I "believe" I have a 350chev 1986-1995 4 bolt motor. It was installed in the car 13months ago and the motor originated from a place called suburban imports here in Australia.
I believe it is one of the 2 engines in the image attached, but can't confirm. According to the guy at suburban, it is this(one of) motor but can't confirm if it is HO cam or Roller cam.

My question/s are this:
If it has 300hp rating, would it still be stock heads? (can't get the casting numbers)

If it is stock heads, would replacing the cam increase power or is the engine maxed out already?

If so what cam would i replace it with?

The engine has since had a TPI top end put on.

 

Depends heavily on what heads it has on it, and what cam is in it right now. It may be a big benefit to upgrade, it may also not change anything, or even drop HP.

 

Pull a valve cover off and copy down the head casting number, they we can help you dig up more details. If i had to venture a guess, i'd say that like the majority of non-performance oriented crate engines yours probably has a mild cam in it. Thus it could benefit from a larger cam. That said, id-ing unknown cams is a bitch, so you may never be sure. You could set a dial indicator up to measure the lift at a lobe and estimate the cams specs using that. Are you prepared to tear this motor apart?

-Zander

 

either side?

 

yes either side will do, your are looking for a 7-digit sequence cast into the head.

 

yes, it should be between the middle sets of valve springs. if you get the number, go to mortec.com and they have a complete listing of sbc/bbc casting number references. just look the number up in the list and it should tell you where the heads came from. you can do the same with the block and see what it originated from as well. it also may help you in determinin if it has a roller cam.

another easy way to see if its a roller cam is, while you have the valve cover pulled off, you can look through the pushrod holes or oil drain holes into the lifter valley, and see if you have roller lifter retainers or other hardware identifying a roller cam. good luck!

 

Only way to know is to pull off the intake and see. Alot of factory roller blocks never had the finish machining done to accept a roller setup, because trucks came with flat cams. Being a rebuilt engine too, it could also have had a flat cam installed where a roller used to be.

 

yes this is true, but if it is a roller cam, then you will see the lifter retainers no matter what. you also dont need to take the intake off, you can see through the heads just fine. its a lot less hassle and work for thes same end.

even if the machining isnt done the lifters have to have retainers otherwise they would turn sideways if the bores and then youd have a "catastrophic failure."

 

Gary at Suburban builds engines with mix and match parts so your engine will not be the same config as any stock engine that came out of a car.
In this case he has used a late model roller cam Block with what appear to be early heads.I doubt the heads are anything special.
The difference between the 2 engines is whether it has a roller cam installed.
The base Chevy crate engine from GM is rated at 290Hp with a wimpy cam.
Only one way to find out what you have