Let me know what you think.

[SUX 2BU]

Howdy folks. Please see my signature for the info on my truck. It weighs about 4000 lbs. I bought those heads based on an excellent article I found online that Hi Performance Chevy published. I was actually considering stock Vortech heads and then I saw I could get genuine Darts for the same price! Sign me up! I'm hoping for at least 350 if not 375 HP. All indications I've researched seem to point that 375 is attainable including the free CompCams desktop dyno program. What do you think? Any ideas on what it might run in the 1/4? I also have an 05 Dodge Magnum R/T with the 5.7 Hemi. It runs nice and quick for a 4400 lb car and I'd like my truck to run about as quick as it does (low 14s at least).

[want-a-be]

350 hp on you 350 ci engine is only 1 hp per inch. Rather easy goal. Haven't looked up your cam numbers but it might be a bit conservitive. Had a 268H comp cams over 20 years ago. Traded out the old 327ci 350hp cam for it and hated it. My opinion is ...if your going to by new heads . Why get stock sized intake runners. At least go a lil larger. I prefer the Holley carb over the AFB type also.
All this is my preference only but you ought to be making at least 400 hp with the correct parts.

Later, Don

[SUX 2BU]

My reasoning for going with what I did was I have a 4000 lb truck with a 3 speed auto, stock converter and a tallish rear end. I didn't have to have a real soft bottom end and a powerband that starts at 3500 rpm. If I did, I'd buy a Civic with a turbo :p I like a fat bottom with strong pull up to about 5500 so small ports and runners allow that, but the design of those heads is good for nice breathing too. They flow similar to a stock Vortec head which is okay by me. Way better than the heads I have now. Right now my motor stops pulling at 4000, valve floats at 4500 and won't rev past 5000. It's embarrasing. I was hoping for some input by Bill as I've seen him iterate similar rationale for another person with a truck.

My cam has these specs:
Duration at 050 inch Lift: 224 int./230 exh.
Advertised Intake Duration: 268
Advertised Exhaust Duration: 280
Advertised Duration: 268 int./280 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.477 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.480 in.
Valve Lift with Factory Rocker Arm Ratio: 0.477 int./0.480 exh. lift
Lobe Separation (degrees): 110

It's the Xtreme Energy and not the regular High Energy 268 cam, so it has better lift. Should be pretty nice. And the report I saw said the 165cc heads actually measured out to be 178cc, so that's a bonus. I forgot to list that I chose the 72cc chambers and I have stock rods. Should be around an 8.75:1 compression ratio?

[want-a-be]

you'll like that cam then. lol...bills all yours.

[Awesome Bill]

You are exactly right about quitting @ 4500 rpm. Thats all that hyd will do with the stuff you have in there and that big puddle of oil under the lifter seat squishing in and out with rpm. This is what I would do. Put 1.6 rockers on it, get those junk push rods out of it and put in .105 wall trend stuff, you may want to check for proper length and geometry. Bet they are short right now. Check the seat pressure of the springs and then throw them away. Get the new compe stuff and put them in as tight as you can if you have a roller. Preload the lifter to .010 of bottom so it is still a hyd roller. I assume its a hyd roller? If its not your going to have to do a break in first before loading the lifter. CC the engine after you had TDC's it so we know what we are talking about with compression. The camshaft will work great. Those things what I have told you will move the rpm range to 5500. After that, its over. You may want to advance the cam 2° from what they want the intake valve to be at for chain stretch. Even 4° might work better to run @ 2° afvanved for added recoverey int he shifts with that tight converter and tall gear. let us know after that. I would start there. Fuel for your actual compression along with proper timing will wake her up!

[SUX 2BU]

Thanks Bill. I can clarify that right now, I just have stock smogger heads on it. The new Iron Eagles will go on hopefully this summer along with the new Comp Cam. The heads are already assembled and i bought them from Aerohead Racing, which I understand is also Indy Cylinder Heads. I don't know if that's a bad thing or not, but the mag review was good and so was the price. My impression was that Aerohead buys the bare castings from Dart and then assembles them with their own parts. They came to me in Dart boxes, already assembled. The heads have .525" springs, so I can use 1.6 rockers and have just a smidge left of room before going over that .525 limit. I fully plan on going with 1.6 rockers, but a person whose opinion I trust, didn't have lots of good to say about using 1.6 vs. 1.5. Would there be any drawback to using 1.6 rockers?

The cam I bought is a hyd flat tappet, no roller. The rockers will be roller though. So yes, I will have to break the cam in and I was going to use Shell Rotella oil for that because of the high zinc content it still has vs. other modern oils which now have reduced zinc levels in them. Sound about right? I would like this motor to pull strong to 5000 and rev to 5500 if need be, but I don't need 6000 rpm. The motor currently has stock 350 rods, flat top pistons and a .060 overbore. The new heads have 72cc chambers, so what does that work out to for comp ratio?

Thank you for your info about the pushrods and lifters. I'm undecided yet if I should do the swap myself or have a shop do it, but I need to find a shop that knows stuff like you do instead of just taking stuff off and bolting it on blindly. I can at least arm myself with this info and ask that they do the same.

[Scott McMullen]

350 chevy STOCK Rods and Crank
KB Flat Top Hyper pistons
XE284 Comp cam.507 .510 240 246 @ .50
Box Stock Dart Pro 1's 200cc
Edlebrock Performer RPM dual plane intake
780 cfm Holley Carb (Pro Systems)
1 5/8 headders
makes roughly 400 hp on pump fuel
The heads are a little big IMHO but he can grow into them
In his 3400 lb car Footbrake 2800 stall and a 4.10 gear
12.08 @ 110 mph


350 .30 over flat top 4 valve reliefs
Stock 1970 Lt-1 Lower half ie Pink Rods and a Steel Crank
Dart S/R 165cc Box Stock
GM performance parts LT-1 (1971 Spec) Solid Cam .485 Lift
Gm Z-28 Aluminum intake
Holley 780 Vintage
Points ignition
GM Stall convertor
3.42 Gear
1972 Nova TH 350 3450 with driver
13.23 @ 104 Wanna be Pure StockRide

[want-a-be]

sounds good

Don

WCRE

[Awesome Bill]

Actually is it better on the lobe when you run the 1.6 rocker but a little more on the rocker which will easily take it. You do have to remember to take your lobe lift and x's it by the rocker ratio to come to gross valve lift which also will be net with a hyd. Don't forget to get the comp cams break in lube that they sell. I think #153 or 159. One is assembly lube red, the other is black and nasty. We sell these in the speed shop to everyone who purchases the cam and lifters to keep the come backs down. I think your combination will do what you want and a really good thing to do is run her first, get some track info, then do your changes and then run again. Real testing like this is the only way to go. DO NOT TAKE ANY ARTICLES WORD FOR YOUR END RESULT. Most times there is a little basic thing called exageration factor and they ususally work from very worst to absolute best situations. Have fun. The 72 cc's is going to hurt not help with the flat tops 9/1 maybe. Make sure you get a Cometic .027 gasket with a 4.060 bore. Just used them yesterday and they made up 3cc's.

[SUX 2BU]

Thanks Bill. I picked up a bottle of the black stuff by CompCams for break-in oil additive. You said 'nasty'. Is this not good to use? I'm also doing the first couple of oil changes with Rotella 10W30. I was just pondering the chamber size this morning and kinda wishing I'd gone with the 64cc but I have what I have and at least I know I won't HAVE to run premium fuel if I don't want to.

I still have to confirm what ratio my stamped roller-tip rockers I have in the truck are now. What's your opinion on Proform rockers? Speed shop sells stamped roller-tips for only $80 a set. Almost 1/2 the price of the CompCams stamped ones but I dunno if it's cheap Chinese crap that will bust on me.