Search results
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Backfire on one side
I talked to my bro, who has far more knowledge than I w.r.t. engines. He says you likely have an air leak into the exhaust system, probably where the header connects to the exhaust pipe. The exhaust gases at idle, flowing past the leak, suck air into the exhaust pipe, and create a combustible...- rich weyand
- Post #5
- Forum: Engine & Performance
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Backfire on one side
Sounds like a small air leak to me. When the throttle is open at all, you are running a lot of air, and the leak doesn't affect anything. When the throttle is closed, vacuum is high and air flow is down, and the air leak can cause a an intermittent lean miss followed by a backfire in the...- rich weyand
- Post #4
- Forum: Engine & Performance
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Cam recomendations
That's what I figured you meant. The L-46 and L-82 ran the same cam, but the L-46 was pre-emissions and the L-82 was the smogger engine. Which would be great if the OP wanted to run 11:1 compression and burn $5/gallon avgas illegally on the street to get 350 hp and 380 ftlb with a 50-year-old...- rich weyand
- Post #12
- Forum: Engine & Performance
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Cam recomendations
What is so sacrosanct about that torque converter??? I don't get it.- rich weyand
- Post #10
- Forum: Engine & Performance
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Cam recomendations
The production L-48 in the 1980 Corvette was 190 hp, while the L-82 was 230. What am I missing?- rich weyand
- Post #9
- Forum: Engine & Performance
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Rebuilding the 350 finally
For all the work you're going to do, pull the engine, and leave the transmission and transfer case in place. You don't want to do all that work over the fenders and through the front. You can thank me later. And once the engine's out, changing the torque converter is easy. Look, you're at the...- rich weyand
- Post #26
- Forum: Engine & Performance
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GM Goodwrench cam choice
That cam's torque curve actually comes on pretty quick, with 320 ftlb at 1500 and 395 ftlb at 2500, with headers and a dual-plane manifold, so it might be OK. It's not as soft in the bottom as I expected, looking at the curves. You might want to go a touch higher stall in the torque converter...- rich weyand
- Post #4
- Forum: Engine & Performance
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Air gap intake
He's not talking about the difference between the Performer (2101/2701) and the Performer RPM (7101 e.g.), but between the Performer (2101/2701) and the Performer Air-Gap (2601). The answer to the original question is that the Air-Gap manifold allows for more precise control of carburetor...- rich weyand
- Post #4
- Forum: Engine & Performance
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Rebuilding the 350 finally
Basically, yeah. http://hughesperformance.com/tc-stall/- rich weyand
- Post #24
- Forum: Engine & Performance
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Rebuilding the 350 finally
Thinking about it, I would really worry about a 2800 rpm stall torque converter if there's a G80 in the diff. That's a lot of torque on hand when the clutches grab....- rich weyand
- Post #22
- Forum: Engine & Performance
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Cam recomendations
You should mark sarcasm so someone doesn't take you seriously. That is, I assume that was sarcasm....- rich weyand
- Post #5
- Forum: Engine & Performance
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Cam recomendations
With that set-up, I would look at the 12-239-3. Probably 407-ish hp and 436 lbft. It's amazing what more compression and bigger valves can do for you at the top. You don't want to go much higher in torque than that, or you'll dynamite that TH350. Biggest stock engine with a TH350 was 410...- rich weyand
- Post #3
- Forum: Engine & Performance
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Rebuilding the 350 finally
It'll be OK with a 2800 stall, but you don't need it. That cam will run just fine with a stock torque converter. Changing torque converters on a K truck is a PITA. But, since you're going to do the cam anyway, it might be easier to pull the engine and do both at once. Easier to do the cam...- rich weyand
- Post #20
- Forum: Engine & Performance
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Rebuilding the 350 finally
BTW, "the General" = General Motors.- rich weyand
- Post #17
- Forum: Engine & Performance
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Rebuilding the 350 finally
Basically, yes. 420 lbft is sort of the end of the line for a driveable 350. Not sure there isn't some marine cam totally unsuited to road use that goes higher, but the 12-300-4 is about the end of the line for torque in a roadable 350 (without changing heads or pistons or a bunch of other...- rich weyand
- Post #16
- Forum: Engine & Performance
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Rebuilding the 350 finally
Horsepower is the wrong metric. You race horsepower, you drive torque. Horsepower is the correct target for racing, because you are going to keep the engine RPM up in the 5000 rpm area, in the middle of the fat part of the horsepower, for the whole race. When you drive, you spend 99+% of the...- rich weyand
- Post #14
- Forum: Engine & Performance
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Rebuilding the 350 finally
Comp Cams produces all three of the above. Usually when someone says bigger for a cam, they mean duration, not lift. That will make the idle rougher. Next step up in duration from the 12-235-2 is the 12-339-3. From the 12-230-2, you could go up to the 12-234-2 or the 12-238-2. Above that...- rich weyand
- Post #12
- Forum: Engine & Performance
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Rebuilding the 350 finally
A note on cams I have posted in the past to queries like this. ================ A word on cams for you. 12-230-2 will work fine. With dual-plane and long-tube headers, 290hp/420lbft. Lift is .432/.444. RPM range is 600-4600. 12-235-2 will wind a bit tighter. With dual-plane and long-tube...- rich weyand
- Post #10
- Forum: Engine & Performance
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sending unit questions
The pipe plug on the driver's side head is apparently a 5/16" square drive, which is a common pipe plug size, See here: http://www.corvetteforum.com/forums/c4-tech-performance/3628174-how-to-remove-pipe-plug-in-driver-side-head.html Given the 5/16" female square drive, that is a 3/8" NPT plug...- rich weyand
- Post #3
- Forum: Engine & Performance
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Having trouble picking out a cam
Probably something like a Comp Cams 12-230-2. 288hp @4500 and 372ftlb @2500. 12-235-2 would also work, with 292hp @4500 and 365ftlb @2500. The lift is higher, though, at .447/.462 vs. .432/.444 for the 12-230-2, and your trading torque for hp, which is a bad deal in a truck, especially for...- rich weyand
- Post #2
- Forum: Engine & Performance
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350 Popping backfiring fire
When you snap the throttle open, the air speeds in faster than the fuel circuit can accelerate to keep up, the air/fuel ratio goes up over 17:1, and the fire goes out until the gas flow catches up. To compensate for this, carburetors have an accelerator pump. It squirts raw gas into the bores...- rich weyand
- Post #2
- Forum: Engine & Performance
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Whose got the best body replacement parts?
All the body shops around here say Goodmark is best. I guess they bought GM's dies. Note that all aftermarket panels punched since 1992 are galvanized on the back side, like modern car sheet metal, so they will not rust for a very long time if at all. Original panels that are parted out are...- rich weyand
- Post #11
- Forum: Paint and Body
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Idle & vacuum questions
Yeah, even the General gets it wrong sometimes.- rich weyand
- Post #13
- Forum: Engine & Performance
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Idle & vacuum questions
When I learned to tune a car, back when the ink was still wet on my driver's license, all vacuum advances of the major mfrs were run on manifold vacuum, because, pollution aside, that's the best fit to the combustion chemistry. It had been that way for nearly 30 years. My '61 Chrysler, my '62...- rich weyand
- Post #11
- Forum: Engine & Performance
