1SICK90RS

ok so i've got this 1984 chevorlet 350 motor, i was wondering if i could take the vortec heads off of my 1990 305 and put on the 350, would it work, or would i have problems with oil and water?

NathanLewis

Don't put 305 heads on a 350, thats just silly.

Just my 2 cents.

InfernalVortex

iTrader: (4)

What did the 350 come out? The 305 heads may work well, they may not. I dont know much about the 305 Vortecs beyond that they have nothing to little in common with the 906/062 350 Vortec heads other than the bolt/intake port pattern. They'll have smaller intake/exh valves for less flow, and a smaller chamber for higher compression. I dont know enough about their flowrates to say whether they'd be as good as some LB9 305 heads, but if they're the same it wouldnt be a bad idea to put larger valves in them if you've got dished pistons in your 350 and your stock 350 heads are smogger style junk. 1984 was around the time they were starting to get their **** together so they may not be too bad, but it just depends on a lot of things.

1SICK90RS

It's just gunna be temporary,until i can get me a set of good aluminum edelbrock heads

BlackenedBird

iTrader: (5)

Your 84 intake won't fit the Vortec heads. So your "temporary" solution would cost a little more coin because you'd have to buy a new intake.

bluers91

They didn't make vortec heads in 90. Which casting numbers you got?

Guest

The '90 305 TBI heads are swirl-port. No flow. For mild commuting, they are tolerable up to 3500-4000 rpm.

1SICK90RS

idk the casting numbers... but they guy i got the car from said it was all original, his son smacked into a tree a few years back and hit it hard enough to break the distributor... so yea my temporary solution is gunna cost a little more than i expected, the heads are centerbolt heads, which i've always called vortec heads...

1SICK90RS

and i have the intake from the 305... once again "temporary"

Guest

This is the fault of Chevrolet's marketing people. '87 was the first year of centerbolt heads, and all '87 TBI SBCs and 4.3s had high-swirl heads. The '87 4.3 got called the Vortec.
When car people refer to Vortec, we only care about the '96-up Vortec 350, with the high-flowing heads.
No other "Vortec" stuff is useful for high performance.

gwarren007

iTrader: (1)

Your 305 should be throttle body injected, no way to mount a carb.

1SICK90RS

ok... i'm real confused right now, so i'm gunna tell u everything that i have goin on to the 84 motor, i have the centerbolt heads, and intake from the 305 which is throttlebody... goin on to the 84 350 which is carbed... will it work

five7kid

iTrader: (14)

Yes, it will "work".

Now, "How well will it work?" is a different question. To answer that, we need more information about what this '84 350 is out of. If it was a truck, the pistons will most likely be dished, which means the smaller chambers of the 305 heads will be fine for a final compression ratio. However, if the 350 pistons are flat tops (even with the valve relief "eye brows"), the compression ratio will be too high with the small chamber 305 heads.

Taking the high-percentage guesses, here are my predictions:
- The heads will be fine because the 350 pistons are dished.
- You will need a different flexplate, because the 350 came from a truck with a 168-tooth flexplate, which won't work with your 305 starter (which would be best to use in a 3rd gen), and the 305 flexplate won't work because the '90 305 is 1-piece rear main seal, and the '84 350 is 2-piece rear main seal. Simple solution - go to your nearest chain parts store and get a flexplate for an '84 3rd gen V8 auto transmission (don't tell them it is a 350, because their computer won't show a 3rd gen f-body 350 in model year '84; and it doesn't matter, because a 305 or 350 of the same year will use the same flexplate).
- The car won't run very well with a 350 and 305 tuning, and 350 with 305 exhaust. But, it will run.

Orr89RocZ

iTrader: (20)

You can put them on, and it will run just fine...just dont expect much out of it.

Only thing you may need to watch is compression, i'm not sure what the cc chambers are on the 305 castings, but if they are 58cc then you may run into high compression on iron heads with small cam so it may not like pump gas, especially with any kind of timing advance in it. I know the later 80's 350's had 12cc dish pistons so 58 cc would put you at 10 to 1 which is high for iron heads...usually need a decent sized cam to be ok on pump gas.

What do the pistons look like in the 84?

edit; I've been tree'd see above post

N.J.-SLICK-1

Thank you, thats exactly what I was thinking, they came out in 1996 up to 2000 if I'm correct?

five7kid

iTrader: (14)

The "good" Vortec castings are 906 and 062, came on light truck 350's from '96-'99, with a few in 1 ton trucks in '00.

The only thing you "need" to know is the casting # - if it isn't 906 or 062, you don't have the "good" Vortec heads.

five7kid

iTrader: (14)

All 3rd gen 305 heads had 58cc chambers (roughly - within normal factory tolerances).

Guest

I thought CHP or Super Chevy reported that the LO3 heads were 55 cc, stock?

five7kid

iTrader: (14)

They may have. Reports here vary from 54cc to 60cc. The "target" was supposedly 58cc.

My polished chamber (no unshrouding performed) World S/R 305's cc'd at 64.

1SICK90RS

i've just decided to convert it to carb for right now, seeing as the 305 heads will need to be reworked... what all will i need to convert it to carb and electronic ignition?

1SICK90RS

crap 305 is out and gone, upgraded to a 4.8 ls based engine

DRock89RS

lol well thats a ample solution. good job

1SICK90RS

TA-Rocks

I ran 14.35 with my L98 and 305 heads. I have yet to learn more about mine since I just bought it. I had some questions regarding this though.

https://www.thirdgen.org/forums/tpi/...ml#post5335993