Brain Pickin Time
Thread Starter
Racer
Joined: Dec 2003
Posts: 304
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From: Pasadena Maryland
Brain Pickin Time
OK. This is technically not a C-3 Question but because it's a corvette engine I'm going to pick everyone's brain. I basically tore down a 327 to the short block on my son's T-Bucket. New Comp Exptreme Cam with 282 duration and about a 494 lift. New Pro comp aluminum heads, timing gears, roller rockers, and a brand new custom built tunnel ram with a three duece set-up. New Mallory Unilite (No Vacuum Advance) Distributor and coil. Can't get the engine to idle. Keeps surging up and down almost like a vacuum leak. The only vacuum sources are a PCV connection and a 1/4 in. vacuum source for the Turbo 350. Eveyone tells me the Unilite is a POS, but I've been running one in our Jeep with a SBC for over three years. I know we are going to need a Stall Converter but have to get it running first. Looks like we are going to miss Ocean City Cruisin next weekend it I don't get it running right. By the way the three dueces are Rochester's and only the center one has any adjustment on it. The other two are dumpers. 
Drifting
Joined: Dec 2004
Posts: 1,345
Likes: 3
You may have vaccum leak between the manifold and heads. Spray water around the heads at the manifold joint and at the base of the carb. If the RPM changes you have a leak. This won't find a leak on the bottom side of the manifold and head connection.
Race Director
Joined: Dec 1999
Posts: 11,096
Likes: 990
From: Sierra Foothills CA
I'd be more inclined to think it's carb/intake related. If it's the Unilite at all it could be the mechanical advance, but I doubt it. I've run a Unilite in a smallblock for over 25 years- other than 2 early module failures when the design was relatively new, one of which was probably my fault, the unit has functioned flawlessly.
I'm thinking vacuum leak or carb tuning issues like the others. Assuming you've eliminated all vaccum lines or other vacuum leaks as the problem and can't improve it by carb tuning, I'd start swapping distributor or intake/carbs one at a time to nail it down. Good luck.
I'm thinking vacuum leak or carb tuning issues like the others. Assuming you've eliminated all vaccum lines or other vacuum leaks as the problem and can't improve it by carb tuning, I'd start swapping distributor or intake/carbs one at a time to nail it down. Good luck.
Thread Starter
Racer
Joined: Dec 2003
Posts: 304
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From: Pasadena Maryland
Thanks guys. I gave it a break today. Been working on it for the last 4 weekends. I was going to try again tomorrow. I will concentrate on the vacuum issue. The Intake and tunnel ram setup was jet coated and they even jet coated the underside of the intake. I will start at that point. I even considered pluging off the PCV valve at the tunnel ram to eliminate that source. That will only leave me the vacuum source for the Transmission. When I was younger I used to spray a little carb cleaner around to see if the idle increased. I hate the thought of taking this engine apart again. We'll it is easy to get to. You can see the back of the T-Bucket in my second picture that I have posted. This is the first spring I don't have to do anything to my 78. Better knock on wood.
Dominic
Dominic
Thread Starter
Racer
Joined: Dec 2003
Posts: 304
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From: Pasadena Maryland
Answer to my question
Brought in my nephew yesterday to try and solve this surging problem and while my son was bumping the starter so we could check the valves he said he saw a spark in the vicinity of no 1 plug. We thought he was seeing things. We started the car and my nephew put his timing light on it to check total advance and he actually got shocked. We saw a pretty blue spark jumping from the engine mounting bolt to the chassis. Come to find out the guy we bought the car from failed to put on a grounding strap from the engine to the chassis. This could be the reason we burnt out two Mallory Modules. The old 327 is running strong but definitely needs a stall converter. We're not going to Ocean City this weekend as we are going to put in the converter. We also decided on a MSD Ignition system with the 6A box as well. Who said this hobby was fun? I'm getting to old for this. 
