1.25 Rockers Installation Question

[thefladge]

I have a set of Scat 1.25 rocker arms in my parts collection.

I'm considering installing them on my 2110cc engine.

Can I do this without replacing the push rods with a different length?

I'm currently running an Engle 120 cam with Manton push rods and stock rocker arms. I built the engine and set up the rocker geometry with these parts.


Thanks.
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1957 Vintage Baja Bug.
2110cc engine, 40 IDF Webers on Gene Berg manifolds, Engle 110 cam, Bugpack 40×35.5 Street Pro Heads, W8CC plugs, 12.5 pound Flywheel, Kennedy 1700 pound pressure plate.

[rustybusjef]

Maybe . Try it .

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engines with 1.25 rockers use shorter push rods than the same engine with 1.1 rockers.
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[thefladge]

Damn. I was hoping this would be simple.
_________________
1957 Vintage Baja Bug.
2110cc engine, 40 IDF Webers on Gene Berg manifolds, Engle 110 cam, Bugpack 40×35.5 Street Pro Heads, W8CC plugs, 12.5 pound Flywheel, Kennedy 1700 pound pressure plate.

[mark tucker]

possiably yess possiably no. so do some dont. you will have to find out for your self.

[craigman]

can you? Sure.
Will the geometry be right? Nope.
Have people done it without problems? Probably.

It's up to you.

[thechief86]

I'd just cut the pushrods.... It isn't that hard, and once you get one right, all 7 of the other ones should be the same length. At least that's how it was with my motor with the same rockers...
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"A poor workman always blames his parts... Ya gotta have skillz to hang junk." -johnnypan

[thefladge]

[Quokka42]

You can estimate it by taking half of the increased lift you will obtain, but 1.25s are notorious for not giving an accurate ratio. The other way is to put a shim under the rocker blocks and call it good enough. Just putting them in is asking for trouble, and you always need to check again for coil bind.
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There has only ever been one man who was perfect, and they nailed Him to a cross.

[neil68]

I've retained the stock length pushrods when switching from 1.1 to 1.25 rockers simply by shimming the rocker stands.

While it might be ideal to use shorter pushrods (which I do with my 1.4 rockers), I never noticed any issues with 1.25's in many years of usage with Engle 100 & 120 cams.
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Neil.

Der Kleiner Rennwagens
68 Beetle 2332 cc, 204 WHP
12.5 seconds @ 107 mph
Dynojet Test: https://www.youtube.com/watch?v=M9B_H3eklAo

[77charger]

I did it many years ago on a 1641 i had without any issues.

Will i do the same today in my 2275? NO

Back then it was my first vw baja bug and they were in a box of extras so i tossed them on.It was a stock motor as far as cam,heads,rods go so not a high revver.

These days i knows theres a correct way and a temporary way i prefer my stuff to last longer.
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2275 built by me
Auto linea alm case,82 dpr crank wedgemated by DK machine
cb 5.4 h beams,12 pound DPR f/w,Slr xv294cam,cb straight cuts,hpmx 44s,40x35 heads ported by brothers machine

[deadkombi]

Depends on whether you have 1.25's with the adjuster at the pushrod end or the valve end. If the valve end with swivel adjusters, you can shim by about .040 - .060 under the rocker blocks. If you have the adjustment at the pushrod end you need shorter pushrods. I just tried a set of scat 1.25's and they measured out at 1.37. I was advised not to go more than .500 lift with a engle 120. CB 1.25's will give you .498. Good luck.

[thefladge]

I think I may go forward with the 1.25 rocker conversation after the beginning of the year.

With my 2110cc engine with a Engle 120 cam, 40 X 35.5 valves and 8.5 to 1 compression, what sort of performance improvement should I expect?
_________________
1957 Vintage Baja Bug.
2110cc engine, 40 IDF Webers on Gene Berg manifolds, Engle 110 cam, Bugpack 40×35.5 Street Pro Heads, W8CC plugs, 12.5 pound Flywheel, Kennedy 1700 pound pressure plate.

[bugguy1967]

It depends on how well your heads are ported, if they're even ported at all. You're looking at almost .500" lift, and 40 intakes' gains begin to diminish after .450". If your engine is fresh, and you set everything up properly, you may squeeze out another 5 HP.
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"A petrol engine can start readily, run smoothly and give every appearance of being in good order, without necessarily being in good tune." - Colin Campbell, "The Sportscar Engine"

[thefladge]

[mar-tay1]

You never mentioned what you are doing with the car? Drag racing only, grocery getter, daily driver? Or for that matter valve spring pressure, operating RPM etc. Shimming a rocker set may make the parts fit on the car but unless you have longer valves too (or lash caps)the geometry at the valve will be off. I've seen elephant feet on cars with who knows how many shims underneath, way off, you could see it from across the shop! YOU can not move the rocker away from the valve without changing the geometry. If you want more power up the compression, run better fuel. This will help power from idle up, ratio rockers only help at extreme RPM's and how often do you drive at 5k RPM?

[mark tucker]

the issue with the oe type pushrods are they dont have a ballend, just half a ball and they can be put in a bind with the pushrod cup in the rocker if not carfull. the 1-2 side is worse as I recall due to the head offset&pushrod angle being more than the 3-4 side. so...your better off getting a cheep set of cut to length pustrods and do it that way. I have remechined both ends of the rockers so the adjuster go's up farther and is square to the rocker(rockers are forged and not quite square/straight on the end) and also Ive reworked the pushrod cup end for better clearance with the oe type pushrods,but I dont recomend it,Ive also reworked the pushrods so they have more of a ball end,but then again I dont recomend it. with all this done you still have to have the geo in the right "aera" I say aera as there are somany diferent ideas on just what is right.for me my way is right...but....there are many ways to do it and it work just fine.so...there is somewhat of a good "aera where it will work ok. but usualy not by just putting it togetaher. I did that on my first goround with my vw.and I noticed the lash was set @.004 but I could push on the pushrod end of the rocker and get a .010 to slide right through I know the pushrods cant be flexing that mush with my finger pressure.so...thats when I found the pushrod tip to cup interfearance with oe type half ball setups.I suspect that is a reason somany cars have a loud valvetrain. as they are getting a false lash setting. that is when I under cut the oe pushrods.all was good then,,well for the most part.the geo wasent optimum and the pushrods fles was more than I could be at ease with, so a few weeks down the road I reworked it with new chromoly pushrods ,and set the geo where I wanted it.those heads have well over 100000 miles on them with the oe guides.

for the most part the engines Ive done with the 1.25 swivelfeet rockers I rework the rocker on the swivel end so the adjuster can go up about .060" more(about same as the beam on the rocker, then make sure the oil hole lines up in the theards. then deburr the rocker cup aera,add a slight oil trough from the oil holes to the grove(if the shaft is groved)or add a slight snake grove from hole to hole around the bottom side of the rocker only!. so the tip geta good oil like it needs. and the load aera gets oil too. adn usualy the 1.25's when I do them dont need any shim or at the most a .030 shim, but the heads will determan that.(cam can also).so... are they bolt on???well sort of,sometimes,no,yes,possiably...not.just because they fit and go on and the engine starts doesnt mean there right or doing what they need to do. just like the pushrod bind and lash at .004 but a .010 can slip through when rocker is pushed on the pushrod end...well the rocker has just lost possiably all it was susposto add. and is noiseyer too boot!!! but dont be skeered it's not hard to do...well for some it's terriably hard and cant be done correctly....like my spellen's

[bugguy1967]

Lol! Tons of good info in there. It's just hard to read.
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"A petrol engine can start readily, run smoothly and give every appearance of being in good order, without necessarily being in good tune." - Colin Campbell, "The Sportscar Engine"

[mark tucker]

sorry I dont speak or right english well...Im american. uusualy the oe pushrods can be utilized if the rockers are trimed so the swivel can go higher, but must check for the bind I stated.also depends on cam. also the cb rockers have a much much better cup aera of thier rockers than any body elses of this type of rocker.

[bugguy1967]

Thanks Mark. That actually confirmed what I was thinking about my current build. I need to mod the tips of my pushrod because I'm getting false readings.
_________________
"A petrol engine can start readily, run smoothly and give every appearance of being in good order, without necessarily being in good tune." - Colin Campbell, "The Sportscar Engine"