i have a 305 with stock heads in my 88 iroc, can i put the 350 vortec heads and intake on the 305 block?will it improve flow?Enough to justify doing the job,even though i want to do it anyways cause im sure the gaskets could use replacing soon and i want the expierience.
any certain trick or particular thing i need to know or do?
thank you very much.
take care guys ...
Dan

 

The heads will bolt right on, but putting 350 heads on a 305 is gonna reduce your compression, effectively negating any power you would gain. Sure they'll flow better but it's not gonna be worth the swap, especially since you'll need the Vortec TPI base which is hella expensive. If you're gonna pull the heads to do a gasket job anyway I'd just give the stock heads a good port job and 3-angle valve job and put em right back on...you'll probably get more power that way and it's a LOT cheaper.

 

Yes they will fit.
You will need a vortec intake manifold of some kind.
I don't like the fuel injection set up on those vortecs are expensive to replace stuff on.

 

thanks guys..i have all the 350 stuff from the old block...so i do have the vortec intake for the 350 and all the other stuff...
so far i think im going to do it...any other warnings or suggestions?
thanks again..
Dan

 

If you do the swap, your best bet would be to have the heads milled to reduce the chamber volume. This will bring back the lost compression due to the 350 heads. The chamber volume on a 350 is 64cc and a 305 is 58cc, so a difference of 6cc can be milled away (close to anyway). Also buy the thinnest head gaskets you can find (high quality), and voila a vortec 305. You might also want to check the valve clearance with the cylinder bore because the valves are larger (1.94/1.5) than a 305. You also might lose some bottom end torque due to the longer runner's in the vortec. I think they are 170 or 190cc and the 305 are down around the 150s. Good luck!

 

By all means go for it. Im running the Vortec heads milled .020 with the fpp-1094 (I think) gasket thats .017" compressed. Everyone that had used it said they didnt have any leaks, and I sprayed Hi-Tack on it before I put them on, 1000 miles later no problems. The heads coupled with a Performer RPM intake and a stock LT1 (.447/.459 205 207) with a stock TBI on top make pleanty of power, I just cant seem to find the ground lol. It starts pulling about 3000 and pulls STRONG to 5500. Cant wait till I get my whole setup dialed up, as right now Im having my share of difficulties (understatement of the year lol). Hot Rod also did their 305 build up and made 17 hp over the SR Torquers when they switched to Vortecs, but they had them milled .040.

 

I am running vortec 350 heads on my 305 and they work well. I am using the fel-pro 1094 head gasket to keep my compression ratio at the stock ratio. My heads are advertised at 64 CC but they measured at 60 CC and with the .015 1094 head gasket I did not loss any compression.