Engine and Transmission Tech

I'm looking to use a distributor, 4bbl 215 intake, and older style front cover and oil pan on my 4.6L Rover v8, and I have a lead on a NOS factory-spec cam from a Buick 300.

I understand that cams for those engines generally are interchangeable, but I know nothing of their specific specs, and I'm a bit behind the power curve when it comes to cam choices.

Would a stock 300 cam be a reasonable match for a 4.6? I also have a set of aluminum 300 heads, if that might change the math.

Dave

I know they list the 215 as interchangeable with the 300 and 340. I don't know if the later Rover V8's changed the cam bearings or not. Stock 300 cam is pretty mild, your 4.6 cam may be better specs. You would have to use a Buick cam gear and timing set also. I know the later Rover cam nose is different..

Just order up an aftermarket cam for a 215/300. Stock cams are not well suited for a lightweight sports car. The early Buick/Olds/Rover engines had no cam retainer. The later 4.0/4.6 did. The aftermarket cams have the nose that is not set up for a cam retainer. If you plan on running the old style front cover and a dizzy, then no worries. Just run the aftermarket cam with no retainer. The dizzy drive gear and the rest of the old style pieces will hold the cam in place. Your other option is to pick up a full circle cam retainer from Rimmer Bros that fit the 4.2L Rover engines and have the nose of the cam turned down in a lathe to accept the cam retainer. As long as you use bolts with a short enough head not to foul the timing gear, you can run the retainer. Don't need it, but you can run it. I use to run the old cover with a cam retainer on the race car. Had to run the old pieces because of the rules, and used the retainer because it reduced the wear and tear on the cam gear/dizzy drive. Just built a 4.6 myself for a TR8. Going with all the old school TR8 pieces but running a turned down cam and a retainer. Back to the cam. Make sure you don't order anything with a lift over .470 unless you plan on cutting the valve pockets deeper and installing taller Chevy springs. Anything over .470 and you could experience valve springs binding and snapping. Lower lift cams under .500 or so and you can run Chevy lifters. Taller lift cams you need to run the slightly more expensive Buick lifters. That has to do with where the oil hole is drilled in the side of the lifter. Taller lift cams will raise the chevy lifter high enough to expose the oil hole outside of the lifter bore and you will loose oil pressure. If your in the New England area, I can give you the name of my engine guy. He's done at least 100 of these things. If you want, I can post photos of what the different cam noses look like. The cam retainer ordered from England should be here by the end of the week. I have the new aftermarket cam that needs to have the nose turned down, and the stock one that came out of the 4.6 sitting in the garage now.

My 4.6 has the intermediate cam cover with distributor and gerotor oil pump, 215 four barrel factory manifold, and the crower cam that many use. It seems as though multiple combinations of parts are used to accomplish our goals

Any given cam will seem a bit milder on a larger displacement engine, a bit more radical on a smaller one. So with the larger engines you can and should go bigger on the cam.

Jim

Many thanks for the fine details everyone,

I now have lots to research on Google while the in laws are in town!

It's the idea that a mild cam for a big engine might be "hotter" when put in a smaller one that had me wondering if a 300 cam would be a good fit for a smaller displacement Rover build. I did not account for the simultaneous drop of at least 1000 lbs in the car it will be used in.

I'll see if I can dig up the specs for the stock cams somewhere. Would be interesting to see how they evolved.

I have also heard (and it's easy to believe) that improving the flow of the head makes a cam 'hotter'. The Fox Mustang HO guys could port their heads, install an intake and headers and use the stock cam with excellent results.

Pocket-porting heads isn't hard and gets the most gains.



Edited 1 time(s). Last edit at 12/22/2016 02:40PM by pcmenten.

I tend to believe that an aftermarket cam, especially a non-roller, is better for a performance build than a stock factory cam. OEM cams are made with considerations for normal street use, mileage, emissions, etc. I don't want Grandma's grocery getter or only-drove-it-to-church-on-Sunday cam in my performance engine!

If you are trying to save money, sometimes putting the stock cam back in the engine is a workable strategy. In general that will be good to about 5500 rpm where valve float will occur earlier or later depending on spring load, which you can vary to suit. (A stock cam can run to 7000 rpm with the right springs.) But if you are replacing the cam anyway there is enough to choose from that there is little reason to stick with the OEM cam. You might as well take advantage of the opportunity to tailor your engine to your driving style, however bearing in mind these are conversions we are talking about here, power is not going to be an issue. At least not initially, as there will be way more than there was before. So first and foremost, consider your driving style and evaluate if it has changed any. If you like having gobs of torque available in any gear at any speed (a lazy shifter in other words) you might consider an RV cam for an abundance of low speed torque. If you love going through the gears and holding it until redline, trying to get that last iota of power, get a more performance oriented grind. If gas mileage is important to you get an economy grind.

Jim

Thanks everyone,

I have some info on the vintage cam that started this thread, but I could use some help interpreting it:

I called Crane Cams, and the guys there quoted these specs:

Flat-tappet cam
.483 lift
Duration at .50 is 232
Would make best power from 3500-6500 rpm
No more cam blanks available

Sounds like a *not stock* cam, yes? Power band is very high, and I can't align the numbers above with any modern cam I can find on the internet from Crower.

This may be a very odd cam?

For reference, i found these specs on the internet for the stock late-model Rover 4.6 cam:

4.6: Intake and exhaust lift .424

Duration @ .004, intake 269, exhaust 274
IO 14-BTDC, IC 75-ABDC
EO 68-BBDC, EC 26-ATDC

Duration @ .050, intake 205, exhaust 206
IO (12)-ATDC, IC 37-ABDC, lobe center ~111
EO 38-BBDC, EC (12)-BTDC, lobe center ~115



Dave



Edited 1 time(s). Last edit at 12/28/2016 01:34PM by RDMG.

Great cam, lopey idle, revs well & move the power upstairs. Don't expect good fuel mileage, though. ;)

Likely a good bit hotter than what you are looking for.