What's the best and closest solid lifter cam that's sold now for a 70 LT1. Thanks for any info. Jim
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Re: 70 LT1 cam
The exact cam built to the GM blueprint (including Parkerizing) is available from Federal Mogul, part number CS1145R. You can buy one from NAPA or any other source that offers Sealed Power and Speedpro, which are F-M brands. You can look up this part number at napaonline.com and see the specs or use the cross reference for 3972178.
The inlet lobe is from the L-72 cam (with a slightly smaller base circle) indexed at 110 deg. ATDC, and the exhaust lobe is from the 30-30 cam, but indexed four degree later at 122 deg. BTDC.
As far as lifters are concerned, only the piddle valve type that were OE on big blocks are available AFAIK, and they will work fine in a SB. They allow more overhead oil flow than the OE edge orifice type SB mechanical lifters.
Duke -
Re: 70 LT1 cam
Thanks Duke I will check that out. I had heard crane makes a match but not good reviews on it. I've read that the lifter need the groove near the top as the OE does do you know if the ones you are talking about have this groove. ThanksComment
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Re: 70 LT1 cam
Crane has ground several of my custom designs using OE lobes, and I think most of their OE replacement cams are accurate, however, Federal Mogul offers just about all the OE cams, and they are my first choice for OE lreplacement cams. In fact I recommend F-M OE replacement parts for all engine restorations.
I'm not sure about the lifter issue you mention. As I said previously your only choice nowadays is the big block lifter, and many have installed the Fedearal Mogul CS1145R cam and piddle valve lifter with no problems, and with careful installed height setup, the F-M OE replacement VS677 valve springs will go to 7200 before a little valve float sets in, but unless you massage the heads it won't make useable power to that engine speed.
DukeComment
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Re: 70 LT1 cam
Hi Duke,
Do you by chance have the part number for a Federal Mogul cam for my "65 327-365? No need to go to a lot trouble locating it if you do not have it at hand.
Thanks,
DaveComment
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Re: 70 LT1 cam
Thanks for that info Duke. Another funny thing I've found is all I've heard is 64cc heads on these LT1s. My engine has never been taken apart still std bore and it has 68cc heads. So where is the 11.1 compression coming from? Is it because of the .100 dome on the piston to make up the difference???Comment
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Re: 70 LT1 cam
james-----
How do you know it has 68 cc heads? Have you had the heads off and CC'd (measured) the chamber size? If so, are you sure it was done accurately?
1970 LT-1's had domed pistons to achieve the 11:1 advertised compression and this was based on 64 cc combustion chambers. I have absolutely no information that any domed pistons, presumably with a higher dome, ever existed, let alone used with 68 cc heads.In Appreciation of John HinckleyComment
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Re: 70 LT1 cam
Yes they are 100% 68cc. That's what I don't understand. The engine had never been out of the car or apart. I've talked to the last owners and confirmed that it had not been touched. I have 186 castings. Build date was 11-3-69. Car build date was 1 -12 -70.Comment
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Re: 70 LT1 cam
...not off hand but, the OE 365/375 HP "30-30" cam is a very poor choice for even a high performance road engine due to the very soggy bottom end. I recommend the LT-1 cam for these engines, and so does Chevrolet. GM figured out that the 30-30 cam was not worth keeping around. When released, the LT-1 cam replaced the 30-30 for all prior 30-30 applications, and the 30-30 disappeared from GMPD.
Some might come along and claim that the LT-1 cam doesn't "sound" like a 30-30 cam even if they've never owned either one. I know at least two guys who replaced 30-30 cams with LT-1 cams. They had some concern up front, but say there isn't any significant difference in sound or idle behavior, but the LT-1 cam has noticeably more bottom end torque and about the same top end power. That's what simulation programs say, too.
DukeComment
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Re: 70 LT1 cam
Duke,
Thank you for the reply and I suspected as much. My 65 365 is noticebly soggy on the bottom end just as you indicated. I have an original 70 Z-28 Camaro and the difference as far as bottom end performance of these 2 cars is like night and day. I am getting ready to pull the motor out of my 65 and go thru it. It runs great, but unfortunately I have a rear main seal leak that needs to be taken care of.
Michael, thanks for the part number for the 365 cam. I am inclined to replace the 30-30 cam with the LT-1 cam while the motor is apart. Thanks for the info everyone.Comment
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Re: 70 LT1 cam
How do you know the chamber volume if they've never been measured?
The advertised CR and horsepower are pipe dreams. The advertised compression might be achieveable with careful blueprinting, which usually requires decking the block since high decks are the biggest production variable, but you don't want to do this on a restoration engine.
As built by Flint, CRs are typically 0.3 to 0.6 lower than advertised. Managing compression ratio during a rebuild has been discussed here many times and in The Corvette Restorer. You need to take some measurements and run the data through a CR calculator. This process is usually ignored by "engine builders".
The 461 heads with large valves are about 64cc, but 462 and later heads eliminated the small quench area on the spark plug side which increases chamber volume about 1-2 cc.
Typical 462 and later heads that have had a little grinding to eliminate side overhang come in at about 66 cc assuming they've never been surfaced.
DukeComment
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Re: 70 LT1 cam
James,
Scroll down to page five for Duke and John's compression ratio article:
His San Diego seminar is also good, but I don't have that handy.
JoeComment
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