I really don’t know what Mobil 1 they put in these cars, the dealer handles that, since the dry sump system is very tricky to do your self. Also, GM is now mandating Dexos approved oils only for the ZR1, and since the engine is under warranty, I just let them handle that too.
How do you check whether the engine has flat tappets or rollers ?
If it’s pre 1984 and in a ford it’s flat. If it’s been replaced, the easiest way I know is to pull the intake. There will be a spider plate in the valley that pairs the valves to prevent valve float.
Thank you. Its a '68, XR7, 302, but it looks like its had some modification done to it. The air intake is a Edelbrock Performer 289 (which seems odd ?) and the rockers look newish, so its possible they have been replaced
Do you have a picture of the newish rockers? If they are not roller, I would say the came is not ether.
Oh yeah, pull the valve covers and if the rockers are flat without a wheel on the tip…flat tappet. Boy, that’s so much easier than my suggestion.
I do not think rocker tips have any bearing on roller cam or not. Also, the valley spider is for the lifters, not the valves. It does not “prevent valve float”, it (and the H-shaped plates it retains) locates retrofit (and OEM 5.0) type lifters so they do not turn in their bores.
Well, every roller cam car I’ve ever worked on had the spider plate. Just an observation.
Spider plates would indicate a roller cam as they are part of the roller lifter locating in such an engine, this is a correct statement (but have nothing to do with valves or valve float as you suggested).
The other thing I was referencing is what Dennis (cougar2) said about roller tipped rockers indicating a flat tappet cam, this is incorrect as well.
Just an observation (or two)!
Here is an OEM 5.0L rocker:
As we can see, it is not roller tipped, but the cam in such an engine is roller and uses roller lifters.
I do not mean to be harsh (although I may tend to sound that way, if so I’m sorry!), just trying to shed light on what is correct.
Regards,
Bob
You’re right. I’ve been working overhead cam too long. How silly of me.
It’s all good friend! Welcome to CCC and good luck with your wanting a classic Cougar, we (obviously) love 'em around here!
Thanks chaps, Until I have a chance to take off the air intake, I think I will assume flat tappets and use zinc heavy oil.