"Great discussions.
Would like to get into question of valve train instability, shaft flex, and efforts to stabilize, but should probably go to new thread as this one is too long and old to follow well.

Regards,
John
V-performanc.com"

It's time for that new thread & discussion when you have the time :)

I'm interested in what you think about such things & some more details on that street performance cam of yours.

I'll start with my opinion that stock valve springs are junk & barely capable of being used with a D grind & stock pushrods aren't much better.


Cheers,
Paul.

Paul. have you or others explored fitting early Holden,Chev, Ford V8 rockers with pivot studs instead of shaft?. A steel bar of right proportions can be fitted to original rocker shaft bolt holes. Bar can be drilled and tapped to take pivot studs, pushrod guide plates can be fitted to bar.Yella Terra roller rockers could be fitted. A splash feed lube system could be set up as oil delivery is already at head.Roller ratios are Holden 1.65, small block1.5, big block 1.7, 302 cleveland 1.73, 351 windsor 1,6. These engines run well at higher revs so a b20 might benefit, just a thought. Just about every valve spring i have removed had to be cracked with hammer to release retainers, i would have thought two matching tapers would lock into each other, why do you reckon it is detrimental?. Regards Jack.

First our street performance cam. The basic info is on our website.
As you know I don't like to go into a lot of details on this as the details are
not as important as the concept of matching everything up, not using a long duration cam to try to make up for poor port flow in a street car, looking at lobe shape and midlift range duration rather than duration at .020, more duration in the exhaust, etc. In fact there is not just one cam, if we find that a little more or less here or there will yield improvements, the specs may change. A little secret in playing with this is using rockers with slightly different ratios to simulate
changes in the lobes. For example, will more exhaust duration help? Try rockers on the exhaust with higher than stock ratio. If there is an improvement on the dyno, then a change may help.

As to the valve train, we really need to separate street from racing as the requirements are so different. Street B18/B20 engines have to stay under
7,000 RPM as the rod bolts will not take any sustained running over that.
For race we are looking at a system that will run at sustained 8,000 and will takebursts in the course of shifting up to 9,000. Heat in the springs, probably caused at least in part by vibrations - unwanted motion in the springs - causes them to soften up pretty quickly. For the race cams we use we have to have fairly high spring pressures compared to stock, approx. 120 lbs on the seat and 300 at .500, so we end up using fairly large springs, 1.44 diameter, dual with damper, and this has worked out best over many years of testing. The pain has been getting them to fit under valve covers. Depending on the engine, cam, application, etc., we may or may not use roller rockers or higher ratio stock rockers. This would essentially be part of the tuning process and a judgement of whether a little more HP or more reliability is more important. Higher lift ratios put more pressure on the valve train and make it more susceptible to failures. Customers would prefer a setup they can run season after season rather than one where you have to replace the springs after every couple of race weekends.

Where the question comes in on the race setup is ways to stabilize the valve train. We have measured .030 - .040 less lift, static on the outer exhaust
valves then on the inner ext. valves, due to flex in the stock shaft. Obviously with this type of flex at zero RPM, the thing has to be whipping all over the place at 8,000. Have experimented with various ways to stabilize this, but are not sure we have come up with the best solution and are still working on it when
there is any time. KG and others in Sweden offer a Vipparmsbrygga Heltackande.
Have also played with this but do not see it as being a total solution without modification. Does anyone have any experience with this?
Am also looking at installing a crank vibration damper to help with the vibrations that are transmitted to the valve train throught the cam drive. This is one reason that in other engines they change from gears to belt drive for the cam, it reduces the vibrations transmitted.

Other than the springs and retainers, the street performance valve train is pretty much the same - dual 1.25 OD valve springs, non stock lifters and pushrods - although the problems are minor due to the lower RPM and cams with less lift, less agressive lobe shape, etc. Obvious problems with stock lifter wear and pretty flimsy stock pushrods. Dual springs are a safety factor and the second spring acts as a damper on the frequency vibration of the main spring. Don't see any disadvantages of the dual spring setup, not really any more expensive than new stock springs, so we use them on all street rebuilds, and then we have a very flexible head that will work for a customer who will never take the engine beyond 5,000, and is still good when he sells it to someone who is going to take it up to 7,000. One disadvantage of the dual springs with a little more pressure could be more flex in the shaft, but this is not evident under static conditions.

As much as I have time for now. Probably enough to continue the discussion.

John
V-Performance.com

Hi John,

I haven't paid much attention to how much the shaft flexes, but I don't use high lift on the exhausts anyhow as there is very little point. The biggest cam I have used has .346" lobe lift but I only use that on the intakes, biggest I use on the exhaust is .315" lobe & it has more timing all the way up to .200" lobe lift which is nearly full flow on the exhaust ports anyhow. For springs I use Isky grey & whites set to 135lb of seat pressure on the intakes & 120 on the exhaust. They rise up at 320lb/inch.

For mild cams I still use the same spring, set down to 100-110 on the seat. A lot of people think just because they can rev to 7000+ rpm that the stock spring is adequate, but things can be out of control across the entire rpm range & the engine will still function. With the stock springs you have to hit the retainer with a hammer & a socket before disassembling, this is a sign that all is not well. I have seen engines with D grinds benefit from having dual springs, it nearly always shows up as more top speed. The stock spring go through a very bad patch around 5500rpm that you can rev through in the lower gears, but you find during slow acceleration the car stops dead at 5500 in top gear where dual springs let it go faster. Dual springs also produce a more consistent run on the dyno across the entire rpm range, not just at the top end. Another good reason to use dual springs on mild cams is cheap insurance against dropping a valve.

For pushrods I make my own from 5/16" chrome moly ones intended for type 1 VW's, the local VW shop is also good for springs, they have Crane springs that a very similar to the grey & whites. Retainers start life as something scavenged from old datsun or toyota heads chopped up to suit, B21 retainers are also a very good start, the just need a touch in the lathe for the inner spring to sit on. I don't see too much wrong with the stock lifter. If they pass the hardness test, they get a regrind.

Vibration Dampers are an interesting topic. We have one made locally by Romac. Seems to stop bits falling off the engine. It's smaller in diameter than the standard pulley to underdrive the water pump & alternator.

Cheers,
Paul.

My B20 has an Iskenderian valve train; Pontiac solid racing lifters, tubular push rods, dual valve springs, VV71 cam(same as ipd sreet performance). You also get your choice of steel or aluminum retainers. It's been good for ~10 years and 2 engines.
As George says, though, the stock springs probably aren't any good past ~7500RPM.
--
Jim McDonald

Jim, Solid lifters from what pontiac? Push-rods from what source? Thanks fopr the clarifications.

Merci

Yvan
--
65 122s/73 1800es/80 262c(350ci v8)/89 745t/87 780/89 740/89 740t/ 86 745 and too many parts cars and projects to list

Iskenderian, as I said.
The B20 lifters they sell also happen to fit small block Chevys and Pontiacs.
http://www.iskycams.com/pdfcatalog/PAGE157.pdf
--
Jim McDonald

Paul, John- I'm actively looking for a harmonic dampener. Money with me is always a bit of a factor, but for the most part I can be on the phone giving a credit card tommorrow. The 89mm stroke is breaking stuff, more to it than that, but yeah....




FWIW, and I'm not saying it is chosen for anything except my out of the mainstream useage, I'll put down from memory what I've got:

As far as valvetrain, I have Crower 68142 (I think, might be 68145 or 46?) giving about 90 on seat, but only about 185 on .450. The nice thing with these is they are helping get good durability out of my rather harsh Enem A10 cam (248 adv, .461 gross lift). They also will accept up to .620 lift. They are 1.235" diam with a flat dampener internally. I could probably shim them if I were a revvy kinda guy. I don't know when/if they float. They work with Crower titanium retainer and the GM locks on the GM valves (round groove). As I've said, for engines seeing 5750 plus, I'd look at single tapered coil springs over anything else, based on V8 experience.

For pushrods I am using Volvo stock ones for now. I have IPd ones (assume Isky? or Smith Bros?) but the cups don't fit the ball adjuster on the stock rockers well at all. I figured since the Volvo ones are shorter, that might have offset some of their weakness. When I change cams in a couple months, I'm probably going to take out the Volvo lifters and take them onto sandpaper in a figure 8 just to prove it works and get up the nose of a co-worker who's a purist. I'll use a pair of new Crane GM lifters for comparison to get the radius right. If I feel conservative (or grow up ;) I'll talk to Rhys on this board about having my Volvo lifters properly refaced or maybe consider putting the Chevy ones in. I don't esp think in term of Volvo vs GM, that one is much better than the other. Weight is a little more on the Chevy, but since valve float is generally thought to start on the valve side if the rocker, I'm not convinced weight matters. Anyone? Volvo did make the cross drilled ones, and I have one to look at on the shelf.
If I were going racing & they were allowed, I'd likely not build any motor with less than Schubeck lifters. Seems to me in peace of mind and reusability they'd pay for themselves


I have my roller rockers assembled on a shaft, and when I get to that I will use Comp Cams double ball end pushrods (5/16 x .080" wall chr_moly) assuming that they fit the cup type aduster throughout the range out motion. Looks good that way so far. Advice from anyone?

Romac make a balancer for B20's, one of my cars was the guinea pig. Smaller than stock diameter to underdrive the water pump & alternator. For your stroker, you are probably better off adapting a B30 balancer to it. In the long run strokers are a pain in the bum. Would be best if you crank a welder up & weld some counterweights to the crank.

Weight matters everywhere. Nothing wrong with regrinding the Volvo lifters if they hardness test OK. Make sure the cam grinder doesn't parkerize the sides of the lifter, otherwise you have to sand them all to make them fit in the holes.

Paul,
I missed this last week. Could you give some additional information on the Romac balancer?

John
V-Performance.com

Myself as well, Paul. I'm serious about one.

My other options are to send a crank to Tim Lightfoot @ Fisher, or try to have a b230 one adapted.

I've been away for awhile, I'll get on to this soon. For your stroker I would adapt a B30 Balancer.

Cheers,
Paul.

I should try to tidy up my correspondence with the balancer issue so I knwo where I'm at. An American company- Fisher- do custom balancers, and I know someone online who has had done done. I've been lax about following that up. If you could confirm a Romac balancer is available to buy, I'd appreciate it.

IIRC, Paul, you mentioned the b30 balancer was not a good/direct fit to the b20 nose, which surprised me. Any idea what it would take to adapt? It's in the back of my mind that I'd probably want to have the b30 balancer remanufactured, so that pushes the cost upward .. perhaps partway toward a new one.
I'm also interested in doing this on my OHC engine. Does anyone have any idea if I could turn down the nose and use the balancer/pulley set up from a b230? I'm very close to buying an engine core for the crank/balancer to study. Be great if someone was there before me.


I'm wondering about you comment about welding the crank. The crank balanced just fine after the offset grind, requiring less change than many stock ones. As I'm sure you know this is NOT (caps to encourage lurkers to understand this) like a v8 where the counterweights balance the rod-piston weight, so I'm unsure what you might refer to (weld on weights?).


I feel it's a combo of the car not having very good isolation characteristics- in my 142GL, I'm sure I'd be happier- as well as having quite powerful combustion events, and a reduced rod ratio (1.69 vs 1.81). I have broken off the alternator mounts on my rigged alternator/generator bracket, which is more the bracket desgn fault. Also I can feel severe vibration through the tuning pipes across the engine. Really I think it's more a subjective problem than something that's going to result in catastrophic failure, but I'm willing to spend a bit to be safe, and hope that in doing so I cure a small amount of the general vibration in the engine/car.

I've not used anything but stock valve springs. I float them occasionally
but not often. My biggest heartburns in the valve train are OEM lifters,
fiber timing gears and variable cam quality.
--
George Downs, Bartlesville, Oklahoma, Central US

When I did my engine swap from a b18 to a b20fi, was lucky to find it in the junkyard. I added the singel weber, dual valve springs lightwieght pushrods, titnium retainers, K cam, Valve job and light weight valves, mahel pistons and so on. Runs great and lots of power. Its always good to build the engine in a way that you know won't give you problems in teh future. IPD has alot of information and thats where I got all my parts.