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Old 08-14-2008, 03:59 AM
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small block chevy question.help????

I put together a 305 with free parts and haven,t put it all together yet and was wondering how you guys think it will run? My step dad is a mechanic and he is the one that gave me most of his smallblock stuff. The combo I am using: stock 305 shortblock dish pistons not flat, He gave me a set of 350 heads that have a 196 intake, not sure exhaust, 64cc, he said that they are rare heads and that those are the last year they were made? He gave me a set of brand new springs to take the cam that I am puting in it. New moly pushrods, rollertip rockers,the cam is the edelbrock rpm cam with .488 in/.510exh,for lift, and 234in/244exh with a operating range of 1500-6500rpm,and an Lsa of 112 and an isa of 107. I am puting with it an edelbrock performer rpm intake on it matching the cam with a 600 cfm edel on it. also a mallory hot hei distributer. With hooker shorty headers and 2 1/2 in flowmaster dual exhaust. the gear ratio is stock I think like in the low 3's somewhere. My step dad gave me the motor it only has 500 mi on it, and was doing it on an extremely tight budget. Just wanted to hear some other opinions, I would greatly appreciate you time. thanks in advance.

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Old 08-14-2008, 04:24 AM
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The compression ratio will be very very low.
Change the pistons or get a blower.

In a 305, that cam will shift the torque curve way way up.
The little 305 won;t get busy until well after 3000rpm.
You'll want a 3800-4000 rpm stall 9" torque converter and 4.56 gears to make use of the RPM cam in a 305. Thats assuming you correct the compression ratio.
Right now its way, way way too low. Stock 305's come with 52 to 58cc heads. With 64cc heads your cr will be a good bit lower than stock.

If you were to swap the pistons for some KB144 domed pistons and use a thin shim style .015" head gasket (felpro #1094) your cr would be in the ball park for that cam, using 64cc cylinder heads. {Assuming a stock .025" piston deck clearance 9.9:1 cr}

You'll need to recurve the HEI distributor mechanical advance curve so it has more initial base timing (24++ at idle) and a quick curve to 36deg total.
Might even try locking out the advance curve for 36deg fixed timing.
Other wise the low end and throttle response will be pretty weak.

If you cannot do all this, then change the cam for a much shorter duration cam. that matches your low compression ratio and mid 3.?? gearing and budget. Save the big RPM cam for a high compression motor.

Last edited by F-BIRD'88; 08-14-2008 at 05:05 AM.
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Old 08-15-2008, 03:54 PM
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Quote:
Originally Posted by F-BIRD'88
The compression ratio will be very very low.
Change the pistons or get a blower.

In a 305, that cam will shift the torque curve way way up.
The little 305 won;t get busy until well after 3000rpm.
You'll want a 3800-4000 rpm stall 9" torque converter and 4.56 gears to make use of the RPM cam in a 305. Thats assuming you correct the compression ratio.
Right now its way, way way too low. Stock 305's come with 52 to 58cc heads. With 64cc heads your cr will be a good bit lower than stock.

If you were to swap the pistons for some KB144 domed pistons and use a thin shim style .015" head gasket (felpro #1094) your cr would be in the ball park for that cam, using 64cc cylinder heads. {Assuming a stock .025" piston deck clearance 9.9:1 cr}

You'll need to recurve the HEI distributor mechanical advance curve so it has more initial base timing (24++ at idle) and a quick curve to 36deg total.
Might even try locking out the advance curve for 36deg fixed timing.
Other wise the low end and throttle response will be pretty weak.

If you cannot do all this, then change the cam for a much shorter duration cam. that matches your low compression ratio and mid 3.?? gearing and budget. Save the big RPM cam for a high compression motor.
Do you think it will at least run? just for a driver and maybe a little fun for now?
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Old 08-16-2008, 12:36 AM
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Quote:
Originally Posted by motorhead454
Do you think it will at least run? just for a driver and maybe a little fun for now?
Yes it will "run" but with the low compression ratio don't expect much out of it.

If you are not going to make the changes nesessary to allow the cam to work then you are really really much better off with a (much) smaller cam.
You can always slip the rpm cam in later once you make the nessessary compression, porting , rear gear ratio etc changes.
Without these other parts of the "combination" its going to be a dog.
It all has to work together.
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Old 08-16-2008, 10:29 AM
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64 cc vs. 76 cc heads

i know a 305 with there stock heads are 58 cc chamber an carry a 8.5 to 1 so ur likely a 7.5 to 1 using the 64 cc chambers could shave the heads down 10.000 help bring it up some one thing you wont have to worry about gas ratio no valve pinging thats for sure! and if there stock chevy heads there 1.94 intake valve an 1.6 exhaust valve i took a set 305 heads cut out to fit in 1.94 intake valve an 1.6 exhaust to up my compression ratio!
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Old 08-17-2008, 06:36 PM
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Quote:
Originally Posted by F-BIRD'88
Yes it will "run" but with the low compression ratio don't expect much out of it.

If you are not going to make the changes nesessary to allow the cam to work then you are really really much better off with a (much) smaller cam.
You can always slip the rpm cam in later once you make the nessessary compression, porting , rear gear ratio etc changes.
Without these other parts of the "combination" its going to be a dog.
It all has to work together.
I am going to put the 305 heads on them I found out the 305 heads intakes were made bigger and they are 58cc and have less than 500 miles on them so I put the bigger springs on them to work with the cam so hopefully that will help a bit? What do you think, decent?
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Old 08-17-2008, 07:19 PM
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chevy 305 heads

the 305 intake valve size is 1.88 an a 350 or 327 1.94 both use the same exhaust size 1.50 and yes the chamber is smaller if were my heads i'd do a bowl blend in the valve pocket and gasket match the intake ports and rase the roof on the exhaust ports will help you out alot with your motor!
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Old 08-17-2008, 07:26 PM
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Quote:
Originally Posted by rachet ralph
the 305 intake valve size is 1.88 an a 350 or 327 1.94 both use the same exhaust size 1.50 and yes the chamber is smaller if were my heads i'd do a bowl blend in the valve pocket and gasket match the intake ports and rase the roof on the exhaust ports will help you out alot with your motor!
Will they work decent the way they are? Will it make a difference over the 350 being a smaller chamber? I know I have a big cam in it, I wanted it to sound good but I want it to be a little pepy over stock. Not planning on racing it but just a little rip around fun and driving to work.
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Old 08-18-2008, 05:03 AM
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305 heads

they'd work ok but they'd be better if you blended the valve bowl cut away the casting mold line causes restriction in the valve flow but you can just leave them alone if you like but bowl blending helps out alot at least give you 10 to 15 horse power gain
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Old 08-18-2008, 01:35 PM
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It's going to be a major dog. That comb needs much more cr, much more gear, and much more stall. And it needs long tube headers!

You will have a hard time getting that combo to idle in gear with a stock converter. It needs a 3000 rpm stall.

Do yourself a favor and get a much smaller cam to match the low compression and a 2400 to 2800 rpm converter to match the torque of the 305 and the low 300 series gears.

If you plan you spin the tires at all, get a cam with about 205 degrees duration on the intake, 210 on the exhaust, and 106 to 108 LSA.

I would also use a stock set of 305 heads or use a thin gasket with the 64cc heads. You can find 305 vortec heads for cheap. You really need to get the compression ratio up or buy a super charger.
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Old 08-19-2008, 12:44 AM
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Quote:
Originally Posted by F-BIRD'88
The compression ratio will be very very low.
Change the pistons or get a blower.

In a 305, that cam will shift the torque curve way way up.
The little 305 won;t get busy until well after 3000rpm.
You'll want a 3800-4000 rpm stall 9" torque converter and 4.56 gears to make use of the RPM cam in a 305. Thats assuming you correct the compression ratio.
Right now its way, way way too low. Stock 305's come with 52 to 58cc heads. With 64cc heads your cr will be a good bit lower than stock.

If you were to swap the pistons for some KB144 domed pistons and use a thin shim style .015" head gasket (felpro #1094) your cr would be in the ball park for that cam, using 64cc cylinder heads. {Assuming a stock .025" piston deck clearance 9.9:1 cr}

You'll need to recurve the HEI distributor mechanical advance curve so it has more initial base timing (24++ at idle) and a quick curve to 36deg total.
Might even try locking out the advance curve for 36deg fixed timing.
Other wise the low end and throttle response will be pretty weak.

If you cannot do all this, then change the cam for a much shorter duration cam. that matches your low compression ratio and mid 3.?? gearing and budget. Save the big RPM cam for a high compression motor.
If I change the cam would I be able to get away with using the intake at least with the performer cam not the performer rpm cam? If so How long and difficult would it be to swap the cam out if the motor is in the car?? Thanks so much for your input and help!!!
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Old 08-19-2008, 06:39 AM
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305 w/ 350 heads

I personally would stay away from that idea. The stock 305 HO didn't produce that much power anyway. the HO motors (ss monte 86) came with 58cc double humps, with 1.84/1.50 valves, and they were mabey 8.5:1-9:1 at best. with 350 heads your gonna be down to like 7.5:1, assuming they really are 64cc heads. Do you know a casting # for the heads you planing on using, because most of the 350's i've seen have 76cc heads stock, exept the old fuelies but if you got those, they should have 2.02/1.60 valves. Did you give the adv. duration on your cam? that cam could end up dropping your compression even more. I persanally have like 6 sets of the 305 HO, i'll sell you a set for $40 IF U want them. any way, if you do this, IT WILL BE A DUD!!!! something's gotta change, flat tops, domes preferably or you will be very dissapointed. If u really wanna get the power get the DART iron eagle 49cc heads, w/ stock dish piston, and your cam, you might see 300HP. get at me if u need some 305HO heads, i just don't wanna see you waste your time.
Danny
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Old 08-19-2008, 06:47 AM
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cam swap

you got 2 options after you get the accesories outta your way,

1).remove motor mount bolts, remove tranny crossmember and lower the tail shaft of the tranny to the ground, this should bring the front of your motor up high enough to do the swap

2). i missed what car its in but you might be able to just pull the radiator out and get enough room that way in a LARGE vehicle.
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