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Tech / General EngineIs your car making a strange sound or won't start? Thinking of adding power with a new combination? Need other technical information or engine specific advice? Don't see another board for your problem? Post it here!
Not sure where you get your data from but I'll say that's simply not true.
I'll agree that the old outdated grinds are "easier" on the valvetrain but to say that the newer offer nothing but trouble is incorrect.
Certainly Billy Godbold wouldn't release a series of SBC cams (and these are decades old now) directed strictly towards street performance and quick action valve movement. His XFI series of lobes (and cams) have the same lobe lift as the Jones cam I have at .360". The gives a .570" with my rocker arms.
Use good lightweight parts like a beehive spring and tool steel retainers and perhaps most importantly, proper valvetrain geometry, and they'll give tens of thousands of miles of reliable service. I've done it. Still have my custom COMP XFI too show for it too.
What I don't recommend, and this is regardless of the cam chosen, is to expect high RPM reliability with well used parts. I've done that too. My "gentle" COMP XR288HR with a .347" intake lobe outdid the old tired top tier roller lifters (COMPs short ravel tool steel lifters). A link bar failure isn't a pretty thing but that failure was to due to age and RPM. 7000 will do damage with any cam if the rest of the parts aren't up to it. Those lifters also had tens of thousands of miles of heavy duty service. My bad.
Truly modern lobes, despite having fast ramps, raise and lower the lifter gently so as not to be hard on parts. The inverse radius (again such as Jones and others) is what accomplishes this. So the noisy valvetrain, roller rockers notwithstanding, isn't what it once was.
No further to your comment about offering nothing but, it's been proven over and over again, that the faster you can get the valve open the less it needs to be open. IVC can be later and cylinder pressure is increased all else being equal. This is a benefit to all things low RPM. Simply stated it puts more lift under the curve, allows for a shorter cam which in turn improves drivability and fuel economy. This is to put it into a street performance perspective although the the term street is very subjective.
This isn't an overlap discussion as that's an entirely different topic. Its lobe profile is what this is about. At least that's what I'm describing here.
As always Fast, your mileage may vary.
The lobe profile will make very little difference in something cammed as a true street engine. You are talking at best 2-3% on a 400 hp small block for a given 0.050 duration spec. 0.360" lobe lift can be enough to expose the lifter oil groove in some OE roller blocks and result in lower oil pressure as well. I will take the longevity, reliability as I still made 502 hp and 520 tq from an 11:1 383 with old Comp Magnum lobes. Beehives can often be a disaster waiting to happen. Lloyd Elliot recomeends a good dual spring for everything including LS builds. The 862s he ported and worked for me have dual springs and so do my aluminum small block heads.
get your facts straight, I slammed OEM stamped steel rocker arms. They have always been junk with any kind of spring pressure upgrade.
Pretty sure my facts are straight.....aren't rocker arms part of "valve train"? I thought they were.... No? What "valvetrain" (sic) were you referring to here:....?
Originally Posted by Fast355
Give me a GM grind or an old grind; easier on the valvetrain......the valvetrain is stock like quiet even with.....Valvetrain is silent in his truck
Rhetorical question....don't need to answer and it doesn't matter. Whatever point you're trying to sell in these tiring posts of yours....they ain't convincing ME to go buy boat parts. I hope others don't fall for it either. As you were.
The lobe profile will make very little difference in something cammed as a true street engine. You are talking at best 2-3% on a 400 hp small block for a given 0.050 duration spec. 0.360" lobe lift can be enough to expose the lifter oil groove in some OE roller blocks and result in lower oil pressure as well. I will take the longevity, reliability as I still made 502 hp and 520 tq from an 11:1 383 with old Comp Magnum lobes. Beehives can often be a disaster waiting to happen. Lloyd Elliot recomeends a good dual spring for everything including LS builds. The 862s he ported and worked for me have dual springs and so do my aluminum small block heads.
I get your point on all counts although I'll say there's more HP and TQ with a modern cam. That said, as we know, making 400 HP is a piece of cake these days. So it's not much of a point to make I suppose.
FTR: Between my COMP XR288HR (288/292, 236/242, 110 LSA, 106 ICL, 71° overlap) and the Jones 280/284,( 232/236, 108 LSA, 104 ICL, 66° overlap), all data suggests that the shorter cam will make more more power and torque everywhere up to 6k. The Jones cam has 8° less seat timing which is great for the street, 5° less overlap (also good) and yet is only 4° short on the .050" duration. There's that piece of cake and eat it too thing I was talking about.
Obviously I'm big on building cylinder pressure.
Plenty though have good results with the Magnum lobes. Although he's as dated as those profiles are, DV used them in his SBC build books. Who am I to argue? But then again, that was then.
As for the beehive spring, there are more builds than I can recount that rely on that single spring. Not that I care about LS engines for the purposes of this conversation, the OEMs are happy to warranty them in all manner of transport. I've run them reliably to 7k. The PAC version came recommended by my cam grinder too. It's the weight savings that's the real benefit. There's no need for the dual spring in order to control the valvetrain. And out of control is what breaks parts. Well, that and high mileage!
Again, to each their own.
On a personal level, although closer now than I have been in years, there'll be some track testing. I'll have time slips to compare the two cams on essentially (but not entirely) the same engine. MPH will tell the tale.
I'm also targeting some chassis dyno time although it might be a safe bet to say that at best I'll get back on the road this year and the racing will be next year. Our season ends here early October. It depends on how the project goes together (for the tenth time) and whether there are new slicks in my budget. I've spent a small fortune already.
I have faith too that the highway mileage will exceed that of the 288 as well. Best I could tune for was 21 US MPG steady state highway. That's carburetted. I was happy with that as it was street car primarily and from the looks of my torque converter choice this go around, will still be street orientated rather than more track specific.
I ran a few of the calculators with my goal of peak power at 5500-6000 rpm, and I think what I'm finding is that when I was thinking I was going to stick with the 350-355, the 180 heads would have been perfect. Now that I'm entertaining the lickelyhood of getting a 377-383 short block, that extra displacement really pushes me to needing the 195s.
One key calculator showed for a 377ci v8 to hit peak power at ~5500 rpm, you need a min csa of 1.9 sq-in. The 180 heads are only 1.81, where as the 195s are 1.905, which would sound about perfect!
Is this sound logic? May order at least heads gaskets, valve covers soon to take advantage of fourth sales... need a starter too, so I'll put everything together and use a 10% coupon at summit.
I ran a few of the calculators with my goal of peak power at 5500-6000 rpm, and I think what I'm finding is that when I was thinking I was going to stick with the 350-355, the 180 heads would have been perfect. Now that I'm entertaining the lickelyhood of getting a 377-383 short block, that extra displacement really pushes me to needing the 195s.
One key calculator showed for a 377ci v8 to hit peak power at ~5500 rpm, you need a min csa of 1.9 sq-in. The 180 heads are only 1.81, where as the 195s are 1.905, which would sound about perfect!
Is this sound logic? May order at least heads gaskets, valve covers soon to take advantage of fourth sales... need a starter too, so I'll put everything together and use a 10% coupon at summit.
That's the approach I used when developing the 383. That ultimately became a 357.
MCSA is one indicator of engine potential. It can be argued that there are other that are as important but, logically, the science makes sense. Which science generally does.
I see no error in the 195's. This will swing the cam spec and I'd certainly like to see what you go with. I'm hopeful it's not some forum based "it worked for me" grind but rather one that's also based on science.
I'd posted my Jones spec. Two of them actually and those were for a small headed, 175 cc, 1.90 MCSA port. My guess is that with the 195 port and requesting peak HP of 6k, the cam will be small in comparison to what you might think.
Have your compression ratio dialed in before the cam. That's advice I can offer from experience. And that experience didn't produce the best results.
FTR: A cam for a 383 will not be a cam for a 377. And if you go to a 4.125" bore for the 377, you might as well go to a 406. Ah...the proverbial snowball.
FTR: A cam for a 383 will not be a cam for a 377. And if you go to a 4.125" bore for the 377, you might as well go to a 406. Ah...the proverbial snowball.
Maybe I miss spoke, I was under the impression when you stroke a 350 with a new block that is still 4.000 bore you get a 377, vs a 383 that results from the bore being bored .030 over... im looking at one of the two short blocks i pasted above. The blueprint one has a note that says actual displacement 377 ci, the other one just says 383 everywhere, if this is not the case please explain why the bluepring is actually 377ci... not sure which I should go with... I've heard only good things about blueprint, bit the other one looks good too and has a few more forged parts I think.
Well... it has begun! Just placed my summit order for the afr 1040 195 heads, cast aluminum valve covers, and the new starter I needed!!!
My plan is to port the intake and heads (width only) to the 1205 gasket, but then use a 1206 for assembly because the 195 port is actually taller than the 1205 gasket...
Maybe I miss spoke, I was under the impression when you stroke a 350 with a new block that is still 4.000 bore you get a 377, vs a 383 that results from the bore being bored .030 over... im looking at one of the two short blocks i pasted above. The blueprint one has a note that says actual displacement 377 ci, the other one just says 383 everywhere, if this is not the case please explain why the bluepring is actually 377ci... not sure which I should go with... I've heard only good things about blueprint, bit the other one looks good too and has a few more forged parts I think.
Actually, it's me that misspoke as there are two versions of a 377. A standard bore with the 3.75 stroke gets you one of them, a 4.155 bore with a 3.48 gets you the other. The latter is a .030" deal. And yes, further to your comment, a 30 over 350 with the 3.75 is the 383.
Carry on...
Originally Posted by raptere
Well... it has begun! Just placed my summit order for the afr 1040 195 heads, cast aluminum valve covers, and the new starter I needed!!!
My plan is to port the intake and heads (width only) to the 1205 gasket, but then use a 1206 for assembly because the 195 port is actually taller than the 1205 gasket...
Keep in mind that one of the critical points in the manifold to head interface is the roof of the port. The 195's are taller as that's where some the gains in CFM are made. There's a better look at the intake valve in other words.
That said, other than a gross misalignment, it's been shown that the gains are minimal with the traditional gasket matching approach. In my own pile of parts, there's no gasket matching but I did ensure that the port didn't overhang into the manifold opening and the roof and common wall were lined up as much as possible. An inspection camera/borescope is the ticket here.
As for Blueprint engines, at one time there was a considerable knock against them but over the last couple of years, once all that pandemic crap sorted itself out, they seem have earned a decent reputation.
Not sure I'd use them for a true racing engine (and I didn't) but for my streeter/wanna be drag racer, I'd be price point vs what do you get shopping and decide from there. There's the warranty and customer service to consider as well.
As I've said, I'm slowly accumulating parts for my planned winter build.
I was just test fitting things last night and found that the intake bolts I got don't fit the afr 1040 street cnc 195cc sbc L98 gen I heads. Looks like the bolts are 3/8, but the tapholes are 5/16. My searching tells me the standard should be 3/8 for an sbc I. I saw vortec are 5/16, but the pattern and length are very different... Also noticed the holes are not chamfered, which it seems the rest of the tap holes on the head are... I even found and old bolt I removed and replaced when I installed my HSR years ago, and they are 3/8, same pitch as the new ones I got...
That seems unlikely but you never know.
This may seem an obvious question but worth asking just the same.
Have you tried to screw in a 3/8"-16 bolt into the heads? It'll be the same size and pitch as the accessory holes in head ends.
I talked to AFR. Their initial thought was that because no chamfer was performed on those holes, that was causing the issue. I was skeptical at first, but I tried out the only deburring tool I currently own, which is maybe a 45 deg one for ammo reloading, and what do you know... with a little additional force, the ARP 3/8 intake bolt did start going in. It was just so much tighter than I expected it to be, or maybe I'm not familiar with the drag of the threads into aluminum?
I will say I measured all the holes and they were smaller than AFR said they should have been, so I'm considering this a bit of a stacking of issues problem. According to AFR the ID of the 3/8 holes were supposed to be .310 to .312". I measured all of mine and they were .306 to .3075, quite consistant though, I guess. Threads must be at smaller end (or maybe below) min tolerance, and the material pushed over the hole from machining the surface kept the bolts from going in easily. Apparently they machine the holes first, then machine the intake surface, then deburr...
AFRs QC has gone down the tank the past few years. Their Enforcer heads have a missed machining step that prevents factory GM centerbolt valve covers from being installed on them as well. They did not machine the inside of the perimeter bolt boses and the steel valve cover collides with it before the gasket touches the valve cover rails. The older USA made AFRs were machined correctly as are Edelbrock heads like the Etecs in that respect.
My AFR heads came with 3/8 rocker studs. I have a set of 3/8 rockers I'm considering using, but they have the self aligning tabs. With the dual adjustable guide plates, and narrower 8mm valve stems, I think there is a chance I can align them so that even with the play in the guide plates, there would still be clearance between the valve stem and the self aligning tabs... I know this is a contentious topic... but I would like to test fit things to see.
If I do decide to buy new rockers, do I need to be replacing my rocker studs with the bigger 7/16" ones? Are 7/16" studs neccissary for 1.6 rockers running on a cam with less than 0.575 lift?
My AFR heads came with 3/8 rocker studs. I have a set of 3/8 rockers I'm considering using, but they have the self aligning tabs. With the dual adjustable guide plates, and narrower 8mm valve stems, I think there is a chance I can align them so that even with the play in the guide plates, there would still be clearance between the valve stem and the self aligning tabs... I know this is a contentious topic... but I would like to test fit things to see.
If I do decide to buy new rockers, do I need to be replacing my rocker studs with the bigger 7/16" ones? Are 7/16" studs neccissary for 1.6 rockers running on a cam with less than 0.575 lift?
The question you have to ask your self is how much spring are you using, and how fast are you spinning it. Because they can and will flex a bit.
I went with 7/16th because I was spinning to 7200rpm and have a pretty aggressive spring rate.
The question you have to ask your self is how much spring are you using, and how fast are you spinning it. Because they can and will flex a bit.
I went with 7/16th because I was spinning to 7200rpm and have a pretty aggressive spring rate.
The AFR site says the following about my springs: PAC Racing Spring 1.290" OD Hydraulic Roller Dual Valve Spring,
140 lbs on seat, .600" maximum lift, Max RPM 6300-6500, less than 235* duration, upgraded spring #8019 recommended for higher RPM & larger cams
So if I'm only planning to run up to about 6000 rpm, then am I totally fine with the std 3/8 rocker studs that came on my heads?
The AFR site says the following about my springs: PAC Racing Spring 1.290" OD Hydraulic Roller Dual Valve Spring,
140 lbs on seat, .600" maximum lift, Max RPM 6300-6500, less than 235* duration, upgraded spring #8019 recommended for higher RPM & larger cams
So if I'm only planning to run up to about 6000 rpm, then am I totally fine with the std 3/8 rocker studs that came on my heads?
Technically you could get away with 3/8" studs on a high rpm engine.
Honestly, its a weakness of the SBC platform and why LS series engines moved to a shaft rocker system, significantly more stability in the valve train.
I have the AFR 195cc heads with the 8019 springs and the titanium retainers, which are 155 on the seat and 448 open. BUT, I regularly take the engine to 7000rpm, and have actually touched the rev-limiter at 7200rpm on upshifts. Its GLORIOUS! I wanted the minimum weight possible on the valve train.
6000rpm is nothing to a small block. Even an L98 with the right valve springs to control the valves can do 6000rpm on the pressed in studs.
The oem springs will be fine for the AFRs.
Last edited by Thirdgen89GTA; 09-04-2024 at 09:12 PM.
It depends.
I broke a 3/8" stud with a little cam that saw few revs. The unknown was whose studs were they. The engine had upgraded Vortecs (I supplied my originals and they were modified by my go to machine shop) however I can't say if used a "jobber" stud or GM or ARP. I suspect the former. The break came at cruising highway speeds with no "spirited" driving..
Here's a link to that thread with more detail if you're interested.
Does AFR give a P/N for the studs? I'll say that if they're ARP's then run with it. More importantly is that when you're setting up the heads and checking for proper geometry, you don't have any weirdness going on. Geometry correct (as in mid-lift method) and no binding. At one time I had the guide plates aligned but after some run time, something I hadn't seen was that the pushrod was making contact at the guide plate as designed, but also in the hole in the cylinder head. This wasn't a factor in that broken stud episode, but caused me grief in the build that followed.
This also might something to consider when running a self guiding rocker. It's really one or the other. Guided rockers or guide plates. My experience that both is a recipe for failure.
This isn't to argue the point as I'll agree on the 3/8" pressed in stud deal as I've done it. Box stock Vortec with OEM springs bouncing of 6K now and again but I wouldn't recommend it. You might think 6k is not a lot of revs but you'd be amazed at what's happening in the valvetrain at that RPM. Stuff moves around like you can't imagine. I've always considered .575" lift as getting up there for the streeters I've assembled. The Vortec had a COMP 268H hydraulic flat tappet at .454". Nice cam but sleepy. Remember too that it's not necessarily that lift, but the lobe intensity. A lazy lobe like COMP Magnum, is easier on parts than say a COMP XFI profile.
Yup, my AFR heads came with ARP #134-7104 - 3/8" ROCKER STUDS (+.250 LENGTH)
So I'll stick with the 3/8" ones they came with for now. BTW. 575 would be absolute max lift, I expect to be much closer to .550. Also duration will be between about 220 and 230 for my cam. Maybe slightly less... so I should be pretty safe...
I know everyone says self aligning rockers OR guide plates, but if you can align everything so there is no binding and there is still clearance between the valve stem and rocker aligning ears theough the entire rocker sweep, I can't understand why it would be a problem... can someone explain this. I have my current set of comp cams ultra pro magnums, I'd really like to be able to re-use...
I did a quick bench mockup on my AFR's and my factory stamped rockers, and it seems plausible.
The best way to explain is to think about the mayhem in the valvetrain at 6k.
That rocker arm isn't necessarily going to want to track perfectly in line with the valve tip. It'll swing side to side to some degree. With no guide plates and a self aligning tip you keep the rocker from riding off the side. The pushrod moves with the rocker tip.
With guide plates the pushrod is held in line and travels (more or less perfectly up and down). the rocker tip will walk across the valve tip a certain amount.
Now if you constrain the pushrod in it's vertical motion via a plate, and constrain the tip of the pushrod via the guided roller. when the rocker wants to swing across the valve tip (in a concentric pattern to the rocker stud) you'll create this bending moment at the plate. Effectively trying the bend the pushrod. The guide system on the roller tip will take a hit also. It may be the weaker link as pushrods are designed to take a beating.
As I had mentioned, I had interference at the pushrod hole in cylinder head and the guide plate. Different scenario but similar effect. It made a mess of my pushrods and may have possibly contributed to the excessive valve guide wear I was experiencing ( although that is probably due to incorrect geometry).
Can you get away with it? Think about all the SBCs built. I'll bet it's been done although what is the compromise? I doubt that you can simulate the possible interference that would occur when setting this up statically. The real action happens at RPM.
But as the saying goes, your mileage may vary.
When you're in the mock up stage, post some pictures if you want further discussion. I for one would be interested if you are.
I guess I haven't clarified, but I'm using Comp Cams Ultra Pro Magnum full roller rockers. Considering those rockers and the dual adjustable guide plates, seem like they would keep the rockers moving in a pretty straight up and down sweep...
I ran the calculations below. Here is my logic. The AFR heads run 8mm valves which are slightly smaller than the standard factory 0.3413" (8.6690 mm) which will allow grater clearance. The roller tip is 0.375" so that would be the minimum space between the self-aligning ears, allowing 0.060" clearance for the valve. Then considering the maximum amount of movement of the pushrod in the guide plate, with 0.0185" clearance, even multiplying by the 1.6 rocker ratio, you would still only experience 0.0296" of movement at the tip, which is less than the clearance between the valve and the rocker ears. So, I'm thinking that as long as I properly center the roller tips on each valve, then slowly rotate the engine to make sure there is no binding in the push rod to head, rod to guide plate, or rocker ears to the valve. I can't see how I would end up with issues/interference/binding, unless there is REALLY SIGNIFICANT bending of components in the system, but I have a hard time believing there would be. Also, given that the rocker should always be in contact with the valve with the lifter force, even if the valve came near the self-aligning ear on the rocker, wouldn't it just guide it back to the middle of the roller like it normally would if it was being used without any guide plates on a self-aligning engine?
It appears you've covered all of the bases. A careful inspection at mock-up should reveal any significant binding. It might be worth the effort to use a light checking spring so you can check on the ability to spin the pushrod. As in, with a light spring, even under load, you should be able to rotate it with your fingers. You'll want to rotate the engine through a few revolutions so as to pass across the base circle as well as maximum lift. If it doesn't bind against the rocker rail and guide plate, and the clearances you've stated make it unlikely, then there's some reassurance.
A couple of things come to mind.
One is I'm interested to know if any of your rockers will be noticeably cocked to one side during setup. I've got adjustable plates as well and despite my best efforts, one or two rockers were stubbornly slightly off centre. As a consequence, (I've run COMPS Pro Magnums as well as Crower's Enduro series, with the same results) the roller is a touch off the side edge of the valve tip. (As a side note, each rocker produced a slightly different geometry and required a slightly different pushrod length.)
The second are the dynamics of a running engine. I've expressed my thoughts on that. If you\re confident moving forward, and you sound like you are, it wouldn't hurt to pull a valve cover ( or both) and examine the pushrods and rocker roller rails for signs of distress after a few miles. Maybe at an oil change interval.
Keep the updates coming.
Posts 12 and 13 are on the same page as me. I feel like the rest of the posts are people just repeating general warnings, because they are not being diligent and paying attention to all the details, dimensions, and proper adjustment...
I've been through the binding game as I mentioned. It's difficult to quantify the effects it has although I can say one thing for sure. Bronze valve guides aren't particularly durable and any unnecessary loading will eventually take them out. The effect is subtle but if you log considerable miles as I have, the results are there to see.
Guide plate and cylinder head interference. Not detected in mock-up although evident at an inspection interval.
Stuff moves around a lot at RPM.
Given your due diligence, and the clearances stated, your results aren't likely to be the same.
Question for you though: Considering that I went the guide plate route with my original Vortecs (they were OEM equipped to use guided rockers) I've never had the opportunity to examine a guided roller tip. I'm curious as to its level of robustness (for lack of better word).
06-30-2024, 02:16 PM
