The arrow points to the slot in the HEI distributor that determines the amount of mechanic
Joe Moskowitz via Car Craft.com: I have a '72 Olds Cutlass with the original Rocket 350. It didn't run when I got it, so I yanked the engine and rebuilt it. After assembling it, I got the timing to where it will run pretty well, but it diesels once in a while, and there is some off-idle hesitation. My problem is that I don't know exactly where to time it. It has stock compression (8.1:1, I believe), a Lunati Bracket Master II cam with 0.496/0.520-inch lift, an Edelbrock Performer RPM intake, and a Speed Demon 650 carb. Any advice as to where I should keep the timing would be greatly appreciated.
Jeff Smith: We've got a couple of suggestions, Joe, but some of it you may not want to hear! The bad news is that a combination of 8:1 compression with a long-duration camshaft is not good. First of all, according to our Motor's Manual for a '72 Olds, the static compression for the 350 is 8.5:1, so it's a little better than you thought. The '71 350s were rated at 8.1:1.
Regardless, your problem stems from a lack of cylinder pressure. Static compression ratios are computed based on the comparison of the volume of the cylinder with the piston at bottom dead center (BDC) versus the volume at top dead center (TDC). In a dynamic application, cylinder pressure is dictated by the position of the piston at intake closing. We researched your cam in the Lunati catalog and found the duration to be 224/234 degrees at 0.050 inch tappet lift with a 112-degree lobe separation angle. All longer-than-stock-duration camshafts close the intake valve later than on a stock cam. This means that at low speeds, the engine is squeezing less air and fuel than it would if the cam were stock. The cylinders are squeezing less air because the piston position was higher when the intake valve finally closed. One good thing with your camshaft is that the lobe separation angle is wider at 112 degrees. This reduces the amount of overlap that also bleeds off cylinder pressure. Overlap is when both the intake and exhaust valves are open at the same time.
Your cam is not huge, but it still has a later intake closing point than stock. That means less torque. You can get an idea of how far off your engine is by performing a compression test. Ideally, a good performance engine should have between 180 and 195 psi of cranking compression. Your engine could be down as far as 170 psi or less. If it's up around 180 psi, consider yourself lucky. Another point worth mentioning is that the word on the street with Olds engines is they tend to run better in the car with a single-pattern cam. Single-pattern cams use the same duration and lift figures on both the intake and exhaust lobes, while a dual-pattern cam like yours uses a more aggressive lobe on the exhaust side. The single-pattern cams tend to enhance torque, which is what the Olds is famous for.
This is a bit of a long way around to answer your questions, but it's still relevant. Low-cylinder-pressure engines will require more ignition timing because there is less densely packed air and fuel in the cylinders. For initial timing, we'd suggest a minimum of 14 to perhaps as much as 18 degrees with a total of around 36 degrees. With 18 degrees of initial timing, this means the mechanical advance in the distributor will need to be 18 degrees to produce a total of 36 degrees. The stock initial timing for your engine is probably 8 degrees initial, with the total somewhere around 30 to 32 degrees of total advance. This means the distributor will have more than 18 degrees of total advance. So when you dial in the 18 degrees initial timing with over 20-plus degrees of mechanical advance, the total will be more than 36 degrees. This means you will have to braze or epoxy a portion of the mechanical advance slot in the distributor to reduce the mechanical advance of the distributor. If this is not something you want to do, you can take your distributor to a specialist with a distributor machine, and he can do it for you.
With less initial timing, this may also explain the slight hesitation you're experiencing, since there's insufficient timing combined with low cylinder pressure. You might also try adding a bit more accelerator pump shot, but I think you have more of a chance of making the engine run much better with more initial timing and by reworking the distributor to create the 36 to 38 degrees of total timing. Also, retain the vacuum advance and use it. This will help driveability and also make the engine a bit crisper at part-throttle. But remember, when testing for total mechanical advance, always disconnect the vacuum advance. Otherwise you're actually reading both mechanical and vacuum advance on your timing light. This is a common oversight that can make the numbers very confusing.
Gabe Tapia via CarCraft.com: I'm in the process of planning how to rebuild my small-block 318ci Mopar engine. It is completely stock except for headers and mufflers I added. What I am planning to do with it is to make it a daily driver/street/strip engine making around 400 hp. I plan on using 360 cylinder heads with 1.88/1.60-inch intake and exhaust valves, heavy-duty valves and springs, and 1.5:1 roller rockers. That's all I have planned so far for my engine.
I was wondering if you could help me out with my plans? I want to know what kind of cam, pistons, and carb, to use. Can I still use my stock crank? How do I measure the stall speed of a converter and do I need one? What rear gear ratio should I run?
Jeff Smith: Wow, we've got a lot to talk about. We'll try to reel you in, Gabe. First of all, let's start with 400 hp from a 318ci engine. Simply dividing 400 hp by 318 ci equals 1.25 hp per cubic inch. The problem is that you'll be lucky to make 1.1 hp/ci (which is 350 hp) from stock iron heads, even if they are from a 360. In comparison, a larger displacement 360 at 1.1 hp/ci is right there at 396 hp. It's an old saw but no less true that displacement is the easiest way to make power. If we can talk you into starting with a 360ci short-block, it'll make more torque and horsepower. But assuming you want to build the 318 because it's easier to bolt in, that's what we'll deal with here.
You can certainly make more than 350 hp with your 318, but that means you have to put a longer-duration camshaft and more compression in the engine and spin it much faster to get there. This also makes the engine less streetable, murders the fuel mileage, reduces its durability, and generally makes for a miserable engine to drive on the street. Since you said this is a daily-driver engine, our parts selection will need to be somewhat more conservative and also focused on making this affordable. This may not be romantic, since this means no talk about mechanical roller cams, aluminum cylinder heads, and 13:1 compression ratios, but your street engine will be much happier without all that Rickey Racer stuff.
A large cylinder bore helps airflow, but your 318 is somewhat limited with a 3.91-inch bore compared with a 327 Chevy or even a smaller 302 Ford, which both benefit from a 4.00-inch bore. The 0.090-inch difference will affect airflow by shrouding the intake valve. Your choice of the 360 head is good, since it offers much larger valves at 1.88/1.60 than the stock 318 1.78/1.50 diameters and will flow better. But keep in mind that the smaller bore will hinder flow somewhat. The 360 head's chamber volume is also the same at 70 cc, so there is no loss of compression. Yes, you can keep your stock crank and rods. Have a good machine shop grind the crank and rebuild the rods with ARP rod bolts.
We'd suggest aiming for a compression ratio of around 9.0 to 9.5:1 so you can run pump gas. There's not a ton of selection in stock replacement cast or forged pistons. The attraction for cast pistons is they are inexpensive, and if you don't plan on engine speeds above 6,000 rpm, these will work fine. PAW sells a stock replacement cast 318 piston and a moly ring set for less than $170. That's hard to beat. Forgings will cost more but are stronger. Speed-Pro offers a stock replacement forging for around $400 (PN L2329F 30) from Summit Racing, but it can only muster 8.25:1 compression with a 68cc chamber; this will hurt power as well as mileage. If you can mill the heads enough to reduce the chamber volume to 60 cc, this will bring the compression up to 9:1.
Assuming the compression is adequate, we'd stay conservative with a flat-tappet hydraulic camshaft of less than 220 degrees of duration at 0.050-inch tappet lift. Edelbrock offers a Performer-Plus camshaft that is designed to work with its Performer dual-plane intake manifold, and this may be a great place to start with your street engine. This is oddly a single-pattern cam, meaning the duration and lift are the same for both the intake and exhaust lobes at 204/204 degrees at 0.050 with 0.420 inch lift for both valves. This is based on a 1.5:1 rocker ratio. This cam is designed to work with the Edelbrock Performer 318/360 dual-plane intake manifold (PN 2176). As for a carburetor, any 600-cfm carb, such as a Holley, Road Demon, or Edelbrock Performer series will work just fine. You don't need a big 750-cfm carb because the engine does not need that much airflow.
This would make a great combination, assuming you have a set of 151/48-inch headers and a free-flowing exhaust system with 211/42-inch pipes all the way out the back. Even on a small-displacement engine like the 318, mufflers are an important component. Any of the well-known brands such as Flowmaster or DynoMax can keep the backpressure low, which is key.
For the transmission side of things, stall speed is the amount of slippage in the torque converter. The easiest way to check this is to mash the brake pedal as hard as you can and then, watching the tach, see what rpm the engine goes to without the tires spinning. A stock converter will be around 1,800 rpm; for your application, we'd stick with the stock converter for now. A higher stall speed allows the engine to launch closer to its peak torque rpm, which is the equivalent of launching a manual trans car at a higher engine speed. The negative side to a higher stall speed converter is that in everyday driving it also slips more, which reduces fuel mileage, and that may be a concern with prices well over $3 a gallon. As for a gear ratio, your 318 would like a little more gear than a larger motor since it makes less torque, so a 3.30 to 3.50 rear gearset would be a good compromise between highway rpm and good acceleration. Have fun!
It's All About Length
Chris Warner via CarCraft.com: I am the proud owner of a '94 Mustang. When I got the car, it had the original 3.8L with 173K on it and bad rod bearings in it (big surprise). I traded a pool table and $200 for the car, so I wasn't even close to complaining. At the time, I owned a '67 Galaxie 500 four-door with 80K on the original C-code 289 and FMX transmission, so I yanked the drivetrain out of the Galaxie and swapped it into the Mustang. While the motor was out, I replaced the head gaskets, stuck it with a solid cam (0.477 inch lift and 310 degrees of duration-advertised) I ordered from Tony Branda Shelby along with solid lifters, and replaced all the other parts I removed to swap the cam. I topped it with a Performer 289 intake and 600-cfm carb, both from Edelbrock. Fumes are expelled through 151/48-inch headers to an H-pipe with 40-series Flowmasters hushing it just a bit. The car is fast, but I know the heads are holding it back. I purchased a set of 1965 C5AE iron heads that have been fitted with 1.94-inch intake and 1.60-inch exhaust valves and dual valvesprings. My friend tells me those are Chevy valves and will likely cause an interference with my pistons saying the valves are longer. My pistons are stock. With my camshaft and 1:6 roller rockers and poly locks, can I put on these heads without either replacing or fly-cutting my pistons? All but one of my friends hound me regularly to put a real motor in it (EFI 5.0), but I'm keeping the 289, so please help!
Jeff Smith: Let's start by addressing the differences in valves in your head. Your friend says the 1.94/1.50-inch valves are Chevy valves, and he's probably correct. This valve-size combination is a common upgrade for small-block Ford heads over the stock 1.78/1.45-inch valves. The Chevy valves use the same valve-stem diameter, but stock Ford valves came with a taller tip length, which is the dimension from the lock groove to the tip of the valve. Original Ford valves were designed to be used with rail-type rockers, using a pair of rails parallel to the rocker arm tip that straddle the valve tip and keep the rocker aligned over the valve tip.
According to our handy Manley catalog, small-block Ford valves used with rail-type rockers have an overall length of 5.08 inches that includes a tip length of 0.395 inch. Valves designed for the small-block Chevy, like the 1.94/1.50-inch valves in your head, have an overall length of 4.911 inches with a tip length of only 0.250 inch. The difference in the overall length is the difference in the tip length. This does not affect valve-to-piston clearance. This clearance is determined by a combination of camshaft timing, piston top design, piston deck height, head gasket thickness, whether the heads have been milled, and a few other minor variables. The best way to know if you have sufficient valve-to-piston clearance with this big cam is to place a wad of modeling clay on the piston top in the valve-relief areas, install a head with the head gasket you intend to use, and then set up a solid lifter, pushrod, and rocker arm for both the intake and exhaust valves for that cylinder. Turn the engine through several valve-lift cycles and then pull the head and measure the thickness of the clay impressed by the valves. Minimum valve-to-piston clearance is 0.060 inch on the intake and 0.100 inch on the exhaust side.
You also mentioned you will be running roller rockers, which is good because you cannot run stock Ford rail rockers with the shorter valve-tip-length Chevy valves or the rail rockers will contact the retainer and cause more grief that you'd be better off avoiding. However, the shorter Chevy valves will affect rocker-arm geometry. This means you should check your rocker geometry, which is also very easy to perform.
Use a Sharpie or machinist's dye to mark the end of an intake-valve tip. Next, mock up a solid lifter with a pushrod and rocker arm on that same intake valve. Make sure the intake is on base circle of the cam lobe and then wiggle the rocker arm to make a witness mark on the valve-stem tip. After removing the rocker arm, determine where the witness mark places the rocker arm roller tip relative to the valve tip. If the pushrod length is correct, the mark should be on the inboard third of the valve tip. If the pushrod is too long, the mark will be somewhere near the middle of the valve tip or closer to the outboard side of the engine. If the pushrod is too short, the mark will be too close to the inboard side of the valve tip.
Generally, with a shorter Chevy valve, your pushrods may be a bit too long for ideal rocker-arm geometry, but this is why you should check. Using a shorter pushrod to establish a more ideal geometry will create a happier valvetrain that will be more durable. It would also be a good idea to check valvespring coil bind and retainer-to-seal clearance to be sure the valvesprings can handle the valve lift you intend to run.
A Cam With Kick
Dustin Lyall, Somewhere in Canada: I need some help with a cam recommendation. I'm looking for a cam to put into my '71 Nova. The drivetrain is a 350 engine with a four-speed and a tall rear gear-around 3.08 or so. I'm aiming for a good daily-driver engine that has a moderate kick to it. I'm looking for a cam with an LCA of 114 with a duration of no more than 220 to 224 degrees at 0.050 and a valve lift of around 0.460 to 0.490 inch. I have been looking at Lunati, Comp Cams, and a few others and haven't found anything that matches up the LCA, duration, and valve-lift numbers.
I have an SBC 350 (from a third-gen F-body) in my '69 Beaumont; I'm guessing the compression ratio is approximately 10:1 based on the pistons we used with stock heads. It also has an Edelbrock Performer RPM intake, headers, a GMPP LT4 Hot cam, and a 700-R4 with a 2,000-rpm stall. I want to hit 400 hp and torque, but streetability and durability are much more important. I don't mind a rumbly cam and have access to 94-octane pump gas.
I am very disappointed with the heads; I have bent a pushrod twice, and the valves just don't sound good. The guy at the machine shop referred to them as 416s, but I've never heard of that model. I was thinking of stepping up to aftermarket heads like Dart's Iron Eagles or the Edelbrock Performer RPM, but they are pricey. What size combustion chambers and runners would work best with this combo? What about valve and spring size and rocker ratio?
Jeff Smith: First, let's address your cylinder-head question, and then we'll get into the cam specs. You mentioned your machine shop told you the heads are 416s. This is typical hot-rodder cylinder-head shorthand that refers to the last three numbers of the cylinder-head casting number. Assuming we have the right head, the full number is 14014416, which is a cast-iron 305 head used on small-block 305 engines from 1980 through 1986 that came with 58cc combustion chambers and rather small 1.84/1.50-inch valves. With these small-chamber heads, we can see why you have 10:1 compression, but whatever the small gain with compression you enjoy is more than offset by the rather weak airflow potential of these heads.
These heads were decent production castings for a mid-'80s 305, and we think these were even used in the short-lived L69 305 Z28 Camaro engines rated at 190 hp. But bottom line, there are dozens of heads out there that will flow more air than even a highly modified 416 head. Let's look at your options. Our first recommendation from a budget standpoint is the GMPP iron Vortec heads. These heads not only offer outstanding port flow at below 0.500 inch valve lift, but they also do it with a small intake port that delivers excellent flow velocity, which equates to better torque. On several small-block Chevy engine packages we've built over the years, we've made 375 to 390 hp with a camshaft similar to the one you mentioned. These heads will require a dedicated, Vortec-style manifold. The best one we've found is the Edelbrock Performer RPM Air Gap. The Vortec heads will also need a different valvespring and machined valveguide bosses to accommodate the additional lift of a 0.490-inch-lift cam. The best deal here is to buy a set of modified Vortec iron heads from Scoggin-Dickey Performance Center. The company offers a modified head with 0.525-inch-lift valvesprings and guideplates for $399.95 each (PN SD8060AGP). That's a great deal. With 64cc chambers, the compression drops slightly, but this might cost 1 percent power, if that. The additional airflow the Vortecs offer is worth a solid 30 hp over your existing 416 heads and perhaps more.
The next option is, as you mentioned, the Edelbrock Performer RPM aluminum heads (PN 60999). These heads tend to be overlooked because they've been on the market for a few years, but they deliver excellent airflow combined with a relatively small port area that enhances torque. You can expect to make a solid 50 hp over your stock iron heads with these Edelbrocks, not to mention the extra benefit of a weight savings. The heads sell at Summit Racing for $499.50 each. The advantage of aluminum heads is that if damage ever occurs, aluminum is much easier to repair than iron.
We're about to test a set of Dart's new Platinum-series iron small-block heads that are the first of a new series of heads using Dart's new wet-flow technology. What we've seen on a 215cc head on the dry-flow bench is impressive, and we're going to test these heads against Dart's original Iron Eagle series, which was a pretty good head a few years ago. These heads may be a bit big in port cross-section for a 350 engine, but they sure look killer on the flow bench and promise to make even more power on the engine. These are the heads we used on the big-cammed 355 used in this month's test on E85. Dart does make a 200cc Platinum head that is pretty good. The part number for a 64cc iron casting with 1.437-inch-diameter valvesprings is 10311112P and sells out of Summit Racing's catalog for $537.95.
Now let's address your cam question. First, let's spec your existing GMPP LT4 Hot cam. This is a hydraulic roller camshaft (PN 12480002) with 218/228 degrees of duration at 0.050 inch tappet lift with 0.492 inch lift when used with a 1.5 rocker-arm ratio. The cam also has a lobe separation angle of 112 degrees. These are very close to the specs you asked about, so we're not quite sure why you'd want to change the cam. And if you did install a cam with the slightly shorter specs you mentioned, that would only kill a little bit of horsepower. Frankly, in our opinion, your existing Hot cam is a perfect match for all three of the heads we mentioned, and especially for the Vortec iron heads, since those heads are a bit limited on the exhaust-flow side. The Hot cam's longer exhaust duration will help scavenge the cylinder better, improving top-end power. We'd recommend buying a set of heads; keep the cam and have fun making a bunch more power. But that's just us.
T5 Ranchero Swap
Jeff Baker, Bremerton, WA: I have a '64 Ford Ranchero with a 289 and a T10 four-speed. I'm doing this project on a budget and have some questions. Can I swap an unmodified T5 using a Mustang kit? Some Web sites say you need to put a different tailshaft on your trans to make the shifter fit in the stock hole. I would rather not do that, since a modified trans will cost more. I don't care about modifying the floor, but I would like to keep my bench seat. Is this possible? Could you tell me the difference between where the T10 shifter mounts and where the T5 does?
Jeff Smith: We decided to find an expert on this question, Jeff, and spoke with Bruce Couture, who owns Modern Driveline, a company specializing in T5 swaps for early Mustangs and Fords. Most of the critical information concerning your swap can be found on his Web site, and we suggest you spend some time there to extract all the gritty little details. But the short answer is that the shifter placement of a stock Ford T5 transmission places the shifter too far back in the chassis, which would then interfere with your bench seat. Plus, the T5 shifter ends up coming through the floor right where there is a shifter floor support, which, if removed, would weaken the floor. Adding to this dilemma is the T5's deep input shaft that adds another 31/44 inch to this conversion compared with a typical T10 four-speed.
The simplest, easiest swap is to go with one of Modern Driveline's complete conversion kits that include everything you'll need to bolt all this together. These kits retail for $2,600 and up, depending upon the options required, which obviously does not make this a budget approach. According to Couture, using one of his T5 Front Shift converted transmissions will move the shifter forward roughly 8 inches to clear the bench seat. This still requires a custom crossmember, clutch linkage, speedometer cable, and probably a shortened driveshaft. A new T5 trans with the shifter conversion is $1,595, but this makes it much easier to swap without major sheetmetal surgery. It's also possible to have Modern Driveline convert an existing T5 over to a front-shift model that would be considerably less expensive. If you haven't purchased a trans yet, it might be a good idea to read our T5 rebuild story in the September issue for transmission and gear-ratio applications.
Couture's other recommendation is to go with the T5 cable-linkage-style bellhousing. This system is easy to install, less complex than a hydraulic system, and makes for a clean installation using Fox Mustang-style parts.
Obviously, none of these ideas involves bargain-basement finances, but there doesn't seem to be an inexpensive way to perform this swap. Even if you swap to bucket seats or modify the bench seat, the shifter is still roughly 8 inches farther back than stock, which would be awkward at best.
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