We have lift Off !!!

[dave ridgway]

Hello All

Finally started my engine for the first time on Thursday. Yippee !!!

Had a couple of things to sort out, coolent leak etc. Sorted them all out and started it up again today for a bit longer. No leaks but I do have a couple of questions if anyone can help.

One of the header pipes got really hot, I mean glowing red hot. i'm sure this is not supposed to happen. Any ideas as to what might cause this ??

Also after running for about 5 minutes at 1800 rpm I got a lot of engine run on after switching the ignition off. I am using an HEI dizzy with an MSD 6AL ignition unit. Again any ideas greatly appeciated.

Cheers

Dave

[Miket]

Hi Dave

I had the same problem, the headers where glowing, It also blued my intermediate pipes.

Mine was the combination of a very tight engine and the timing was too far advanced.

My Cob is now finished and waiting for the SVA, so it has not been on the road yet, but all seems ok in the garage now engine has bedded in and timing sorted.


Miket

[wilf]

Dave - congrats at last!!

On the red hot header and run-on, I would suspect these are linked, and due to the engine running too hot. If your ignition timing is bang on, then it is down to incorrect mixture. From memory I think it is too lean a mixture that causes overheating - but check with other members.
If that is the case you might go up a jet size on the primary main jets before you run it around, or get it set up properly on a rolling road/dyno asap. You can get this done approximately even before the engine is run in, it's worth doing so. Make sure the operator knows you want an approximate setting on a engine not yet broken in. After it is run in, get it done again.
If one header pipe got noticeably hotter than the rest, you might try to see if there is a vacuum leak on the intake side of that cylinder somewhere.

As I said before, this cam run-in operation is a trying time for an engine, they will get very hot running at those rpm's static. My own engine will run-on if I stop it suddenly after a period of heavy loading, if I let it tick over for a minute or so it doesn't do it.

Wilf

[dave ridgway]

Thanks for the info, one other engine related question. Do you know which of the vacuum ports on the Carb I connect to the dizzy. There is a way of testing it but I can't remeber how to do it.

I am using an Edlebrock 750CFM Carb.

Cheers

Dave

[wilf]

Mike - looking onto the front of the carb, there are 3 ports down towards the base of the carb, two small ones either side of a large one. The centre, large one, is for your PCv, the other two differ in that one is "timed" (i.e. does not "suck" until the throttle is cracked open, i.e. above tickover, and then reflects manifold vacuum, the other "sucks" all the time, amount of suck dependant on airflow throught the carb).
The easiest way to check which is which is to see which one sucks at tickover. Not having had a vac advance for ages, I can't remember which one you want, but I think it is the timed one - i.e. no vac advance at tickover. Sure so else will jump in if I'm wrong!

Wilf

[STOMPER]

Nice one dave
My headers glowed cherry red due to lean mixture.
Bit worrying when you see it,They do get very hot and discolour the stainless
is not much of a heat sink like the orignal cast iron items.
All the best.
Paul :7 x(

[russell_ram]

Wilf,

I think Mike probably should use the 'constant' vacuum port. This gives max advance at idle and closed throttle over-run (max vacuum), good for emissions. This is certainly the set-up for RV8 anyway and I don't see why a Chevy should be any different.

As for the glowing manifolds, if it's not an air leak then it's most probably due to retarded ignition, ie fuel still burning as it exits cylinder.

Russ

[wilf]

Russ - thanks for that, I really wasn't sure, and couldn't figure out the logic from scratch. One thing though - I have heard that the "constant" port on the edelbrock doesn't actually reflect inlet manifold pressure, rather it shows the pressure drop at the carb venturi, and this would be directly related to airflow. Again, I am not sure about this - will check it out this coming weekend with a vac guage on my car.

Wilf

[dave ridgway]

Cheers Kev

Just what I needed to see !!

Cheers

Dave

[kdavies3]

Here you go see photo attached from my 383 as supplied by The Engine Factory in Florida.

Left hand port blocked off, centre port to PCV, right hand port to dizzy.

All I need to do now is get it into the rest of the car and like you fire it up and listen to the music. I have seen mine run on video on a test stand.

Kev Davies