Looking for some advice in setting up the valve train on my 401. I'm not chasing huge HP just want a little more 'bang' for my bucks. My engine is a 40thou over 1962 block with 425 heads and will be running a 70's Ford top loader (Due to what's available here in Oz) all in a 28 A RPU with Halibrand QC. I'm now looking at setting up the valve train and don't want to spend money on something I don't really need. I have B262 intake but no carburetors for it yet, so............. A. What would you recommend? Over here in Australia Edelbrock's are the easiest to source, any particular model I should be looking at ie; 600-650cfm be suitable? B, Is there really any advantage to using roller rockers over stock rocker arms? Any guidance on lifters (Hydraulic or solid?), push rods and valves that would suit? C, Cam, I would like to step up the cam a bit. Have been told endless different ideas on what works and what does not. As you have noticed I'm on a steep learning curve as the Nailhead is VERY rare over here. Any and all advice would be much appreciated! Thanks, DocWatson.
650 may be a bit small , roller rockers for a nailhead are expensive but yes there are advantages but not at the near stock level, cam? ask Russ Martin as below have a dig around this site https://www.nailheadbuick.com/26-most-common-mistakes
Answering your questions in order- A) Depending on the other answers, 650 is a bit small if doing other modifications. I have an Edelbrock 800 on my fresh 401. With a B262 intake, dual 650s would work. B) Because of the quench and exhaust port design, unless building a racing motor, the stock aluminum rockers will give adequate lift. Stainless steel HP valves will help flow. Porting the heads would give the most bang for the buck, but should only be done by an expert as the water jackets are close. Buick used the same head casting for 364/401/425. C) I put a TA-25 Cam in mine. Slight lump but takes advantage of the torque curve. Good hydraulic lifters and adjustable pushrods with stage 1 dual valve springs. Use an adjustable cam sprocket set to degree in the cam per specs. Pay attention to the CR. Stock Buick pistons had a 1.925" compression height, and all aftermarket pistons are lower. Aftermarket head gaskets add more, and you could wind up with a CR in the 8s. I took .025" off the deck of my 401, and used the steel shim head gasket to get a 10.0 CR using Silv-O-Lite pistons.
Thank you for the help, I was thinking of porting but don't want to risk stuffing that up (It took a few years of searching to find a pair of heads!). I will be ordering what I need from the Martins when it comes time to put it together, just want to be sure I get the right the right parts for my build.
Russ and Matt will steer you in the right direction. Before you order parts, have your machine shop evaluate the valve seats in the heads. Depending on what is found will dictate the valves you need to buy, as they make slightly oversize valves. Since you can't use bronze guide liners, BBC guides will fit.
About the only thing roller rockers will do for you is that you will have the ability to say, "yeah, it's got roller rockers too".
Centerville auto told me that the roller rockers require bigger valve ccovers. Also that they alone will not improve ypur engines horsepower. To get the best advantage, you will need porting and polishing, modefied intake manifold, better caarbs. and a cam etc etc. Its not a cheap fix.
Just curious, this is for my info, why can't you use bronze valve guides on these heads/motors ? Like to have a nail head for the wife's project 50 stude pickup.... ...
According to the experts, bronze guides or liners will wear quickly and fail due to the unique valve geometry of these engines. Nail heads rely on a guide to valve stem clearance of .002-.003 with no seals being used on the exhaust side. Roller rockers, because of the added lift, will also require piston modifications and close attention to valve to piston clearances because of the quench design.
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