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Old 08-05-2012, 05:12 AM
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350 sbc with 305 h.o heads will this work whats the ups and downs

I have a 3970010 350 and i have a pair or 81's h.o heads laying around what would be the ups and downs can i run 87 pump gas.also have a 2000 rpm-6000rpm cam laying aorund with a 480 lift what would happen if i leave stock stall in thanks for looking :d

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Old 08-05-2012, 06:34 AM
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Originally Posted by smallblock383 View Post
I have a 3970010 350 and i have a pair or 81's h.o heads laying around what would be the ups and downs can i run 87 pump gas.also have a 2000 rpm-6000rpm cam laying aorund with a 480 lift what would happen if i leave stock stall in thanks for looking :d
I do know those heads are going to run the compression ratio way up and it will need more ignition advance. Do a search on the site we have talked about this same swap several time on here. JMO



Cole
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Old 08-05-2012, 06:58 AM
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...
also have a 2000 rpm-6000rpm cam laying aorund with a 480 lift what would happen if i leave stock stall in thanks for looking :d
...
You'll be the guy shifting into neutral at every stoplight.

You'll also be the guy with one foot on the gas, the other on the brake while paralell-parking. This will be more difficult now, without power brakes, because you have very low vacuum.

You'll find getting started on a steep grade to be embarrasing. There's nothing worse than a "hi-performance engine" that couldn't pull a popsicle stick out of a bowl of pudding.

What is this engine going into? The heavier the vehicle and the taller the gears (lower numerically) the worse it gets.

Bottom line ... you ain't gonna like it. Get a stall convertor.

I am saying all of these things from experience.
1966 Ford Galaxie 500 with a 351C-4V with the stock Cruise-O-Matic (FMX) and convertor. I am sure that those BIG intake valves/ports didn't help either.
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Old 08-05-2012, 08:13 AM
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Originally Posted by smallblock383 View Post
I have a 3970010 350 and i have a pair or 81's h.o heads laying around what would be the ups and downs can i run 87 pump gas.also have a 2000 rpm-6000rpm cam laying aorund with a 480 lift what would happen if i leave stock stall in thanks for looking :d
I'm doing this build as we speak, with some minor porting and polishing done to mine. Your compression will likely be way too high for 87, and the heads really need some help to make them worth using. From what I'm reading, and listening to people who have done it before your going to want less cam then that, where that one starts to come into its own is when your heads stop moving air. You should be looking at something closer to an RV grind that promotes low end torque over breathing up high. I'm using the Lunati 10001 which I'm hoping makes a ton of torque down low to compliment the heads....but agin, currently I'm just talking out of my *** as its all parts on a bench until next week lol.....
Good luck!
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smallblock383 (08-05-2012)
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Old 08-05-2012, 05:05 PM
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Originally Posted by 66gmc View Post
you'll be the guy shifting into neutral at every stoplight.

You'll also be the guy with one foot on the gas, the other on the brake while paralell-parking. This will be more difficult now, without power brakes, because you have very low vacuum.

You'll find getting started on a steep grade to be embarrasing. there's nothing worse than a "hi-performance engine" that couldn't pull a popsicle stick out of a bowl of pudding.

What is this engine going into? The heavier the vehicle and the taller the gears (lower numerically) the worse it gets.

Bottom line ... You ain't gonna like it. Get a stall convertor.

I am saying all of these things from experience.
1966 ford galaxie 500 with a 351c-4v with the stock cruise-o-matic (fmx) and convertor. I am sure that those big intake valves/ports didn't help either.



i will have low vacuum becouse of cam or because of the 305 ho heads should i just get a pair of 350 voetec heads ?
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Old 08-05-2012, 05:08 PM
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Originally Posted by bygddy View Post
i'm doing this build as we speak, with some minor porting and polishing done to mine. Your compression will likely be way too high for 87, and the heads really need some help to make them worth using. From what i'm reading, and listening to people who have done it before your going to want less cam then that, where that one starts to come into its own is when your heads stop moving air. You should be looking at something closer to an rv grind that promotes low end torque over breathing up high. I'm using the lunati 10001 which i'm hoping makes a ton of torque down low to compliment the heads....but agin, currently i'm just talking out of my *** as its all parts on a bench until next week lol.....
Good luck!
yeah let me no how it turns out my buddy had the same set up and it had balls on low end with 87 oct
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Old 08-05-2012, 06:49 PM
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I had a 350 with 305 heads(416 casting if I remember),I allways ran 93 octane in it. What you will end up with is a motor that your freinds will think is more motor than it really is based off of stop light blasts,but will poop out at 5000 rpms. I ran a summit k1103 cam 214/224 @050 443/465 lift with a 600 vacuum holley and my car ran mid 14s all day long on greasy street tires.
305 heads on a 350 is a good poor man's trick for a fun snappy street motor in a driver.
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Old 08-05-2012, 08:22 PM
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I agree, fun ^^ if you want a lil more out of the heads Pocket port and gasket match the intake entries at least 2.5" back inside the runners, as well as the intake...

the cam, it is to big and is the reason youll have low vacuum...go with around 215@.050 on the intake and on a 110* lobe sep and as long as you add a lil octane booster to 87 you should be ok, but 93 is always better....

elgin has some less expensive hdy grinds really affordable so does jegs and summit...no experiance with jegs but summit cams are good quality, every one I have ran was without issue and did perform well...

HEY gl those heads are a good choice, just make the right one with a cam/ intake and carb...oh yea and if possible add some longtube headers or if money is tight it will like shorty style headers too
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Old 08-05-2012, 08:50 PM
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i will have low vacuum becouse of cam or because of the 305 ho heads should i just get a pair of 350 voetec heads ?
Yes, low vac will be due to the cam.

I will be running a cam that will be in that RPM range as well, and have purchased all of the parts I need for a hydroboost system that runs off of the PS pump in anticipation of the low vacuum situation. See my journal.

I've also installed a 2400 RPM B&M Nitrous Holeshot converter.
66 GMC 910, 454, TH400 with 3.73 gears.
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Old 08-05-2012, 10:09 PM
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To make any power with 305 heads on a 350 you have to port them and port them good. Inspection of the stock ports will quickly show you these heads were never heavy breathers but on a 305 they didn't have to be. Not long ago I did a medium port on a set of 416 castings and opened up the chambers. We kept the stock 1.84 1.50 valves and reinstalled the heads on a 305 with a gear drive, headers, a .210 duration @.050 summit cam, stealth intake and a Holley 650. It was dropped into a 89 Ford Ranger 4x4 backed by a TH400 and a NP241 transfer case. Needless to say, I really wasn't expecting much out of it being it's a 305 but I got the surprise of my life. At the local mud park, there's lots of guys there running sbc's of course and most of them are stock and some have small mods. That 305 was eating them up and making it look easy. In low range my nephew would wind it up in 1st gear then shift to second and the truck would go crazy. The 38 inch tall old school buckshot mudders would be slinging mud in huge clots.
I never expected it to make that kind of power but it taught me something and that is flow is power. What made that combo work was everything matched, but most importantly the porting of the heads was the magic ingrediant and I've seen many 350's with stock 305 heads, they would have killer out of the hole power, but they had nothing on mid range to top end.
This 305 pulls hard all the way to 5000 RPM and when it shifts to second in the mud the engine holds it's RPM instead of lugging down. Funny I said before I would never hot rod a 305. But when my nephew said it was all he had to work with I set out to the mods as it was a completely new challenge to me. When I first inspected the ports in stock form they were absolutely horrible, closed, kinked up and casting slag everywhere. Open them puppies up and they'll come alive.
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Old 08-06-2012, 01:18 AM
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what would be the best thing for me to do dont want to dump a bunch cash in this motor just want to ride the rest summer but have some balls also what would you guy's say about a 1969 camaro camshaft think the lift is like 288 or some **** want alot of low end power



now i do have a 400 sbc on the engine stand that im doing up for next yr



I have a 1985 cutlass supreme 3.73 rear true duels 350 turbo with stage two shift kit
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Old 08-06-2012, 02:16 AM
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Double I have been there. my learning was on 350's stock 601 58cc and 462 64cc heads with performer cams. Then the RPM package that a friend removed. The 350 performer dyno'd at 210 rwhp. The RPM at 9to1 a little compression shy made 260's rwhp. Never used aluminum heads again. The advertised hp of the rpm package was 420hp. Not sure what to say there, but it was street able.

Keepin it at 9 to 1 87-89 octane is safe.

305 with 58cc heads winding to 5000 with a performer cam is no slow poke. It is a low end cheap build that increases the acceration from the car of the era from 17's to 15's. That should light anybodies desire to continue learning while not spending a fortune.
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Old 08-06-2012, 03:48 AM
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Double I have been there. my learning was on 350's stock 601 58cc and 462 64cc heads with performer cams. Then the RPM package that a friend removed. The 350 performer dyno'd at 210 rwhp. The RPM at 9to1 a little compression shy made 260's rwhp. Never used aluminum heads again. The advertised hp of the rpm package was 420hp. Not sure what to say there, but it was street able.

Keepin it at 9 to 1 87-89 octane is safe.

305 with 58cc heads winding to 5000 with a performer cam is no slow poke. It is a low end cheap build that increases the acceration from the car of the era from 17's to 15's. That should light anybodies desire to continue learning while not spending a fortune.

SO WHAT HEADS SHOULD I USE TO KEEP IT 9 to 1 AND LONG AS I CAN DO 75MPH ON THE HIGH WAY WITH THE 305 HEADS IM COO DONT REALLY CARE FOR TOP END
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Old 08-06-2012, 03:51 AM
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So with the 305 heads can do 75 to 85 miles per hour on the high way if i want dont really care for top end tho
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Old 08-06-2012, 08:53 AM
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So with the 305 heads can do 75 to 85 miles per hour on the high way if i want dont really care for top end tho
If you're planning to do 75 to 85 mph on the highway ... don't do it near Spruce Grove, Alberta. Right Harry? (Inside joke)

OK, seriously now ...
IMO Cylinder heads and camshaft selection won't have a dramatic effect on your car's ability to drive at consistant highway speeds, as I am sure that your engine RPM will be within that range.

With 3.73's and 15" tires, I would guess-timate about 3000 to 3200 RPM in 3rd gear at 65-70 MPH, right? (less with an overdrive trans)

If that is correct, then a stall convertor isn't going to hurt you much either.
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