Bo1226

iTrader: (2)

Ok to start I know I shouldnt build a 305 but thats what it is so if it offends anyone then move on to next post. I got the 305 with all machine work done free and have all my bottom end parts including flat top HYP pistons, Double roller timing chain (cloyes), Comp xe268 cam cyclone intake and edlebrock carb, Hi volume oil pump. I was planning on going with vortec heads for 305 but that fell through. My question is what would be a good set of heads for this that would also work on a 350 in the future? I'm completely stupid when it comes to what combinations work well together. I've seen by many posts on here that 350 heads will not work on 305, so how can I purchase heads for this motor that will also work at a later point on 350? Not sure if there are some stock heads that would work well with my combo or if it is a must to purchase something high dollar. I would love to learn anything possible about heads and what is required in heads to produce the best power with this combo. I'm not sure what CC is necess. whether springs would be issue with this cam, what valve size would be best etc. Any info and suggestions would be appreciated.

Mikz86TA

iTrader: (4)

305 and 350 heads a generally not exchangable. Most stock 305 heads are smaller valves and 58cc chambers. 350s have larger stock valves (and most aftermarkets have bigger) and are usually either 64 or 72cc chambers. If you put a 350 head on the 305, I believe the valve will clip the bore...since a 305 cylinder bore is smaller.
The Vortecs are iron and a good starter head for a 305. World Products makes a 305 Tourqer head that is nice. But its iron too. Mild porting can be done, but dont overdo it. The 305 just doesnt respond to porting like a 350 does. The World head is 58cc so your comp ratio will be the same if your pistons are.
There may be more companies with 305-specific heads and maybe a 'marine' head.

czbigboy

I am about to order a set of World Products 305 heads. I think using them on a 350 later depends on how much power you want out of the 350. They should be good for low end power. They come with springs that will handle your cam. They claim .560 lift for the springs. CC is a measure of volume. The combustion chambers are 58cc, 170cc intake ports, 1.94int and 1.50 ex. stainless steel valves. They even come with screw in rocker studs. You can get them from Jegs or Summit for around $800.00. I hope this helps some.

Bo1226

iTrader: (2)

I appreciate the quick responses...So when I'm lookin on ebay for heads and it shows a set of alum heads for sbc and lists all sb's I'm assuming that you have to tell them which sbc you have?? Thats kinda what was throwing me off. I know from posts that any head with 2.02 valves wont work on 305, also know that 350 comb chambers kill compression so thats why I asked the ?. Also wanting to know how bad it would kill power to run stock 305 heads for a while.

five7kid

iTrader: (14)

Whoa, a lot of misinformation there. 305 and 350 heads are interchangable. 305's have 58cc, true, but that doesn't mean they can't go in a 350. 350's had anything from 58cc (aluminum Vette) to 76cc, but that doesn't mean they can't go on a 305. 350 heads won't "clip the bore", not even 2.02/1.60" valves. Total myth.

A 305 responds to porting just like a 350 does. Not sure where you're getting that.

World is the only aftermarket company making a 305-specific replacement head. They will work fine on a 350 - see sig. What I didn't understand while those heads were on my 305 was the chambers were actually 64cc - go figure. I inquired of World how that could be, they didn't respond. Instead of 9.5:1 CR on the 305, I had more like 9.0:1 - still better than the 8.5:1 of the '82-'84 LG4's.
"Kill" compression is probably an overstatement. See response above. Just depends upon what the chamber volume is, what your block deck height is, what your piston crown volume is, and what head gasket thickness you use. 64cc chamber Vortec heads will wake up a 305, in spite of the lower CR.

Sonix

iTrader: (1)

If you're zero decking your 305, and using flat tops, 64cc "350" heads will give a pretty useable compression ratio.

five7kid

iTrader: (14)

Mine wasn't even zero decked. With 5cc relief flat-tops, .025" in the hole, steel shim gaskets, and 64cc, came out to 9.0:1. Certainly never had pinging problems.

Sonix

iTrader: (1)

Stock flat tops with 1.56 compression height right?

If he's using speedo pro ones with 1.54" compression height it'd be 8.5:1. In that case i'd recommend decking .020" at least, or the full .045" or so, then using a .041" gasket (right back to 9.1:1)

Bo1226

iTrader: (2)

OK now your gettin in over my head with talk about deck ht, 1.54vs1.56 piston etc....lol. I can grasp what your saying but not sure about all the specifics but regardless I def appreciate your input. So what I'm understanding is a vortec head whether its 305 or 350 would work on this as long as it was no more than 64cc? BTW I have speedpro flat top pistons w/reliefs. Does it matter whether I get heads that are from carbed motor, tbi,tpi,lt1 etc..etc....??? By the way what is the differ between decking and milling???

Sonix

iTrader: (1)

decking = milling.

Your pistons have a 1.54" compression height, meaning the top of the piston is .020" lower in the bore than one with a 1.56" height. That means your deck height is .020" more - which lowers your compression.

TPI, TBI, LT1 etc all have different heads. They aren't the same, and LT1 is a completely different ballpark.

58-64cc heads will work nicely for your application. If you do not mill the block then 58cc would probably be best, if you do, i'd recommend 64cc. That would give the optimal compression ratio at least.

Bo1226

iTrader: (2)

decking=milling??? If I understand milling a head is basically machining the contact surface and taking some off right? But your talking about decking the block is that the same thing, removing some of the contact surface where head meets up? If this is correct can you do either/or? So if I ended up with 64cc heads could I mill the heads and achieve what your talking about? Again thanks alot for tolerating these stupid ????
Bo

Sonix

iTrader: (1)

yes

They do the same thing, ie increasing the compression, but in two different ways.
milling the block deck improves quench (look it up, it's a good thing)
Milling the head creates problems - intake lining up, etc. And does nothing to the quench. There are other reasons...

Bo1226

iTrader: (2)

OK so all the reading I've been doing I see that 416 and 601 are desirable heads as far as stock go and with some work and bigger valves flow pretty descent. I have found some with these castings but not sure whether I need to know if they were on tb1,tpi,carbed? Earlier in post I was told they are all different....does that mean that tbi or tpi will not bolt up to carbed intake?

Sonix

iTrader: (1)

Those are carbed heads.
TPI won't bolt up to a carbed intake - that doesn't make any sense.
TBI, with ana adapter will bolt onto a carbed intake - but why are you even asking that?!
I thought you'd be using a carb on this anyway?

Bo1226

iTrader: (2)

Yes I will be using a carb thats why I'm asking....Never dealt with TBI or TPI so I didnt know if heads that were off of theses would bolt up to a carbed intake or not. So your saying the 416 and 601's are all carbed heads?

Sonix

iTrader: (1)

Yes.

Bo1226

iTrader: (2)

Ok great, I know what to look for then. I see your running 416's on your 355, do you prefer those over the 601's? What about the 081's sounds like those are TPI if I'm not mistaken..I have a guy wanting to sell me those but I didn't think they would work.

Sonix

iTrader: (1)

I had 416's on my 305 that I pulled out of the car, so it was an easy choice. If both were sitting on my bench i'd probably have picked the 601s.

The 081's are supposed to be quite similar, but I think just slightly better than the others. Apparently a better chamber shape. They take center bolt valve covers, and I think need self aligning rockers as well.

I H8 WWD

iTrader: (5)

What about GM fastburn heads.

I was told these will fit due to their vortec AND 23* angle intake bolt pattern.

Plus it goes well with the zz4 cam.

Let me know....I have a 305TBI.

Bo1226

iTrader: (2)

OK sonix thanks for all the replys and info. Last ? I have is will the 018's work on carbed intake? The guy says they were on a TPI so I'm going from what you said earlier in post the tpi heads wont bolt up to carbed intake. He says they will work but getting conflicting info.

Sonix

iTrader: (1)

Ok, you confused me. The intake bolts to the heads, not the other way around.
You can bolt a carbed intake onto 081 heads, you just need to slot the two center holes on the intake manifold. A die grinder can fix that pretty easily.
Then just remember to buy valve covers based on post 1987 heads (ie. center bolt style). And use the correct rocker arms- I think you need self aligning for those heads.

Bo1226

iTrader: (2)

OK not a problem there, I have an aftermarket intake that has the adapters for the center holes to use on 87 and up heads. Is there a big difference in cost between self align rockers and standard? Was wanting to go with some roller rockers do they come in self aligning?

five7kid

iTrader: (14)

'85 & '86 TPI used the same heads as '82-'86 carb'd.

'88-up needed self-aligning rockers. '87 was kind of a weird year. Just look at the pushrod holes in the heads - if they're round and larger than the pushrods, you need self-aligning rockers. If they're ovate and the same width as the pushrods, you need non-self-aligning rockers.

You can get roller rockers in self-aligning. Comp Pro Magnums would be my recommendation.

91greenbird

iTrader: (4)

trickflow makes 175cc heads for small blocks with 56cc should be good on a 305

Bo1226

iTrader: (2)

Ok guys well I appreciate all of your info and feedback...this forum is a lifesaver for me, it is an excellent means of gaining info and knowledge. After all my checking and searching on here and ebay, turns out that I have a set of 601's sittin at my fathers garage. So I'm going to try my hand at porting these, then have 1,94/1.60 valves w/z28 springs put in them. If anyone has any other advice for these I'm definately open to hearing it. Once again thanks to all who replied.

izcain

Just take your time and dont get to carried away with the port work. Do plenty of research before starting.

I ran the 305 Torquer heads for quite a while on a hopped up 305 and they made great power!

Bo1226

iTrader: (2)

Ya you bet I will. I'm gonna order the port kit from SA I believe it is and they have a complete breakdown step by step how to do it and I'll be taking any advice from here lol.