400 cam
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4wd Low
Joined: Feb 2023
Posts: 10
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400 cam
i figured i would throw this out there to get some opinions. truck is a 79 f250 4wd with 37s and 4.10 gears and a 4 speed. i just rebuilt the 400 with trickflow 190s and autotec pistons that give 9.6 to 1 compression the cam is a custom hydraulic roller 550 lift, 222 230 at 50 with a 109 lsa. the issue is the motor is super soggy below 1600 rpm and does not want to lug at all, above 2000 its a beast. i am pretty sure the cam just has too much overlap and duration and cant handle loading at low rpm but figured i would get some opinions before i call lykins and get a different cam. i also tried a edelbrock and new 670 holley and issue is the same.
Hotshot
Joined: Jul 2020
Posts: 10,551
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From: Near Salt Lake City
I would change the power band of the camshaft you have at some point
I am sure you will get a ton of advice on that
Changing your gear ratio will help a ton (more IMO)
With 37's you need to be in the 5.13 range
It will be expensive regearing both axles
I'd do that first and see how it drives at around 2000 RPM
I am sure you will get a ton of advice on that
Changing your gear ratio will help a ton (more IMO)
With 37's you need to be in the 5.13 range
It will be expensive regearing both axles
I'd do that first and see how it drives at around 2000 RPM
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4wd Low
Joined: Feb 2023
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Likes: 2
ok yeah that is definitely a reasonable cheap thing to try before going with a different cam. i like my gearing currently for highway driveabilty and all around usage so lower gears are not an option atleast until i go to an overdrive. thanks for the replys
Cargo Master
Joined: Oct 2020
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Your engine is way over cammed for the application if low end torque is your goal. I'd do a single pattern grind and I'd probably drop it back to about 212 @ .050 on about a 108 lobe sep in on 104-106. That would be a ton better.
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4wd Low
Joined: Feb 2023
Posts: 10
Likes: 2
ok yeah, i think i maybe was not being totally honest with myself when describing my intended usage. especially since the cam manufactruer i have dealt with before and i knew likes to be on the more aggressive side with their cam specs.
Cargo Master
Joined: Oct 2020
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For what its worth a few years ago I rebuilt a 373 inch Cleveland for a Pantera. The customer was adamant that the engine be very mild with a good idle etc. They also wanted a hydraulic roller cam. The engine had a set of Boss 302 heads, factory aluminum intake and Pantera chassis headers. I did a single pattern cam that was 214 degrees at .050 duration on a 108 lobe sep. I was amazed that the engine still ran to a 6000rpm power peak even with and idle around 800rpm.
With a given displacement and valve sizes for a given rpm there will be a fairly specific amount of duration that is needed. More just costs torque especially below the torque peak as well as engine response.
With a given displacement and valve sizes for a given rpm there will be a fairly specific amount of duration that is needed. More just costs torque especially below the torque peak as well as engine response.
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