305 vortec heads and factory intake on old block??

[CumminsFever]

If it is a '77 check the cam lobes really well. Late 70 to early 80's were known to have soft cams.

My brother had a 73 nova that originally had a 307. It wiped a cam at less than 100k miles. Machine shop warned us about the cam issues as we hunted for another engine. So yes, the cams can be an issue.
It isn't "all" of them though. Just ones from a certain plant... that I of course can't remember! This is if I am recalling my details correctly.
I wouldn't have a problem using the old engine with vortec stuff clamped on top of it. It will get you down the road for a while, and maybe for a very long time!
I've personally taken a 77 350 and clamped tbi heads/intake onto it, just to prove it can be done. No problems with tbi.
Vortec may be different, but I bet it'd work too. You'll need to follow the advice regarding timing cover and flywheel.

 

[Scooterwrench]

My brother had a 73 nova that originally had a 307. It wiped a cam at less than 100k miles. Machine shop warned us about the cam issues as we hunted for another engine. So yes, the cams can be an issue.
It isn't "all" of them though. Just ones from a certain plant... that I of course can't remember! This is if I am recalling my details correctly.
I wouldn't have a problem using the old engine with vortec stuff clamped on top of it. It will get you down the road for a while, and maybe for a very long time!
I've personally taken a 77 350 and clamped tbi heads/intake onto it, just to prove it can be done. No problems with tbi.
Vortec may be different, but I bet it'd work too. You'll need to follow the advice regarding timing cover and flywheel.

You are correct. It wasn't all of them and not even sure it had anything to do with what plant they were assembled in,some were just bad.

 

[Sean Buick 76]

Use a dial indicator to see if all of the rockers are rising as designed.

 

[Nad_Yvalhosert]

Why do you keep repeating this? It has zero basis in reality. Flat tappet 305s had knock sensors starting in the early 80s and all the TBI small block trucks with flat tappet cams had them too.

Because personal experience with that exact swap. A Vortec OBD2 is gonna be MUCH more sensitive than an OBD1 TBI or an early 80's feedback carburetor ECM.

 

[L31MaxExpress]

Because personal experience with that exact swap. A Vortec OBD2 is gonna be MUCH more sensitive than an OBD1 TBI or an early 80's feedback carburetor ECM.

I have done the same swap numerous times. My L30 even had a fairly aggressive cam and Rhoads lifters in it which some claim causes the knock sensor to go haywire and I never saw that issue in any of them.

 

[CumminsFever]

I grew up in my dad's shop, and I sure saw my fair share of gmt400. I did do my fair share of messing around with them too. The only time I saw a knock sensor issue, it was a tuning issue (on a stock truck) that a customer didn't opt to get it reflashed. So I removed knock sensor from the engine, installed a plug in it's place, then ran a ground wire clamped to the sensor so the computer would be happy, and sent the guy on his merry way.
My experience leads me to say that I don't see the knock sensor being a problem with flat-tappet lifters.

 

[Erik the Awful]

Cut a little circle of paper and stick it between the knock sensor and block. That's what the engineers told us dealership technicians to do if we had an ultra-sensitive knock sensor, but I never ran across one.

 

[98 Nitro]

A 77 z28 should be a 350. 87 would likely be a 305. If you are using a 77 2 piece rear seal block you need the flex plate with it. An 87 would be a 1 piece rear seal and you could use the one from your truck. You'll need the vortec timing cover, balantercer and crank reluctor. Use a holley timing cover. If the 305 is or off an 87 Camaro it probably has a roller cam. If you can get it right go for it. Not a hard swap and will get you back on the road

It might not be the original engine in that 77 and i believe roller cams were 88. Check the casting #s to find out.

 

[98 Nitro]

My brother had a 73 nova that originally had a 307. It wiped a cam at less than 100k miles. Machine shop warned us about the cam issues as we hunted for another engine. So yes, the cams can be an issue.
It isn't "all" of them though. Just ones from a certain plant... that I of course can't remember! This is if I am recalling my details correctly.
I wouldn't have a problem using the old engine with vortec stuff clamped on top of it. It will get you down the road for a while, and maybe for a very long time!
I've personally taken a 77 350 and clamped tbi heads/intake onto it, just to prove it can be done. No problems with tbi.
Vortec may be different, but I bet it'd work too. You'll need to follow the advice regarding timing cover and flywheel.

My 73 Nova had a 350 and the sky roof(which leaked and the engine blew) really love those years 68-79, I owned several.

 

[Schurkey]

Cut a little circle of paper and stick it between the knock sensor and block. That's what the engineers told us dealership technicians to do if we had an ultra-sensitive knock sensor, but I never ran across one.

The knock sensor on a SBC is pipe-thread. Where does the paper go?