I'm looking at a great deal for a fully complete and running ls1 motor for my wife's 79 corvette. She wants a mildly built ls1. This ls1 has the hotcam (ls6) and a zo6 valvetrain. Only thing I'm uneasy on is its got stock 853 heads. I have a set of 241 heads hanging out in my garage would it be worth it to port them and move all the valvetrain stuff over or will those 853's be fine.

 

All ls1 heads are within a stones throw of each other. Anyone who tells you one set is better than the other in terms of power is stupid.

However, a few have advantages/disadvantages.

806 heads have perimeter bolt valve covers which can be a pain in the ***.

Some 853's have a pry notch which limits you to a stock style composite head gasket.

Other than that, all ls1 casting heads flow almost exactly the same and can produce the same amount of power in all forms. (Ported, milled...etc).

 

In your case, I would go ahead and do what you want to the 241's, simply because you can still drive the car and not have it torn down for weeks waiting on the heads to be ported or whatever. You can simply swap them out.

Also, if your 853's have the notch, you don't run the risk of buying gaskets just to find out they won't work.

 

That is not true. 243 heads flow much better than the 853 heads. That is not an opionion.

 

Hmmm, that is because 243s are not LS1 heads

 

Beat me to it...thanks pred.

 

the only difference between the 853's and 241's was the process used to cast them. Otherwise the port design and flow is exactlly the same. Dont worry at all.

 

i think the OP is generally referring to all LS1 specific heads. and yes... in stock form they suck. but they have a lot of meat to work with when porting.

 

Still, compared to just about any old school small block heads the 853's are outstanding. But you could always look into an AI 241 CNC port job and make quite a bit of power. Fwiw, if you're not after big power, a stock LS1 with bolt ons is a blast to drive. I'm still stock internal and managed a 7.62@90.73 1/8th, havnt even pulled a valve cover. This thing stock runs nearly as good as my previous 383 sbc.

 

I have 853 heads on my L33 bottom end & using MLS gaskets with no issues & it runs just fine.

I have flat top pistons & milled them .015 to bring up a little comp. If you look at the pic you can see the blue spot at #3 & 5 cyl that deals with the notch.





Another LS1 tech old wifes tale busted. LOL

 

I'm familiar with a bolt on ls1 I had one for 5 years lol. Never did any head work though so I was asking about the negative hype I always see from 853 heads.

 

Yea they are better than SBC heads by leaps and bounds. It's just that there are much better alternatives for cheap these days. 243's are a cheap and easy power-upper, and so are 823's for 6.0's.

 

My car made good power with the 806 heads which are "worse" than what you got

 

There is nothing wrong with 806 heads except the slightly larger chamber and the crappy valve covers.

 

I'm guessing someone already sold the 799 heads that came with that motor before you bought it?

 

853's really respond well to a moderate amount of port work. I did a set just to see what they might do. Nearly a 40 cfm increase at max lift.
STOCK, .100 EXH. Ported IN. .200- 146 cfm + 6 cfm
.200-140 cfm .200- 101 cfm .300- 212 cfm + 13 cfm
.300- 199 cfm .300- 136 cfm .400- 255 cfm + 23 cfm
.400- 232 cfm .400- 162 cfm .500- 268 cfm + 36 cfm
.500-233 cfm .500- 176 cfm .600- 272 cfm + 39 cfm
. stalled after that. .600- 184 cfm

Exh. went to 207 cfm@ at .600 lift( +28 cfm) and gained at every level. This was all done with stock valves and 1/2"radius beads of clay (intake) and NO exh. pipe, on a Super Flow 600 at LJ's machine in Napa Ca. So none of it was a guess. Rocker "bump" removed, swirl step removed, guide boss streamlined and bowl blended, intake runner just smoothed out, not enlarged.

 

Yeah, 853's are so bad that our ex ASA Monte Carlo road race stock car would only run 182 mph through the tri -oval on the Daytona Road course in the Crane Cams V8 StockCar races. The Car lapped in the 1:57-1:58 range utilizing stock long block with the exception of a mild road race cam, 1 3/4" crossover style stock car headers, GMPP 4 bbl intake and a Holley 650 4 bbl. compression was stock, and no porting. Car weighed 2800 # with driver, utiilized Jerico 4 speed and quick change rear end. Made about 420 HP to the wheels.

We also ran similar times with a nearly identical motor that used the 706 heads with the smaller intake valve. Made noticibly better torque but with a corresponding bit less top end. Performance fell of dramatically at 6500 with the 706 heads.

Like others have said, they are still way better than the old "Fuelie" small block heads of the past.

 

I have 853 heads, cnc ported by Advanced Inductions. See numbers in sig. My previous setup was a streetsweeper cam with these heads unported, did 405 rwhp with the same intake setup and headers.

 

Yep I bought the bottom end & just needed a pair of heads to get it running & not looking for peak performance as its just a daily driver.

Still runs damn good.

 

lol ....