Author Topic: Jets and Rods for mildly upgraded 454  (Read 516 times)

Offline jstreet44

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Jets and Rods for mildly upgraded 454
« on: May 12, 2017, 11:35:33 AM »
I purchased one of your SR kits, as well as idle pickup tubes for my 7044500 QJet back in November 2016. The kit is installed an the car is running great.

The car is a '74 Caprice with a 454. The motor is a low compression (8 or 8.5:1) smog motor. I am going to be installing a Lunati 60201 cam (213/219@0.050"), Weiand Street Warrior intake, Full length headers and 2.5" dual exhaust.

The jetting is stock and I believe it has 75 primary jets, 41 primary rods and DH secondary rods. Let me know what changes will need to be made for this setup so that I can get parts ordered from you!

Thank you,

- Lloyd


Offline Cliff Ruggles

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Re: Jets and Rods for mildly upgraded 454
« Reply #1 on: May 19, 2017, 06:14:04 AM »
That is a tiny cam in a 454 engine and it will not gain anything from headers and a high rise intake. 

Keep in mind that the stock cams were bigger than the one you are putting in there.  A stock 396/325hp cam had 290/303 seat timing, 214/218@ .050" duration and 115LSA.

The Lunati 256/262 cam will idle smooth, and strong at low rpms, but DONE very early in the RPM range well before it will benefit from the free flowing headers and larger intake.

As for tuning it's probably going to be good to go as-is or at most a very slight jet size increase.....Cliff

Offline jstreet44

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Re: Jets and Rods for mildly upgraded 454
« Reply #2 on: May 25, 2017, 09:45:46 PM »
Point taken. I understand what you are saying about the cam profile, headers and intake.

The car will just be a cruiser and I am looking for torque to move the big Caprice around.

My understanding is that the stock cam in the '74 Corvette spec'ed out at:

210/210 at .050" and .440"/.440" lift with 115 LSA

I assumed that the cam in the Caprice would be the same, if not smaller.

I don't currently want to touch the bottom end of the motor, change the torque convertor or have any vacuum issues. Hence my selection of that small cam. I have read good things about Harold Bershire's Lunati cams thus I was debating between the Voodoo 256/262 and the Voodoo 262/268. Harold himself in old posts from Chevelles.com recommends the 262/268 as the largest cam for a motor at my compression level. I am still new to all of this so I appreciate your input.

Let me know if you have another cam recommendation based on this info.

Thanks for the quality carb kit and help thus far!

- Lloyd

Offline Cliff Ruggles

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Re: Jets and Rods for mildly upgraded 454
« Reply #3 on: May 26, 2017, 03:22:16 AM »
I also hear good things about Lunati Voodoo camshafts, but nothing more than a few "seat of the pants" assessments, which are pretty much meaningless in camshaft evaluations.  Any tiny cam is going to throw all the power at you early and narrow power curve so the engine will "feel" very responsive, but it will not pull hard in the upper mid-range and top end. 

Keep in mid that the 454 is a huge engine, so I'd be looking at bigger cams and on a wide LSA since it's relatively low compression.  Here is a camshaft that we've used over the years as a stock replacement camshaft that works very well in "mild" low compression 454 engine builds.

https://www.summitracing.com/parts/sum-1301

It will have a smooth idle and very broad/flat power curve and TONS of mid-range power in your application.......Cliff