[eatonde]

Hey guys, I was just wundering if some one could tell me the difference between the retrofit cams and the ones that are made for a block with factory roller provisions?? I've not jumped on the "Roller" band-wagon quite yet, infact I This is the first roller block I've ever had. But the deal is I got on doug herbert website earlier cuz I'm STILL having trouble deciding on a cam for my SBC 406, and they had some cams listed that didn't say "retrofit", but insead just said that they would fit a 55-87 SBC... BUT, I thought it said 55-97, so when I got home I tried to slide one of the OE roller cams I have layin around into my 73 350 block that have Brand new bearings in it, and it fit like a glove.... I just now went back to the DH website and seen that it says 55-87 and not 55-97, so I no there must be a difference, but what is it?? I don't have a good Mic any more cuz my nephew dropped an intake on my good digital one so I can't measure it. How much do they differ in size??

Anyone know the lift/duration on an OE roller cam in a 98 vortec engine?? I'm curious how much lift can the stock valve springs take?

Is anyone running this cam?? Doug herbert HERCH2-H, 285/285 dur/ 242-242 @ .050"/ 555-555 lift?? How would this cam do in a 406 with 10.2:1 CR and a 100-150 shot of NOS?? I've been told that if running Nos its better to go with a split lift/dur. cam, Is there any truth to this?? Would I be better off to go with the HERCCH7-H?? It has 278-286 dur/242-246 @.050"/567-585 lift??

Sorry I have so many questions and so little time, The machine shop is kinda puttin the pressure on me to choose a cam so the cam finish my heads. I need to know a good spring for these cams as well

[SSedan64]

Originally Posted by eatonde

Hey guys, I was just wundering if some one could tell me the difference between the retrofit cams and the ones that are made for a block with factory roller provisions?? I've not jumped on the "Roller" band-wagon quite yet, infact I This is the first roller block I've ever had. But the deal is I got on doug herbert website earlier cuz I'm STILL having trouble deciding on a cam for my SBC 406, and they had some cams listed that didn't say "retrofit", but insead just said that they would fit a 55-87 SBC... BUT, I thought it said 55-97, so when I got home I tried to slide one of the OE roller cams I have layin around into my 73 350 block that have Brand new bearings in it, and it fit like a glove.... I just now went back to the DH website and seen that it says 55-87 and not 55-97, so I no there must be a difference, but what is it?? I don't have a good Mic any more cuz my nephew dropped an intake on my good digital one so I can't measure it. How much do they differ in size??

Anyone know the lift/duration on an OE roller cam in a 98 vortec engine?? I'm curious how much lift can the stock valve springs take?

Is anyone running this cam?? Doug herbert HERCH2-H, 285/285 dur/ 242-242 @ .050"/ 555-555 lift?? How would this cam do in a 406 with 10.2:1 CR and a 100-150 shot of NOS?? I've been told that if running Nos its better to go with a split lift/dur. cam, Is there any truth to this?? Would I be better off to go with the HERCCH7-H?? It has 278-286 dur/242-246 @.050"/567-585 lift??

Sorry I have so many questions and so little time, The machine shop is kinda puttin the pressure on me to choose a cam so the cam finish my heads. I need to know a good spring for these cams as well

Factory OEM roller cams have a step machined on the nose or front face of the cam & use a retainer plate to hold the cam in place. Retro fit cams look just like a standard cam on the nose/face & use a cam button to hold it in place. Bearing sizes are the same for flat tappet or stock roller. I'll add some Pics of the cam noses & retainer below.
I would try to use the springs reccomended for the cam or at least match the spring pressures/rates as close as possible. The stock Vortec springs only have about 70lbs. seat pressure & are able to handle about .450 lift, mainly because of retainer to seal interference. Do a search on here for tons of Vortec Info. or look here >> http://www.nastyz28.com/forum/showthread.php?t=56505
Factory Style Roller lifters are (MUCH) cheaper than Retro fit roller lifters.

[curtis73]

I agree with SSedan. The retro roller cams are basically the same from the snout back, but since the older non-roller blocks don't have provisions for the thrust plate you have to use a button.

You could use a retro roller cam in a roller block, but the extra cost of the button and cam doesn't make sense.

But I've never encountered a situation where the retro cam's grind was different from its OEM roller sister. If you're looking at a Comp 284 in retro and OEM roller appications, the lobes are the same, just the snout is different. Since they know you need the retro configuration for a non-roller block, they soak you on the price.

[ap72]

those two cams are the exact tow I'm trying to choose from! that's srange that we both are looking at the same cams from the same guy, especially when he's a smaller cam man.

I'm leanign towrads the single pattern for two reasons, it'll give me a hair more midrange torque and its easier on the valvetrain. If I decide I want more lift later I can always upgrade to 1.65 rocker arms and springs to match but for now .555 lift is plenty. With a single pattern you want to go a little overboard in your exhaust setup.

I'm looking at the one with 112 LSA, though 110 would probably be better for your application. He can also grind it in with whatever LSA you want for an extra $20. A 108 may not be out of the question if you're looking for better track performance.

[eatonde]

Yea AP, I agree the 555/555 cam would be good for the mid range. However I was always told That ESPECIALLY what running NOS or any type of forced induction that is better to run more lift/dur. on the exhaustto make up for the smaller valve and thus increase your engine ability to "exhale".
I've never ran any forced induction or power adders YET, this will be my first one, so i really don't know how much of a difference it makes and how necessary it really is. The basic concept does make since tho, as it was explained to me, However i have also been told that one can achieve basically the same thing with a 1.6 rocker on the exhaust side.
Can anyone help explain this thoery or discredit it???

SSedan, how can you use regular OE roller lifters in a old style block?? I know they fit in the bores, but how would you keep them from spinning in the bores with out the vertical bars or using the OE retainers??? Is this what you meant or did I mis-understand you??

[ap72]

another one if you want more midrange and a split pattern is the ol' 847 cam from GM. a LOT of people really like that one. and its easier on the valvetrain.