Stock 400 small bock with bigger cam

[Craig Nedrow]

Just read this about the 400: https://www.chevyhardcore.com/tech-...e com!&utm_campaign=Chevy Hardcore 08/26/2025

 

[Patman]

heading back home today, looking forward to getting my hands dirty. my wife found he carb booklet so im sure that'll help a good bit.

 

[Patman]

Fuel pressure gauge installed, it’s bouncing all over the place.

Had a hot rod mechanic come by the shop on a chance visit. He dropped my park rpm to about 830 (from 1000) and had me put my timing light away, pulled timing out of it till it was hard to start, then added a little back. Changed everything. In the meantime, I’m shopping for another fuel pump as that’s the likely cause of the variation on pressure.

I’ll update when it’s replaced.

 

[Patman]

Ok, much has been learned since my last post. The fuel smell was because the evap canister is gone and it’s just venting into the engine bay. Not ideal. I know…

Had an old hot rod builder come by the shop by chance and he told me to put away the timing light. He had me pull timing out of it until it’s difficult out to start. Then add a little more back. That solved the hard hot start issue.

We set the park idle at 750rpm and that helped solve the overrun issue as did the timing.

I’m pulling about 17in/hg of vac from the manifold port on the carb.

My fuel pressure is bouncing from 2-4.5psi, I can see air bubbles coming into the window on the fuel filter. I’m guessing that I’m sucking on air through one of the lines.

Still, its running much better!

So. The Evap canister. Since the avs2 carb does not have a bowl vent port, I’m guessing that I can just use a generic two port canister?

I’ve driven it a few hundred miles. It’s a thirsty beast and is burning oil. Was recently rebuilt, so I have other concerns…

 

[Patman]

Fuel pressure gauge installed, it’s bouncing all over the place.

Had a hot rod mechanic come by the shop on a chance visit. He dropped my park rpm to about 830 (from 1000) and had me put my timing light away, pulled timing out of it till it was hard to start, then added a little back. Changed everything. In the meantime, I’m shopping for another fuel pump as that’s the likely cause of the variation on pressure.

I’ll update when it’s replaced.

Feel free to ignore this post. Tried to delete it and can’t. :-/

 

[xm20k]

Could be a small crack in the rubber line somewhere and its sucking air in, just something to check if the new pump does the same thing.

 

[Patman]

Already started replacing them, my thoughts exactly.

 

[Sad Sack]

Is it a glycerin filled fuel pressure gauge?

 

[Patman]

I figured out that my tuning problem was actually an intake leak problem.

 

[Patman]

Yes sir on the liquid filled gauge

 

[Patman]

So, while trying to get my engine to TDC so I could get the distributor sorted, I was under the truck and turning the engine over and I can hear air hissing inside the oil pan. Was kinda funny, I sounds a bit like a wet fart.

I asked chat gpt and got that it was likely a head gasket, rings not seated properly, or valves hanging open. Considering that it was recently rebuilt, maybe 3k mi ago. I’m guessing head gasket or rings not seated well.

Either way, I’m hoping I can still get this tuned properly. I need it back on the road.

I have a video of it making the hissing sound as I’m turning it over, but can’t upload it, only pics.

 

[Ricko1966]

Air hissing in the pan is just as likely perfectly normal air seeping past the rings,no problem at all. If you are worried run a compression test.

 

[Patman]

Finally got it started today. Thought that I killed my starter in the process. Seem like the starter is trying to spin too fast, made a whining.grinding sound, but still started the engine with no problem. Pulled the starter and noticed the wiring.

The wires going to the starter and to the fuel sending units are routed behind the block and into a tube that is bolted to the block. That tube, I assume is to protect the wires is normally bent towards the block, cleanly routing the wires toard the starter. In this cace it was bent away from it, as a result, the tube was making contact with the exhaust manifold, right before it connects to the down pipe. One of the wires (fuseable link) closest to that part of the tube melted and grounding out. I can only assume that this is the issue. I was working the starter pretty hard once I got it back together and figuring out the timing and such. I do have another starter that I might clean up and put on while im at it, just to be be on the safe side.

I've also replaced my power steering pump and lines. all three of the metal lines ends leak. They all seem to seat well when tightening them but the leak terribly under pressure. frustrating...

 

[Patman]

2nd new intake installed. First one failed immediately. Pretty sure I got it sorted now though. I got a thicker gasket to make up for the delta from the aftermarket intake and stock heads.

Installing drivers door hinges today while I’m waiting for the RTV to set.

 

[Ricko1966]

2nd new intake installed. First one failed immediately. Pretty sure I got it sorted now though. I got a thicker gasket to make up for the delta from the aftermarket intake and stock heads.

Installing drivers door hinges today while I’m waiting for the RTV to set.

How well did your bolt holes line up on both intakes?