I just aquired a 350 long block out of a 94 Suburban and i plan building it to replace my 305 in my 87 GTA. My question is whitch motor has the better heads? I plan on getting the heads ported as well.

 

The 305.

 

if the 94 has vortech heads they are the ones to keep. the 305s usually have 58 cc chambers so it will bump the compression quite a bit but they also only have around 155cc intake runners which will make your motor run out of breath around 4500-5000 RPMs, but it'll have AWSOME bottom end up to 3500 rpm. we built a 350 for my cousin(he was CHEAP!) we used 305 HO heads, cam of 204* at .050" ,flat top pistons,stock intake(lost torque with aftermarket intake), quadrajet, HEI. and nothing else. we installed 3.73 gears and it had a TH350. the car would TOTALLY enialate the tires rolling at 15-20 mph. MAJOR torque moster but it ran out of breath at 4000 rpm, some of this was because of the cam. but i have talked to others who ran the same combo and they ran cams around 218* .050" and said they would run out around 4750 rpm.

 

I've heard the iron vortech's from trucks aren't that good, something about valves or the like..... eitherway aftermarket vortechs are cheap as hell and perform great

 

The 305 heads are way better because the 94 Suburban would have used the crappy L05 swirlport heads. Terrible heads for performance.

 

If your 87 center bolt valve cover 305HO motor has 081 casting heads they will work nicely on your 350 project with some home porting and new larger 350 sized valves. Get either 1.94 x1.60 or 2.02 x1.60. The ports on these heads are the same as 350 l98 cast head ports. Once you install bigger valves in the 305 heads they will work well. And better with porting.
Check the head casting number before you go investing money on machine work etc.

You want to avoid swirl port heads
191/193

 

Thanks for the reply's guys, I know the 350 heads are not vortecs so it looks like the 305 heads are the way to go. are the combustion chambers on the 305 heads smaller than the L98 heads, more compression would be nice.

 

58cc for 305 vs. 64cc for L98. The truck engine most likely has dished pistons, so the smaller 305 chambers will improve compression. Put in 1.94" intake valves, unshroud them while doing the porting, they'll do you good.

 

Is there a way to check the casting # on the 305 heads in the car? also does this sound like a good combo: 350 with 1.94 1.6 valves and ported 305 HO heads, ZZ4 cam, headers, ported TPI, 24 lb injectors in front of a WC T5. This is all I can afford right now and I would like to get 275 to 300 horses out of it.

 

You have to pull the valve cover to see the head casting #.

Sounds like a pretty decent combo. I wouldn't bother with 24# injectors, though. AFPR, shorter runners would be better use of funds.

Also, with that much lift, you need upgraded valve springs; and screw-in rocker studs, or drill/pin the stock press-in studs to prevent pull-out.

 

I already have AFPR, I heard that the stock 19 lb injectors would not feed a 350 like it should but I guess if you increase your fuel pressure you can compensate for the smaller injectors. also what runners do you recommend, I would like to have good pull up to about 5500 RPM. Thanks for all the help