I have a 1969 Chevrolet 327 cu in engine in my 1931 Ford. I would like to upgrade from the stock 1.5 stamped steel rocker arms to Comp Cams cast steel (roller tip) 1.5 rocker arms. I'm not changing the rocker arm ratio, but I'll check to be sure the rocker arm geometry remains acceptable. My questions this: For those you who have made this upgrade in the past, do I have to buy new push rods? Obviously, I would like not to spend $100 for new pushrods if it is not necessary. Thank you.
I've ran those rockers before and found no benefit and found issue's with the ball to socket of rocker being badly mated to one another. Tell us more about your engine because if it's pretty much stock, stay with the stock rocker's. Those thing's have proven themselves for many years of trouble free service. However if a roller tip is what you want ?, go full roller rocker. That way the pivot point is always at a constant which is a plus above what your considering and the stock unit's. As far as push rod length, that's something that should be checked anyway's even if the manufacture say's your stock one's will work. Been there and I understand your asking in advance but things just do not go together easily just because one say's so.
^^^^^^^^^^^^ what he said! The cheap roller rockers add nothing and actually cause roller contact problems with the valve tip.. Poorly made. Plus they are one more thing to come apart and rain metal into the oil pan... Been there!!
Are you talking about these? or these? If you are talking about the first ones, then I agree with everyone else, they are eyewash, no better than the stockers. total waste of money, IMO.
The bottom ones while not cheap will last a long, long, long time...I have a set of Harland Sharp and I have probably 20k miles at least on them with no issues..As long as the engine has good oil supply the stock rockers on a stock engine should last a long time...
As above stick with the full roller rockers, and go with a good name brand. I've had troubles in the past with the cheap blue rockers from overseas. It wasn't my choice but what a customer wanted. The cheap rocker ended up pushing the pushrod seat up into the rocker and breaking pushrods. They left a void above the pushrod seat for some stupid reason or other. I've also run into problems with the roller tip rockers burning the balls up for no reason at all, and many of the roller tip rockers are actually a 1.52 ratio instead of the 1.5 ratio. Yeah it's not a big increase but does need to be factored in.
I'm sorry, but I have to go away from the advice given, and just give you my experience. I bought a new IROC in '89, one of the first things I did was put in a set of Comp 1.6 roller tipped rockers, now they have only lasted 135K miles, so maybe I should look at them? The quality of a good brand casted rocker, roller tipped or not, is much better than the rubber stamped OEM rockers, might just be my opinion, but has been fine for me. Only built 2 other motors with Comp roller tips since then and each has less than 35K on them, but I kinda think the rockers will last. Note: I am not a pro engine builder, I just use what has worked before, also...I just ran factory sized PR's in then engines, pattern din't look like in the Summit vid (and none of my other engine builds did either). My patterns showed a lot more sweep of the contact area, has any one ever had that thin of a contact?
what we are saying is that they are no better than the stock ones, which would ALSO have lasted 135K. oh, and on the sweep? Yes.
I see what you are saying..I took things a different way...back to the basement for me... On the sweep, man, I've always shot for an even run on the tip, maybe I was taught wrong, but I've never seen a contact pattern like shown in the Summit vid, I have a fresh 318 in the shop, I'll have to see what a near factory build will yield, just has a real mild cam in it...I had the shop do the full assy, because I had no experience with the shaft mounted rockers.
Ill be honest, I didn't watch the summit video, but a narrow sweep is desirable. I guess I should watch the video before I comment, but as a general rule, ideally, I want to see a sweep of around 1/16, and I want it as centered as I can get it. If I have to choose between width and having it perfectly centered, I will choose a narrow pattern slightly biased toward the outside over a perfectly centered pattern that's wider. As a general rule, a narrow, centered sweep gives the most lift at the valve. If I remember, I'll watch the video tomorrow and give my opinion on it, but that's all it is, is my opinion. Bedtime. By what you said, I am guessing I will agree with what they show on the video.
Theres a forum where some very sharp engine builders hang out. Guys on here often get pissy when I mention this, so I am being obtuse. click on this Valve/Rocker/Pushrod Geometry
Same basic info for starter up's. Just in case OP doesn't know. I'll agree, there's some stuff that should be further addressed. Like not using a juice lifter even if it's (so you think) pumped up.
Yes a 1/16th sweep or even a tad larger is what I would expect, the Summit vid by my eyes) looks like a straight line on the stem, one showing too long of a PR. one too short,,,but it was the thin (or lack of) sweep that caught my eye. Never been able to do what they showed (such a small sweep).
Just put stock OEM rockers back in. Full roller rockers are only needed when the Valve Springs get heavier and they'll start cracking in the slot area. If you use full roller rockers you'll need to put oil gallery restrictors in the back of the block. Full roller rockers don't meter the oil flow, whereas the stock stamped rockers control the oil flow when the hole in the rocker aligns with the hole in the pushrod [squirting oil in pulses] Roller rockers are a "glamour part" that is the first thing you see when you pull the covers. There is no HP gains from the rockers by themselves, but they do allow for steeper cams and heavier springs
Roller trunion rockers will increase power and lower oil temps. No doubt about it. Roller tips don't do very much.
I have used the Comp Cams ball socket roller tip rockers on a 327 and the geometry was correct with a stock length pushrods, but variations in valve height and reground cams with a reduced base circles can affect the geometry as well. If the valve geometry was correct with the stock rocker , it should be fine, but definitely go through the process to verify things are correct. The car I put those rockers on now has 80k since the rebuild with no issues. It has a mild cam under .500 lift. when you get into high lift cams and high spring pressures is where you really get the advantage of full roller rockers. You didn't mention what cam and springs you were running. that is important to consider when choosing a rocker . A full roller rocker with live happily with high lift and heavy spring pressure that would gall a ball socket type rocker.
Everyone keeps babbling on about the mileage they have on the Comp ball trunion crap. No one is saying they are INFERIOR to stock stuff, what we are saying is they are NO BETTER than stock stuff. These rockers are basically a gimmick for guys who want to have "roller rockers", but don't really need them. The roller tip does virtually NOTHING, all the friction is at the trunion, not at the tip, the roller tip is just romance. As long as spring pressures are kept low, and there is adequate oil supply to carry the heat away, ANY ball trunion rocker that makes it through break-in will last virtually forever. I have seen stock sbc's with stock rockers with well over 150,000 miles on them and stock rockers. In fact, back in the day, it was pretty common for me to rebuild a 100,000 mile sbc, with mild performance parts and re-use the stock rockers. As a rule, the cam and timing chain gave up LONG before the rockers did. And any combo that runs enough spring to create problems with the stock rockers will have the very same issues with the Comp rockers.
I disagree with the "no hp gain from the rockers themselves" statement as applied to real roller trunion rockers, but the above statement is 100% correct, and a lot of guys overlook it.
When I have found failed rockers in stock small-blocks, its never been the rocker itself, something else has happened elsewhere that restricted oil flow to the rocker, and the trunion failed due to heat.
Last year I rebuilt a '57 283 for my '55 Delray. I used a set of the Comp roller tip rockers. Camshaft is a 097 solid lifter matched with the correct valve springs. Within a 100 miles couldn't keep the lash adjusted, .012 intake and .018 exhaust. I've been building small blocks since the '60s and never had this problem before. Contacted Comp and was told they had supplied the wrong pushrods. Since I had checked pushrod length on all cylinders and verified that the geometry was correct it wasn't the length but the three piece pushrods that were the problem. But the ball pivots and rocker pockets were turning blue and the rocker arm sockets were eating the pushrods. This engine is basically a stock rebuild with an original GM oil pump 20# at idle and 40# running. Comp replaced the rocker arms and new one piece pushrods. I did not install them. I'm using a set of Chevrolet stamped rockers and original GM pushrods. No issues with lash adjustment now and I agree with the others either go full roller or use stock GM parts.
Roller tips reduce valve stem tip wear, so saying that they are no better than stock rockers is B.S. Full rollers are certainly better, but the roller tips are still an improvement over stock. Additionally, a stiffer material will flex less than a weaker (stock stamped) material. I've never had any trouble with my roller tips on a SBF.
I would recommend getting the new pushrods to go with the rockers. As for the advantages, disadvantages of the roller tip rockers, I have a set of the cheap summit stamped steel roller tip rockers on a solid lifter 327 I built years ago, before doing any research on the rockers,(before I knew any better) and they have been trouble free, not really an advantage or disadvantage, but an observation. Currently, I have a set of Comp Cams 1.52 roller tip rockers on a 327 I just built. The reasoning at the outset was that the cam I had been given was an old P.A.W. cam, similar to the L79, with slightly less lift. based on a test I had read that stated most stock rockers came in at about 1.43 or so due to production variances, and the tighter variances in the comp pieces, I would have a slightly higher, more consistent lift ratio. Once again, the price thing comes into play. While I would most likely have realized a real horsepower increase with roller rockers, a good set was out of my budget. That said, I needed rockers, period, had none laying around. So pricewise, getting the comp 1.52 rockers was only a slight increase over what I would have paid for new stock rockers and less than a good set of roller rockers.
This is the exact issue I had. It was like having variable lift it seemed, I'm mean it really. If the rocker can not pivot correctly it will rock like a rocking chair over a rock and never the same way twice.
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