Inliners International Forums General Discussion Engines mercruiser cam and water pump questions

Putting together a 250 motor for a somewhat hopped up street project. I plan on putting it in a full size chevy car (mid 60's impala, biscayne, bel-air or similar). I'm looking to make it kinda of mean for the street.

I've built a 292 that is made for mild performance, so picking the components was easy. Looking to get some input on this build though.

So far I've collected a set of headers and a 4bbl intake. I'm working on getting a HEI dizzy and considering BBC roller tip rockers.

I've considered running a mercruiser cam. I know they act like an RV cam, but I'm wondering about the limitations and what the effective RPM band is. Does anybody have any specs for these cams? I've also considered running a big lift cam with Rhoads lifters for more street friendly manners, but also have bigger power toward the top. I plan on mainly using this car for hustling around town while I finish my other project. Will most likely have a 4spd manual or a Powerglide auto behind it.....maybe TH-350? I'd like to be able to make a few fun passes down the track every now and again for some of the nostalgia flag drags we host annually and not get laughed at too bad. Suggestions welcome.

Other question is about water pump. I know that the 292 water pumps are larger and push more fluid since the impellers are larger/deeper. Would there be any benefit to running one of these pumps on the 250 or is it overkill?

Mercruiser Marine Camshaft Specifications
Mercruiser P/N 430-3161
Chevrolet P/N 3891590

Duration: 288/288 @ 0.004" lift, 192/192 @ 0.050" lift
Lift: 0.403"/0.403"
Lobe Separation: 112

Very mild cam. First step up from a stock cam. Power should come on by 1000 rpm. Install if you want to use "factory" parts. Other aftermarket cams would be more effective as this cam has a relatively low lift of 0.403". Fine for working truck service or good fuel economy.

If you want to use this mild a cam (0.050"duration at or below 200 degrees) you may also want to consider the following cams which have lifts between 0.436" to 0.460":

For power in the 1000 to 4000 rpm range:
Isky 231-M, Mile-A-Mor
Crower 240HDP
Crower 248HDP
Comp Cams C60-240H-8

You could easily run a hotter cam and be fully streetable. Most run a 0.050" duration of 200 to 212 degrees for mid-range street performance.

For power in the 2000 to 5000 rpm range:
Comp Cams C60-260H-10 (popular)
Crower 272HDP
Isky 262 SuperCam
Langdon "292 H.O. Marine" (for 250)
Schneider 130H

There are a number of cams that fit in between the two groups also.

Many marine engines are reverse rotation, so make sure that wont cause you any "sticky" issues with distributor rotation,etc....

Carefull on getting to wild of a cam, your car will be pretty heavy and a 250 doesn't have much low end power to give up.

A 292 pump WILL NOT FIT in the 194,230,250 Blocks.There is also
a difference in the Back side of the Pumps,Not just the impellers.

Thanks for the suggestions. I will be sure to check the tooth direction if I pickup a mercruiser cam.

Good to know about the 292 pump.

Hoping to find something middle of the line. That's why I asked about the Rhoads lifters. They say that they act like a smaller cam at lower RPMs with radical cams. I'm wondering if I go with a mid-range cam and add the Rhoads if it will retain the low end but have a better mid to upper end.

Has anybody used these lifters before? If so what are your thoughts? Thanks.

i have used the rhoads lifters on my 292 with a clifford 270 cam. it does help tame it down. idles better. still performs. i did not care for the lifter clatter noise they produce at idle. other wise they work as claimed. tom

I tried a few sets of Rhoads lifters & different cams.

They do work good.
They sound like solid lifters,maybe a bit louder actually.

My wifes ex co-workers husband is married to one of the Rhoads son.

They send cards to us,,,,sorry guys, no discount here.

MBHD

Tom & Hank (or anybody really) did you try different oil viscosity to 'adjust' the bleed down?

I don't recall reading that in the Rhodes literature, but I've heard of it being done (from several people, but theye were relaying it from someone else)

at that time i was running 10/40.