Guys,
I have a 66 Chevelle SS 396 which I have added a new Eddelbrock Air Gap intake, and a new Holly 750 DP. OTher than that, it is stock. The heads are the 109cc closed chamber oval port heads. I would like to install a Lunati 402A3 cam. I understand I need to replace the Powerglide converter to a 2500 stall converter. I only plan to drive once in a while on the street, and will not race it(?). My question is, will my stock rockers and springs hold up for a while, until I can spring for roller rockers and springs. I want that beefy rough idle sound. Does any of this make sense?
Are you saying that your 66 Chevelle SS 396 has a powerglide in it?
In a 396, that cam is going to want a good amount of compression. Do you know for sure where yours is at? Then it's going to want probably closer to a 3500 converter, especially if you have a powerglide. Then it's going to want some fairly steep rear gears. Do you know what you have? If you don't have these things it will be a slug at low rpm's, which is where most of your street driving will be done.
Like the others have said, you will definately need new valve springs.
Tell us more about your combo. I think there's better cams out there for you that will still give it a rumble.
I didn't think they came with Powerglides, but i just looked it up and that sounds about right. I learned something there.
Your compression is probably good enough for that cam, although I'd say it could use more. That 1.something first gear of the Powerglide and a stockish stall converter would make you hate the combo as far as take offs go. I don't think that cam will come on until 3000+ in a 396. That's why I mentioned the 3500 stall earlier. It's still gonna want some rear gear also.
Are you set on a solid cam? There are some hydraulic FT cams that can give you the rumble and probably work with the valve springs you have now.
I woldn't skimp on springs. I used some old springs on a cam change and I floated all the valves and shredded a bunch of shims and sent metal all through my motor (except for the cylinders). What a mess.
Stock springs are only good for the .398"/.398" or .461/.480" lift cams back then depending on cam so install the recommended springs for that cam or you will be shortly SOL!!
He, He!! "Sh*t outta luck"!!
And right around 96.7 to 101 cc heads, again, depending on casting number. And run the stock .020" thick steel shim headgaskets too!
you should try the UD 280/288 cam that several peple here are using and have used in the past. I don`t remember all the specs but it seems like a nice cam and should work qith the rest of your stuff but will probably require a spring change for sure.
Yeah, you will have to change the springs also if you are wanting go with that cam... No way stock springs will work with those lift numbers without destroying themselves!
Guys,
I have a 66 Chevelle SS 396 which I have added a new Eddelbrock Air Gap intake, and a new Holly 750 DP. OTher than that, it is stock. The heads are the 109cc closed chamber oval port heads. I would like to install a Lunati 402A3 cam. I understand I need to replace the Powerglide converter to a 2500 stall converter. I only plan to drive once in a while on the street, and will not race it(?). My question is, will my stock rockers and springs hold up for a while, until I can spring for roller rockers and springs. I want that beefy rough idle sound. Does any of this make sense?
I ran that cam in my 396 with a manual transmission. I bought the complete valvetrain from Lunati-springs, lifters, locks, and retainers. I have 215 heads which are the same size chamber as yours. Since you have an automatic, I would not run that cam, you won't have any low RPM driveability and it will surge. I got away with it because I have a manual. I will tell you that the car picked up 3 tenths at the strip with no other changes but it was on the edge of being streetable. I'd go with the next size down.
I took that cam and now run it in a 439 (454 .60 over with a 396 crank) and it likes the larger cubes much better than it did in the 396. JMHO
the 063 heads with stock 396 pistons makes 10.25:1 rated CR. Often closer to 10.0:1 actual.
Not only will he need springs but the guides have to be worked for the extra clearance needed for so large a cam. Then pushrod lengths etc will need to be checked. None of this is too difficult but it is easy to get in over one's head if you do not do the research of CALL THE FACTORY REP and ask them exactly what is needed...or call the best performance engine shop that you can find.
kettbo,
excellent advice! I will call Lunati. I don't mind changeing springs, but do not want to get in over my head. I am not dead set on solid cam either. So, seems I have to back off espeicially if i want low end for the street? Want that nice low rumble, low end response. I do not want to have to completely reowrk the heads.
That 238 dur. Lunati would be a nice cam, similar to the Comp 282S solid cam which would be sightly milder. 282S would have very good low and mid range. I ran this in a 325 hp 396 in a 62 Chevy pick up years ago and it was a great sounding cam. Also ran it in a 455 Pontiac and lashed at .025 I pulled 17" of vacuum and it had a throaty idle at 1000 rpm. Lash it at .020 and the vacuum was 14-15" and it then had a nice lope to it.
Gentlemen,
Thanks for the input. I have narrowed it down to the Lunati 402A3 or Voodoo 60203. I plan on getting new springs and stall converter regardless.
So... I guess it would probably be worth while to pull heads and have reworked, and check for piston type? Can you tell the piston type on the piston head?
Would it be worth while to pull cam before ordering new cam to determine if the oil groove is at front or rear? I do not have the block number.
Honestly, from my experience there's not a big difference in sound at idle with that cam (UD276/284) in a 454 with 110 LSA vs. your 427 and the 107 LSA. If I can convert the video I'll let you hear for yourself.
Kev,
Beautifull car, and ya sold me on the 402A3. Sounds great. What was that idle at? Around 1K? Not too aggresive, but sounds great. If yours is an auto, what kind of stall are you using?
Keep in mind that the 402A3 is listed as having a "Fair" idle. Not a "rough" idle (if that matters to you). Don't overlook the fact that Kevin has pointed out that he had his ground on a 107 LSA. So the tighter LSA gave his engine the rougher idle. Unless you have it custom ground for you like Kevin did, that cam comes with a 110 LSA. That will undoubtedly smooth out the idle atleast a little bit. The wider LSA will also tend to produce a less intense but broader power delivery("broader" meaning that the power would begin at a slightly lower RPM, and hold on until a slightly higher RPM than the tighter 107 LSA will).
I spoke with harold about that cam in my 454 build and he stated stall speed for that cam would best be 3000-3500. If you dont go with at least a 3000 stall with the 402A3 in a 396 the low end you want may not be that great. 402A3 is by no means a radical cam but its quite a cam in a 396 street car. Also take note if you do go with this cam I suggest you read SWheaton's stickys about breaking in a flat tappet cam. Plan on dual vavle springs and installing only the outers for break in for example.
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