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bigger valves vs rocker am ratio

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skyway
Posts: 3
Joined: January 30th, 2021, 9:50 am

bigger valves vs rocker am ratio

Post by skyway » January 30th, 2021, 10:34 am

Hi all i'm new here but not new to jeeps , i'm currently freshing up a 01 4.0 for my jeep and have a question about which way to go for a head.
the motor was from my old jeep that never gave me any problems at 180k the jeep rusted out . I pulled it and stared putting new gaskets in and when i went to do the valve stem seals i found the exhaust vales where pitted and weren't holding pressure . pulled the head and was planning on getting it rebuilt but now im leaning towards getting a reinforced 0331 head . I was toying with going to 1.7 rockers but i see clearwater has heads with bigger valves so i'm not sure which way to go . i'm no expert on engine building but i think doing both might be asking for trouble as everything else is stock I plan on getting a tune eventually but i'd also like some that i can run untuned as well.
Again i'm no expert but i do understand how changing rocker arm ratio works, im open to hearing options .
thanks

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derf
Posts: 6
Joined: November 23rd, 2020, 9:12 am
Stroker Displacement: 242
Vehicle Year: 1987
Vehicle Make: Jeep
Vehicle Model: Comanche
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Re: bigger valves vs rocker am ratio

Post by derf » February 2nd, 2021, 10:31 am

What is your goal for the engine?
1987 MJ project: 4.6/AW4/ORD Magnum Box/Ford NP205/Dana Super 60/Dana 80/40's
2001 XJ: 4.0/AW4/NP242/D30/D44/32's
My gear ratio calculator: http://www.grimmjeeper.com/gears.html

jsawduste
My keyboard is getting warn out
My keyboard is getting warn out
Posts: 1036
Joined: February 28th, 2008, 3:13 am
Stroker Displacement: 4.9
Location: Michigan

Re: bigger valves vs rocker am ratio

Post by jsawduste » February 2nd, 2021, 10:46 am

Factory ratio is 1.6

Pretend numbers.

.400 x 1.6 = .064 lift
.400 x 1.7 = .068 lift

Had a set of 1.7’s for years that I bought on impulse.

Ended up finally giving them away as the net was simply not worth it.

Did anyone mention that some 1.7 designs simply move the pushrod closer to the fulcrum ? Meaning that the head itself may need to clearanced ?

skyway
Posts: 3
Joined: January 30th, 2021, 9:50 am

Re: bigger valves vs rocker am ratio

Post by skyway » February 2nd, 2021, 4:08 pm

This motor was going to replace the motor in my current XJ that has many problems but now I’m leaning towards a stroker . Always wanted one figured nows the time , been looking at clegg kits but leaves me with many questions. I did send Russ a message waiting for a reply .

Russ Pottenger
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Posts: 828
Joined: August 15th, 2009, 1:27 am
Stroker Displacement: 4.7
Vehicle Year: 2000
Vehicle Make: Jeep
Vehicle Model: Cherokee

Re: bigger valves vs rocker am ratio

Post by Russ Pottenger » February 19th, 2021, 10:40 am

Hopefully I did respond and answer your questions.

I do offer a new upgraded 0331 ported LS valve head

Russ

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