dad of an Eagle Scout, and a Life Scout