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Old 11-08-2011, 12:34 PM   #1
big72red
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GM LT4 "hot cam" questions

Has anyone on here had experience with this cam in a 350? I have a 350HO crate motor in my DD. It has a hydraulic flat tappet cam in it right now. I know that my engine shares the same block as the other factory roller cam blocks. I'm cosidering swapping the hot cam into my engine. I have a couple of questions though.

1. I know I'll need the cam, hydraulic roller lifters, "spyder" retainer, and valvesprings (going to use the Comp beehives for LS motors because they are said to go right onto to Vortec heads without machining). Assuming I will need shorter pushrods? Am I missing anything guys?

2. GM recommeds 1.6 rockers with this cam. All the specs on the cam are measured with 1.6 rockers as well. I'm thinking that I may go with 1.5 rockers to eliminate the need to enlarge the pushrod holes in the heads. I'd really prefer to swap this cam without pulling the heads. Valve lift with the 1.6s is .525" so it should measure .492" with 1.5s. Has anyone run this cam with 1.5 rocker arms?

Those are the questions....gimme your oppinions guys. Thanks in advance.
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Old 11-08-2011, 12:53 PM   #2
GASoline71
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Re: GM LT4 "hot cam" questions

No idea on the lift factors. But I'm curious why you would need to enlarge the guide holes for the pushrods by switching to the 1.5 rockers?

Also... the block just may need to be drilled and tapped to accept the bolts for the spider.

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Old 11-08-2011, 03:13 PM   #3
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Re: GM LT4 "hot cam" questions

You will need the cam, roller lifters, the retainer hold down and bolts (the spider), the lifter retainers (dog bones), the cam retainer plate and bolts, the roller cam pushrods (7.20" IIRC), the roller cam style timing chain and gears, the mealonized distributor gear, unless your distributor already has it, the correct retainers and locks for the beehive springs, and the necessary gaskets. I think that's about it.

I don't have any experience with 1.5 rockers on that cam.
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Old 11-08-2011, 04:56 PM   #4
Lee H
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Re: GM LT4 "hot cam" questions

Do the springs come with retainers and keepers?
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Old 11-08-2011, 10:31 PM   #5
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Re: GM LT4 "hot cam" questions

I think Comp sells them seperately. At least last I saw that is how they were sold.

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Old 11-09-2011, 05:40 AM   #6
big72red
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Re: GM LT4 "hot cam" questions

First of all, thanks a lot guys. I forgot all about the cam retainer plate and the timing set. I knew I was going to need the retainers and locks with the springs and the "dog bones", just wasn't very clear in my description. Yes, I already have a melonized gear on my distributor. And, my block is already drilled for the spider.

Gary, what I was saying is that I want to stay with the 1.5 rockers. I read in Car Craft ( I think ) that Vortec heads won't allow you to run 1.6 rockers without enlarging the pushrod holes. Something to do with the pushrods location on the rocker arm in relation to the rocker studs. The 1.6 rockers change the angle at which the pushrods travel through the heads causing them to bind if the holes are not enlarged.

Thanks again guys.
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Old 11-11-2011, 07:30 AM   #7
sean1969c10
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Re: GM LT4 "hot cam" questions

Is the stock fuel pump pushrod ok to use with the GM HOT cam? This wasn't addressed earlier and I have wondered myself.
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