No, I am telling you to follow the cam card. It has a recommended Intake Centerline to install the cam. Most are installed 4* advanced, but you have to verify that with a degree wheel. I hope you aren’t planning to just put it at 4* based on the key ways, you have to degree any cam these days.
Hi Larry I'm relatively new to 455's but not without experience elsewhere. 17 years as an Engineering Officer in the Royal Air Force, many Rover builds including a current one which you'll find here in the small block section. That engine is expected to exceed 600bhp on the dyno. So quite simply if I dont know something I'll ask. My last question is simply should I set this one straight up or pull the power band down a bit by going 4 degrees advanced, all I'm looking for is someone with experience to give me the benefit of their experience. I dont need technical advice on how to degree a cam, or what a cam card is for, but thanks anyway. Either way I cant set the cam timing until I know what the cam is doing. Hence the reason why the engine is currently sat in my workshop looking like this.
OK, as long as you know you have to degree the cam. That goes for any cam in any engine. Most cam cards have the cam going in 4* advanced. That makes up for eventual chain stretch. The cam card will say, degree intake lobe to ---* like this, Nine times out of ten, it will be 4* advanced. What does your cam card say? I'd follow that unless of course you want to play with the power curve some, less low end traded off for more top end.
Well that was an interesting morning. Having verified TDC and with a DTI on both the piston and the rim of the lifter I set off to degree this cam. Cam card calls up: Intake opens @ 1.5 BTDC Intake closes @ 41.5 ABDC Although I had decided to set the cam 4 advanced I set the cam and crank wheels to straight up. I like to verify everything against the cam card first. The results made me think I had something wrong so I checked and reset everything. Intake opening was ATDC. In the end to set this cam at 4 advanced I've had to set the cam and crank wheels at 8 advanced - furthest counter-clockwise of the crank keyways, and tooth number 8 counter-clockwise of the outer dot. (First picture below) So the cam now has intake opening at 5 degrees and intake closing at 38 degrees for a duration of 223 which is what the cam card calls for. However, one other thing worries me. The cam card calls for lift of 0.297". As you can see from the last two pictures total lift is 0.287" (apologies for the angle of the photo but I couldn't get my phone in any closer. My faith in the accuracy of this cam has taken a beating and the only way I would use this cam is if I degree each and every cam lobe to make sure there's nothing amiss elsewhere. As always your thoughts and guidance are always welcome.
The picture in post #22 shows a mag base and indicator on the edge of the #1 piston' it should be positioned in the center of the piston for finding TDC. Not sure if you found your TDC using one of the methods below or just used the indicator until it stopped moving? If you did then your readings won't be accurate. Install indicator to contact the piston near the center to minimize the effect of piston rock at TDC. Rotate crank through TDC in normal direction and 0 indicator at the highest reading. Continue to rotate crank in normal direction of rotation and record the degree wheel reading at .100 indicator reading before TDC. Continue rotating until you are at .100 after TDC. Record your degree wheel reading. TDC will be half way between these readings. You can use a point other than .100 as long as it’s the same point on each side of TDC. Adjust your pointer to read 0 at this point. Top Dead Center is now accurately known. This is a very important step because there is a point a few degrees before and after TDC when the piston moves very little. This method measures the same point on each side of TDC where piston movement is much greater per degree of crank rotation than at TDC. A positive stop such as a strap with a bolt to hit the piston can be used. The crank is rotated until the piston hits the stop and degree wheel reading is recorded. Rotate the crank in the opposite direction until the piston hits the stop and record the reading. Halfway between the readings is true TDC. If the heads are on the engine a stop can be screwed into the spark plug hole to contact the piston. Be sure to remove the rocker arms on that cylinder or you risk bending a valve if it hits the stop when open. Either method is accurate. Very cool project by the way. And if you did want to play with the cam timing to move the power band slightly, IMO a couple degrees retarded would be the way to go and you'll still have plenty of low end torque to break the drivetrain bolted to it.
@300sbb_overkill thanks for the reply. The picture at #22 is before I started and it's just where the DTI ended up when I stuck it on the block. TDC was measured in exactly the manner you describe. On Rover builds I use a strap and stop so will make one this mornng for the 455 and see if we get a different result.
Ok, so another morning in the workshop. I followed JW and 300sb_overkills instructions and confirmed that I definately have TDC accurately marked. So I pulled the gears off and reset them to straight up. And this is what I get Intake opening 4 ATDC and intake closing 47 ABDC LC is 115.5 So in what should be the straight up configuration this cam is 5.5 degrees retarded. And the lift still checks out at 0.287" as opposed to the 0.297" it should be. Is it possible that I dont actually have a 284-88H cam?
Looks like I may have found the culprit http://www.v8buick.com/index.php?threads/rollmaster-experience.351766/
From the post I linked above it looks like the Rollmaster has a 4 degree retarded 'error' in it which would account for why I had to set it a 8 advanced to get the 4 advanced I want. So apart from the lift discrepancy it looks like I've bottomed this one out. I'm going to do a quick check across all lobes to verify the lift is only 0.287" on all of them @300sbb_overkill you advise a couple of degrees retarded, any particular reason why given it's outright bottom end that I need. Overall gearing gives the Land Rover a theoretical top speed of over 160mph at 5200 rpm. I doubt I'd ever push this vehicle over 100mph which is comfortably under 3500rpm. Thanks to everyone who contributed.
It's kind of hard to kill the bottom end of a BBB. It makes so much, especially when modified that you can afford to lose some. The switch pitch is going to put you right in the sweet spot anyway.
@Schurkey, No I pulled the cam and set it up in vee blocks on the surface plate and checked each lobe. All lobes checked out at 0.287" +/- 0.0015 Another question: Today I've got to the point of fitting the SP1 intake manifold. I have a choice of modifying a standard valley gasket to make a baffle or making a baffle for the PCV. I'm happy to do either. If I go with using the valley gasket do I use the rubber end gaskets or not? Question answered http://www.v8buick.com/index.php?th...talling-a-new-sp1-intake-on-my-72-455.312646/
Even if you do use the rubber end seals you're going to also want some black RTV. I usually skip the black rubber seals, they can have a tendency to squish out.
Thanks for the advice. The gap between the block and the intake where the gaskets fit was 4.3mm (about 11/64th) which feels a bit big for just RTV. I've fitted the seals along with a smear of RTV so will see what happens.
You might need to grind on the timing cover according to this thread, http://v8buick.com/index.php?threads/romac-balaner-quesiton.29242/#post-211047
