72 Super Edelbrock Upgrade

[randy500]

If it's green then it's probably temp sensor for the gauge, should be plugged into the head, think connector is slotted to go over a round flat post.

[rharris]

Changed my mind - grabbed it quick

[rharris]

Originally Posted by randy500

If it's green then it's probably temp sensor for the gauge, should be plugged into the head, think connector is slotted to go over a round flat post.

I will look for that tomorrow after work, thanks. Was thinking about re-routing it after I find where it goes. Thanks again for all your help.

[randy500]

I just posted, not sure where it went...
30 on intake sounds about right, valve covers snug by feel with a 6 inch long ratchet.
Green wire is temp and think it should be on drivers side...

[randy500]

That is the temperature gauge for sure.
Temp sensor for trans controlled spark is light green

[randy500]

http://www.gmcpauls.com/70-72_TCS_RPO-Option_Wiring.jpg
Here is the tcs wiring diagram. I thought the throttle solenoid was part of the tcs wiring but apparently it is just separate and goes through the firewall in the same grommet to the right of the engine wiring connectors, you can see from the diagram it plugs directly into the fuse box and is ignition unfused

[rharris]

Finished the truck today, with the exception of wire clean up, new fuel line, and finishing touches like valve cover bolts, air cleaner,etc. The job went well (thank you very much Randy). It took a few cranks to get started and ran rough, moved distributor to 12 BTDC and it purred nicely.

[GR8-68]

Looks great !!!

[randy500]

Your welcome. Your install looks clean, I like your intake plugs and your linkage looks good too. How did you end up wiring the HEI? I can see you used the throttle solenoid for the choke. Keep an eye on that rubber fuel line, they tend to go bad quickly with the alcohol in the fuel
There is a reason gm used an all metal fuel line on the engine....

[raggedjim]

Looks great and Randy did a great job helping you get through it all. I will add this, I had heard for years from people who don't like the plastic see through fuel filters, but I had one on my blazer for 5 years or so (not the same one, just the same type) with no problems. Well, they were right, this spring I had one split in half and spray down the engine compartment while I was driving to town. Scared the crap out of me, but I got lucky and it didn't catch fire. Now I have an ugly metal one, and a fire extinguisher.

Nice work, Rg

[rharris]

I pigtailed the choke wire back near the firewall - soldered and heat shrink. I also re-routed the temp wire along the frame and then to the heads instead of laying on the valve cover/manifold. I plan on going to tubing on the fuel line or using the edelbrock steel fuel line inlet to steel with the steel filter. The kickdown cable snapped into the edelbrock bracket, however the throttle did not. I have to alter the bracket a little bit. I will probably start a thread of parts used and some lessons learned/tips for any other amateurs out there. Thanks again for all the help.

Thanks for the tip on the filter Roger; steel one in the near future.

[geezer#99]

I predict future oil leaks for you if you don't put a breather on the passenger side valve cover.
And what's with the upside down valve cover on the passenger side.

[Coley]

Ok.....now you have to get us some information on how the parts change out has affected the performance of the truck.
Noticeable? how?....still tuning? or....does it still feel pretty close to the original set up or?

....looks good tho'!

Coley

[rharris]

Coley - I'll get back to you on detailed performance - happy so far.

Geezer - thanks for the heads up - I do have a breather, I just used the original fill cap. Should I use another PCV and T it into carb, or just a breather? I put the passenger valve cover on after the 12 pack ran out....just kidding. I just figured the Chevrolet should read the same way looking from the front, and the oil fill or pcv should go towards the front. My buddy dinged me on that as well. I'll change it this week. Also moved the vacuum advance to the correct port on the carb.

[AussieinNC]

Nice job !

To me, it looks like you have the rocker covers on the wrong sides...the passenger side has the pcv vale to the rear, and the drivers side then has the oil fill plug at the front,,,that way both Chevrolet reads correct on both sides...replace that plug with a breather...and you are good to go.

Have fun!!!

[geezer#99]

Just one pcv needed. And one breather.
What do you mean by 'moved the vac advance to the correct port'?
Your motor decides that. Some like it on manifold vac, some on ported.
Let the argument begin!! LOL!!

[AussieinNC]

Oh geezer...you really know how to get em going...

Manifold vacuum- low pressure in the intake manifold below the throttle plates. At idle usually around 17-21 in/hg. As the throttle plates open, vacuum drops.

Ported Vacuum- This is vacuum that is not present until the throttle is open. This is taken above the throttle plates.
This vacuum increases as throttle opens up.
This is usually used to control vacuum advance on Chevy distributors, and various other vacuum controlled devices.

Manifold vacuum should be used for brake boosters...

While not all cars use ported vacuum for advance, most Chevy and GMC do

.

[rharris]

Originally Posted by geezer#99

Just one pcv needed. And one breather.
What do you mean by 'moved the vac advance to the correct port'?
Your motor decides that. Some like it on manifold vac, some on ported.
Let the argument begin!! LOL!!

Ok, let me back up - I moved it to where edelbrock says it should go. I tried to make it clear that I am new at this - so I can only go on what I've learned and or read. I'm very happy there are still some 'Randy500's' left out there.

With that being said, what would I notice as far as a difference on manifold or ported vacuum?

[rharris]

Originally Posted by AussieinNC

Oh geezer...you really know how to get em going...

Manifold vacuum- low pressure in the intake manifold below the throttle plates. At idle usually around 17-21 in/hg. As the throttle plates open, vacuum drops.

Ported Vacuum- This is vacuum that is not present until the throttle is open. This is taken above the throttle plates.
This vacuum increases as throttle opens up.
This is usually used to control vacuum advance on Chevy distributors, and various other vacuum controlled devices.

Manifold vacuum should be used fro brake boosters...

While not all cars use ported vacuum for advance, most Chevy and GMC do

.

Thank you. So it sounds like the vacuum move was correct. I can only go by what is suggested to me - obviously its a low hp engine so there isn't much performance to notice a small change

[AussieinNC]

Ported vacuum is correct fro your build...see my previous response re rocker covers on wrong sides of engine

[rharris]

Originally Posted by Coley

Ok.....now you have to get us some information on how the parts change out has affected the performance of the truck.
Noticeable? how?....still tuning? or....does it still feel pretty close to the original set up or?

....looks good tho'!

Coley

Coley - The original carb was rebuilt by PO. It started fine when cold, but warm or hot it was a few more than desirable seconds cranking. My uncle who re-builds 56's (no 55 or 57 - don't ask me why) explained what the proplem was but I don't recall. It also seemed to hesitate and didn't have very great throttle response. All in all it ran ok and didn't need changed. My curiosity is what led the swap. I wanted to work on the truck a little.

I debated between a 500 or 600. I read some posts with the same setup with both carbs, so I went with the 600 since I would like to try a head swap. The 600 works well and starts very easily on cold, warm, or hot. The four barrel kicks in and it is noticeable and the transmission kickdown seems to work at a little better range. I'm sure someone who can tune and knows Rochester's could have made it work just as well or better. I am very pleased with the edlebrock so far, and had fun with the swap. I have a slight hesitation when giving a little more than 'normal' driving throttle. Light and full throttle is fine. I haven't tuned it at all; just adjusted the idle. With that being said, maybe the 500 would have been more suitable for the few ponies that the 307 produces. Also, I really wanted the black intake and carb, but it was over $200 more for the same setup. I'm not knowledgeable enough to determine what advantage/disadvantage the distributor made. I used the cheap summit distributor.

[rharris]

Originally Posted by AussieinNC

Ported vacuum is correct fro your build...see my previous response re rocker covers on wrong sides of engine

Thanks a lot - will do!