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  #31 (permalink)  
Old 08-05-2012, 05:14 PM
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400 sbc

Ok I had a little time this week so I installed the power valve on the primary side 4.5. Then installed new spark plugs. Upon pulling the #3 plug it was arcking out on the hedders and I thought the sputtered was due to the backfire much smoother now. But I still need to recieve the distributor. And ill post up. How do you know when 34-36 degress of timing is met when the timing mark only goes to 18. And do I capp the vacum advance when doing so.

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  #32 (permalink)  
Old 08-05-2012, 05:26 PM
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you need to use a timing light that has a scale on the gun. set it to 34 then look when the light matches zero. or put a timing tape on your balancer. When I had no money I used to make a crayon mark on the balancer.
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Old 08-05-2012, 05:34 PM
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400sbc

Ok but on the distributor it need the two med. Spring but which weights. On my timing light there is a 34 mark set it there and watch the pointer on the tab move to 0 degrees is what you saying and that will give me 34-36 timing and that's with the vacum advanced plugged
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Old 08-05-2012, 06:01 PM
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the timing light only indicates the timing thats happening with or with out vacuum. 34 ish with out vacuum is where you want to be,or close to that.
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Old 08-12-2012, 01:18 PM
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400sbc

@f-bird88 I know this topic is about 2-3wks old. You mentioned something about poor man's racing heads. I was breaking down a motor this week end that came out of this 73 c-10 short bed before I put the 400sbc in. The casting number was block 3956618 & heads are 3932441 what info could you give me on this. I know you said in a comment back that porting these heads on a 400 would scream. I was going to rebuild this motor as a street deal for my 73 vega any comment would help.
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Old 08-12-2012, 09:19 PM
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400 sbc

I have been following this thread. I read that you said you has 15 inches of vacuum before it backfired. You also said you replaced the old power valve with a 4.5 power valve. To get the right size power valve you take a vacuum reading at idle and divide it by 2 and replace it with the closest number to your reading. EX: 15*2= 7.5. Summit racing list 6.5 for the 600 cfm. While you had the carburetor off you should have backed off the curb idle screw. About .020 of the two slots in front of the primaries should be showing. Next you would need to setup the distributor If setting the initial timing at 20* you will need to set the mechanical advance at 16* max. Do a search on here about setting the mechanical on a HEI. This is with the vacuum hose off and plugged from the distributor. So you have 20 initial + 16* mechanical = 36 total. Now you ready to fire it up and make adjustments to the carburetor. Hook up a vacuum gauge to a manifold vacuum source and adjust idle screws until you get the highest reading. To check the total timing set the dial at 34 and check timing. it should be reading close to 0 on the scale if you have everything set right. You asked about the springs on the dizzy, yes you can use 2 light springs so the timing is all in by 3000 rpms.
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Old 08-12-2012, 09:30 PM
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3956618 & 3932441

Check out nastyz28.com forum they have the block and head casting numbers. That block could be a 69 302 4 bolt main, 69 327 2/4 bolt main, 69 350 2/4 bolt main. Measure the mains if 2.3 it's a 327, 2.45 it's a 350. The heads could be 67-72 327 or 350. 1.94 intake valve, 1.50 exhaust valve. Then it also has them listed as 67-79 76cc chambers. I also saw another site if they have the steam holes and have 1.94I & 1.60E they could be a 400 head. Check out 3932 441.
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  #38 (permalink)  
Old 08-14-2012, 07:27 AM
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poor man's racing heads

[QUOTE=hotboy454;1582207]@f-bird88 I know this topic is about 2-3wks old. You mentioned something about poor man's racing heads. I was breaking down a motor this week 400sbc in. The casting number was block 3956618 & heads are 3932441 what info could you give me on this. I know you said in a comment back that porting these heads on a 400 would scream. QUOTE]
at one time the 441s would have been a score, i built a 11 to 1 400 with heavyly ported 492s (simler to 441s) for my super street stock and it did scream. I ran around there at half trouttle till the idiots had crached themselfs out and then when there was just 6 of us left i could open her up, get the rears just smokin hot.
Rebuilding those old heads is hardly cost effective today, they dont have the hard seats in them ether the exasut seat is gona wear if it ant worn out already.
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