Hi All,
My apologies if this is long winded, so I'll attempt to keep this as short as possible. I currently have a few bad lifters in my 78 Pontiac 400. So, rather than do the easy thing by simply replacing the lifters, I'm contemplating on swapping out my Edelbrock RPM performer cam for that of a hydraulic roller. First off, I'm very happy with my cam's current performance, but perhaps I'm missing out since I have nothing to compare against in terms of cam evaluations within my specific motor. I'll list my current specs below, but I can provide other stats if needed. Probably the most important piece of this puzzle is that I'm running the Edelbrock 72cc RPM heads, edelbrock rpm intake, a 2200 stall, and 3.73 rear in a streetable weekend warrior. I really don't want to make a $500-$1K+ mistake by falling into the common trap of over duration and thinking that 'bigger is always better', so I'd like to hear from anyone that may have experience with a similar setup.
1.) My current cam stats can be found here
http://www.edelbrock.com/automotive/mc/camshafts/locator.php?part_number=7157&submit=go 2.) I don't want to sacrifice low end torque, but I'm also tinkering with increasing my duration by 5 degrees... Bad idea? My intake is designed for 1500rpm, so would the roller cams with the 2200rpm-6500rpm be too much? Would I end up with the dreaded 'bog' on heavy acceleration if I take it one step up? Is the power band mismatch from 1500 vs. 2200 too much?
3.) I've been looking a few rollers and will list them below, but most of them recommend a 2800rpm stall. I understand that's a subjective value to some point depending on compression and other factors. Would my 2200 be ok? Do I really need a 2800 with my other motor elements?
4.) I've got zero understanding on valve separation angles and what the recommended 'max' values should be for a power break application?
5.) Perhaps I've not looked hard enough, but I couldn't find a roller cam with the same duration as the rpm performer cam that also start at the 1500rpm power band range. I've found some rollers that started at 1500, but it's always a step down in duration vs the edelbrock rpm cam. Anyone see a good roller duration cam starting at 1500?
Cams I've been kicking around in my head:
https://www.summitracing.com/parts/cca-cl51-433-9/overview/make/pontiac - One step 'up' in duration vs. my current cam
https://m.summitracing.com/parts/lun-20510712 - Better matched to my current cam, but higher rpm start range
Car's current setup:
Edelbrock RPM performer heads, rpm cam, and rpm intake for pontiac 400
Stock but rebuilt bottom end (.30 over) 400 pontiac block - I don't trust pushing it over 5500rpm
2200 stall, I don't want to go higher if possible since it is still used on the street on the weekends. (Seems silly to me to run a stall at almost 3K when the motor pops at 6.5K)
3.73 rear gears and 350t tranny with shift kit
1.5 ratio generic roller rocker arms
Weekend warrior use (some drag track runs from time to time)
Power brakes
650CFM Edelbrock Carb
Doug's headers with dual exhaust / no cat
MSD 6-AL Programmable
So all this said, should I just replace the current flat tappet lifters? Better roller cam suggestions? Have I 'overkilled' things for the street with these choices?
Many thanks for your considerations.
TA101