Hi folks. I posted this over at the Nailhead group but I'll just paste the post to save me having to type it again. Any help would be appreciated and will be posted on Buickstreet.com for others to use.
Cam Specs.... Here you go Bill!.....These specs were taken from an old GSCA article. It was written by Dennis Manner....If I get my scanner going again, I'll send you a copy.... 1) Valve size... Intake Valve size - 1.875 Exhaust Valve size - 1.5 2) Shape and size of exhaust ports... If Round (inside diameter) - If Square - If Rectangular (Height x Width) - 3) Camshaft... (1)63-65 425 (2)63-66 401, 66 425 Rocker arm ratio - 1.6 advertised (actual is less....Tom T?) Intake duration (degrees) - (1)290 (2)295 Intake valve duration @ .050" (inches) - (1)209??? (2)209??? (not sure where I got this info) Opens (degrees BTDC) - (1)29 (2)28 Closes (degrees ABDC) - (1)81 (2)87 Exhaust duration (degrees) - (1)299 (2)295 Exhaust valve duration @ .050" (inches) - (1)213??? (2)209??? (not sure where I got this info) Opens (degrees BBDC) - (1)71 (2)76 Closes (degrees ATDC) - (1)48 (2)39 Overlap (degrees) - (1)77 (2)67 Lobe separation (degrees) - **Spacing** (1)109 (2)114 Intake Lobe centerline (degrees) - Installed at (degrees) - (1)1/2 degree adv (2)5 degrees adv Lifter type - Hydraulic Bore - (A)401- 4.1875 (B)425-4.3125 Stroke - 3.64 Bore/Stroke ratio - (A)1.1504 (B)1.1846 True compression Ratio - 10.25:1 advertised
Cool, thanks Walt! Are 425 and 401 cams the same? If so, then it would be a milder cam in the larger engine - true? Also, the earlier cams seem to be quite different than the later cams. Is one better than the other for my 401? If so, why do you think that is? Thanks again for the info. Can't wait to get the design specs for the 'perfect' set of Nailhead headers and then down the road I go with the G-Tech plugged in.
According to the article, the 63-66 401 cam is milder and smoother idiling. It was also used in the 66 425. So, for higher rpm 'performance' use, the 425 cam would be recommended. Buick even recomended this cam could be retarded 2.5 degrees for even more top-end performance. The most notable difference seems to be the lobe separation. Most nailhead cams seem to use 114 degree lobe separation. Some of the wilder profiles, like the Posten 600, and the Isky 310 I'm using, use 108 degree ls. I assume less lobe separation= more overlap=more hi-end power, but at the expense of low rpm power. Of course, Buick's customers were more concerned with a smooth idle than we are....I'l bet that's why they used the milder cam on all 66's. Funny how we now want the opposite! BTW, don't rely on the duration @.05" specs I gave, I'm not sure where they came from...I had it penciled in for some reason. I read TT's info on the rocker ratios (biucknailhead.com....goodies page)....The ratio starts out at 1.6:1, but deteriorates to near 1.45:1 as valve lift approaches .500". Be careful when measuring intake port size...the opening isn't perpendicular to the direction of flow...that is, you'd be measuring a diagonal 'slice' which would be larger than the actual cross-section of the port. Know what I mean? Later,
Thanks for the info Walt. Yep, I know what you mean about the port. I think the main reason he wants the port is to prepare for the outlet rather than to make a performance decision based on port size.
Hi Bill, I think at this point in the game there is only one grind available if you really want to run a stock oem grind. Same deal as the 400/430/455 guys, there's only one oem grind these days, but lots of aftermarket hi-perf profiles.
Thanks John, I can imagine that when it came time to actually pick a cam I'd look at the available choices and would most likely go with the an aftermarket cam. There are a few threads around the traps about hi-po nailhead cams that I could search for when that time comes. Sooner rather than later I hope.
While On the Subject of Cam Specs Is there anywhere where someone has gathered up all the aftermarket cam specs in one place, like the Charlie Evans cam table on the Chicagoland GSCA website? It has all the cam card data from every aftermarket 400/430/455 cam. We sure could use something like that for the 401/425! I took that old GSCA article to work today and scanned it in, and sent it off to Bill to get it put on his Buick Street website. So there, we have a start. Anybody have a cam card they'd like to share?
Thanks John, I received it and will post it on a special Nailhead Page that I will create (may take a few days). Is there anyone I need to get permission from in order to publish this document?
