1sick-Z

iTrader: (3)

I know what your thinking I have a set of DART 250 cc CNc heads I plan on revving the motor like a bitch tho they will make power up top I have already talked to every 1 at dart and a couple of my dads retired GM engineer friends they all said it would be insane on the top end, so aside from all that I had my car tuned a couple days ago and they claimed a 2.08 intake valve could not be run on a stock cubed motor because it would hit the cylinder walls

has anyone done this I was thinking because of the fact that it was an aftermarket head that it would be fine because dart never mentioned it and they knew my setup the entire time they were making them for me

If it wont work its no big deal the motor is coming out for the winter and il just have to go a little bigger

vettenuts

iTrader: (4)

I can't answer your question, but the World LSx heads for 346 installed the same size valve. You can read about it at Vette magazine's web site.

Shawn MacAnanny

iTrader: (12)

I have also heard they will hit the cylinder wall.

j99fbody

iTrader: (1)

i was told 2.08 was to big for stock bore

JFM-jr

iTrader: (23)

I can tell you the 2.08's in my 5.3 heads dont hit the cylinder walls in my stock shortblock LS1. I did however need to flycut the stock pistons with the LG cams I have run.

1sick-Z

iTrader: (3)

I was hoping because they were after market heads they would work on a stock bore I wanted to throw some hardened rods in it and make it a screamer but then again while the motors out I have plenty of room to grow with the 250 cc runners so I might as well do the stroker while its out if the issue arises

405HP_Z06

iTrader: (11)

2.08" intake valves are too large for a 3.898" bore. The shrouding caused by the large valve and small bore won't allow you to take advantage of the flow these heads provide. You would be better off with a 205 or 225 Dart head, ported appropriately.

For the CNC 250's, Dart states this about these heads:

transwiz

iTrader: (26)

I have 2.08's in my 317 heads that are milled to 62 cc.I have a tr224 cam on a 346 and I don't have any problems.I was told my cam wasn't big enough to worry about.If dart says they won't work you probably should
not use them on a 346 block
__________________________
2000 t/a ws6 with lots of mods

Kingc8r

iTrader: (21)

Interesting read, I would follow what DART suggests

1sick-Z

iTrader: (3)

thats what gets me because darts website says no but darts personel says theyr just fine I have heard from many about the shrouding effect off the cylinder walls with big valves thats y I was asking. These heads flowed 354 cfm @600" lift which i dont think I would utilize all of it anyways do to a plastic intake manifold but still I would just like some feedback to know if these big valves would even work

405HP_Z06

iTrader: (11)

You would need to see the flow numbers for these heads on a 3.898" bore to understand what you would really be getting. The flow numbers advertised for these heads were performed on a 4.0" bore.

I think the bottom line is they will work, but your not doing yourself any favors by running them on a small bore.

1sick-Z

iTrader: (3)

very good point now what bore would you personally go with I know that I can keep my same block and do a 383 stroker kit but if I go ls2 or ls3 short block how big could i go

405HP_Z06

iTrader: (11)

LS2 minimum, preferably LS3 for the CNC'd Dart's.

The 383 is also a great option. For this I would go with a TFS or Dart 225.

Beaflag VonRathburg

iTrader: (176)

If you're stuck on using those heads I would not put them on a 3.9xx bore. At the bare minimum I'd use a LS2 block, but the larger the bore the better. Like someone said before the valves are going to be so shrouded on that small of a bore that the flow is going to be killed. Not to mention it is going to feal like a dog down low with minimal port velocity.

1sick-Z

iTrader: (3)

maybe I will do a 383 ls1 I hear that they are not reliable tho as the stroke is more then the bore is there any truth to this????

Beaflag VonRathburg

iTrader: (176)

There's no reliability issues with a 4 inch stroke if it's assembled properly. Those heads may physically fit on a 3.90x bore, but they will perform like crap compared to a properly setup combo. You're wasting your time using those heads on an LS1 block.

Carlos_Garza

I guess I'm going to have issues with my setup. I have a set of AFR heads big bore with 2.08 valves and an MS4 cam.... This will go on an LS1 engine... What do you guy recomend I do. Keep the setup as it is? Go with a 383 stroker? Or look for an LS3 short block?

JFM-jr

iTrader: (23)

Cant you flycut the pistons?

Carlos_Garza

Yes, most likely we will have to flycut the pistons. I bought the heads used, also the cam, i'm kind of short on cash at the moment...

JFM-jr

iTrader: (23)

Sent you a PM Carlos