OIL PRESSURE CONCERN , AND HORSEPOWER.91 omc cobra 4.3l

[barnstormerj]

I have rebuilt my 1991 4.3l engine, it has been line bored, balanced, new crank, rods, bearings, oil pump ect. Ran it last summer , break in, was not to concerned, it seemed to show about 35lbs oil pressure , cruising at about 3-4000 rpm, ,I am a certified auto mechanic, most times 20 lbs is sufficient with a gm engine, idle oil pressure in a car engine can run at 5-10 lbs with no problems,. My boat runs bout 15 lbs o.p. idle 170 degrees f. What do boat mechanics usually agree on with oil pressure ranges? thought about a new sending unit, but do not think there is much need for concern, engine runs fine.
Also, what horsepower would this engine make ( ruffly) it started I believe at 175, as a two barrel carb, it now has the cam and holley 4 bbl off of a 225 hp engine?

 

[Bondo]

Re: OIL PRESSURE CONCERN , AND HORSEPOWER.91 omc cobra 4.3l

I have rebuilt my 1991 4.3l engine, it has been line bored, balanced, new crank, rods, bearings, oil pump ect. Ran it last summer , break in, was not to concerned, it seemed to show about 35lbs oil pressure , cruising at about 3-4000 rpm, ,I am a certified auto mechanic, most times 20 lbs is sufficient with a gm engine, idle oil pressure in a car engine can run at 5-10 lbs with no problems,. My boat runs bout 15 lbs o.p. idle 170 degrees f. What do boat mechanics usually agree on with oil pressure ranges? thought about a new sending unit, but do not think there is much need for concern, engine runs fine.
Also, what horsepower would this engine make ( ruffly) it started I believe at 175, as a two barrel carb, it now has the cam and holley 4 bbl off of a 225 hp engine?

Ayuh,.... Rule of thumb is the same, 10lbs. per 1000 rpms,....

"T" in a mechanical gauge if ya wanta check it,...

2bbl carb is 'bout 180 hp, 4bbl. carb just over 200 hp,...

It'd probably take a set of Vortec heads, 'n a tight quench, to reach 225 hp,...

 

[Walt T]

Re: OIL PRESSURE CONCERN , AND HORSEPOWER.91 omc cobra 4.3l

Electric gauges are just there to say "Yep, there's some pressure here!" It's when you see something off from what it normally reads that should concern you. It's just a glorified idiot light. If you want to know the pressure, screw a mechanical gauge in a T with the sender. just pop open the cover to see what it really is. I don't recommend running a mechanical gauge tube all the way up to the dash unless you can install it so it will never get a hole rubbed in it and leak all over your wife's purse that she stashes in the cubby under the line and get oil all over her tampax and trust me if she's got that in her purse your day is already tense.

 

[Maclin]

Re: OIL PRESSURE CONCERN , AND HORSEPOWER.91 omc cobra 4.3l

Electric gauges are just there to say "Yep, there's some pressure here!" It's when you see something off from what it normally reads that should concern you. It's just a glorified idiot light. If you want to know the pressure, screw a mechanical gauge in a T with the sender. just pop open the cover to see what it really is. I don't recommend running a mechanical gauge tube all the way up to the dash unless you can install it so it will never get a hole rubbed in it and leak all over your wife's purse that she stashes in the cubby under the line and get oil all over her tampax and trust me if she's got that in her purse your day is already tense.

Amen brutha

Ditto on the mechanical gauge. Once you trust the build then it can be removed and used on the next project!