Looking at rebuilding a stock bore ,piston 401 for a 65 skylark .thinking of doing the doc mod to the intake and port matching it .steel head gaskets don't know about milling the heads would like a little better than stock cam .what s best for the nailhead still a street car but would like another 40-50 hp.Jim
The TA-25 is an all round good street performance cam. I also had a 218/230 cam ground by Camcraft that I like a lot, Tom just put one in a customer's car so maybe he can let us know how it worked out there..
Rhett, do you guys (you, Tom, and Joe) prefer Camcraft over Comp? What lifters does CC sell? I was considering a custom 224/236 from Comp. It's based on their X-treme Energy series, which are 218/224, 224/230, and 230/236. Pairing the bigger exhaust lobe with the smaller intake lobe works well on paper. The big ole Isky (244/244) in my blue car is getting annoying with the 3.42 vs the 4.11's it had. Jim, it's tough getting that much extra hp from a near-stocker. Head work will help. Are you using stock pistons or aftermarket? Stock pistons may get you 9.8 compression, aftermarket ones sit lower in the cylinder and will drop compression more, milling would be required to get the compression up. Smaller cams feel good on the street. A bigger cam will be a bit lazy at low rpm's unless you also increase the compression. Bigger cams run better at higher rpm's, it really depends on how you are going to drive it, as well as the rear gears, transmission, and even tire size you use. The 375hp 396 was solid lifter, wasn't it?
Walt - I've got Camcraft cams in both my 401 and 455, they came with Johnson hydraulics. I used a 218/230/110 on the 455, it reacted just as the desktop dyno predicted, and the RPM range right where I planned it. The grinds are right on, but the nailhead cams are a little off on the LSA indexing so they have to be degreed. They are fast ramp cams, and have all the noise associated with the valve shutting so quick but again, they make good power and are generous with lobe lift. I've run them with both solids and hydraulics, but I think making L78 power with a cam swap in a nailhead with just a cam swap may be unreasonable.. as part of a package (blueprinted compression, bowl clean up and all other aspects optimized) you might get close.
comp cams have a faster ramp and will give you the more HP and TQ over camcraft, if bottom line is NOT more power and want less lifter noise, easier on the valve train, well made modern camshaft that would be camcraft. i used a 218-230 hydraulic but on a 425 with ported heads and not a 401 with less TQ. the wide duration hurts low and mid range power and really only gains after you reach your peak rpm horsepower. even with ported heads your not going shift much higher after peak HP with a nail head motor. a solid lifter flat tappet fast ramp way better than a hydraulic fast ramp.
Hi the 396 was a325 block with fully ported ,heads& intake edelbrock, holley ,comp cams 510 lift cam with a700r4 and 3:31 gears would have liked to try 3:50 gears nice hwy car. 401 has very little wear on it so I'll keep it stock piston I'll check closer this winter but stock gs posi so 3:42? Just know. There has to be a nicer cam setup after 55 years . No real racing would like it to sound good at idle most power down low 20-70 if I'm rebuilding it would like better then stock .jim
214-218 on a 109 lsa would be one size bigger than the stock cam. 750 cfm with an open air cleaner , doc intake mod would give maybe 40 more HP over stock.
The stock chev 396-375 had a pretty big cam! 242/242 duration, 0.520" lift with 114* lobe separation. Also had the big valve square port heads and 11:1 compression. It would be tough to duplicate that with a nailhead. But you could build a nice street performer nail with lots of torque. It just won't have the high rpm power of the hi flowing 396. Rhett and Joe, thanks for the cam info. I'd be using Toms roller rockers, so solid lifters will be easy to adjust. The camcraft with a bit more rocker ratio may equal the comp grind.
Hi if real compression is only 9.7 how much can you mill the block ? Or Heads to bring it up to 10.5 or is that a bigger problem with the cam lift ,gas knock.Jim
The issue will be dome to head interference if you do much more then square the deck with aftermarket cast pistons. This is all while the flat of the piston is still at least .050" from the deck. The 425 we built would lift the head on two pistons without the .015" steel shim gasket after rebuilding it with just the minimum to square the deck. We had to skim the edge of a few domes with a file while upside-down on the engine stand and then check clearance with playdough until satisfied with the clearance. I think a custom piston with more compression height and a dome that better mimics the combustion chamber would be a better answer to more compression. You are going to change the pushrod length and how well the intake fits the heads with excessive milling of the head or deck. I recall that .005" off the head or .004" off the deck is equal to one cc or a .1 change in compression. You would have to input all your values in a good compression ratio simulator to know for sure. Tom T. om this site (and others) sells custom forged pistons for the Nailhead that would take care of your concerns. Cheryl
It has been a long time, but I remember it as the the corner areas to the outside of the engine (not the valve side). It needed to be filed on a 45* angle from horizontal to the top. It was more of a chamfer. It did not take much to make it right. Cheryl
