I found a set of 56cc rebuilt vortec heads, and I was wondering if I would be correct in assuimg I would need a different intake manifold than the stock one. Also, I would be swapping these and a lt1 cam in at the same time, would I run into any problems (esp computer problems?). What type of gains would I be looking at with just that, L69 air cleaner, with no exhaust mods (yet)? Thank you in advanced! Edit: I found another set also. What is the diference in casting number 12552520 and casting number 14102167? Thanks!

Math homework break, I can't give you numbers but let's put some things into perspective. Vortec heads are GMs BEST iron heads and they use small valves (good for the 305 small bore issue). Lt1 cam has the perfect lift for a 305. The duration and lobe seperation are EFI friendly so the computer won't through fits (as long as you install a vac AFPR or do a custom eprom).
I guess that I'm saying is you're looking at the range of 240-250hp with current crap exhaust and probably 260-270hp with a nice flow exhaust system. Brian Felts used an Lt4 cam and I'm betting it was running about 280-300hp but he's got a great exhaust and milled the heads.
If you're going to keep the 305 then the Lt1 and vortec heads are perfect match for a street machine.
Like you said, you'll need a new intake but they're <$200 and I would go with the RPM or a single plane. Since I only know of the victor jr single plane you're probably better off with the RPM dual plane. The victor jr is really ment for a larger cam and more cubes. Hope this helps and ask Brian Felts if you need info. Him and NJSpeeder seem to be the only guys around here that have kept the 305 and done heads, cam, intake etc. Everyone else is either doing a 350 swap or a power adder.

Wow. I knew the stock heads were pretty bad, but I didnt know they were that bad. Thank you fer the info. Hope I can pull this off. Now, what would the PN of the RPM manifold that i need be? Also, is there anything I should watch out for in doing these swaps?
I hate to ask so many stupid questions, but what will I need to swap cam and heads? Which gaskets(everything?), and maybe assembly lube? Thanx

What you need to "watch out for" is the retainer to seal clearance and to have good springs on the heads. I don't know if the stock Vortec springs are good for anything except maybe the stock LO3 cam.

I also had better luck with the stock GM Vortec intake gaskets.

I can check the casting number on mine if you still don't know what set is what.

Please do, if its not to much trouble.

I havn't forgotten you. I will try to do it today!

Thank you!

Watch the casting numbers on those heads.

You only want the L31 vortecs. The ones off the 350's..
their are only two casting #'er.. one is 063, and the other.. i can't remember exactly.. they are bothe 64cc.. the 305 vortec heads are different, and don't put nearly as much power.. don't even bother with them.

305 Vortec heads gave trucks 230 HP
350 Vortec heads gave trucks 250 HP. Nothing to sneeze at if the price is right.

i put l30 heads,lt1 cam,supervictor vortec intake(for sale) and a 454 TB on the RS awhile ago before the lt1...
everything worked nice. but the computer as LOST!!!
i was burning the chips and get it running ok..pulled good too..
but i didnt have the tuning skill i have now..

made a bada.ss lil 305.. suprised many 4thgen snobs..

anyway ttyl,
RS
:lala:

im in the same boat. i have an 89 305 TBI, and want to go with the vortec heads and LT1 cam, but have NO idea how to burn a PROM or even what a vac AFPR is. any suggestions? and would and LT4 cam fit?

Well, the only number i can make out in the picture is 14102167. is that the 'good' number?

According to Mortec the two #'s are

12558062...98......350..........L31 Vortec, truck, 64cc chambers, 1.94/1.5, 170cc intake port

12552520...97-up...305..........Vortec, truck

If the ones in the pic are the ones you bought, you may have gotten the shaft.

This is the closest number I could find for the ones that you showed. Sometimes the #'s are hard to make out. If that 6 is maybe an 8, you just bought a set of crappy 305 heads.

14102187...87-91...305..........1.84"/1.5" valves

If you didn't buy the, then your OK. Buy the 520 heads instead. Those are the Vortec heads. Just keep in mind that you will lose the EGR crossover with the Vortec heads.

AJ

lucky me has not made the purchase yet!
Thanks for the info! :hail:

Yea. I just edited the errors I made so read it again.

AJ

Yeah, I visted that site, just to check it out, and I concure with you. again, thanx fer answering!

Are the "14102187...87-91...305..........1.84"/1.5" valves " the TPI ones?

Buck I'm sorry to take so long but after getting back from the shop and waiting my turn at the computor last night I fell asleep.

But anyway the casting #12558062 as was stated by AJ/Mortec was correct.

The part number if you need it is 12558060. It's the one that everyone sells new as far as I can tell. This is the 350 head with the 1.94 intake valves.

Later.

Ok buddy now for your questions;

Yes the LT4 cam will fit . It will work with all the other stock parts. I installed it when I was running the stock heads with stock springs. I cannot remember what fuel pressure I was running but this can be played with. It would also run to 130plus as I stated in another post but not as quick as with the Vortec heads and intake and 1.6 rockers.

As far as prom tuning I did not have to change much with just the cam change other than things I have changed for a baseline chip such as no speed limiter and changed idle to 750.

Good luck!!