Ratio rockers

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  • #235990
    Royal
    Participant

    @royal

    In another thread about carburetion, I mentioned that I was considering “bolting on” some higher lift ratio rockers. I have no experience with them, but I can see how they might help the engine breathe and perhaps get a small boost.
    I have a good running 1600 single port, stock cam, Holley Bug Spray carb on an isolated runner manifold, EMPI 3487 exhaust, ported and polished heads with new valves and heads.
    Kent has offered that he thought I might expect a few hp boost and I’m “itchy” to do some tweaking on my own car, now that we are at the end of the tunnel on Happy Jack’s rebuild.

    Does anyone else have any experience with 1.25 or 1.4 lift rockers in a stock SP setup? Prices seem to go from about $100 up to $300. If I could do it for $100 or so, I’d consider. Not $300 (I’d rather split the case and put a cam in).

    I’m really hoping for some before-after kind of comparisons. Please share, thanks.Royal2016-01-11 06:14:55

    #266873
    edward ericson
    Participant

    @edsnova

    The single port intakes would appear to be the limiter here, Roy. 

    #266874
    KentT
    Participant

    @kentt

    I ran 1.25s on a stock dual port once, with an extractor exhaust and 30 PICT carb with adjustable main jet (too bad those neat adjustable main jets are no longer available!). There was a noticeable, though not huge difference in the “seat of the pants” dyno. With your other mods/tweaks, your engine should be set to take advantage of improved breathing. So, you should see a noticeable difference. (Your exhaust, though better than stock, will likely become your next bottleneck…

    Ratio rockers not only increase valve lift, but tend to slightly increase the effective cam duration – the amount of time the valves are effectively open, flowing fuel/air mix. Consequently, you may notice a few additional RPMs of peak power. Not as much as a cam swap, but still different from stock.

    The best thing about 1.25 rockers is that they are truly a bolt on, and don’t require stronger or shorter pushrods, nor setting up the valve geometry like 1.4s or a radical build requires. As I mentioned in the other topic, you may want to consider going to solid rocker shafts at the same time to eliminate the weak spot of stock wavy washers/clips on the rocker shafts. As RPM approaches 5000 RPM, the side pressures on the rocker arms with the increased valve lift can compress those wavy washers enough to increase side travel of the rocker on the shaft, vibrating the retaining clips off or even breaking them. In normal driving, it shouldn’t be a concern, but in frequent or sustained “redline running” stock rocker shafts can fail. Buying a ratio rocker/solid rocker shaft combo is much cheaper than buying them separately, and could provide the foundation for further tweaks/mods.

    Speaking of which, replacing the Empi 3487 with a true equal length extractor exhaust would definitely improve higher RPM breathing, and a better distributor than the 009 may make a noticeable difference. Or, as Ed suggests, switching to dual port heads. But, you may find that it’s the single ports that make your Bug Spray work so well for you. Swapping to dual ports might induce some off-idle bog, as that large carb opens up. Bug Sprays performed well on heavier Baha bugs with single ports, where you were looking for torque instead of high RPMs and HP. Dual ports alone boosted the stock 1600cc by 3HP, and made a better flowing foundation for more improvements. Have fun with it!KentT2016-01-11 09:00:50

    Early FF TDr on 69 VW pan
    Slowly coming back from the ashes...

    #266875
    crash55
    Participant

    @crash55

    go to aircooled.net they have a ton of good tech articles. also if they don’t like a product they quit sell it ! and say why gene berg is also a great source of info.

    #266876
    Royal
    Participant

    @royal

    Hey guys. Thanks for the comments. I got a whopping good deal on some new 1.25’s and decided to go ahead with the experiment. I plan to carefully record before/after data on my measured course (a drag race 1/4 mile type).

    John from aircooled.net in a private communication thought it was “a waste of time on a single port”.
    But applying my “the time you enjoy wasting, is not wasted time” logic compels me to proceed.

    I’ll let you know what I find.

    By the way, ICYDK, aircooled is super good about very quick (2hrs) response to technical questions. I’m hoping that they forgot to add “for the money, unless you do it yourself” to their advice. Stay tuned.

    #266877
    edward ericson
    Participant

    @edsnova

    Good luck, Roy. I’ll be interested to see how this turns out.

    #266878
    Royal
    Participant

    @royal

    OK TDr-land. I have decided against installing the 1.25 ratio rockers after all.  (Eye problems.  Not one of the things you ever think of…..until it happens.) 

    But I do have a brand new set of new 1.25 rockers with the shafts and with new extended studs for the pedestals and a full 12 pc set of EMPI shims (21-2310-0) that I am going to sell. The rocker arms are new, complete and unused, but I seem to have misplaced the packaging and the receipt and invoice.  ( I had bundled them all together and put them in a place where I would be sure to not lose them. – know what I mean?)

    Anyone interested? Please send me a PM.

    #266879
    billnparts
    Participant

    @billnparts

    Hope the eye problems are temporary and not too serious.

    Bill Ascheman
    Fiberfab Ford
    Modified 5.0, 5sp., 4:11
    Autocross & Hillclimb
    "Drive Happy"

    #266880
    Royal
    Participant

    @royal

    Thanks Bill, I’ve had problems with double vision since just before last Carlisle. Gotten worse, but maybe it’s better now. The worst of it is the cost and loss of confidence. There was a period of about 2 months (Dec-Jan) that I couldn’t drive, couldn’t read, couldn’t play the organ. Age and genetics related. Sucks!Royal2016-03-05 13:50:38

    #266881
    edward ericson
    Participant

    @edsnova

    Dang. That does suck. Hope it gets better and stays that way for at least a long time.

    If no one here bites on those rocker arms, you might try listing them on the Speedster Owners Group’s classified thread. Lotta dudes there might be interested.

    edsnova2016-03-05 13:53:47

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