Hyd. FT cam for vacuum class truck puller

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Hyd. FT cam for vacuum class truck puller

Post  Green 72 on July 15th 2017, 11:19 pm

This is a all cast class. 466 with flat tops,.040 quench,C8 ported heads,SCJ intake and truck manifolds. Need some suggestions on cam. Need to pull 14 inchs vacuum.

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Re: Hyd. FT cam for vacuum class truck puller

Post  rmcomprandy on July 15th 2017, 11:48 pm

Green 72 wrote:This is a all cast class. 466 with flat tops,.040 quench,C8 ported heads,SCJ intake and truck manifolds. Need some suggestions on cam. Need to pull 14 inchs vacuum.

Not enough information:
1. what actual compression ratio ?
2. what diameter valves
3. What intake manifold modifications ?
4. what carburetor ?
5. Exhaust Manifolds ... what size pipes ? mufflers ?
6. how much ignition timing does the vacuum advance have and add to that RPM mechanical advance ?
7. at what RPM is that amount of vacuum needed ?
8. hydraulic or solid lifter ?
9. valve train and cylinder head valve lift limits ?

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Re: Hyd. FT cam for vacuum class truck puller

Post  Green 72 on July 16th 2017, 12:17 am

Randy CR should be 11.5,2.19 1.71 valves,intake has opening modified to just devider in center not 4 holes,has to be single inlet carb,exhaust wil be 2 1/2 with straight thru mufflers do not know about timing,heads have 930 Com Cams springs but can be changed if needed any help Randy would be a great help.Thank in advance.

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Re: Hyd. FT cam for vacuum class truck puller

Post  Green 72 on July 16th 2017, 12:21 am

Randy vacuum needs to be at 1000 rpm and it is hyd.cam. Thanks for your quick reply.

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Re: Hyd. FT cam for vacuum class truck puller

Post  rmcomprandy on July 16th 2017, 10:42 am

Something custom would certainly be best however, with vacuum advance adding 20 degrees at 1,000 rpm, a catalog Lunati Grind # 61003 VooDoo would work; part number 10340703.

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Re: Hyd. FT cam for vacuum class truck puller

Post  Green 72 on July 16th 2017, 11:09 am

Thanks Randy

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Re: Hyd. FT cam for vacuum class truck puller

Post  rmcomprandy on July 16th 2017, 6:24 pm

Green 72 wrote:Thanks Randy

I was quoting from memory ... the actual Grind # is 61603; the part number is correct.

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Re: Hyd. FT cam for vacuum class truck puller

Post  Straubtech on July 17th 2017, 8:58 am

These vacuum rule classes are the truest testament to the phrase "Devil's in the Details". To get these cams right you need to do the following: Flow the induction and flow the exhaust....meaning the heads need to be flowed on the intake side with the carb, intake and heads bolted as 1 on the flow bench. Then the exhaust with the headers to be used. Engine combination being used must be detailed.

If the above is done then the truck will be exceptional.

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Post  Alpine2013 on July 17th 2017, 9:59 am

Rhoads Lifters do a great job of increasing vacuum at idle by reducing lift and duration at low RPMS/ idle. You need an adjustable valve train to use them.

http://www.rhoadslifters.com/


For all racing applications, our  V-Max Variable Duration Lifters are the answer. They increase low-end torque and engine vacuum up to 50% more than Original Rhoads Lifters...and they rev higher too. This makes them the best choice for all racing applications. Typical vacuum increases range between 2 to 4 inches at idle when used with bigger cams. They are fully adjustable and require an adjustable valve train. Adjustment is similar to solid lifters.
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