18* ?

[ckyracer00]

Other than heads what would be needed to convert a 23* motor to a 18* motor on a lil M block and what is the best head on the market? Thanks in advance

[dynoman14]

You will probably need Intake Manifold, heads, rocker arms, pistons, pushrods and possibly offset lifters. Of course you will have to change headers probably have to update the camshaft to match the heads.

If you go from 23* and want to make a big upgrade SB-2's require about the same parts but you also have to change the cam as the intake/exhaust firing pattern is different.

Have you ever thought of going with a top level set of 23* heads? Some of them flow over 300cfm and will make 650-700hp with the right combination of parts. Profiler & Brodix Head Hunter are a couple.

[sj valley dave]

We have had 2 SB2.2 engines. The first one had a standard firing order 18436572 cam, the second has a LS-1 firing order 18726543 in it...You don't need to have a 7/4 and a 3/2 swap cam for a SB2.2 engine...But I do agree with Dynoman about the 23* head effort...the AFR245 head is seeing 340-350 cfm flow numbers...That would be some stout numbers for a 23* deal...Should make over 700 hp fairly easily...

[perfconn]

Not sticking up for anyone but I think all he was saying was that if you change from 23 to sb2.2 is that you have to change the cam not the firing order.I agree with both of you that going to a better 23* head would be much more economical.My last set of 23* RHS RR steel heads were 336cfm at. 700 and 305 at. 500

[sj valley dave]

Hey Perfconn, those are some good numbers...There is a guy that races an injected 360 out here that has a set of the AFR 245's that flowed 361 cfm...pretty cool for a 23* head! The only reason I brought up firing orders was that Dyno said that you have to change the cam "as the intake/exhaust firing pattern is different." That is not really accurate and that is the only reason I mentioned it. you can run a standard firing order, a 7/4 swap or a full LS-1 firing order...The one thing we noticed was that the idle seemed a lot smoother with the 18726543 firing order, even though both engines made roughly 820 hp...

[perfconn]

Dave,
Those RHS raised runner steel heads are killer steel heads.HVH did them for me.I was pleasantly surprised that I got 685hp out of an all steel 23* 361ci engine on gas.

[ckyracer00]

Are these flow numbers for the afr245 " out of the box" or is this with alot of work done to them?

[sj valley dave]

Factory CNC ported heads...Flowing 350 cfm compared to the mid 320's in the AFR 220 heads.The 245's from the factory are set up with a 2.12/1.60 valve combo. Can not run stud rockers, has to be shafts as they opened up the CSA by moving pushrod location in the head some..

[perfconn]

Dave,
What is csa?

[Leftterns]

I believe that's a reference to Cross Sectional Area.

[dynoman14]

I guess I should have been clearer on the camshaft firing comment, the firing order of the engine is the same as a standard chevy, the order of the lobes on the camshaft are different so a stock chevy cam will not work with SB-2 heads.

With that being said, I have run multiple firing orders with the engine and there are a couple special ones that work way better than the rest but you have to start out with a round lobe billet cam core at about $800 unground. Then you have to couple your headers different to make them scavenge right and then you can really tell a difference. Folks that just try different firing orders on engines without changing the headers around are only doing 1/2 of the work.

I think there are a couple stainless guys out there like SPD that make tri-y's that have multiple sleeves on the y's so you can change the patterns from cyl to cyl on the dyno and fine tune your exhaust system to your firing order.

Some folks wonder how I get extra power out of engines, crate engines especially. Not all headers are created equal and every small block does not like the same tube pairings. You might want to take a close look at the winners headers, if you can see them in tech you might learn something.

There is a reason some headers cost $500 and some cost $2500, if you don't already know the differences then you might want to learn some more about header tuning. I just tested 4 more sets of headers today on a 604 crate and there was +/- 22hp from the best to the worst and this is after I have had 17 different sets custom built ( over 2 years ) with something different in them every time they are built.

[sj valley dave]

Dyno, if you have a proper set of headers, for the firing order, have you ever seen any torque/hp number changes if you run a std firing order, a 7/4 swap or the full 7/4 & 3/2 swap...Lefterns is correct..That is what I meant by commenting on the CSA of the AFR 245 heads...

[perfconn]

Everything that dyno said about pairing up tubes and firing order only applys to tri-y headers.Regular headers are only critical about tube and collector size.Lots of people think tri-y headers are a magic bullet and they are not.

[dynoman14]

Dave,
My biggest problem in testing cylinder swap cams is obtaining cores for the engine I want to test on right now, simply not available. The next thing is headers are not plentiful and the ones I have tested pretty much suck.

My next little project will be a LS headed Ford so firing order will be right, cams easy to get and all I need to do is get headers built the way I want them. Been talking to Joe Beyea as he builds all of the stuff I want and just tells me it won't work until it does and then he tells me it is just because I build wierd $hit that other folks would not even consider.

I have been present at some pretty high buck Comp engines with swap stuff and it was big above 7500rpms. Gebler and Calvin ??? headers around $3500 set were piled in the floor like cord wood.

I have some crate stuff running bigger tubes than some of his Super Stuff, go figure...

[dbr25]

I personally would never invest in 23* heads when rules allow otherwise. Those PEAK flow numbers don't mean much on the racetrack, they are pulled at a steady vacuum( i.e. 28" water) Do you think an engine pulls a steady 28" on the track? Even if I had to give up some peak flow to get 18* (or less) I would, your torque curve will be much flatter. The air gets "jammed up" on a 23*(at higher rpms) because the air is directed more toward the cylinder wall, where a flatter valve angle is directed more downward, towards the crank. I'll probably get blasted for this post, but I'd go for 18*. I have raced guys that had 23* stuff and I had 18 or 15, and they were done at the flagstand. I would gain several car lengths on a long straightaway. Doesn't make as much difference on small 1/4 mile tracks, but does help on them too, especially qualifying.

[sj valley dave]

We run SB2.2's so we don't have a dog in this race. Just gotta say that the AFR 245's show great numbers at not only at peak valve lift, but throughout the range of lift. They have reduced the pushrod pinch area that 23* heads suffer from greatly...This helps reduce the airflow stall that you normally se e in a 23* head over 7500 rpm. They can and have made 725-750 hp with good torque numbers....

[let-r-eat]

Can't speak for the AFR 245's but those RHS 235 RR 23* heads are nice!

[hpontap]

I used a set of Brodix CNC Track I's and was really impressed. Out of the box on a 393ci they made 720hp and over 640ftlbs all below 7,200. Basic stuff , nothing trick 13.8-1 compression and with a slightly worked Victor 2975 intake to boot.

[perfconn]

dbr25 is exactly right as far as making the choice of whether the 18* will make more power than a 23* but sometimes your budget enters into the equasion.Its easy to make choices when you are spending someone elses money.

[butch haney]

I saw alot of Mullins 23* motors running up front at volusia. 1/2 mile hammer down track!