Big Block Distributor Question
 

Those of you with a 396/402, what are you running for a vacuum advance can? B26 or B28? I have an 1111498 distributor with a B26, but I've been told I should be looking for a B28 for my spare motor that I'm running. I converted a 1111500 distributor with a Pertronix III, but I need a new a new vacuum can for it.

http://i1164.photobucket.com/albums/...531_191534.jpg

Re: Big Block Distributor Question
 

The B28 is a low vacuum can. So any solid lifter or rad. cam Chevy should use it.
It will start to pull in at 4 and be all in at 8in Hg.
You want it all in at idle.

Re: Big Block Distributor Question
 

Yup. Depends on the cam. If you have a L34 or a mild aftermarket cam, stick with the B26. I don't 100% agree with full manifold source to the can in ALL applications. If the idle circuit in the carb is correct, you don't need a boatload of advance at idle. Also, make sure you are limiting the can to 10-14 deg of timing. Some replacement cans allow a lot more.

I have a 9.6:1 355 with a 217/225 deg @ 0.050 cam on a 108 LSA (104 ICL), and a B26 can works well for me connected to a ported source (no vacuum advance at idle - 12 degrees initial advance). You'll need to give us more info about the 396 if you want better advice on the right can.

Re: Big Block Distributor Question
 

Yup,novadude. The one drawback with full Vac. to the Dist. is when you crank the wheel with P/S and or let out the clutch the RPM drops, so does the Vac advance and you go into a stall or bucking mode.
Without full Vac.(Ported) mode you have a stronger idle and in most cases you can just let out the clutch without feathering the throttle much.

Re: Big Block Distributor Question
 

I like full manifold vacuum to the Vacuum Advance. I don't run any more than 10 deg max Vacuum Advance,depends on cam and stuff. Ported vacuum advance was made for Emissions.

Re: Big Block Distributor Question
 

Thanks for all the input guys. The engine I'm running is a 1972 402 with truck heads. I have my born with motor stored for now. From what the guy I bought the motor from told me, it has a mild cam and no head work. It's been rebuilt with a/m pistons which I confirmed when I pulled the pan, but I think they're just stock compression replacements. It's real clean and looks good inside, but I'm not expecting that much performance out of it.
I'm running a Holley 3310-3 that I just rebuilt. I was planning on hooking the vacuum advance to a small port on the base plate of the Holley. I'm not quite up on the full ported vacuum vs. manifold vacuum etc. I know enough about advance to be dangerous, but that's about it. I'm planning on making an advance limit block for it though.

Here she is:

http://i1164.photobucket.com/albums/...1_190918_1.jpg

Re: Big Block Distributor Question
 

Simple -- hook the vac to a full vac port ... if the engine has a rough idle and you disconnect the vac and it smooths out, you may need to connect to a ported vac source. That is the bottom line. We can beat this horse to hell all day long and opinions are varied. I have connected vac both ways depending on the motor combination. There is no rule one way or another -- try em' both to see what works best on you application. TAZ

Re: Big Block Distributor Question
 

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: earntaz</div><div class="ubbcode-body">Simple -- hook the vac to a full vac port ... if the engine has a rough idle and you disconnect the vac and it smooths out, you may need to connect to a ported vac source. That is the bottom line. We can beat this horse to hell all day long and opinions are varied. I have connected vac both ways depending on the motor combination. There is no rule one way or another -- try em' both to see what works best on you application. TAZ </div></div>
Thanks Taz. That makes sense. Buying the right can was the big question for me. It sounds like opinions are pretty split there too.

Re: Big Block Distributor Question
 

Not a bad looking motor either ...

Re: Big Block Distributor Question
 

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: earntaz</div><div class="ubbcode-body">Not a bad looking motor either ... </div></div> Thanks Taz. I'm just finishing up going through it. I painted it with Seymour EN48 paint. I'm real happy with how it came out. I still have a few more details to take care of, but I'm just about ready to fire it. I guess she's a bit of a polished turd, but she's my turd...

This is how she started out and ended up:

http://i1164.photobucket.com/albums/...231_201506.jpg


http://i1164.photobucket.com/albums/...508_195750.jpg


http://i1164.photobucket.com/albums/...508_210721.jpg

Re: Big Block Distributor Question
 

Here is a couple pics of the .040 out 454 going in my 71 Nova -- had to get creative to use a serpentine setup with a 4 core radiator and long fuel pump to prevent vapor lock ... happens here in south Texas. TAZ https://www.yenko.net/ubbthreads/pics...9-454_.040.jpg
https://www.yenko.net/ubbthreads/pics...-454_.0401.jpg

Re: Big Block Distributor Question
 

Wow, you put some time into that. Looks great. I'll bet she'll move too. I like those valve covers.

Re: Big Block Distributor Question
 

Nice Work !!
What's the story behind the long fuel pump and vapor lock?? My fresh 427 67 Chevelle rag is giving me some grief. I have a carb heat shield but it still sometimes stalls and hard starts after being parked for a short period when hot out.

Re: Big Block Distributor Question
 

Usually a long pump will have a third fuel return line -- from what I understand the reason is more fuel will move through the pump (some to the carb and some returns to the tank) keeping the fuel cooler. Also, the long pump appears to have more available fuel capacity. I just seems that the long pumps are not as prone to vapor lock as the short pump and I should add that is the pump used on many Chevy truck engines. Of course I had to slightly modify the front crossmember for clearance. Hope this is the answer you are looking for and I am sure others here will chime in if they deem necessary. TAZ

Re: Big Block Distributor Question
 

Taz...that inline filter is a good idea. I usually install them before the pump [area near the frame]...then change once a year. We also change the Holley [in-carb] bronze filters annually for insurance.

wilma

Re: Big Block Distributor Question
 

Yep -- GM used these (sometimes three line) filters just before the carb. Also, (this will probably rile some of the troops) one of the &quot;tricks&quot; was to remove the metal filters on Holley carbs. Theory was those filters would restict fuel movement. That is bad JuJu -- Holley carbs work just fine with those filters installed in the bowls ... last defense to getting trash in the needle/seat, etc. TAZ [img]<<GRAEMLIN_URL>>/scholar.gif[/img]