Sleeving the 409
This Steve Magnante photo from a Sept ’08 Hot Rod story shows the relationship of the 74-d
Eric McFarland; Bethany, OK: I am a long-time subscriber and have magazines from the early ’80s. Recently, I purchased a complete ’65 Chevy 409 engine for a fantastically low price. On teardown (the engine was seized), we found that the No. 2 cylinder was full of rust. We also discovered the No. 7 cylinder had walked the wristpin out until it rubbed a slot in the cylinder wall and was deep enough to hit water. The connecting rod seems to be slightly twisted. This is a standard-bore, standard-bearing engine, and all the other cylinders have the crosshatch from honing still visible in the walls.
What is the proper technique to sleeve the affected cylinders? This is a truck block with the compression- lowering cutouts in the combustion chambers. I have asked three machine shops this question and have gotten three different answers. Apparently, this is not as simple as it seems. I have previously used re-sleeved engines with excellent results, but the Chevy W engine—particularly the truck blocks—seem to present special problems. I would like your opinion.
Jeff Smith: I mentioned your plight to veteran machine-shop owner Don Barrington, who has plenty of experience with both the 348 and 409 engines. He says that while installing sleeves in this engine is slightly different than in a typical 90-degree V8, he has successfully performed this operation many times. In fact, his shop has the only BHJ torque plate in existence for these engines; Barrington commissioned BHJ make a 348/409 torque plate for him, and they told him it was so difficult they never want to make another one.
This piston shot reveals the two diverging piston-top angles on a high-compression 409 pis
For those of you who may not be aware, the W-version 348 and 409 engines were the original big-block Chevy engines used in Chevrolet production cars and trucks between 1958 and 1965. What makes these engines unique among all Chevy engines is that the combustion-chamber side of the cylinder head is virtually flat, with only small recesses for the valves. The combustion-chamber space is relocated to the block, changing the block-deck surface angle from 90 degrees to 74 degrees. Stranger yet, the piston tops have two angles, the upper portion of the piston matching the 74-degree bank angle, and the lower half of the piston top at 90 degrees to the crank centerline, which is much lower than the deck surface. This creates a wedge area between the piston and the head. But this design also creates a cylinder wall that stops far below the deck surface. The photos here make this all a little more clear. This was an engineering attempt done in the ’50s to improve combustion efficiency by using the piston and head to push air and fuel into a section of the chamber, therefore creating a wedge effect. This might have been the origin of the term “wedge” that now refers to most non-hemispherical combustion chambers, but the evidence has probably been lost to history.
To get back to your question, Barrington still has the torque plate, and he says that sleeve repairs are not difficult if you are willing to ship your 348/409 block to its Los Angeles-area shop. The address and telephone number are included below. Just for grins, we did a little more research and found that Edelbrock makes a set of 348/409 aluminum heads (Summit Racing PN 60819, $2,100/pair), and if you really want to go off the deep end, World Products makes an aluminum 409 block that would be the ultimate in alloy retro technology.
Barrington Engines; Van Nuys, CA; 818/442-9409
Edelbrock; Torrance, CA; 310/781-2222; Edelbrock.com
Lamar Walden Automotive; Doraville, GA; LamarWaldenAutomotive.com
World Products; Ronkonkoma, NY; 631/981-1918; WorldCastings.com
More Clearance, Low Pressure
Jake Summerville; Apopka, FL: I have been working on a rebuild of a ’79 Camaro 350 two-bolt main small-block Chevy for an ’87 Monte Carlo project car. The motor is all buttoned up with new parts, except the crank and rods. When we first crank it up, it holds about 55 psi or more of oil pressure, but after warm up, it dives down to single-digit levels. I’ve heard from others that small-block Chevys only need 5 or 6 psi of pressure at idle. Others stated that the norm was 10 psi of pressure for each 1,000 rpm. Others still have said the crank was shot or possibly the passages were too big. What can I do to check this issue? Are there any remedies that can be done without removing the motor? It’s currently installed in the Monte. The motor has Pennzoil 10w30 oil, Clevite bearings, a Melling 55 psi of oil pump, a mild street cam, KB pistons, roller rockers, an Edelbrock Performer RPM intake and 600-cfm carb, shortie headers, and an HEI distributor. The engine starts and runs OK, and there are no knocking or weird sounds, just the oil-pressure dive issues.
Jeff Smith: Here’s what I think is happening, Jake. While the crank probably looked good, the clearances are a bit wider than ideal on both the mains and rods. So if 0.0025 inch on the rods and mains is considered an ideal bearing clearance, your engine is probably closer to 0.0035 inch. That additional area allows more oil to move past the bearings with reduced pressure. Because of this additional clearance, you have plenty of oil flow, therefore signaling that pressure is the issue. Pressure is an indication of a restriction to flow. By reducing the flow restriction, the pressure drops. When the engine is cold, the oil is more viscous (thicker) and creates a greater restriction to flow, hence making the pressure higher. As the engine and oil become warmer, the oil thins, and the pressure falls. The hotter the oil, the lower the oil pressure. This is where most car guys tend to freak out. The reality is that the engine is getting plenty of lubrication, but because the oil-pressure gauge reads lower than normal, many believe there’s something radically wrong. While the situation is not ideal, it’s not life-threatening.
Comp’s Hot Rod oil comes in both 10w30 and 15w50 and is a blended or semi-synthetic, while
You are correct that changing to a 20w50 oil will help the hot oil pressure, since the oil will be more viscous and resistant to flow when hot. However, this also means it will be even more viscous when cold. You need to be careful when the engine and oil are cold, because the oil will be much more difficult to pump, pushing the pressure much higher. Under normal circumstances, if you rev an engine with cold oil, the oil filter cannot accommodate the same volume of thicker oil, so the bypass valve opens to prevent excessive pressure buildup in the filter (again, an indication of a restriction to flow). With 20w50 oil (much more viscous than 10w30), the pressure is higher when cold. If you rev the engine with cold, high-viscosity oil, the typical result is a rupture between the oil filter sealing gasket and the block, causing oil to pump out all over your engine compartment and garage floor. If you’re really unlucky, it could hit a hot header pipe and catch fire. None of these results will result in a happy ending, so be careful.
What you should ultimately be concerned with is where the oil pressure stabilizes once the engine and oil are hot. Ideally you will have 40 to 45 psi of boost at 6,000 rpm. This will be sufficient pressure to protect your engine. Some may cite the classic 10 psi of pressure per 1,000 rpm rule, but I can tell you we just finished testing a 680hp, normally aspirated 436ci small-block Chevy that generated a mere 48 psi of pressure at 7,200 rpm, and the engine survived and ran just fine with no issues. We were really pushing it with thin, 5w20 Joe Gibbs racing oil and minimal oil volume in the pan in an attempt to make some hero horsepower. You will see that engine tested in an upcoming issue.
If you don’t mind dropping the oil pan on your engine, it’s possible that a high-volume oil pump (M-55HV, $33.95 Summit Racing) will help, as the volume of oil now running through your engine has greatly increased. This may help the oil pressure slightly, but there are no guarantees. I would try 20w50 oil first, then go from there. Another suggestion is to use an oil filter that represents less of a restriction. For example, Fram’s HP series (HP4, $9.95 Summit Racing) uses a higher-flow filter media that does not catch the very small particles that a normal, production-car Fram filter does, but the company assumes the end user will change the oil much more frequently, so reduced filter efficiency should not be an issue. The advantage is that there is less of a pressure loss across the filter; when the engine warms up, the rods and mains see a little more pressure. There are other good high-performance oil filters, such as K&N
Another thing to consider is a high-quality oil that uses a really good base stock. We just had a meeting with Lake Speed Jr. from Joe Gibbs Driven, the company that sells race and street lubricants. Speed told us about a new, very high-quality base-oil lubricant called Advanced PAO Synthetic that offers an improved viscosity index (VI). You may have heard about viscosity-index improvers, additives that actually get thicker when subjected to high oil temperatures. With a standard-base stock oil, greater quantities of VI improvers are needed to maintain a given viscosity at the standardized test temperature of 100 degrees C (212 degrees F). A better base stock, such as this new Advanced PAO synthetic, does not thin out nearly as much at the test temperature, which means lower quantities of the VI improvers are needed. This makes the oil much more stable over a greater temperature range. I’m not necessarily recommending this new Joe Gibbs oil to you (the HR-3 15w50 is $10 a quart or $120 for a case of 12), but you might look into a racing oil from any of the good companies, as those lubricants will also contain higher concentrations of zinc and phosphorous, which will protect your engine. Because your engine has a hydraulic flat-tappet camshaft, it’s important to use oil with higher percentages of zinc and phosphates (ZDDP) to protect your camshaft. Current production-engine oils that display the API SM or SN “donut” tag do not contain sufficient levels of ZDDP, which may cause excessive wear between the cam and flat-tappet lifters. As another alternative, Comp Cams has recently released a Hot Rod motor oil with higher zinc and phosphorous concentrations for engines such as yours. It offers a 15w50 Hot Rod blended synthetic oil (available through Summit Racing for $7.50 per quart, case of 12) that’s less expensive than race oil. As a 15w50, it will be a little less viscous at lower temperatures, making it seemingly a good choice.
Autolite/Honeywell (Fram); Danbury, CT; 203/830-7800; Autolite.com
Comp Cams; Memphis, TN; 800/999-0853; CompCams.com
Edelbrock; Torrance, CA; 310/781-2222; Edelbrock.com
Joe Gibbs Driven; Huntersville, NC; 866/611-1820; JoeGibbsDriven.com
K&N Engineering; Riverside, CA; 800/858-3333; KNFilters.com
Roll On Power
Timothy Bragg; Gray, TN: I am building a 383 pump-gas engine for a ’68 Camaro. I plan on using a Comp cam, and I want you to choose it. This is what I have: ’70 four-bolt block, Patriot 190 Freedom heads with a 64cc chamber, internally balanced Scat rotating assembly, KB pistons, 9.8:1 compression, MSD billet distributor and 6AL box, Victor Jr. 1-inch-taller intake, a 750-cfm Speed Demon carb with mechanical secondary, a Turbo 350 with a TCI Super Street Fighter converter, and a 12-bolt posi with 3.73:1 gears. I want a solid roller cam that will give me the most torque and horsepower from idle to 7,000 rpm. I also want this engine to sound like it is the baddest thing ever put together. This is a street-only car and not a daily driver. In my opinion, you are at the top of the list for engine knowledge. You have probably forgotten more about cams than I will ever know. Any help would be greatly appreciated. Thanks.
Roller cams offer significant lift advantages over flat-tappet camshafts. Newer cylinder h
Jeff Smith: Your request, Tim, comes with perfect timing, since I literally just returned from a two-day small-block Chevy cylinder-head test/thrash at Westech Performance on its engine dyno. You will have to wait for our Sept. ’12 issue to see the results, but one of the heads we tested was a Patriot 185cc intake port head (PN 2168) that is probably similar to your slightly larger 190cc version. At this point, we haven’t had a chance to evaluate all the results, but we can say that the Patriot did very well compared with a tough field of quality cylinder heads. We can also say that the cam used in the test was a budget-oriented, flat-tappet hydraulic cam, so the lift was limited to less than 0.600 inch. From a 9.6:1 compression 350, we saw 400-plus horsepower, and it appears that your combination is slightly more aggressive with a single-plane intake manifold. The mechanical roller is a good choice, since the roller lobe can generate far more valve lift than a typical flat-tappet lifter. I also like your approach of looking for maximum overall torque and horsepower. You mentioned the KB pistons, which I will assume are the hypereutectic versions. While these pistons perform well, many enthusiasts don’t realize these are still just slightly stronger versions of a cast-aluminum piston. I mention this only because I don’t like to spin hypereutectic pistons much more than 6,200 to 6,400 rpm, because as engine speed increases, tension on the wristpin boss increases geometrically as the piston accelerates away from top dead center (TDC). The connecting rod yanks on that pin pretty hard to accelerate the piston, and g forces really escalate as the rpm increases, so given what you already have, I’d suggest limiting the engine speed to 6,500 rpm rather than 7,000. I’ll also assume that the arm in your 383 is more likely a cast crank rather than a 4340 steel unit, which makes the 6,500-rpm maximum carry even more importance. Remember that a longer 3.75-inch stroke engine has to accelerate and decelerate the piston that much quicker because the piston is traveling a greater distance than a 350’s 3.48-inch or 327’s 3.25-inch stroke.
The basic task of choosing a camshaft can be made simpler by looking at how each cam specification affects engine operation. The most important consideration is duration. Increasing intake duration effectively moves the peak torque rpm point higher in the rpm band. Let’s assume for the moment that a stock cam with 200 degrees of duration at 0.050 tappet lift has a torque peak of 4,000 rpm. By adding a longer-duration cam of 230 degrees, for example, with all other engine parameters being equal, the peak torque might move up from 4,000 rpm to 4,500 rpm. Now, if we assume that the engine will produce a powerband of anywhere from 1,500 to 2,000 rpm, we can then predict that peak horsepower will occur somewhere between 6,000 and 6,500 rpm. The definition of the powerband is the rpm span between peak torque and peak horsepower. Over the years, we’ve seen improved cylinder heads able to widen powerbands out to 2,000-plus rpm, which is generally a good thing, because now you can use that effect to slightly shorten the camshaft duration. This is a good idea for a road car because unlike a race engine, street-driven engines spend a majority of their time at idle and part-throttle. So if we can choose a camshaft with a little less duration and overlap, it will be more tractable on the street.
To address your specific question, I think a mechanical roller camshaft with an intake duration of 236 to 242 degrees at 0.050 inch of tappet lift would be a great cam for street performance in your 383 small-block with the 190cc heads, a single-plane intake manifold, and 13⁄4-inch headers.
Next on the list would be lift, which is where the roller cam has a decided advantage over the flat-tappet. Because of its design, a roller cam can generate much faster ramps, which allows the lobe designer to pull more lift from a given number of degrees of duration. As an example, a flat-tappet hydraulic Comp Cams Xtreme Energy cam with 230 degrees of duration at 0.050-inch tappet lift generates 0.490-inch valve lift, while an Xtreme Energy mechanical roller with the same 230 degrees of duration at 0.050 is capable of 0.552 inch of valve lift. Now, you will have to subtract the lash from this figure, but you are still generating a solid 0.030- to 0.035-inch more lift with a roller. Plus, the roller will allow you to increase valvespring pressure to compensate for more rpm. Crane offers a 238/246 degrees at 0.050 camshaft with 0.595/0.615 inch lift (PN 138601, $426.00 Summit Racing) that would make outstanding overall power without running past our artificial rpm limit. Comp offers a similar grind with 236/242 degrees of duration at 0.050 with 0.564/ 0.570-inch lift. Both cams run with a 110-degree lobe-separation angle, so there will be quite a bit of overlap. Keep in mind that you have to subtract the lash from the gross valve-lift numbers. The Crane uses a 0.020-inch lash while the Comp runs 0.016- and 0.018-inch lash on intake and exhaust. This still keeps the lift right around 0.550 inch, which should work well with your Patriot heads. Most cylinder-head companies offer springs that will handle 0.550-inch of valve lift.
The pushrods should also be considered when building an engine with a strong mechanical roller cam. I’d recommend no less than the standard small-block 5⁄16-inch diameter pushrods with a 0.080-inch wall thickness. These pushrods are stronger than stock and less likely to deflect under high-rpm operation. Pushrod length is also important. With this combination, you should have a very strong little small-block that will be fun to drive and a blast when you plant the throttle. With one of these cams, you could expect to make an honest 450 to 475 hp. Considering the conservative nature of the engine, those are numbers worthy of praise.
Comp Cams; Memphis, TN; 800/999-0853; CompCams.com
Crane Cams; Daytona Beach, FL; 866/388-5120; CraneCams.com
Patriot Performance; Rainbow City, AL; 888/462-8276; Patriot-Performance.com
3V Tech Tip
We pulled this photo from the Lisle instruction manual. It shows how the tool threads into
Tim Carroll; via CarCraft.com: There is a tool available from Lisle Tool (LIS65600) that can remove the broken part of the spark plug from the head. It works like a charm. There’s a pusher that pushes the remainder of the porcelain down into the shank. Then you slip in an aluminum spacer and the puller down into the plug bore. The puller threads into the shank and pulls it out of the bore.
Jeff Smith: Tim is updating us on the piece we did in this column on the Autolite procedure for removing spark plugs from the three-valve Ford mod motors on which the spark plugs often break. If this does occur, this tool will help remove the part that remains in the head. We looked the tool up and found it on Amazon for $59.95.
Currie Enterprises; Anaheim, CA; 714/528-6957; CurrieEnterprises.com
Mittler Bros. Machine & Tool; Foristell, MO; 800/467-2464; MittlerBros.com
Moser Engineering; Portland, IN; 260/726-6689; MoserEngineering.com
Strange Engineering; Morton Grove, IL; 847/663-1701; StrangeEngineering.net
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