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Old 09-28-2008, 09:04 AM
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350 w/305 Hi Po 601 Heads

Does anyone have an oppinion on putting 305 GM "601" casting # heads on a 350 block. I am in the process of a port & polish job on the heads and will be building a 4 bolt .040 over block. Yes the pistons will need to be dished for the 53cc chambers but I have Comp beehive springs and hope to have good flow #'s when the heads are done. I am looking for an economical balance for now and maybe finding some aluminum AFR or Dart heads in the future. These HiPo aluminum CNC heads are over $2000.00 currently.
Any thoughts would be appreciated.
I can have up to .600 lift on my heads.

Thanks,
Roy

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Old 11-14-2008, 06:53 PM
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350 w/ 601 heads

I have done this once and am planning on doing it again. I did a FULL port/polish job, had chambers shrouded to 60cc's (when first cc'ed they were 58cc's even though mortec.com shows 53cc's) and cut for 1.94in/1.55ex. You can get the heads from Allied Motor Parts (alliedmotorparts.com) Any way you want. I paid $230 for a brand new pair already built. Put .550 max lift double springs, screw in studs and guids. Engine had .030 over bore with D dished pistons making 9.5-1 comprestion. I used a doug herberts cam with 284/284 advertised duration .480/.480 lift, 1.6 roller rockers and .100 over push rods. Mallory ignition system, flowtech headers with cherrybomb extrems dumped before the rear end, victor jr intake with 2" spacer. Custom modified Holley 650 DP flowing 730cfm's. This engine was put in my friends stripped 3140lbs. 1980 trans am with th350, 2800 stall and shift kit. Rear gears were 3.73 posi. After break in and a week of driving/tuning it, we took it to the local dyno shop. It made 422HP and 393 TQ. Best pass has been a 12.48 in the 1/4 on street tires. We hope to get slicks for next year, I think we should be right around 12.00 flat.
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Old 11-23-2008, 08:26 PM
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Thanks

Thanks FKR, now I know it is worth persuing. As I go through the porting process it is exciting to see the shape of the runners molded into something that should really improve the airflow. This is time consuming but something everyone should try once.

Roy
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Old 11-23-2008, 09:12 PM
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I used the same thing on a 383 that I built and ran for awhile. They worked really well, I installed 2.02/1.60 valves and ported the heck out of them and that thing had tons of power. It wasn't very good over 6,000 though. Even with all that work.

Why beehive springs? Unless you are hurting for spring pressure at a lower intstalled height than I don't think they are necessary. Make sure they match your cam if you already have them.
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Old 11-23-2008, 09:40 PM
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[QUOTE=Double_v23]I used the same thing on a 383 that I built and ran for awhile. They worked really well, I installed 2.02/1.60 valves and ported the heck out of them and that thing had tons of power. It wasn't very good over 6,000 though. Even with all that work.[QUOTE]

A if you do not have a good matched cam, intake, carb, and ignition for the high RPM'S you will never get them. These heads must have .500-.550 of lift to ever make it past 6000rpm's. My lift all together is about .535 and my engine pulls like a beast from about 2000 all the way to 6400rpm's and I shift at about 6500.
And yes, I spent about 30 hours porting and polishing everything, making it perfect.
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Old 11-24-2008, 03:56 AM
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Yes I have a set of them #601 Heads they have S/S 1.94" Intake Valves 1.50" Exhaust . And Screw in Studs with Guide Plates Z/28 Springs . As for Full Porting Them . Your Looking more Like 30 Hours a Head . To have the Bigger Valves installed with the Screw in Studs and Guide Plates all new S/S Valves and HD Springs . Your Talking some Cash there . Not saying what your Time is worth to Port them Thin cast Smog Heads . I have Ported Many cylinder Heads . But this is the Last set of 305 Heads that Will be on my Bench . If you want a Good set of 305 Heads buy the World Brand S/R 305 Heads . For a 350 Buy the World S/R Torker Heads with the 2.02" / 1.60" valves Screw in Studs and HD Springs ready to Bolt one . Much Better Castings and Flow 170cc out the Box .
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Old 11-24-2008, 07:54 AM
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170cfm! Holy metal Batman! That could make an easy 325hp.


And 30 hours on a head is VERY excessive unless you're doing an all out race job. Even 30 hours a pair is a little on the long side.

As for the 601 castings, if you can make 422 RWHP on a set of 305 heads, then congradulations! That is some true hotrodding there and the best part is when you go into a yard those 305's are usually untouched.
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Old 11-24-2008, 09:59 AM
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I only pay around $125 for a complete HP head kit. All in all, I pay a max of $350. That's the price of the heads and the HP kit. These heads are a dime a dozen and for that they perform very well for the price. I have never heard of any one having these heads crack on them. Alot of people say they are crack prone but I have yet to see that or for any of my friend to have that problem. I just know that if you want cheap HP right now (esspecially if you already have these heads or even 416's this is not a bad alturnative) this is a good way to go. Use them till you can afford a GREAT set of heads (meaning no plan vortecs) something that is really worth while to make a differnece.
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Old 11-24-2008, 12:07 PM
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Quote:
Originally Posted by ap72
170cfm! Holy metal Batman! That could make an easy 325hp.


And 30 hours on a head is VERY excessive unless you're doing an all out race job. Even 30 hours a pair is a little on the long side.

As for the 601 castings, if you can make 422 RWHP on a set of 305 heads, then congradulations! That is some true hotrodding there and the best part is when you go into a yard those 305's are usually untouched.
How much grinding do you think it would Take to make a set of 305 heads Flow as well as a set of World S/R Torkers with 2.02/1.60" valves ? Lot's Right out the Box S/R Torquer Heads on a Flat top 350 can make 375 H.P with an XE268H Hyd Camshaft . Yes that a Street Build for more HP you go 180-200cc Heads . 30 Hours on a set of heads is not at all a lot of time . I have ported heads for many year's . It takes more time when your working on stock castings .
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Old 11-24-2008, 12:25 PM
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Sorry Tango, I replied to yoru PM, I thoguht it was about a different thread. And if you consider 30 hours of porting only work normal then you're probabaly loosing money on the deal. And I know you can port aftermarket ehads faster and better, but I still love seeing factory pieces pushed to the edge with just some time on the work bench.
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Old 11-24-2008, 01:17 PM
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I you Like to Port stock Heads as I do . Start out with better castings Like #461 #462 #186 even 76cc #487 #993 Heads
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Old 11-24-2008, 06:45 PM
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[QUOTE=FKR][QUOTE=Double_v23]I used the same thing on a 383 that I built and ran for awhile. They worked really well, I installed 2.02/1.60 valves and ported the heck out of them and that thing had tons of power. It wasn't very good over 6,000 though. Even with all that work.
Quote:

A if you do not have a good matched cam, intake, carb, and ignition for the high RPM'S you will never get them. These heads must have .500-.550 of lift to ever make it past 6000rpm's. My lift all together is about .535 and my engine pulls like a beast from about 2000 all the way to 6400rpm's and I shift at about 6500.
And yes, I spent about 30 hours porting and polishing everything, making it perfect.

Comp 268H cam, 10.7:1 compression, 750 cfm carb, Performer RPM intake.

The Cam lift has very little to do with how many RPM's your engine will make. You can open your valve to .750 if you want, if the runner doesn't flow well enough you won't see the RPMs. This ain't exactly my first Rodeo, and I am telling you that this combination ran out of power around 5800 RPM.
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Old 11-24-2008, 07:50 PM
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Comp 268H cam, 10.7:1 compression, 750 cfm carb, Performer RPM intake.

The Cam lift has very little to do with how many RPM's your engine will make. You can open your valve to .750 if you want, if the runner doesn't flow well enough you won't see the RPMs. This ain't exactly my first Rodeo, and I am telling you that this combination ran out of power around 5800 RPM.[/QUOTE]

Then Please by all means explain to me how I get higher rpm's than you with small valves. Yes, I have a single plane and you have a dual. The cams are almost the same. I have less Cubes, smaller carb and my compression is a whole point less. Max flow is always at a given lift, and almost any head ported or not will have it's best flow at or around .550. That is a FACT just look any flow chart for almost any head.
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Old 11-24-2008, 09:29 PM
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I would imagine it has something to do with your gearing. The weight of your car and the diameter of your tire. I would be willing to bet that the HP Drops off pretty sharply around 6000 but you don't notice. Also your LSA probably is lower. Also you spent "30 hours" on your heads so they probably flow more than my 8 hours total. And with the runners being so small there is no advantage to having larger valves than 1.94. My internal components could be heavier or maybe The longer stroke is not as condusive to higher RPM.

I am not saying that your combination didn't do what you say it did. I am saying that this combination did what it did. I am also saying that your reasoning for why it revved higher is "out to lunch". You think .015 more lift for a few few hundred-thousanths per second every rotation will give me power for another 800 more RPM?

Last edited by Double_v23; 11-24-2008 at 09:40 PM.
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Old 11-24-2008, 09:47 PM
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If it were me here is what I would do (take it for what it's worth):

Figure out what aluminum heads cc will give me the compression I wanted with flat tops (probably a 64cc head give or take depending on other stuff). Anyways with that in mind I'm going to go find some 64cc Darts that are used, but in good condition. My last set I paid $425 for, the set before that were platinums that I gave $500 for. Not bragging these prices - just trying to say deals are out there. Both of those prices were complete sets of heads - setup for flat tappet applications, ready to go. These heads will work better then any stock GM head out there and when I buy aluminum heads they will still be worth the same as I paid for them (assuming I didn't wreck them).

People love getting a "deal" on 305 heads - great, more power to them. Start adding up what you will potentially have in:

Heads from junkyard
Having them hot-tanked
Having them re-surfaced
Having the valves ground
New Springs
New Retainers
New locks
Tapping them for screw in studs if you are running much spring pressure
New guides if they are worn out
Regrind the valves
Multiple Carbide burrs for porting
Multiple drum rolls for polishing
Epoxy if you are going to get crazy
Sealer if you are going to put down epoxy

The stuff adds up in a hurry. Then a year down the road when you go to aluminum heads what is there resale value? 305 heads typically appeal to the "bargain shopper" - so maybe $100 for the pair at the high end? That's eating a lot of coin just as a stop gap fix.
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