One of the heads I am looking has a valve spring pocket of 1.550". Do I need to use a 1.550" external diameter spring, or can I use a smaller spring? The cam kit I'm looking at has 1.254" springs. Will these work or will I need to get just cam and lifters and purchase the springs separate? I tried to search, but not much came up other than spring rate and seat pressures.

 

What kit are you looking at?

 

Comp cams extreme energy 268 solid flat tappet. http://store.summitracing.com/partde...76%2D4&FROM=MG

 

You could use that spring in the larger pocket, or choose a similar larger diameter spring.

Why do you want a solid lifter cam?

 

I've been told that they make a little more power vs hydraulic flat tappets at similar advertised durations. Desktop dyno, for how little I trust it seems to confirm it. I've been told theyre more stable than hydraulics since they don't pump up but I doubt that would be a problem at the rpms I'm likely to see. I know solids need to be periodically re lashed, but I don't mind this so long as it's not every saturday.

 

With such a small cam you won't see enough difference in power to be worth the extra hassle of lashing the valves periodically.

 

Hmm, then there's little point. I'd go for a bigger cam, but don't want to spin the stock cast crank past 6000. Thanks for the help. Hopefully you're this helpful for my other no doubt simpleton questions that I'll be asking in the coming months to summer.

 

IMO you'd get more by converting to a hydraulic roller, and not have to worry about the periodic adjustment or "breaking in" the cam.

 

Hydraulic roller is the way to go, if you want to spend the money.

 

I would love to go hydraulic roller but can't afford a the retrofit lifters. Does the 3970010 block have bosses to drill and tap mounting holes for a stock roller lifter retainer? If you don't know I'll check, but it'll have to wait for spring. If it does, I can look for a set of rollers and a retainer from the junkyard. Would I need anything past the lifters and retainer themselves?

 

Definitely not. None of the 2 piece RMS blocks do.

 

not to mention the block is not clearanced for the lifter tie bars either

 

What tie bars?

 

the ones that go from one lifter to the other and are held down by the lifter retainer.............for the newer style like he is asking about since the 3970010 blocks are not equipped with the boss's for the bolts that hold the retainer in place............he is better off gettin a set of retrofit roller lifters......ive seen em for 240.00 for a decent set at www.competition products.com

 

We usually call those "dogbones".

 

ahh i see...dog bones or gm's term...tie bars.lol same thing.i just got done puttin a newer style cam in an older block with retro fit lifters.........and used a newer style timing chain as well............ cant wait to fire it up

 

yeah get a roller cam, believe me you dont wanna mess with an outdated solid lifter cam

 

A roller cam and it assorted supporting parts are out of my price range at the moment. I'll snag a hydraulic flat tappet for now and wait on a hydraulic roller for when I eventually build a 383.

 

I would still go with solid if I were you, they do make more power, and valve lash adjustments are no big deal, people will make it seem like you will be adjusting them daily, but in reality, you will set them once, then check them with every oil change, the valves will not just come out of adjustment on there own, the only way you will see signifigant changes in lash is if something breaks.I think they got there bad rep. when gm put them in cars with stock valvetrain way back in the sixties, I could see if you were using them without polylocks they could be a royal pain.
Why such a small cam? Gm cranks will easily spin over 6000 rpm, it is the rod bolts you need to worry about. I would consider a comp 280 cam, you probably will not have to spin it much past 6000, and you will actually be able to hear it!
If you want to use a 1.2 spring in a 1.5 pocket, you will want to use a spring cup to positively locate the bottom of the spring, you will not want it dancing. If you do decide to go with a bigger hydraulic or solid cam, I would use a 1.4 spring, a bigger spring will last longer than a smaller spring of the same specs.

 

I've decided to just buy the heads assembled. Probably some patriot 190s unless I hear something really bad about them. As for the cam, I'd like to go bigger, but am afraid of passing 6000 rpm on the stock lower end. You say the biggest issue is the rod bolts. If I throw a set of these in, will that hold her together to 6500? http://www.jegs.com/i/ARP/070/134-6003/10002/-1
If so, then I'll go for an XE284H, XS274S, or an XS282S, though I think the last one pushes the limits of 6500 rpm. How much extra horsepower will the solids give me over an equivalent hydraulic? As for relashing, once an oil change is half as often as I'd be willing to do it. I just don't need the bottom end blowing through my oil pan.

 

Really not much point to running a solid cam if you're not spinning over 7 regularly. Especially with the way Comp grinds the ramps on their XE series hyd. rollers. The improvements would be negligable.

 

Not getting a roller, solid or otherwise. At the moment, the only possibility is flat tappet, unfortunate though that may be.

 

I would go solid flat tappet over hydraulic flat tappet, hydraulic roller is a real good way to go, but I think his budget dictates a cheaper set-up, a solid flat cam is superior to a hydraulic flat cam even below 7000, it is the agressiveness of the lobes, with a cam of 280 duration or larger, I really think solid is the way to go, valve lash adjustments are not nearly as frequent as people will have you believe, and they have a lobe profile not too far behind a hydraulic roller, for a hole lot less cash.
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Are we comparing a solid flat tappet to a hydraulic roller? Not really a fair comparison due to the cost difference, a solid flat tappet will make nearly as much, maybe more power, for a hole lot less, solid roller to hydraulic roller there is no comparison at all!I thoght we were comparing hydraulic flat tappet to solid flat tappet, in that case, I would go solid if I wanted to make good power, but those hydraulic lunati voodoo cams seem to have a good lobe, and are priced fair, that may be something to look into as well.