Valvetrain Masters....FastBurn heads....maximum lift cam questions
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Valvetrain Masters....FastBurn heads....maximum lift cam questions
I'm building a RamJet efi 383 with the FastBurn heads. I just received the FastBurns, and was ready to order the LT4 HOT cam, when I thought about using a Lingenfelter 219/525 lift cam ( with 1.5 rockers).
Here are the questions. The FastBurns use the LT4 valvesprings rated at a maximum 525 lift. The LT4 HOT cam is rated at 525/525 lift with 1.6 rockers. I already have the 1.6 rockers. If I use these rockers with the Lingenfelter cam - making the effective lift 560/560 - will I exceed the maximum lift for the springs? If so, any recommendations on spring upgrade?
Thanks,
SC
Here are the questions. The FastBurns use the LT4 valvesprings rated at a maximum 525 lift. The LT4 HOT cam is rated at 525/525 lift with 1.6 rockers. I already have the 1.6 rockers. If I use these rockers with the Lingenfelter cam - making the effective lift 560/560 - will I exceed the maximum lift for the springs? If so, any recommendations on spring upgrade?
Thanks,
SC
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Joined: Jul 1999
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From: Loveland, OH, US
Car: 4
Engine: 6
Transmission: 5
The only 1.25" diameter valve springs on the planet that are rated at beyond .500" lift are those GM units, and they're cheaper than anybody else's. What's wrong with this picture?
I would strongly recommend using something else. There is a post not too far down on this BBS (something about over-revving and pulled studs IIRC) from someone who used those springs, and then experienced the universal inadequate valve spring symptom with the LT4 cam and 1.6 rockers. I am positive you will experience total instantaneous valve train failure with the combination you are talking about.
Bottom line - GM has no experience whatsoever in that area of engine design. They have always used aftermarket valve springs in their own racing programs. I'll bet money that in a short period of time and mounting warranty claims, they'll withdraw those springs from the market for that application.
My choice would be Comp 987 springs and the matching retainers, which will require machine work to the spring pockets in the heads.
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"So many Mustangs, so little time..."
I would strongly recommend using something else. There is a post not too far down on this BBS (something about over-revving and pulled studs IIRC) from someone who used those springs, and then experienced the universal inadequate valve spring symptom with the LT4 cam and 1.6 rockers. I am positive you will experience total instantaneous valve train failure with the combination you are talking about.
Bottom line - GM has no experience whatsoever in that area of engine design. They have always used aftermarket valve springs in their own racing programs. I'll bet money that in a short period of time and mounting warranty claims, they'll withdraw those springs from the market for that application.
My choice would be Comp 987 springs and the matching retainers, which will require machine work to the spring pockets in the heads.
------------------
"So many Mustangs, so little time..."
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