E-mail your tech questions to us at carcraft@primedia.com (include the words "What's Your Problem?" in the subject line) or fax them to 323/782-2223. All correspondence must be signed with the sender's real name (not a nickname or a screen name) and include the sender's hometown and state or province. While mail cannot be answered personally, Car Craft will publish as many letters and replies as space permits. Photos are welcome, but no materials will be returned.
Late-Braking Update
In the November '03 issue there was a question/answer about the Granada brake conversion used on the Falcon (also Comets, Mustangs, and so on). Your method is fine, but there is a much easier way! MustangSteve's makes a steel adapter bushing that will allow the Granada brakes to be installed on the original six-cylinder tie rods, or on original V-8 tie rods. The bushings are only $20 each and have saved many a Mustang owner from having to buy expensive custom tie rods costing $90 each. I am not trying to rustle up advertising here, but Car Craft does specialize in doing things on the cheap, so you might want to make the public aware there is an alternative. The bushings can be found at wwwmustangsteve.com/tierodbushings.
MustangSteve
Steve Wilkes
Carrollton, TX
www.mustangsteve.com
mustang.steve@verizon.net
The Phantom Small-Block
In the January '04 issue, we answered a question regarding performance improvements to a Chevy 307, and in doing so we listed the dimensions of that engine as having a 3.875-inch bore with a 3.48-inch stroke, which was incorrect. We'd try to play it off as a typo, but the text went on to explain how the 307 uses a 350 crank and so on and so forth, verifying our intent. Of course, as many of you have recently pointed out, we were wrong about the stroke-the 307 uses a 3.25-inch stroke, which is the same as a 327, not a 350.
Despite the error, our comments regarding the 307's less-than-4-inch bore still hold true-a smaller bore will hinder airflow around the intake valve more than a larger bore. We also stated that that the purpose of the 307 was to provide a relatively high-torque engine that was also somewhat economical (the 307 wasn't particularly good at either), which also remains true even though we got the stroke wrong. Of the small-block Chevy engines displacing around 5 liters, the 305 is the one that uses a 350-style crank with a 3.48-inch stroke, though coupled with an even smaller 3.75-inch bore.
A couple of you pointed out that the 307 has an excellent rod/stroke ratio, and felt that this should actually make it a good street engine, but the small-bore issue is still a relevant factor. However, to get the best of both worlds, so to speak, you could take the 307's crankshaft and drop it in a 350 block to create a "large-journal" 327 (2.45-inch mains rather than the earlier 2.30, found in most factory-built 327s), having the benefits of that 1.75:1 rod/stroke ratio and a 4-inch bore.
P-Head Scavenger
I have a 351W block that I'm planning on rebuilding in the future to drop in an '86 Bronco for daily driver duties. I was following the "Battle of the Titans" in your magazine and noticed that in your Nov. '03 issue, you stated that the GT-40P heads you installed were used on several production vehicles, including the Explorer. My question is, which years of Explorer were they used on? I'd like to try to find a pair in the boneyard and perform the conditioning work at home, but I was curious whether there were certain model years of Explorer to look for.
James Benson
Casper, WY
Actually, the Explorer is the only production vehicle that was equipped with the iron GT-40P heads, which was probably due primarily to the fact that it was the only vehicle at Ford still using the 302-inch pushrod V-8 when the GT-40P heads debuted. The V-8 engine option was first offered in the Explorer for the '96 model year, and reportedly those 5.0L engines were equipped with the earlier iron GT-40 heads. The Explorer V-8 was basically a '93 Cobra-spec engine, using a 65mm throttle-body mounted to a unique upper intake that was bolted to a GT-40/Cobra lower intake on top of those iron GT-40 heads first seen on the '93 Cobra 5.0 engine and the '93 Lightning 5.8. The Explorer's camshaft was also unique to that application. For the '97 model year, Ford replaced the GT-40 heads with the GT-40P castings, which were updated to use a fast-burn combustion chamber for more torque and cleaner emissions as a result of a more efficient burn. The GT-40P remained on the 5.0L engine for the rest of its run, ending with the '01 model year.
Ford performance fans found that the improved efficiency meant more power, so just like Chevy guys using Vortec heads, the GT-40P became a favored low-buck performance head. If there's a downside to these castings, it's that the spark plug angles were altered significantly to allow the tips of the plugs to be more centrally located in the combustion chambers, and this can cause interference issues with many aftermarket headers. However, most header manufacturers seem to know whether or not a particular application is compatible with the P heads.
As for finding a set of P heads in the junkyard, good luck. Most Explorers so equipped are still on the road, and the engines from those that have been wrecked are typically sold as assemblies by dismantlers, rather than broken up for individual parts. If you were to find a junked Explorer, check the passenger-side head in between the first spark-plug hole and the first lower head bolt for a cast-in "GTP," signifying the GT-40P head.
Don't Make 'Em Like They Used To
I'm curious why I haven't seen more flow numbers on small-block Chevy cylinder heads. Not the high-buck aluminum (which hardly any of us starving rodders can afford), but the stuff like the old "fuelie" castings and fully ported 882 castings and stuff like 461, 462, 186, 291, 292, 487, and 487X castings. I have heard more arguments from the "old-timers" (who, by the way, I learned from) that these castings were far superior to heads like the Vortec right out of the box. After all, these came on engines that produced 300-375 hp on 327s with ancient, crappy camshafts. How do they compare?
Not Quite an Old-Timer,
Chris Barbor
Via the Internet
The old-timers telling you that Vortecs aren't as good as the earlier heads obviously haven't worked with Vortecs. Shortly after the Vortec heads went into production on light truck engines (for the '96 model year), the potential of these heads as performance upgrades began leaking down from GM engineers to magazines. Early tests showed that a box-stock Vortec could outflow a GM Performance Parts Bow Tie iron head without a problem. Multiple magazine flow-bench and dyno tests soon followed and continue to this day. All seemed to show that the Vortec could in fact, outflow and outperform all previous Chevy production iron heads. In fact, sister publication Chevy High Performance magazine actually compiled and published flow numbers on a wide array of small-block cylinder heads, although not much attention was devoted to earlier iron offerings. The rationale was that the earlier heads were basically obsolete from a pure performance standpoint; the cost to purchase and refurbish a set could quickly surpass the price of a brand-new set of Vortecs, and that wouldn't include the time and effort involved in porting the older heads.
Still, a set of 462 iron castings was part of the flow test, and the figures are presented in the accompanying chart along with numbers on a Vortec head. Neither were ported and both had stock valves. As you can see, the Vortecs soundly trounce the 462s on the flow bench, showing nearly 30 cfm more flow at 0.400-inch lift than the 462s, and nearly as much at 0.500-lift. As an aside, we've seen other assembly-line Vortecs show as much as 243 cfm on the intake side at 0.500-lift.
Of the head castings you list, the 487X is probably the most desirable to veteran small-block racers. This is one of the castings used for the early-'70s LT-1 350s, and while it is probably the most sought-after, it's still not radically different from other early performance factory castings. Even the later "Turbo" heads offered over-the-counter at GM dealership parts departments-at one time the absolute hot ticket-take a back seat to the Vortec in terms of flow.
You may counter that early castings ported by a pro could be made to outflow the Vortec, but that's really not an apples-to-apples comparison, since, as we showed in the July '03 issue (pg. 67), the Vortecs can also benefit from porting. Also keep in mind that most of the early performance heads you cite came with 2.02/1.60-inch valves, while the Vortecs only have 1.94/1.50-inch valves. Testing has shown that the Vortecs can benefit from port work on the exhaust side, and some tweakers have even stepped up to a 1.55- or 1.60-inch valves.
There is one important aspect of these heads that you haven't considered: the combustion chamber. The Vortecs run a 64cc chamber, just like many of the old performance heads, but that's where the similarity ends. The chamber is actually the key to the Vortec's efficiency, and is based on high-swirl and fast-burn technology. The resulting increase in combustion efficiency requires less ignition lead (Vortecs usually seem to like around 31-33 degrees total timing rather than the typical 34-36). This also makes a Vortec-equipped engine more octane-tolerant, giving you the option of running cheaper fuel or more compression.
As for your comparison to early performance small-blocks, consider that the GM Performance Parts 350 H.O. package, which uses Vortec heads, is rated conservatively at 330hp; it's able to generate this figure using only 9:1 compression and a very mild camshaft. This magazine has built several small-blocks using Vortec heads, most recently in our "Battle of the Titans" series. In that shootout, a 355 with Vortec heads that were modified only to permit extra valve lift made 427 hp running 10.4:1 compression and a fairly healthy hydraulic cam with a dual-plane intake on pump gas. That figure would have most likely fallen on the low side of the 400hp mark with a typical unported fuelie head.
Baby Block
I always see you guys building and testing the Chevy 350, but it seems you forget about us little guys with the 4.3 V-6. I recently bought a used engine from a junkyard to replace the one I have in my Blazer now. It's an '89 4.3 with throttle-body injection (TBI). I'm trying to get 250 hp out of it, and I want it to hold at least a 75-100hp shot of nitrous. Could you guys give me a setup that would work using the stock block and the stock heads? I'm willing to replace, bore, mill, and port everything else. I just can't seem to find a good combination out there. I am also on a budget of $2,000-$3,000. Thanks in advance for the help.
Eric Pardy
Via the Internet
We haven't built or tested a 4.3 V-6 in Car Craft, though this little engine has some performance potential, since it is basically a Chevy 350 with two cylinders lopped off. Hot Rod actually built and dyno'd one last year with fairly positive results. They began with a non-Vortec roller-cam block like yours, and had the engine rebuilt using Speed-Pro pistons intended for a 350 (PN LW2256-F-060) hung from the stock rods (not the same as a V-8), fitted with Milodon small-block rod bolts, which had to be slightly modified to fit by clearancing the bolt heads. They used the stock crank with Sealed Power tri-metal bearings (unique to the 4.3) fastened with Milodon main-studs designed for a V-8. The oil pump was a performance unit from Sealed Power (224-43469V) matched with a performance pickup (224-14263) designed for the V-6.
As with any engine, the cylinder heads are the key to improving output. The stock heads flowed a miserable 138/116-cfm intake/exhaust stock, but improved to 208/190-cfm after blending the bowls, opening up the ports, and swapping in Milodon swirl-polished 2.02/1.60 valves. The compression would have been 9.68:1 with a 0.041-inch compressed head gasket, but the Hot Rod team milled the pistons for 9.08:1 in anticipation of a blower. Another performance key was the Comp Cams hydraulic roller, used with the stock roller lifters. The biggest grind for the 4.3 is the 280HR, which isn't really that big, measuring 224/224 duration at 0.050-inch tappet lift and having 0.525-inch lift with 1.5:1 rockers. The HR guys used 1.6:1 roller rockers for increased lift (0.560-inch) and topped the engine with an Edelbrock Performer and an Edelbrock 500-cfm carb. In this trim, it generated 288 hp at 5,400 rpm and 303 lb-ft of torque at 4,400. A swap to a 650-cfm Demon carb boosted power to an even 300, still at 5,400 rpm while torque jumped to 316 lb-ft, also at the same rpm as the previous configuration.
With the forged pistons and high-strength main and rod fasteners, the HR 4.3 would seem aptly capable of handling a 100hp nitrous hit, and in fact, could probably take more. To duplicate that motor would cost about $3,000, as estimated by the HR team, and that included every little detail. Keep in mind that running the TBI induction will hinder power somewhat, and will require custom programming to really be optimized. Turbo City in Orange, California, can help with that when and if the time comes.
A Well-Oiled Machine
I have a '70 Chevelle SS with an LS5 big-block. My car has been in the paint shop for two years, and I'm finally getting ready to start the engine soon and would like to know the best way to prime the lubrication system.
Ed Prince
Albany, NY
You simply need to pick up a priming tool and pump some fresh oil through the engine prior to firing it. The priming tool fits in place of the distributor but does not engage the camshaft drive gear. This allows you to spin the tool with a power drill, which in turn spins the oil pump, circulating lube throughout the engine without having to actually start it. When you hook up the drill and start to spin the priming tool, you should initially feel little or no load on the drill, but within the first few seconds, a pronounced drag should kick in, indicating that the oil pump has just developed pressure. The length of priming time seems to vary from one engine-builder to another; some spin it just long enough to generate pressure and fill the oil filter while others will spin the drill for another 30 seconds or so, then rotate the engine with a breaker bar and continue. Basically, if you prime the engine long enough to have fresh oil coming up through all 16 pushrods, you're ready to fire it up. The tool for Chevrolet is probably the easiest to find, and is available from many local auto parts stores and speed shops in addition to mail-order houses like Summit and Jegs, or you can make your own out of a discarded distributor.
Our Mistake?
Regarding your response in November's "What's Your Problem?" to the question about Ford distributor swapping, you are correct in your dissertation except for one minor point: The reader stated he has a 351M, as in Midland, commonly called 351 Modified. The 351M/400 series engines use a common distributor with the 429 and 460 big-blocks, and in fact, they have longer shafts than the small block 302s. What he needs to do is get a '75-'84, 302 Duraspark distributor. It will plug right into his old harness. This also answers the oil pump driveshaft problem. The 351 Windsor distributor is unique because of its 1.3-inch-taller deck height.
Ray Vaira
Ash Flat, AK
In case you haven't already been flooded with mail, the November issue of Car Craft has a mistake in the answer to "Distributor Discrepancy." He can't get the distributor to work with the oil pump shaft because the 302 uses a small-block distributor while the 351M uses a big-block distributor. He needs to find a 302 distributor from the late '70s/early '80s to keep the ignition from the '79 truck. Also, a 351W distributor won't work with a 302 because the block is taller, hence a longer distributor. Nobody walks on water; we all make mistakes.
Sean Perry
Via the Internet
In your November "What's Your Problem?" article, there was a question concerning the 302 distributor fitting into the 351M engine. There is no way that distributor will go in there! The 351M uses a larger hex and has a larger-diameter body (where it fits into the block). He needs a 302 distributor to fit the 302 block. He could just swap the innards from the 351 distributor to the 302 distributor.
Steve Wilks
Carrollton, TX
Thanks for all your input, but if we all go back and read that question and the response, you'll hopefully find that no one asked if a 351M distributor would fit into a 302, nor was any advice offered to attempt this. The question was whether an early 302 distributor will fit in an older 302. By the way, those of you who pointed out that the 351W distributor is taller than the 302 distributor need to take another look at both of those engines. Despite the fact that the 351W has a taller deck height, the distance between the cam gear and the distributor mounting pad is basically the same (check the photos). However, you are right that the distributor for the 351W is unique, though it's the cam gear that makes all the difference.
#462 Iron Head
1.94/1.50-inch valves
62cc chamber
156cc intake port
Vortec Iron Head
1.94/1.50-inch valves
64cc chamber
170cc intake port
