Advice on new cylinder heads.

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Advice on new cylinder heads. Empty Advice on new cylinder heads.

Post  78ranger on August 14th 2019, 10:27 pm

Thinking about a head upgrade. Currently running ported big valve doves in a 521. Been driving it a couple years and wouldn't mind a bit more hp. Guess first question is any idea what I could get out of a head and probably cam change. Cam currently is about 247 at. 050 615 lift. Looking at the afr heads. Seem like good bang for the buck. Have 30 cc dish pistons in it now. What kind of lift could I run without valve reliefs, or do I need to cut some regardless. Appreciate any insight and feedback. Thanks.

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Post  stanger68 on August 16th 2019, 10:39 pm

Edited. Wrong post. My bad

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Post  dfree383 on August 17th 2019, 8:05 am

Check out the TFS street line, their are a several bolt on options that will not require a piston swap.
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Post  78ranger on August 19th 2019, 7:22 pm

Thanks. Looking at their heads looks like the 290 or 325 would keep my compression close to the same. Exhaust valves on both are 1.76. Intake on the 290 is 2.20. The 325 is 2.25. Don't know which ones would work or be best for my application. Four wheel drive truck that mud races a few times a year. Lots of wheeling and street time. Any ideas on how much more up I could make with better heads and as much more cam as I can run while keeping it steerable.

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Post  rmcomprandy on August 19th 2019, 9:30 pm

78ranger wrote:Thanks. Looking at their heads looks like the 290 or 325 would keep my compression close to the same. Exhaust valves on both are 1.76. Intake on the 290 is 2.20. The 325 is 2.25. Don't know which ones would work or be best for my application. Four wheel drive truck that mud races a few times a year. Lots of wheeling and street time. Any ideas on how much more up I could make with better heads and as much more cam as I can run while keeping it steerable.

The 325's are CNC ported, the 290's have ports as cast.

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Post  78ranger on August 19th 2019, 11:05 pm

Saw that. Would rather do the 325 unless I'm going to run into valve clearance issues.

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Post  Colt Macara on September 23rd 2019, 1:47 pm

78ranger wrote:Saw that. Would rather do the 325 unless I'm going to run into valve clearance issues.

I know you will check valve springs, just be aware, one of the 325 heads come with a hefty spring. Somewhere around 250 seat pressure. Might not be streeable. Of coarse a lot depends on your cam and lifter choice. They are good to about .800 lift, but your flycut question would be answered if you are going to a big lift cam. I bought a set of these. They are quality heads. I think they have 2 other combos of springs in the 325, but come with a steel retainer instead of the titanium, but not 100% sure.
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Post  Colt Macara on September 23rd 2019, 6:21 pm

Tried too list comparison......Summit buggered comparison after time!
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Post  Mike R on September 23rd 2019, 9:53 pm

I bought a set of 325's bare, nice looking pieces. I had Scott Main at Cam Research spec me a cam and bought all the valve train parts from him. My plan is to dyno my engine for a base line and then upgrade the ports from there.

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Post  Colt Macara on September 24th 2019, 5:30 pm

Mike R wrote:I bought a set of 325's bare, nice looking pieces. I had Scott Main at Cam Research spec me a cam and bought all the valve train parts from him. My plan is to dyno my engine for a base line and then upgrade the ports from there.

I just purchased different springs on mine. The biggest reason was to be able to run the Crower rockers that have clearance for a 1.625 spring O.D.. The 1.640 OD springs were not going to work. The springs I bought (PAC) also eased the seat pressure to 230 lbs. and a hair off of the spring rate at 630 vs 650 lbs. The 1.640 springs as they come from Trick Flow are 250 lbs set at 2.000". The 1.620 I bought are rated at 230 lbs at 1.950". If I install them at 2.000" It might ease the 230 lb seat pressure a little more. I will have to check with a spring check when I get ready to install them. I'm only running a .717 cam lift with SR lifters. Also the same titanium retainers will work.
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