Dart 10024370 heads

Vortec
175 cc runners

What do you guys think of these? Also, what do you think of this valve job?

Overall the heads look like they'll clean up real nice. I inspected the valves and below is what I found.

 

Plan to use them on a flat top 350 tpi with scoggin base. Would it be worth the effort to mill these down to 64 or 62 cc?

 

Not a fan. Those are 165cc port Iron Eagle heads adapted for use with Vortecs. They do not flow well at all and also have a 67cc chamber. They are far from even a decent performing head. The only thing they had going was they were less crack prone than GM Vortecs which made them gpod for mass rebuilders building stock engines for soccer mom Tahoes. They were dead last in a distant 5th place in the 5 way Vortec head shoutout that was done in the mid 2000s on a basic 350 with a 223/230 @ 0.050 cam. 4th place was a stock production Vortec and they spanked the Darts badly.

 

Interesting. I wonder what the story is behind the 165cc claim. I see it all over the Internet, even that article you reference, but the head part number points to the spec sheet here. 10024370. Being 175cc

https://www.motortrend.com/how-to/148-0507-street-style-vortec-head-test

 

I dunno.

A quick google search of Dart 10024370 produces this on Dart's own site and says 165cc.

Are there two versions of this head?

Dart has a good reputation, but this statement seems a little strong for this head..."Our precision cast ports and chambers produce outstanding air flow without time consuming porting. " I do like the look of the chamber shape though.

https://www.dartheads.com/shop/cylin...DlrV-t_SSl57B1

 

Some more digging and seems like the Summit Vortec Heads are actually the darts.

https://www.summitracing.com/parts/s...Jre9Upbd4PK3nt

 

They are or were Darts. They also have a weird raised eyebrow in the top of the intake ports like the early 90s CPI 4.3L heads do. They are definitely 165cc though.

 

I get the same sheet.
Notice that you must use self-aligning rocker arms and the valve guide spacing has been moved .030" from stock.
On the plus side, the valve job looks nice.

 

I currently have 083 350 TPI heads, which are 64cc. Assuming that the Darts will give an ample bump in HP paired with the GM 6492 cam I have on the shelf, how much performance am I leaving on the table if I forgo milling the new heads and plop the 67ccs down as is, once they are cleaned up? 3-5hp? Or more? Also. Will 67cc chambers sound and perform any different? Dart advertises that heads can go down to 60cc, but I was thinking 62cc would be safe if I was going to go through the trouble. It's a 1992 and I have verified that there are flat top pistons with my scope.

 

Don't EVER mill heads and then have to run a thick head gasket. That's stupid.
Only have the surface machined if it is necessary.
Simply use a thinner head gasket, paying attention to your quench measurement - try to stay around .040".

 

I noticed that in the photo on the Summit site. I've never seen an SBC head that looked like that.

 

I have a Ram Jet 350 intake manifold and it appears to have the same intake port design with the raised eyebrows that matches these heads. The tip of the fuel injector resides in the raised eyebrow.

 

These Summit Racing Vortec cylinder heads are your Dart Iron Eagle SS Vortec cylinder heads that have been rebranded for Summit Racing.

They are a stock replacement "Jobber" engine rebuilder cylinder head. They aren't some kind of high performance racing cylinder head. They probably started off as a stock replacement "Jobber" engine rebuilder cylinder head for TBI/TPI and other non Vortec SBC applications. It looks like the exhaust crossover for TBI/TPI and other non Vortec cylinder heads are still in this casting just not machined for it and the exhaust flange bolt pattern is the 7-bolt design like TBI/TPI and other non Vortec SBC applications use.

I believe Eric misspoke when he mentioned these heads have 64cc combustion chambers. I don't think Eric measured the the intake & exhaust runners or the combustion chambers on these heads he reviewed in the video.

Eric seems to think they flow about the same and somewhat better than a stock Vortec head according to the flow numbers he has actually measured of other Vortec heads compared to these Summit Racing/Iron Eagle Vortec heads. They could flow better if the machining was improved in the exhaust and intake port removing the huge ledge in the exhaust port and the small ledge in the intake port. A 30 degree back cut on the intake valve would also improve the intake flow.

Are the Dart/Summit Vortec heads going to flow better and make more power than the stock TPI cylinder heads? Odds are real good they will since stock Vortec heads do.

These heads are going to be way better than a stock assembly line installed Vortec head. Stock Vortec heads these days are JUNK. They started off as lightweight, thin wall emissions castings that just so happened to be the best flowing stock cylinder head GM ever installed on a production engine. Vortec heads back in the day were great when you could walk down the sidewalk and trip over a good set just laying on the ground. Back when they were a dime a dozen in the salvage yard off a low mile wrecked truck or you could buy them new for cheap because they were still in regular production and a cheap cylinder head upgrade. Now they are wore out junk and 7 out of 10 of them are cracked and the ones that aren't cracked need a full rebuild.

These Dart/Summit Racing Vortec heads are a mile better than old, wore out JUNK, crack prone production GM Vortec heads.

The TPI Vortec lower intake manifold base is the only one still made today that you can still buy brand new and for a reasonable price. It flows about the same as or maybe just a little worse than a stock GM TPI lower intake manifold base. It's not a high performance lower intake manifold base. It's a make this thing bolt to this thing and fit right part. The problem with the stock GM TPI lower intake manifold base is the shallow intake manifold port to cylinder head port entry angle. Vortec heads and the TPI Vortec lower intake manifold base have raised intake ports. That makes the entry angle even worse.