oldschool85

How many of inches of vacuum are you seeing using this cam Mondello JM 25/28 or similar ?


The specs are 236/248 on a 108 LSA. Lift: 523/544

coppercutlass

i using a 522/539 on a 110 lsa with 233/241 duration. Power brakes work good but on the ragged edge of not working. Dont know the vacuum exactly .

Qwik71442

Depends on what size engine?

oldschool85

455

joe_padavano

108 LSA is going to be pretty low vacuum.

cutlassefi

This is basically a Thump'r cam without the advance.
I do a custom Lunati roller in a lot of my builds. It's 235/241@.050 on a 112 most often. Idles at 850-900, has more than ample vacuum and makes great power. Let me know if you're interested. Thanks.

oldsmobiledave

A buddy has that cam in a 455 in his 69 442 convertible. Street driven with a T400, 2800 stall and a 3.42 gear. No issues with power disc brakes.

Many years ago I street drove my blue 72 442 with a 455 and a JM 4-5 cam and never had a problem with the power brakes.

VC455

I have an Engle (Mondello) RH 95-96 in a 455. Specs are 236-244°, 0.538-0.538", 110° LSA, hydraulic roller.

It idles at 800 with 11 inches of vacuum. I have an electric vacuum pump for the brake booster.

Because yours is flat tappet, tighter LSA, and more exhaust duration, you would have a lower vacuum than mine.

cutlassefi

Actually that part is backwards. If you look at two cams, one flat tappet, one roller, both with the same @.050, the roller will have a higher advertised duration. The reason is you can't yank a roller lifter up that quickly at first. So you'll need a bit more ramp to get it started. Consequently the roller will have more off the seat time, and therefore most likely a bit less vacuum.
Hope this helps.

oldschool85

Thanks for all the replies. I am looking for actual vacuum readings from.this cam or similar for comparison....
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