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Old 05-26-2013, 08:26 PM
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400 SBC, do i need bigger camshaft ?

Engine is 1975 model, the block # is 817 and it's 2 bolt block with main studs Heads are # 882 that have been pocket ported and do have 1.94"/1.5" valves. It's been bored 0.030" over and has piston's that gives 8.75:1 compression Crankshaft and rods are stock.
This engine is going into a 1971 Vega # 2700 lbs curb weight, Th-350 trans, 3000 stall TCI streetfighter converter. 12 bolt with 4.10 gears and posi. and the tires are 275/60x15. Current cam is Crane 260 - H-260-2 Hydraulic Flat Tappet Camshaft for Chevrolet 1957-1987 V-8, 262-400 intake is 2101 Edelbrock Performer, 750 cfm Holley 4150 sitting on top of a 1" spacer. headers are 1.3/4" long tube's with dual 3" exhaust.
This is mostly a street car, but i would like to race some 1/4 mile drag racing once in a while. 75% street / 25% strip

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Old 05-26-2013, 09:08 PM
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The compression ratio is kinda low and the heads are kinda poor...but
Replace the present Crane cam with A Crane Energizer H-238/3347-6 Crane #110651

Find some better 64cc hi flow heads With 200cc+ ports and get a better RPM or Vic JR manifold.

www.cranecams.com

Last edited by F-BIRD'88; 05-26-2013 at 09:36 PM.
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Old 05-26-2013, 09:25 PM
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not a great cam but I guess ok
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Old 05-26-2013, 09:45 PM
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Quote:
Originally Posted by GTVega View Post
Engine is 1975 model, the block # is 817 and it's 2 bolt block with main studs Heads are # 882 that have been pocket ported and do have 1.94"/1.5" valves. It's been bored 0.030" over and has piston's that gives 8.75:1 compression Crankshaft and rods are stock.
This engine is going into a 1971 Vega # 2700 lbs curb weight, Th-350 trans, 3000 stall TCI streetfighter converter. 12 bolt with 4.10 gears and posi. and the tires are 275/60x15. Current cam is Crane 260 - H-260-2 Hydraulic Flat Tappet Camshaft for Chevrolet 1957-1987 V-8, 262-400 intake is 2101 Edelbrock Performer, 750 cfm Holley 4150 sitting on top of a 1" spacer. headers are 1.3/4" long tube's with dual 3" exhaust.
This is mostly a street car, but i would like to race some 1/4 mile drag racing once in a while. 75% street / 25% strip
That cam is perfect for the static compression ratio of the motor. If you want to run more cam, raise the static compression ratio. Be aware though, there is only so much to be had with those heads. More cam would need more heads also. The camshaft is not a single item that stands alone in the motor, it has to be custom tailored with the other characteristics of the motor. Although not all members of this board like this chart, it will give you some idea of the static compression ratio that you will need with what cam timing.
http://www.crankshaftcoalition.com/w..._compatibility

Also, be aware that present day drag racing is actually bracket racing, so that anyone can run alongside anyone else. Theortically, a VW Beetle could race a Fuel Funny side by side, if the Funny didn't do a meltdown waiting for the light. Both cars will have a dial-in on the window and cannot go quicker than their dial or they lose. It's not like it used to be, where the fastest car went home with all the winnings. Now, you have to dial in respectably and cut a good light on the tree.

Last edited by techinspector1; 05-26-2013 at 09:53 PM.
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Old 05-26-2013, 10:27 PM
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Another cam I like for this motor is Isky 284/292 -6 Mega Cam Isky #201284/292-6
Degree it in on a 100 intake C/L
about the best you are going to do with the low compression ratio.

swapping the head gasket for a felpro 1094 .015" shim gasket will help the cr a bit.
(hand trim this gasket to fit the 400 bore, and drill the steam holes)
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Old 05-27-2013, 02:25 AM
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Those cams are bigger than i had in mind. How high is a safe redline on a 400 SBC ?
I was thinking about a camshaft that has redline of about 5500-5800. But i guess you guys are more experienced than me when it comes to hot rodding.
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Old 05-27-2013, 04:44 AM
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Quote:
Originally Posted by GTVega View Post
Those cams are bigger than i had in mind. How high is a safe redline on a 400 SBC ?
I was thinking about a camshaft that has redline of about 5500-5800. But i guess you guys are more experienced than me when it comes to hot rodding.
These are not big cams for a 400. A 400SBC eats up cam duration easily. the operating rpm range is lower when used in a 400sbc than say a 327 or 350.
These cams are all about mid and mid upper torque.Your 882 heads are restrictive.
You will be shifting at 6000 rpm.

With the right valve springs it will easily rev to 6500rpm.
But 5800-6000 rpm shifts are fine. You will not need to rev higher than this.
These cams are about as good as you will get for the 3000 stall and low engine compression ratio and modest cylinder head flow.

Your 400 will pull very well from the stall speed (3000 rpm) to 6000rpm.
A better intake manifold (RPM or Vic JR or similar hi rise) will add power too. The lowly performer manifold is pretty tame.

Either of these cams will make a good bit more power than the tiny cam you got now.

Both these cams have a rough cool sounding street machine idle. Will want a 4.5" power valve swap for the carb and a distributor advance recurve. They both like generous timing at idle. 26deg+ at idle. but the same typical 34-36deg at max advance. ( There for a short limited 10-12deg mech advance curve) Some people simply lock out the mechanical advance system altogether and run fixed timing 34-36deg full time.
You need not eliminate the vacuum advance system but it will need to be re-calibrated with the new camshaft.

This stablizes the idle with the new cam's lower idle manifold vacuum and increased valve overlap..
it will drive and cruise very well and make good power on the street and at the track.
Especially if /when you un cap the headers and add collector extensions and let it breath deep, for track racing.
You need not rev it up any higher than 6000 rpm on the shift.

A cylinder head up grade will add even more power. The 882 heads are pretty modest even when ported.

Last edited by F-BIRD'88; 05-27-2013 at 05:10 AM.
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Old 05-27-2013, 05:19 AM
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A 64cc Brodix IK200 cylinder head will really add power.... The 6000 rpm best shift point remains about the same thou. Just more power within that 3000-6000 rpm power range ...
You don;t need to rev the hell out of a 400 SBC to make it go.
These cams are not too big.

i assume your 400 has a dished piston.....
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Old 05-27-2013, 07:02 AM
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Yes they are dished pistons, but smaller than stock.
Is it ok to rev a short rod 400 sbc to 6000-6500 rpm without a catastropic failiure ?
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Old 05-27-2013, 07:32 AM
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Is your engine balanced and well put together?
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Old 05-27-2013, 01:25 PM
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The engine has not been balanced, Stock crank and rods and 0.030" over pistons. All clearance is good and the mains do have studs.
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Old 05-27-2013, 01:30 PM
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With that light car and gears and stall it'll be quick without much power. If I was to put a cam in that engine I'd like the 274h06 with 1.6 rockers. It's very easy on valve train and works great in low compression engines. It's cheap too. You won't see huge gains over what you have though, maybe 20hp as those heads are really choking it down.
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Old 05-28-2013, 01:48 PM
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How much power should the engine be in the form it's now ? Hp and torque ?
Should peak torque be over 3000 rpm ?
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Old 05-29-2013, 09:00 PM
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300 hp +/- ?
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Old 05-29-2013, 11:24 PM
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Quote:
Originally Posted by GTVega View Post
Engine is 1975 model, the block # is 817 and it's 2 bolt block with main studs Heads are # 882 that have been pocket ported and do have 1.94"/1.5" valves. It's been bored 0.030" over and has piston's that gives 8.75:1 compression Crankshaft and rods are stock.
This engine is going into a 1971 Vega # 2700 lbs curb weight, Th-350 trans, 3000 stall TCI streetfighter converter. 12 bolt with 4.10 gears and posi. and the tires are 275/60x15. Current cam is Crane 260 - H-260-2 Hydraulic Flat Tappet Camshaft for Chevrolet 1957-1987 V-8, 262-400 intake is 2101 Edelbrock Performer, 750 cfm Holley 4150 sitting on top of a 1" spacer. headers are 1.3/4" long tube's with dual 3" exhaust.
This is mostly a street car, but i would like to race some 1/4 mile drag racing once in a while. 75% street / 25% strip

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