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Topic Review (Newest First)
11-12-2012 06:10 PM
cobalt327
Typo

Quote:
Originally Posted by cobalt327 View Post
You need a vacuum source for the PCV system. This is usually a larger port at the rear of the carb base.
Should read to the front port, not the rear. Rear can be the booster if you want or the manifold- it doesn't matter as long as its large enough and is manifold vacuum.
11-12-2012 12:20 PM
mistagoodbadguy Stem holes have been drilled and heads resurfaced
11-12-2012 11:15 AM
mistagoodbadguy Ok so this is completely different then how I have always set up a carb fitting on the intake to the trans rear base to the break booster front to the pvc also I do kno the dates and will look at the wholes just I'm almost certin there the same ones iv always used
11-12-2012 06:39 AM
1Gary A 165 thermostat is more appropriate given the 400's steam hole cooling system.

Any crossover head in use,other than a 400,needs to be drilled for the 400's steam holes.
11-12-2012 06:36 AM
cobalt327 Here is a page on the 400 SBC steam holes.
11-12-2012 06:26 AM
bnun12 Be sure to drill steam holes in the 307 heads for a 400sbc if you use the 307 heads
11-12-2012 06:06 AM
cobalt327
Quote:
Originally Posted by mistagoodbadguy View Post
They are dished pistins and the heads where org made for 307 327 350 and the carb has the stove also does the 400 use the same thimisat and spark plugs? And what about the exhuate manafold gaskets and can the choke mech be changed to electric? And where would I put the power wire too the alt also are there any simple vac dieagrams
The intake is where the stove is located. Any chance you could post a photo of the carb (choke side) and the intake right below the carb? Otherwise we could be chasing our tails here.

The exhaust manifold gaskets are the same between the 307 and 400. I would recommend the metal foil backed gaskets if you're using cast iron manifolds. Retighten them after the engine has run. Keep checking them until they take a set.

Use a 180 degree thermostat.

You can use an electric choke. The exact type of electric choke depends on the carb you have. If you can't post a photo of your set up use eBay to copy a picture from that looks like your carb: quadrajet carburetor | eBay

307 SBC engines were made during the years that the tapered seat plug was introduced, so unless you know what year the heads are (date code under the valve cover), the heads need to be looked at to see if the plug seat is for a tapered or gasketed plug. I would use a 44 heat range AC Delco plug.

Vacuum lines:

You need vacuum to the modulator if you have an automatic trans. Usually from the carb base.
You need a vacuum source for the vacuum advance. Usually from the carb base.*
You need a vacuum source for the power brake booster if you have one. Most often this is a port on the intake manifold, not the carb. Should be same size as the port on the booster.
You need a vacuum source for the PCV system. This is usually a larger port at the rear of the carb base.
*See the section on what vacuum source to use for the vacuum advance here.

Alternator wiring:

10SI: Wiring a Delco (GM) Alternator
11-11-2012 07:46 PM
mistagoodbadguy They are dished pistins and the heads where org made for 307 327 350 and the carb has the stove also does the 400 use the same thimisat and spark plugs? And what about the exhuate manafold gaskets and can the choke mech be changed to electric? And where would I put the power wire too the alt also are there any simple vac dieagrams
11-11-2012 01:13 AM
cobalt327
Quote:
Originally Posted by mistagoodbadguy View Post
One other question I have is about my intake gaskets I noticed the wholes on eather the front or rear... Dident have a real good look is blocked off should this be like this or not I have heard 400s have cooling issues so I would assum the more flow the better should I remove these or keep them in? I will be using org heads from a 307 and a stock intake from a 350 with a crab with the choke that I assume gets heated by the collent or exhaust in the center port sorry to sound like a dumb *** but wanna do it right and when ever iv done intakes iv never used block offs what's the perspose of these and are they needed?? Anyways all the help I can get is very helpfull I love to learn and want to make this perfect for the lady
Think twice before using the small chambered small valve 307 heads on a 400 SBC. The compression could be way too high to run on pump gas depending on the chamber volume and whether the pistons are dished or not- but the chances are very good the CR will be too high. The small valves used in 307 heads (unless they were changed) will choke the engine.

As far as the intake gaskets go, they're made to fit either side of the engine. So having the coolant crossover holes both front and rear does not matter.

The heat crossover blockoffs are used to keep the intake from warming up as fast. On a daily driven non high performance engine it is better to leave them both open or maybe only close one side off and leave the other side open- your choice. If it was ME, both would be open- especially if you are going to use it in cold weather.

The choke adjustment, etc. depends on the type of choke you have. Some are electric and need only a power wire to make them work. Some use hot air from either the intake (most common) or hot air from the exhaust manifold. The hot air gets to the choke through steel tubing that fits into the holes in a cover over a "stove" on the intake manifold. Then there is the divorced choke that has the thermostat coil mounted to the intake and it used a linkage rod to actuate the choke. The carb itself does not contain a choke housing like the hot air choke or electric choke, in other words. If you can show what you have or describe it we can help further.
11-10-2012 01:32 PM
mistagoodbadguy No ideas on the intake manafold gaskets also I have never used gaskets on my exhaust manafolds should I
11-09-2012 05:41 PM
mistagoodbadguy One other question I have is about my intake gaskets I noticed the wholes on eather the front or rear... Dident have a real good look is blocked off should this be like this or not I have heard 400s have cooling issues so I would assum the more flow the better should I remove these or keep them in? I will be using org heads from a 307 and a stock intake from a 350 with a crab with the choke that I assume gets heated by the collent or exhaust in the center port sorry to sound like a dumb *** but wanna do it right and when ever iv done intakes iv never used block offs what's the perspose of these and are they needed?? Anyways all the help I can get is very helpfull I love to learn and want to make this perfect for the lady
11-09-2012 02:10 PM
1Gary Apart of the run test function I did while at Chevy engine plant was to pound in balance pins into the H/B'ers on 400's.They are not the same as 350's or 302's or 262's(yeah on the V8 262's sure am telling my age huh lol) or 307's.
11-09-2012 01:20 PM
mistagoodbadguy Yup I do have the correct flex plate
11-09-2012 12:28 PM
ZPI28 As stated be sure you use a 400 Flexplate and not a 350. Good luck
11-09-2012 11:42 AM
mistagoodbadguy Thanks guys and that's the balancer that I have I just want to make sure I can adjust the timing correctly
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