Stock valvetrain with roller rockers.

[Methuselah]

Two questions (ignore valve cover issues and tuning issues):

1) What ratio can one get away with with the stock springs and pushrods? Pretend Im too stupid for geometry corrections and too lazy to buy stiffer springs :wink:

2) With stock heads unported, what ratio (ie how much lift) would even be useful? The stock cam is so short, Im assuming I can get pretty psycho on the ratio and still not max out flow in the stock ports, but I havent run the numbers.

Self-aligning 1.6 aluminum roller rockers are pretty cheap and would be a useful tuning excercise (Im assuming this would be indicative of changes one would likely have to make with a cam switch). What do you think?

Thanks,
Seth.
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Public Video

 

[jwaller]

Re: Stock valvetrain with roller rockers.

Two questions (ignore valve cover issues and tuning issues):

1) What ratio can one get away with with the stock springs and pushrods? Pretend Im too stupid for geometry corrections and too lazy to buy stiffer springs :wink:

2) With stock heads unported, what ratio (ie how much lift) would even be useful? The stock cam is so short, Im assuming I can get pretty psycho on the ratio and still not max out flow in the stock ports, but I havent run the numbers.

Self-aligning 1.6 aluminum roller rockers are pretty cheap and would be a useful tuning excercise (Im assuming this would be indicative of changes one would likely have to make with a cam switch). What do you think?

Thanks,
Seth.

give it a shot. 1.6 full roller wont hurt. if anyting you'll pick up a few hp from the reduced friction alone.

 

[Methuselah]

Re: Stock valvetrain with roller rockers.

give it a shot. 1.6 full roller wont hurt. if anyting you'll pick up a few hp from the reduced friction alone.

Sounds good. Thanks.
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FERRARI 246 F1

 

[myclone]

Just make sure the push rods dont rub at max lift.. If they do get a louise (sp?) tool and use it.

 

[MotorMouth]

Might want to install just one and make sure that you don't get any coil bind also at max lift. I know 1.6 ratio on my LT1 came very close to binding w the stock springs, not very familiar w/ the springs in the 4.3's yet.

Brian

 

[Methuselah]

myclone: Good point, although I want to leave the heads on...so no drilling.

motormouth: I bet your cam (stock or otherwise) was a smidgen taller than ours...but I'll keep that in mind.

I just see all these sets of aluminum roller rockers on ebay for less than $150... seems like a great deal for an easy bolt on.

Seems like a lot of people would have done this to the stock engine.
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HONDA VFR1200F

 

[MotorMouth]

Yup, I think the LT1 cam has just a smidg more lift than mt Ty. Just figured I would bring it up just in case. I am not sure how close these springs are to bind on the stock lift, probably not to close...

Brian

 

[Eluding]

Sy/Ty cam lift with 1.5 rockers:
Intake: .357
Exhaust: .397

Lift with 1.6 rockers:
Intake: .380
Exhaust: .423

Duration:
Intake: 179 degrees at .050 lift
Exhaust: 194 degree at .050 lift

LT1 cam lift with 1.5 rockers:
Intake: .447
Exhaust: .459
Duration:
Intake: 201 degrees at .050 lift
Exhaust : 208 degrees at .050 lift

FYI, I installed 1.6 rockers on my Syclone with stock springs. The pushrod clears the stock pushrod holes but just BARELY.

 

[Methuselah]

Wow, thanks for doing my homework for me!

Any ideas what you picked up with the rockers? Did Cheatham do your chip before and after the roller rockers?

Thanks.
________
Buy volcano vaporizer

 

[Eluding]

The chip was burned for me with the 1.6 rockers. However, I don't know what the rockers gained for me, because I changed them along with the turbo and chip.