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idahoaj1
New User
| Posts: 2
| Joined: 09/04
Posted: 09/18/04
03:46 AM
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Hey guys, I have a question for you to scratch your head over.ffice![]() ffice" />>>
I have a 1989 Chevy Blazer that I am in the middle of building an engine for. This engine is a mid 70’s vintage 400 small block that I have headers, a set of Vortec Heads that have been pocket ported and bigger valves put in, stock springs from the older style heads. The small block has flattop pistons with a compression ratio of approx. 10.5-1 projected, with Total Seal Rings. I have an Edelbrock Performer RPM Air Gap Vortec Intake for it, and a Holley TBI adapter that is sandwiched between the 50MM hogged out TBI unit with an adjustable Fuel Pressure Regulator, stock injectors, and is fed by a high flow Walbro Fuel Pump. This combo is mated to a TH700R4 transmission that I have rebuilt myself with several upgrades besides the normal shift kit. I will be having a custom Chip burned for the stock ECM to control this engine. This Blazer is being built primarily for off-road fun with the local off-road clubs and possibly be driven to ffice:smarttags" />lace>Moablace> to play. This Blazer has 5.13 gears and 38” tires and several suspension and body modifications that aren’t really pertinent to this question. The stumbling block that I am running into with this engine build is this; Without going to the expense of converting to a Roller camshaft, which cams will allow me to take advantage of the particular combination of the 400 block, Vortec heads, and intake, yet still allow the ECM to effectively manage this motor? I need to have my camshaft selected before I can call my Custom Chip vendor to start configuring the chip. The motor needs to be installed and at least somewhat running in order to give him a log using WINALDL software to properly configure the chip. As you can see by the overall vehicle package, I am not looking for a hot racing type of cam, rather a cam that will give me great low to midrange power and torque. Unfortunately when I called a couple of cam manufacturers for advice, they couldn’t really give me any concrete selections, and in fact, most recommended that I swap a carburetor in instead. I would like to know what profiles work with TBI, what parameters on the profiles change with engine size, etc. in order to make a somewhat educated choice in camshafts.>>
Any assistance that you can give me would be greatly appreciated!>>
Sincerely,>>
AJ Johnson>>
AJ’s Performance>>
lace>Rigby, ID 83442lace>>>
>idahoaj1@yahoo.com>
Edited 9/18/2004 4:50 am by idahoaj1
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mcsjr454
User
| Posts: 104
| Joined: 08/04
Posted: 09/18/04
10:12 PM
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Ummmm...... I hope that you had the steam holes drilled into the vortec heads or you are in trouble, big trouble. Another thing you might want to check in your combo is the valve springs, if I am not mistaken, Vortec Valve springs have a larger diameter than older stock springs. As for the cam, I would call comp cams, and ask for their advice. Just be sure that you get a dual pattern cam with more exhaust duration, to use with the vortec heads.
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mcsjr454
User
| Posts: 104
| Joined: 08/04
Posted: 09/18/04
10:14 PM
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P.S. You might even run into fuel injector problems, another good place to check with would be holley. They are making tpi systems now for small blocks. ask what cam they would suggest.
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idahoaj1
New User
| Posts: 2
| Joined: 09/04
Posted: 09/22/04
09:25 AM
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Yes, I have the steam holes drilled, and I am using the stock springs from the earlier type heads.. I'm a mechanic, so I have all of the basics covered that way, I just don't know enough about the parameters on the TBI computer to know what type of profile I need on the cam.
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Posted: 09/22/04
03:40 PM
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Ok look at it this way ! You have a 400 small block wich does not take to high rpm,s . With those stock springs you will probbly float the valves around 6500 rpms. Your stock ingition coil will be near its energy peak at 4300 rpms. A good grind would be one made for tow trucks or rv,s
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kwatts50
New User
| Posts: 24
| Joined: 01/08
Posted: 08/03/08
04:04 PM
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ok sounds like people have not tried this before so a good cam to run in this combination is a comp cam for the computer controlled engine. as for the injectors you should be ok but if not just get a set for a 454 tbi and they will supply enough fuel. look in comp cams catalog for the compucam section.
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SnoMan
Guru
| Posts: 1320
| Joined: 03/08
Posted: 08/03/08
04:13 PM
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You still want to limit RPM to about 5000 or so if you want it to last. SBC 400's tend to self destruct around 6000 to 6500 RPM unless you have spent some serious money on bottom end. If you plan to crank it you would have been better served with a 377 which would be a 400 SB with a 350 crank and longer rods. Also the ported heads are not going to be kind to lower RPM response and torque because of mixture velocities so you want to use a fairly mild cam if you want some lower RPM power. Also if you have any illusions about running 87 octane forget it and even 89 is not going to do it without compromising timing curve. It is going to need 93 octane.
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