Camshaft ??'s. . first post
Hey guys, thanks for looking in.
I'm a newbie so I hope I'm doing this correctly.
Ok, I got a '77 Firebird with a sbc. Installing a 355 that I bought complete, non fired. Heres the list:
355 0010 block, 4 bolt main
TRW Flat Tops (not sure of deck clearances or anything)
Forgot name, but good bearings (after research) etc.
Double Hump heads off the corvette (had to install acc. bolt holes)
completely redone, new springs, retainers etc.
Crane 272 cam with .454 int / exh.
The car will have either 3.73 or 4.56 gears and a stall convertor.
The problem is, I can't get a hold of anyone who knows enough on this motor to find out exactly what springs are on this engine. I'd like to go with the Lunati Voodoo 268 hyd. But that lift on those cams are pushy.
3 guys I talked to said the engine builder tried to push a bigger cam to the customer. (customer traded off engine before firing for a BBC, this is how I got it) The guys all said it should handle it because the castings on the heads were the only original pieces on them. Said studs, springs, retainers EVERYTHING was replaced, they just don't know stats on springs. The motor is sitting in front of the car, on the pallet with a cherry picker waiting.
What should I do? I'd like to have a very stout car again, and I figure the 272 Crane isn't going to satisfy.
I know logicly, have the springs tested. But what if I can't? Only 2 guys I trust with my engines are busy and talked like they can't get to it before I need engine in the car.
I'm just stuck and need reassurance of what I NEED to do. Leave it alone and drive it? Or try to get what I truly want?
My first old school hot rod (old school to ME lol) in a few years, so I'm just unedgy.
Sorry for long post and thanks for looking. ANY info or advice will be greatly appreciated.
If you want to swap the cam to the lunati then get the springs that match the cam instead of guessing. I will likely guess the springs on your engine as the most common and popular springs, the remakes of the GM "Z28" springs and I have seen many companies remake these and give them different lift limits. Most the time they are used because they are common and cheap.
Since your using a flat tappet cam, whichever cam you use, make sure you get the correct oil to break in the cam with, if you use basic off the shelf motor oil the cam will go flat due to lack of anti wear additives. Valvoline makes a "racing" motor oil as they call it that they claim still has the needed additives in it. However I am sure other guys on this site can tell you what to use better than I can as I don`t keep up with flat tappet cams ever since I started using roller cams.
Do yourself a favor and can the heads. All the cam in the world wont make those heads flow.
the "camel hump" heads are 99% crap especially for a 350 CID motor, those heads were designed for a 327 CID motor MAX, the 1.94/1.50 valves limit flow, as do the 165CC intakes and 65CC exhaust runners, on a 355 CID engine those heads cannot support even a MILD 256 duration cam and if those heads are unmodified have a .455" lift maximum dump the heads, get a set of AFR 195's based off the L98 castings, 2.08/160 valves, and at a 10.4:1 ratio the iron heads make 92 octane a borderline minimum with 93-94 being almost a requirement to avoid detonation, where as aluminum heads make 10.5:1 a 89 octane streetable engine as for cam, EVEN A STOCK CAM can build 350-400 HP..... its all abot head setup and intake and exhaust flow through the heads, more so than a BIG BUMPY cam.... PERSONALLY
heres a perfect street motor in 355CID trim
10.5:1 ( flat tops with 62CC heads)
NX256R Nitrous Roller cam
AFR 195 with 2.08/1.60 Gasket matched and ported
Edlebrock Vic JR Port Matched and Flowed to match heads
Holley or Edlebrock 750CFM carb on 2" wooden or other heat insulating spacer
1-3/4" primary headers, to a 3" collector 3" H piped exhaust
done right that combo is potent up to almost 450 HP at 5500RPM, and with a "stock" ZZ4 cam its in the ballpark of 400... and has a very streetable even with full power accessories at over 20" vacuum
No, the engine builder is out of town on business. No one else knows how to get a hold of the customer who originally had engine built. That guy just traded the motor in to my parts dealer for a BBC. He knows both guys well, but don't know how to get a hold of them for the next week. The customer LIVES out of town, and the builder is gone away on business.
Back in the day, DHump heads were appraised.. a lot. With what I've seen so far recently, in my journey back into resources, I think I'll just drop motor in the way it is, drive the dam thing till I get better heads. Gather, cam, heads and intake to match better for what I'll have.
I'm not much of a head shopper. What do you guys think of the aluminum Vortecs that Jegs has for 629.00? (each) I'll try to get you guys some part #'s today sometime.
You guys are being VERY helpful and considerate. Thanks for re-teaching me and being patient. I appreciate it very much.
That is a very small cam. It should work with the stock converter and 3.08 gears. Should also work with stock springs. Just make sure to check the lift the spring can handle. If you are after a good daily driver with decent mpg and power, that is a good cam.
Yes, those heads suck, but will get you going down the road.
You need to run around 15 degrees of timing at idle and 38 at 3500 rpms. Get an adjustable vacuum advance (crane, summit racing) and set the vacuum advance to 12 degrees and use it on the manifold vacuum source.
Tuning is critical. A 450hp engine in bad tune can make as little as 300. A 300hp engine in tune should make 300.
It shouldn't be any big deal to pull one spring and get it tested.
Although proper coil bind and spring pressures do not mean the spring harmonics actually match your valve train.
By faith you can accept that the setup you have is OK as is.
Installing any cam, I recommend that the springs and cam come from the cam manufacturer purchased as a set. That way IF there is a problem the cam manufacturer has something to look at besides mix and match parts.
It is always better to err on the small side when chosing cam specs. You won't mind snappy throttle response and good seat of the pants feeling, but overcamming will make any driveability seem horrible.
I have seen lots of 450 hp "spec" 350s that only did 385 on the engine dyno.
do a search
that spec I gave was a dyno proven spec build by hotrod magazine granted there was ALOT of grinding done to get everything to match and flow EXACTIALLY as designed BUT the build is accurate and was dyno'd at 450 HP at 5500.. it isnth the cam that determins HP its the manifold, heads, and exhaust, all the cam does is optimise fuel and air pumping ability to the RPM band you want to run in.... a 276 duration is about ALL a street motor EVER needs if its built right
proof in pudding
theres a 10:1 AFR 195 headed motor at 452.2 HP.... SMALL cam, good heads, and the right ammount of port matching everything so flow is inobstructed...
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