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Breaking in a cam

Headers for a Rat

Pierce Peck; via CarCraft.com: I read your article “How to swap an LS engine into your Chevelle” (May ’08). What was the result of putting the Hooker headers on your Chevelle? Was your ground clearance improved? I currently have a ’67 with 2-inch-dropped spindles and am considering replacing the current AFR-headed 540ci big-block with an LS engine and would like to keep as much ground clearance as possible. I am experiencing similar problems with the current mill. It has a set of Hooker 2455 2-inch Competition headers in it and ground clearance is too low despite a 26-inch tall front tire. Second question: Would a set of 2- or 21/8-inch Super Competition (or some other brand) headers give me more ground clearance? These headers were also a very tight fit and required some massaging with a propane torch and hammer to clear the steering column.

Any help you can provide will be welcome. The LS project is likely a couple of years away, so making the current big block more streetable is my first concern.


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Jeff Smith: To answer your first question, we haven’t taken the time to swap in the new headers. We tried to bolt in the Hooker headers, but they require Hooker engine mounts, which locate the engine back about 1 inch from its current position with Edelbrock’s headers and engine mounts. While this in itself isn’t difficult, moving the engine rearward also relocates the transmission, causing the slip yoke on the driveshaft to bottom out in the back of the transmission. We’d need a new driveshaft to fix that problem. Since this wasn’t a high priority at the time, we chose to live with the reduced ground clearance. We’ve also learned that Edelbrock has since dropped its entire exhaust line, so the headers and exhaust system are no longer in production, just in case you were considering buying that package. As a point of reference, Edelbrock used a ’68 to ’72 Chevelle for its prototype, which may partly explain why the header hangs down so far on the earlier models. We really can’t comment on the actual clearance, but we did measure the distance from the cylinder-head bolthole to the bottom of the collector on both sets of headers, and we found more than a 2-inch shorter distance with the Hooker headers, which would lead us to believe that the Hooker headers should fit much closer to the floorpan and allow more road clearance with a lower car.

As for your problems with big-block header clearance for your ’67 Chevelle, going with a larger header tube is only going to increase the clearance problems. With a given amount of room between the engine and the steering shaft, going from a 2-inch-diameter tube to 21/8 inches is only going to make things worse. But, we have an idea that might help you. I just shot a photo of a 540ci big-block Chevy for an upcoming Horsepower! spread. While I was looking at the engine, a friend of mine spotted a slick idea that car owner Rich Blakley used to improve the clearance to the steering shaft. He removed the shaft and set it up in a lathe and reduced the overall diameter slightly in two places to increase the clearance between the header tubes and steering. We would suggest keeping this undersize to a minimum to ensure the shaft does not break, but with power steering, the load to the box is reduced and should be plenty safe.

Big-block Chevelles have always been challenged by ground clearance, and larger tubes don’t help, but if there is more than 1 inch of room between the collector and the floor, there is certainly room to improve the ground clearance. One trick we learned from Mark Stielow is to first place the car on a hoist where you have access to the headers. Using a torch, carefully heat the header primary tubes just behind the collector, then use a long prybar to bend the collector upward. This involves finesse, so work carefully. Stielow says he’s used this method to improve ground clearance on his Pro Touring Camaros. Another possibility is to eliminate that large, three-bolt collector flange. It takes up room on both the floorpan and ground clearance sides. To replace it, you can go with a ball flange adapter kit from Flowmaster or use V-band clamps. The Flowmaster kit uses a spherical ball shape to seal the collector to the exhaust system and has to be welded to the collector. It attaches to the intermediate pipes with a two-bolt connector. These bolts are parallel with the floor, improving ground clearance over the traditional three-bolt collector flange. The best way to go is with a set of V-band clamps. These clamps have been successfully used in the turbocharger industry for years, and Afco makes a set in 3- or 31/2-inch diameter. The clamps use two stainless steel sealing surfaces that are held together with a band clamp. The sealing surfaces have flanges that must be welded to the collector and the exhaust pipe, but to install or remove them, just slip the band clamp over the two sealing flanges, tighten the nut, and you’re done. We used these V-band clamps on my Chevelle exhaust system at the mufflers and the collectors. It’s a quick way to remove the system; they take up very little room compared with a three-bolt flange system and have no gaskets to leak.

More Info

Afco; Boonville, IN; 800/632-2320; AfcoRacing.com
Flowmaster; Santa Rosa, CA; 800/544-4761; FlowmasterMufflers.com

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2 comments
dkoy
dkoy

Hi,What chain of events must occur to allow any new car with a normally aspirated engine to start in any weather and within moments idle nicely at 700 rpm ? Now, assuming whatever recipe is needed is it safe to assume that any normally aspirated engine in sound condition could run like a brand new car (idle at 700 rpm within moments, great acceleration, low emissions, etc) by adding fuel injection ?My situation: I have a 1954 Cadillac Series 62 2 door that I have been building as a phantom Hurst/Cadillac. The engine is a 1970 Cadillac 472, 10:1 compression, homemade headers with 2.5 Flowmaster 70s all the way to the back of the car with a 1975 Cadillac EFI set up (Throttle body,fast idle valve, fuel rail, fuel injectors) , 1981 Cadillac V8-6-4 HEI computer controlled distributor. This is all managed by a Megasquirt 2 V3 computer. Other than the attached parts the engine is bone stock down to the cam. I had the heads redone to factory specs.I have an Innovative Motorsports LC-1 wide band sensor. I have a Walbro fuel pump. I forget the specs. But, the fuel pressure is ~ 39 psi as needed. It has the factory regulator too.BTW, The Hurst part is a Hurst Auto/Stick 1 mated to a turbo 400.I have been having issues tuning this engine. I am running the motor with an alternating bank injection mode. The timing is ~ 0degrees BTDC at the wheel with the Megasquirt in concert with the setting. One thing I do not understand which I think could be causing the issue is that I have wired the alternating banks to 1,2,7,8 and 3,4,5,6 based on the original Cadillac design. But, the firing order is 1,5,6,3,4,2,7,8. Shouldn't the injection order follow the firing order ? How could any engine be expected to run correctly with this conflict ? Problems include a very high idle when cold (1300 1600 rpm) and the WB sensor reading way too lean than way too rich. Adjusting the VE table seems to do little. Lately I am having an issue with the passenger header smoking like crazy. It appears that something is burning from the inside out! When this happens I normally shut it down and re-evaluate.As bad as it runs the car can keep up with traffic easily. The car with this set up has never been able to spin the tires from a dead stop. At one point the car could spin the tires with the stock quadrajet.What is your assessment ?Daniel KesterEast Meadow, NY

401amx
401amx

Just read the Jan issue about oil. I contacted Isky for their recommendations on cam breakin. They told me to use the Brad Penn 30 break in oil and that I also did not need to add any extra ZDDP.

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