high lift cam in olds 350 question about Push Rod length

10

Asked by Guru3WY7S Jun 30, 2020 at 10:24 PM about the 1971 Oldsmobile Cutlass

Question type: General

I put a higher lift cam (RV type) into my 1971 olds cutlass. bone stock engine with only about 3000 miles on it) For them to make a "higher lift" to fit into the olds block, the Base cirlce's of the lobes have to be smaller (by .150") so the lifters are now .075" down in the hole, making the distance from the lifter to the rocker are .075 longer. it seems I need push rods that are .075" LONGER to keep the geometry straight and the valves to not open .075" short.  am I explaining this right ?? since putting in this cam, the car has no bottom end (it is only 205/214 @ 50, .448/467 lift. I am thinking because of the Stock Shorter pushrods, I am gaining the duration but not the lift. get it ?? cam is installed straight up, not advanced) (also 2.56 gears don't help the matter).   any educated opinions on this will be appreciated.   Thank you

6 Answers

10

the cam came ALONE (Elgin). I used new aftermarket crane lifters. was lubed properly, not my first rodeo. the lobes are fine, but SENSE tells me when a lifter and push rod goes .075 Farther down in the hole than it originally was, SOMETHING has to"make up" the difference. and the "Middling" of the hydraulic lifter will NOT take up .075".

1 people found this helpful.

Read this. http://victorylibrary.com/mopar/regrind-c.htm

1 people found this helpful.

And this. https://blog.trendperform.com/how-to-measure-pushrod-length-and-optimize- valvetrain- geometry#:~:text=Inspect%20the%20position%20of%20the,pushrod%20length%20for%20str eet%20engines.

Lastly. https://www.hotrod.com/articles/how-to-measure-for-correct-length-pushrods/

103,215

Your instinct is right, any change in the diameter of the base circle will affect pushrod length. Some old cam books I had showed how to measure for new pushrod length but I don't have those anymore. Try this compcams guide, starting around page 6. http://www.compcams.com/pub/media/productattach/1/4/145.pdf

1 people found this helpful.

Your Answer:

Cutlass

Looking for a Used Cutlass in your area?

CarGurus has 1 nationwide Cutlass listings and the tools to find you a great deal.

Postal Code:

CarGurus Experts

  • #1
    bluRAYwhale
    Reputation
    230
  • #1
    James Sparrow
    Reputation
    230
  • #3
    Gene Arnett
    Reputation
    140
View All

Find great deals from top-rated dealers

Search

Related Models For Sale

Used Dodge Charger
38 Great Deals out of 645 listings starting at $4,888
Used Dodge Challenger
33 Great Deals out of 475 listings starting at $7,999
Used Chevrolet Monte Carlo
7 listings starting at $3,000
Used Ford Mustang
65 Great Deals out of 1,259 listings starting at $4,995
Used Pontiac Firebird
15 listings
Used Chevrolet Camaro
16 Great Deals out of 307 listings starting at $10,500

Content submitted by Users is not endorsed by CarGurus, does not express the opinions of CarGurus, and should not be considered reviewed, screened, or approved by CarGurus. Please refer to CarGurus Terms of Use. Content will be removed if CarGurus becomes aware that it violates our policies.