351w cam specs

Does anyone know what the original cam specs are for an early 80's PCM 255hp 351w.

PCM oddly enough does not have that info anymore but one of you die hards has to have it written down somewhere.

I'm going to upgrade but want to compare to stock specs. Thanks

My best guess says it's a .418/.448 lift cam. It's what's shown in the Holman Moody manuals and the only spec I've ever seen. I have no idea as to the duration as the book shows none, but from others I've seen that are similar, I'd say it's somewhere just around 200 degrees.

nuttyskier2002 wrote: Idle starts to get a little rough at anything over about 216 and lobe separation under 112 deg. For example, Comp Cams sells a cam that is 218/218 (In/Ex) @ .050 with a lobe separation of 110 deg. This cam has a noticeable idle. If you take this same cam and spread the separation to 112 or 114, idle quality will smooth out and vacuum will increase.

I dont have a lot of experience on the subject, but I have to disagree. I installed a cam from Cam Research this past summer with the following specs:

RPM Range: 2500-5200
Duration @.050" (I/E): 218/222
Lift w/ 1.6 Rocker (I/E): .490/.490
LSA: 110 degrees

They have lots of experience selling cams to customers with ski boats, so they were very helpful. I asked about the LSA being less than 112, but they said that 110 would be plenty safe. With my 218/222 duration and 110 LSA, I honestly dont notice a difference in the way the boat idles, even at 600 RPM.

First post in a few months, my time in front of the computer isn't what it used to be.. glad to see things haven't changed much around here...

Juse my two cents on on the flat tappet cams, especially with aftermarket springs to be very careful on the break in, oil isn't what it used to be (they are removing the zinc-d) and its fairly easy to wipe out a lobe with too much spring pressure and standard oils. If you have double springs (like those supplied by tristate on thier gt-40p's) you should remove the inner springs for break in, as well as adding GM EOS (Engine Oil Suppliment) to some conventional (not synthetic) 30w for the break in and an oil change or two thereafter. Its a PIA but not as bad as tearing the manifold and timing cover off to replace the cam, believe me.

Once I finally got one broken in and happy in my 302 (gt40p's, edelbrock peformer intake, scorpion rollers, etc) I have been pretty happy with the performance of my cam
Intake 204 Exhaust 214 (at .050)
Intake .448 Exhaust .472
112 degrees lobe seperation.
It pulls like a bear in an 83 2001 with 900 lbs of ballast and 6 fat a$$es right off the line (you can idle it much lower than you would want to) and will get up to about 4800 rpm or 47 mph in that boat (with the people but not the ballast). I am going a little more extreme in my next project but I will start a new thread for that..

-Joe.

JoeinNY wrote: Juse my two cents on on the flat tappet cams, especially with aftermarket springs to be very careful on the break in, oil isn't what it used to be (they are removing the zinc-d) and its fairly easy to wipe out a lobe with too much spring pressure and standard oils. If you have double springs (like those supplied by tristate on thier gt-40p's) you should remove the inner springs for break in, as well as adding GM EOS (Engine Oil Suppliment) to some conventional (not synthetic) 30w for the break in and an oil change or two thereafter.

This is good advice. I took advantage of Cam Research's break in service- I havent put very many hrs on the motor since then, but so far so good. Cam Research recommends a straight 30w for a certain break in period. After that, I switched to Shell Rotella-T 15w40. Good article here: Hot Rod

As far as the cam specs, Im sure that will give you a real nice power increase. If youre so inclined, I wouldnt hesitate to go a little wilder- I noticed zero driveability issues and gained a lot of power on the holeshot through the midrange. Id trust Cam Research's recommendation, though- Ive been very happy with mine.

Ken, thanks for getting those modern stock cam specs. The cam your looking at is similar to the one we use often and exactly the one captan1 mentioned above. I know it works great in a 302 and should do fine in a 351 as well. Unrelated to the cam, i think you may come up with even more compression than 9:1 CR, as I believe you're going to be dropping from what is most likely a 69-70 cc head to the +/-60 cc P head, and I'll bet you should have it all over a stock ProBoss by virtue of improving at every comparible level or component. I can't remember if you said you were doing a total rebuild with pistons as well, but if you are, I'd go with the flat-tops and you'll surely see the torque increase, but you will definitely be a premium fuel only guy.

I am new here.Iam going to look at past threads,but this topic is what I am looking for help in. 1990 sport all stock.looking for cam,intake,carb recommendations.Family use
3 teenage boys,1 girl. My insurance man loves me.I am going to spend this wonderful weekend
looking thru this forum.Thank you in advance
for all the help.I'm sure this will be a favorite website as I am fairly new to forums.