The Great Pumpkin - '71 Duster
Soooo, looks like I am rebuilding the 340 in The Great Pumpkin. Lemme backtrack a little first...
Last time I went to the drags, I blew the water pump on the way home. Fixing it would require draining the coolant so I thought it was a good opportunity to make a change to the induction system. I had been wanting to try a Thermoquad and had been wanting to try one for a long time. I figured if I had to drain the coolant, it was good time to swap intakes and do the carb. The Proform 750 DP was fine, it ran OK but I guess I really wanted a Plastic Fantastic. I have no real explanation or justification. Maybe it was the NOS Strip Kit I got for it. Dunno.
I bought a W2 Strip Dominator from member dartrunner. I didn't want to run an adapter, I don't need the plenum volume with a small stroke and a single plane on a street car. I got the TQ from member EL5340Demon. He had run the carb on his car and had it set up pretty nicely. His combo was similar to mine and ran pretty close to what my car runs. Got some Superformance gaskets for the intake and made the change. My goal was to get it all back together and try to tune it enough to take it down the track one more time before the end of the season. Didn't happen.
I knew the engine was tired but I didn't realize the extent of it until I had the intake off. Once I popped it off, I looked down at the valves and saw they were badly caked up with carbon and the stems were burned. I doesn't smoke at all but from the way the valves look, I'd bet the valve seals are toast. I couldn't even make out the back of the valve face it was so thick. I knew the piston tops were black because I could see those down the spark plug holes with a light but I didn't think it was as bad as it turned out to be. It ran OK I suppose but I knew it was tired. I believe the engine was built a while ago and raced regularly.
The valley looked OK but some of the cam lobes looked pretty worn. Nothing blue or burned or anything, just normal wear I guess but enough to probably warrant a replacement.
The other indicator that things were not so much was performance. While 12.20 @ 110.8 in the 1/4 is respectable for a stock stroke 340, to me the car is at least a half second slower than what it should be, especially since it only weighs 3,000 lbs. without me. Generally speaking, most any W2 combo should theoretically be good for mid to low 11s if everything is sorted out. Of course ET is not all engine related and half of it is chassis/gearing/converter but I believe the car is down on power. It has to be!
But I digress.... so knowing full well what things looked like inside, I went ahead with the intake and carb thing anyway. I hit a snag when I went to put the intake on and failed to see the tops of the intake gaskets were sticking up past the valve cover rails on the heads. No good! Damn! Everything lined up OK but this was not right. So it was either take off the intake and install brand new gaskets or trim them on top and try to salvage the job.
I ended up taking the intake back off which was a big mistake because the silicone had set up on the china wall and the gaskets were glued in place. I had to see why the gasket was sticking up so far though and wanted to make sure there was nothing installed wrong. There wasn't. I put the intake back on and just trimmed the tops to be flush with the heads.
So after all that, the damn things leak. I re-did the silicone and made sure everything was hunky-dory before putting the intake back on. Clearly though, something must have gotten torn or disrupted when I took off the intake because after driving it around, there was a puddle of coolant on the timing cover. I could see it wicking through the gasket under the front of the intake. No good! Damn!
So either way, this all has to come apart again. With the knowledge of how everything looked inside I knew it was time to pull everything apart for a rebuild. It makes no sense to just re-do the intake gaskets, I can't leave the valves like they are, there is no way they are sealing effectively. I've had it in the back of my mind that I was going to need to do this sooner or later. Seems par for the course how when you fix things, other crap comes up and things snowball. Typical I guess.
I would like to build in a little stroke to help with torque. I really like the 372" combo, I believe it will be efficient. 3.58" stroke cranks with 340 mains are under $375. Some nice Scat rods and lighter 360 pistons will be part of the plan. Not looking to break the bank but I don't like to skimp on parts so it will be a quality rebuild with an eye towards blueprinting things as well as possible. Only other thing I am undecided about is whether to re-use the W2s or use the RHS/Indy heads I have.
Naturally, a new converter will also be something I plan on getting since the one that's in there now is not so great. It's a 10" that stalls around 3,800, I think I could use a little more to get it off the line better. Looking into a Dynamic 9.5".
So, I guess I am done driving the car for a while. Looks like a have a winter project! Wish me luck in getting back together before next summer.
Pics below of the failed intake/carb change.
Behold Ye Mighty Thermoquad. Thanks Mike!
Behold Ye Ancient Holley W2 Strip Dominator! Thanks Frank!
Side by side comparison of intakes/carbs. The Holley/TQ is slightly taller than the Victor/double pumper. It's enough where no air cleaner will fit with the TQ. I will have to remedy that somehow.
Here's the old intake off. Lot's of goo on the china walls. Note red Glyptal paint in the valley to help oil drain back.
New stuff installed and ready to leak coolant.
Closeup of coolant leaking from coolant passage, down the front of the intake.
Things are getting interesting. More to come!
Soooo, looks like I am rebuilding the 340 in The Great Pumpkin. Lemme backtrack a little first...
Last time I went to the drags, I blew the water pump on the way home. Fixing it would require draining the coolant so I thought it was a good opportunity to make a change to the induction system. I had been wanting to try a Thermoquad and had been wanting to try one for a long time. I figured if I had to drain the coolant, it was good time to swap intakes and do the carb. The Proform 750 DP was fine, it ran OK but I guess I really wanted a Plastic Fantastic. I have no real explanation or justification. Maybe it was the NOS Strip Kit I got for it. Dunno.
I bought a W2 Strip Dominator from member dartrunner. I didn't want to run an adapter, I don't need the plenum volume with a small stroke and a single plane on a street car. I got the TQ from member EL5340Demon. He had run the carb on his car and had it set up pretty nicely. His combo was similar to mine and ran pretty close to what my car runs. Got some Superformance gaskets for the intake and made the change. My goal was to get it all back together and try to tune it enough to take it down the track one more time before the end of the season. Didn't happen.
I knew the engine was tired but I didn't realize the extent of it until I had the intake off. Once I popped it off, I looked down at the valves and saw they were badly caked up with carbon and the stems were burned. I doesn't smoke at all but from the way the valves look, I'd bet the valve seals are toast. I couldn't even make out the back of the valve face it was so thick. I knew the piston tops were black because I could see those down the spark plug holes with a light but I didn't think it was as bad as it turned out to be. It ran OK I suppose but I knew it was tired. I believe the engine was built a while ago and raced regularly.
The valley looked OK but some of the cam lobes looked pretty worn. Nothing blue or burned or anything, just normal wear I guess but enough to probably warrant a replacement.
The other indicator that things were not so much was performance. While 12.20 @ 110.8 in the 1/4 is respectable for a stock stroke 340, to me the car is at least a half second slower than what it should be, especially since it only weighs 3,000 lbs. without me. Generally speaking, most any W2 combo should theoretically be good for mid to low 11s if everything is sorted out. Of course ET is not all engine related and half of it is chassis/gearing/converter but I believe the car is down on power. It has to be!
But I digress.... so knowing full well what things looked like inside, I went ahead with the intake and carb thing anyway. I hit a snag when I went to put the intake on and failed to see the tops of the intake gaskets were sticking up past the valve cover rails on the heads. No good! Damn! Everything lined up OK but this was not right. So it was either take off the intake and install brand new gaskets or trim them on top and try to salvage the job.
I ended up taking the intake back off which was a big mistake because the silicone had set up on the china wall and the gaskets were glued in place. I had to see why the gasket was sticking up so far though and wanted to make sure there was nothing installed wrong. There wasn't. I put the intake back on and just trimmed the tops to be flush with the heads.
So after all that, the damn things leak. I re-did the silicone and made sure everything was hunky-dory before putting the intake back on. Clearly though, something must have gotten torn or disrupted when I took off the intake because after driving it around, there was a puddle of coolant on the timing cover. I could see it wicking through the gasket under the front of the intake. No good! Damn!
So either way, this all has to come apart again. With the knowledge of how everything looked inside I knew it was time to pull everything apart for a rebuild. It makes no sense to just re-do the intake gaskets, I can't leave the valves like they are, there is no way they are sealing effectively. I've had it in the back of my mind that I was going to need to do this sooner or later. Seems par for the course how when you fix things, other crap comes up and things snowball. Typical I guess.
I would like to build in a little stroke to help with torque. I really like the 372" combo, I believe it will be efficient. 3.58" stroke cranks with 340 mains are under $375. Some nice Scat rods and lighter 360 pistons will be part of the plan. Not looking to break the bank but I don't like to skimp on parts so it will be a quality rebuild with an eye towards blueprinting things as well as possible. Only other thing I am undecided about is whether to re-use the W2s or use the RHS/Indy heads I have.
Naturally, a new converter will also be something I plan on getting since the one that's in there now is not so great. It's a 10" that stalls around 3,800, I think I could use a little more to get it off the line better. Looking into a Dynamic 9.5".
So, I guess I am done driving the car for a while. Looks like a have a winter project! Wish me luck in getting back together before next summer.
Pics below of the failed intake/carb change.
Behold Ye Mighty Thermoquad. Thanks Mike!
Behold Ye Ancient Holley W2 Strip Dominator! Thanks Frank!
Side by side comparison of intakes/carbs. The Holley/TQ is slightly taller than the Victor/double pumper. It's enough where no air cleaner will fit with the TQ. I will have to remedy that somehow.
Here's the old intake off. Lot's of goo on the china walls. Note red Glyptal paint in the valley to help oil drain back.
New stuff installed and ready to leak coolant.
Closeup of coolant leaking from coolant passage, down the front of the intake.
Things are getting interesting. More to come!