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I've got the opportunity to buy some used vortec heads for the 305. I know that I'd need a new or used stock vortec intake with that to install them but would I need to modify anything else in the '87 LG4 305? Is this going to be a good power gain mod or just a waste of money?
Also, what is a good price to pay for the heads? As I stated they are used and the guy wants $250 for them, is this a good deal?
You may want to reconsider putting Vortec heads on your 305. Factory Vortec heads can be id - 2 casting numbers 10239906 and 12558062. From the factory they were designed with a 64 CC chamber that in real world can vary from 64-68 CC's due to production tolerances. These heads were produced with 1.94/1.50 valves that your 305 can live with. However, most 305 production heads have small chambers 58 to 60 cc's. A stock stock LG4 has 8.6:1 compression with 58 cc heads. If you bolt Vortecs to your 305 without changing anything else your CR will drop below 8.0 (You can find online CR calculator to confirm). Your engine will be a dog with lower compression. Instead of Vortecs I would look for a pair of 601s from the JY. They are like famous mini 462s and have better flowing ports than the 416s stock, and have a tiny 52 cc chamber. That will bring the otherwise stock LG4 from 8.6:1 compression to about 9.2:1. You can have a lot more pep with compression and added flow will increase your top end HP.
You may want to reconsider putting Vortec heads on your 305. Factory Vortec heads can be id - 2 casting numbers 10239906 and 12558062. From the factory they were designed with a 64 CC chamber that in real world can vary from 64-68 CC's due to production tolerances. These heads were produced with 1.94/1.50 valves that your 305 can live with. However, most 305 production heads have small chambers 58 to 60 cc's. A stock stock LG4 has 8.6:1 compression with 58 cc heads. If you bolt Vortecs to your 305 without changing anything else your CR will drop below 8.0 (You can find online CR calculator to confirm). Your engine will be a dog with lower compression. Instead of Vortecs I would look for a pair of 601s from the JY. They are like famous mini 462s and have better flowing ports than the 416s stock, and have a tiny 52 cc chamber. That will bring the otherwise stock LG4 from 8.6:1 compression to about 9.2:1. You can have a lot more pep with compression and added flow will increase your top end HP.
//RF
AH, that makes sense about the compression! This is why I'm glad I didn't do an impulse buy on this one like I have before! What applications was the 601's used on that I'll be looking for?
Oh, dunno if it matters but my engine is a 1987 which means roller cam I believe, does this change anything?
Last edited by Firebird Mess85; 11-21-2008 at 12:10 PM.
Most vortec 350 heads actually cc at 61-63cc, and you can safely flat-mill them to 54cc, giving you 9.0:1 with FelPro steelshim head gaskets for a 350.
This is certainly your best option.
The 601s look good, if you can find them, but 52cc means that they've been milled a bit, they spec at 56cc.
Now, if you have both sets, the vortecs and the 601s, both at 54cc, the Vortecs will still be up a solid 30 horses. Vortecs new cost over $540/pair, so your price of $250 is good so long as there are no cracks. The most common Vortec crack is easily visible on the deck surface, in the center of the head.
You may want to reconsider putting Vortec heads on your 305. Factory Vortec heads can be id - 2 casting numbers 10239906 and 12558062. From the factory they were designed with a 64 CC chamber that in real world can vary from 64-68 CC's due to production tolerances. These heads were produced with 1.94/1.50 valves that your 305 can live with. However, most 305 production heads have small chambers 58 to 60 cc's. A stock stock LG4 has 8.6:1 compression with 58 cc heads. If you bolt Vortecs to your 305 without changing anything else your CR will drop below 8.0 (You can find online CR calculator to confirm). Your engine will be a dog with lower compression. Instead of Vortecs I would look for a pair of 601s from the JY. They are like famous mini 462s and have better flowing ports than the 416s stock, and have a tiny 52 cc chamber. That will bring the otherwise stock LG4 from 8.6:1 compression to about 9.2:1. You can have a lot more pep with compression and added flow will increase your top end HP.
//RF
I couldn't agree more.
601's came on trucks/vans in the '80s. They spec out at 52cc's from everything i've heard?
Flat milling Vortecs gets expensive, once you get them that low in CC's, you've probably got to mill your intake as well, which, by the way you had to buy a vortec specific intake. $150 to mill each, $150 for intake. That's $450 on top of the purchase price of the heads (vortecs cost more then 601's). So yes, you'd be up HP, but at a cost. Your choice.
Own a die grinder? Port up some 601's and you'll be a grinnin'!!
I'm looking for the biggest bang for the buck. How much do you think the 601's would bump HP? What kind of intake would I need and would the valve covers be be center bolts like I have now? Also, woud my rockers, springs, etc. I have now be the same on the 601's?
Not a whole lot... unless you port them
Valve covers would need to be perimeter bolt - $20 summit racing.
yes, same rockers, springs etc. I'd replace the springs while you're there though, if you want to put in a bigger cam down the line, it'd be easy to do now...
Not a whole lot... unless you port them
Valve covers would need to be perimeter bolt - $20 summit racing.
yes, same rockers, springs etc. I'd replace the springs while you're there though, if you want to put in a bigger cam down the line, it'd be easy to do now...
Wouldn't I be better off just porting the stock heads I have now if there would be little gain with the 601's?
That's another good idea.
The only gain on the 601's is a smaller (arguably better) chamber. Ports are very similar, and if you're porting it out anyway.... I would only go to the 601s myself to avoid the downtime with my car.
I don't know much about heads and how much difference going from the 58 to 60cc heads that are said to be in my car from the factory down to the 52 or 56cc the 601's have really means for power. Those numbers seem very close to me but I'm deffinatly no expert on this stuff.
What would be better about the 601's chamber, just that it's smaller? I wasn't planning on porting at all but if you're saying I'd have to port the 601's to see gains than I guess I would.
I know what compression GM claimed for each Camaro engine, but the claims nearly always exceed what you'll actually find if you actually go to the trouble to cc everything with a burette.
Did anyone notice that those are 12552520 casting 305 Vortec heads?
And, for the record, an '87 305 LG4 had 9.3:1 CR - slight dish valve relief almost-flat-top pistons ~12cc total, with 58cc chamber 081 heads.
Why don't we start all over with the correct information?
(For the record, I'd just stick with the 081's.)
Yes, perhaps originator can shed a light on his actual hardware instead of us trying to guess what would be better! Firebird - please post your engine configuration - pull a valve cover find a casting number of your head.
Since you are short on funds here is another thought you may want to consider. For example, increasing (ONLY) CR from 8.5 to say about 9.5 on a pump gas (while everything else stays the same) will increase HP by about 2 to 3 percent. Running higher CR will probably require use of 91-92 RON gas. If you perform mild porting you can probably pickup the same 2-3 percent without significant fund outlays. As fellows noted above all that machine work can get expensive in a hurry! You can gain performance in other places - better exhaust systems perhaps (unless you already have one).
Additionally, I would strongly recommend - before turning a single wrench - do an ROI (return on investment) analysis. Just put down where you want your performance to be and map a path how to get there! You'll quickly see how expensive it can get if you make a wrong decision early in the game!
Alright, I'll get a casting number. Would it be likely I'd need too replace any gasket to put the cover back on? And does it matter which one I remove?
Alright, I'll get a casting number. Would it be likely I'd need too replace any gasket to put the cover back on? And does it matter which one I remove?
If it is a stock '87 LG4 305, it has 081 casting heads. If you don't know the history of the engine, the best bet would be to pull both valve covers (I had an '87 LB9 that had one 081 head and one swirlport head). The center bolt valve cover gaskets usually can be reused.
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Quote:
Originally Posted by Atilla the Fun
I know what compression GM claimed for each Camaro engine, but the claims nearly always exceed what you'll actually find if you actually go to the trouble to cc everything with a burette.
Then let's at least start with the heads he either has or is looking at.
Last edited by five7kid; 11-22-2008 at 02:49 PM.
Reason: Automerged Doublepost
Are these Vortecs fresh from the machine shop, all cleaned and whatnot (I don't think I would ever dare bolt up heads that weren't professionally checked and cleaned - but that's just me)? If they are, then maybe.
If they aren't, by time you're done paying for them to get cleaned and checked, new intake, etc etc blah blah, you're in the range of buying a cheap decent 305 casting, having them cleaned, doing some DIY work, and getting a pretty decent head.
I vote no. I wouldn't pay 250 for some re+ard 305 heads.. Your money could be better spent elsewhere. I plan on using Vortec stuff but only because I got a running (but knocking) Vortec 350 off a guy that owed me a couple hundred bucks. Also if in your shoes I would not bother with any kind of head swap until I did some more research and learned more about them all. And/or had more money to blow on it at once.
No, there not fresh machined heads, just used ones. I'll let him know I'm not taking them. I don't know much about heads so thank you guys for helping me here.
Do not waste time and money porting 305 heads, they flow good enough for a basically stock engine. If you get the L31 heads get them off of a 96 Tahoe or something along those lines, as the ones from GM Performance Parts are made in Mexico and do not flow the same even with work on them.
My buddy invested over 5K to find this out with multiple sets of heads to get it right only to acquire the junkyard heads for cheap and they flow right the first time.
There are some using the L31 Vortec heads on Chevy 305s without any problems as some mentioned. In fact Car Craft did this build below with some good info.
Hot Rod Magazine build produced 400HP. It has almost 11:1CR and peaks power at 7200RPM. Not exactly what you would call a Street motor. http://www.hioutput.com/tech/400hp/400hp.html
Hot Rod Magazine build produced 400HP. It has almost 11:1CR and peaks power at 7200RPM. Not exactly what you would call a Street motor. http://www.hioutput.com/tech/400hp/400hp.html
