View Full Version : High Ratio Rockers = More Wear?
Folks, I'm trying to gather real-world experiences concerning the long-term effects of running 1.6 or higher ratio rockers in Pontiac engines. If you have run high ratio rockers for a significant length of time, please respond to this post with your experiences, good bad, or otherwise. Please be sure to include what ratio the rockers are/were and how long you ran them for. This has been the subject of speculative debate in another forum so I'd like to gather some facts from the real world. Thanks!
Folks, I'm trying to gather real-world experiences concerning the long-term effects of running 1.6 or higher ratio rockers in Pontiac engines. If you have run high ratio rockers for a significant length of time, please respond to this post with your experiences, good bad, or otherwise. Please be sure to include what ratio the rockers are/were and how long you ran them for. This has been the subject of speculative debate in another forum so I'd like to gather some facts from the real world. Thanks!
Old Man Taylor
03-25-2000, 01:03 AM
The valve doesn't know what ratio the rocker is, it just knows how far it is being moved and if the rocker is in the right place (geometry) on the stem. I have run 1.65 rockers for a total of 20+ years. My current engine has over 20,000 miles on it with no obvious problems. The lift is right at 0.600 on each valve. I also have bronze guides. What I did find was that at lifts above about 0.550 you need roller rockers. I broke a guide plate before upgrading to them.
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Jim
No one else has run high ratio rockers for an extended period of time? C'mon, OM Taylor can't be the only person who's done this. Please let me know if you have high ratio rockers, how long you've had them and how they worked. Thanks!
WARPed
03-28-2000, 07:59 AM
Will I had ran the factory 1.65's for seven or eight hard years on my RA IV motor and never had any issues with them. I was using a Crane blueprint 9794041 cam with the rest being stock RA IV parts and clocked 20k miles, and with the 4.56 gear and 25" tall tire the motor probably saw more like 30k.
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10.854@123.44
6.947@100.65
brooksa@gte.net
Skip Fix
04-16-2000, 11:13 AM
BBC use a 1.70 from the factory. 348-409s used a 1.75. BB and Cleveland Fords I believe use 1.72 or 1.75s. The factory had to warranty all of these so if there was increased wear I doubt they would have used the higher ratios.
Skip Fix
Tom McQueen
04-16-2000, 02:02 PM
Old Man Taylor is correct. The actual formula would be;
Incorrect valvetrain geometry = wear
This formula works irregardless of the actual ratio of the rocker arm. I have never used 1.5 rockers on any of my Pontiac motors. The motor I am currently assembling has 1.65 Crower stainless rockers. Check the geometry for the proper pushrod length. Order extras. There is both power and reliability to be gained by getting this right. Those two things are generally mutually exclusive.
Cobrabill
04-17-2000, 12:48 PM
The 427 Side-oiler also uses 1.75s.The 1.65s came from the factory on the RAIVs.If there was a wear issue,that would have equated to warranty issues.Which no manufacturer wants.
Bob Dillon
04-17-2000, 05:18 PM
Will, I use Crane el cheapo aluminum roller rockers (1:65:1) and have 4.5K on the motor with no discernible guide wear (at least it's not using any oil and doesn't smoke.) However, I only have a little bitty cam, 204/214, .462/485. Hope this helps.
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Dad always thought laughter
was the best medicine. I guess
that's why several of us died
from tuberculosis.
Thanks for all the responses guys. I pretty much figured there wasn't any real problem with higher ratio rockers if things were setup right, but in another forum I was roundly chastised for suggesting higher ratio rockers to people by this guy who has a 9 second '69 Firebird. He swears that he ran fine for two seasons with 1.5 rockers then when he switched to 1.65s all his valves wore out in one season due to the increased side-loading on the rocker studs. How that would affect wear on the valve I'm not sure unless it was because the geometry was thrown off. He says that because he had problems with them in his then 10-second engine that anyone who runs them is going to have problems and they just shouldn't be used, period. As for other makes/models using them, his argument was that the geometry is different therefore a comparison to Pontiacs can't be made. Frankly, I think he's full of it, and the experiences related here seem to confirm that. Especially when we're talking about street combos with less than .550" total lift, less than 350 lbs. open pressure and less than 6000 RPMs, which are the only combos I'd feel qualified to make any kind of recommendation on. I plan to run my Harland Sharp 1.72 rockers again as soon as I get a set of heads setup to handle the lift they'll give me and just wanted to make sure I wasn't making a big mistake.