Hot Rodders - The death of the flat tappet cam.
- Thread starter DuckRyder
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1.8:1 on all Gen V engines.
Does direct injection take the lump out of the idle with big cams compared to the same engine with a carburetor?
For $9,000 USD, the 6.6L 523 horsepower gen 5 sounds like a deal instead of spending the same money on a 70 year old engine design.
The legacy V8s from the 50s and 60s are boat anchors in comparison to what’s available in drop in crate engines.
If someone needed a replacement camshaft for a flat tappet application, there's the reground cam shops. You may have to have a good core, original to your vehicle or not. I've never used them, but many slant six modding guys love Oregon Cam Grinding in Vancouver, WA. I believe they grind for all sorts of applications. Seem to have an excellent rep and can be phoned. Many grinds on file or custom.
The L8P cam isn't all that large for a 400ci engine & has a rather wide 121° LSA.
I took the aforementioned Oldsmobile example. The still seem to catalog that 252 High Energy. its 206 @ .050. However every single Comp flat tappet for that olds motor that i checked is "temporarily out of stock".
Surprisingly there is a hydraulic roller that's nearly as tiny at 210 @.050/[email protected] The roller is probably a better cam in all respects except cost.
My prediction here is that we will get some smaller rollers to fill the gap with less aggressive but still modern lobes if no other source of good cast cores is forth coming. Of course they will still have the added complication of drive gears and probably valve springs and such, though valve control may be les of an issue on a slower smaller lobe at lower revs you still have to control the lifter.
RE the Rocker ratio and ramp rate discussion, there been a lot of stuff posted since the cam challenge on you tube, some older stuff too its interesting how rocker arm ratio translates from lobe to valve. its worth watching if that sort of thing is interesting.
Surprisingly there is a hydraulic roller that's nearly as tiny at 210 @.050/[email protected] The roller is probably a better cam in all respects except cost.
My prediction here is that we will get some smaller rollers to fill the gap with less aggressive but still modern lobes if no other source of good cast cores is forth coming. Of course they will still have the added complication of drive gears and probably valve springs and such, though valve control may be les of an issue on a slower smaller lobe at lower revs you still have to control the lifter.
RE the Rocker ratio and ramp rate discussion, there been a lot of stuff posted since the cam challenge on you tube, some older stuff too its interesting how rocker arm ratio translates from lobe to valve. its worth watching if that sort of thing is interesting.
This exact issue is discussed across all automotive forums for classic cars and performance engines. Hang on to your old camshafts and even lifters. Both can be reground and refaced respectively. Not trying to throw a wet blanket on roller cams being the answer however they’re not without issues not to mention the cost. For classic car enthusiasts in the GM world, these issues have made the LS engine conversions more attractive. These old V8s we all love are really hard to keep running with major parts sources drying up. I guess the performance camshaft companies feel that the current Asian, European, and some US made car enthusiasts will keep them busy. Personally I don’t see it….
buy the biggest flat tappet you can now. then you can always have it reground with lobes that suit your application.
Sounds like a similar issue with tire/and wheel size requirements in the SCCA. The spec 7 rx-7 class specs 205/60-R13 tires and 13x7" wheels. Six years ago I think there were six or so manufacturers that offered such a size. From recent searches only Weld and SSR have wheels in that size and they aren't cheap.
I didn't watch the video yet. But there is nothing new about roller lifters, they were around long before WW2. Oh and those ones usually lasted longer than ones nowadays. 
Yes, it’s amazing what a smallish 218/231 @ .050” cam ground on a 121 lsa can do with 1.8 rockers compared to the original small block Chev with 1.5 rockers and 2.02” vs 2.13” intake valves.
The small block Chev designed in 1954 for the October roll out in the 55 model year would require a lot more camshaft to accomplish the same horsepower as the 6.6L L8P.
IMO, camshaft grinders have been selling a rough idle and poor fuel economy for over 60 years.
It’s too bad they can’t think outside the box.
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