The SUV indicated barely 120,000 on the clock, and after yanking the valve covers to judge the engine's condition, Tim Moore instantly made the decision to do the boneyard version of a smash-and-grab. Click to reveal The headers will improve this airflow throughout the entire rpm rangeadding more torque and horsepower. Not looking for crazy HP. I am working on a set of iron GT40s hoping it goes faster. SB Ford GT40 Drop In Valve Springs Kit, Hyd Roller w/ Stock Cam, .450" lift and below. Ill do springs and a moderate cam and go for a good, dependable power plant. He has worked as a tractor-trailer driver and mechanic, a rigger at a fire engine factory and as a race-car driver and builder. .. i would not buy valves unless you need them amd would not switch to studs with these heads for your low hp . We took the heads to Mike Slover of Slover's Porting Service in Sun Valley, California, to do this work, plus some basic pocket-porting to improve flowespecially on the exhaust side. You will have to get special headers to fit these heads since the spark plugs are angled differently than normal 5.0 heads. Without changing the stock pistons. I think one of the finer traits of a true car guy, is the patience to put a prized car away and just let it sit for a while rather than selling it when life gets in the way. Learn how your comment data is processed. They also have emissions legal heads as well. Holten tells us removing the fan is worth two-tenths in itself, which tells us the fan soaks up roughly 20 hp. Always the weak area in the 289 and 302 is the tiny 5/16 inch connecting rod bolts and the miniscule intake and exhaust ports. For both the GT40 and GT40p heads, I STRONGLY suggest upgrading the valve springs. GT40P heads, what kind of performance do they give? This will cost additional money but is still worth it, in our opinion. We were cruising the 'yard a while back and located a 2000 Ford Explorer with an EFI 5.0L V-8 engine. Jeff Smith: It would have been better to know a little bit more about your combination, but the short answer is yeswith a hydraulic roller camshaft, assuming the lifters are in good shape and the roller wheels show no unusual wear, they can be re-used on a new cam with no danger of adverse effects. document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); This site uses Akismet to reduce spam. i'd love to use these heads,. Some ideas never go out of style. 68stang351 Founding Member May 16, 2002 850 HiPo manifolds and Ill be good. For 2018, the Coyote makes 460 hp. You keep stock drivability, and stock gas milage if you can stay out of boost. Anyways, I know the gt40ps will bump . Ford's seminal 302 engine (later re-dubbed the 5.0) has been popular with budget-minded hot rodders for decades. For a better experience, please enable JavaScript in your browser before proceeding. Weiand 7515 xcellerator intake. The Fora platform includes forum software by XenForo. 950.00 us a set and will ship . Advanced: Daily Deals; Help & Contact; Sell; My eBay Expand My . Best of all, no machining is required to install these on your stock cast iron heads! I have a 302 Windsor V8 EFI engine that I converted to a 600 cfm carburetor with a Street Warrior intake manifold. (its not their engine) They were located in Tahachapi CA, and were sold with upgraded springs for $650.00, back in 2002-2003 ish. You didnt mention what camshaft you would be choosing or exactly which 5.0L Ford Windsor engine you are working with. Consider having the head's intake ports matched to the intake manifold gasket. Through Central Coast you can have the heads fully prepped for your combination. Keep in mind that swapping camshafts is a fairly extensive effort. With the P-heads requiring pedestal-mount rockers, we also called up Crane Cams for a set of 1.6 pedestal-mount roller rockers. The Fora platform includes forum software by XenForo. Ford Factory 5.0 Performance Cylinder Heads. The older pushrod engines just dont offer the same kind of power potential for their displacement and it all has to do with cylinder head flow. For a better experience, please enable JavaScript in your browser before proceeding. Well assume it is a 5.0L with stock heads. Took me 7 hours to do one head.but they cleaned up real nice. If you have a early 351W ie pre 76 it probably . We started with a 120,000-mile 5.0L out of a Ford Explorer, removed the EFI and DIS, and pocket ported the stock GT40P iron heads with stock valve sizes. Come join the discussion about performance, builds, modifications, reviews, engine swaps, classifieds, troubleshooting, maintenance, and more! We also added an Edelbrock Performer RPM dual-plane intake and a set of 158-inch headers with no mufflers. ***Most important is theStupid question is the one that was never asked!*** After a couple grand you have a killer set of heads, but there's got to be a less-expensive way of making horsepower. A forum community dedicated to Ford performance owners and enthusiasts. You just want to keep it out of detonation. At 4,300 rpm, the torque peaked at 348 lb-ft, a solid 20-lb-ft improvement, and the Lunati continued to outperform the stock cam all the way through with a peak horsepower increase of 60 hp at 354 hp at 5,700 rpm! how much HP and torque? When I purchased my "brand new" set of GT40P's, I bought them from an Mustang specific machine shop that used to exist called Central Coast Mustang. This modification will help your late-model GT40P heads work better with the old-school carbureted intake setup. When you purchase through links on our site, we may earn an affiliate commission, which supports our community. If you're going to use the stock 289 heads, install 1.84-inch intake valves, then port the intake and exhaust; these mods will net you about 185 cfm of intake port flow at 0.50 lift. I view the GT40P heads similar to Granada brakes. Richard Holdener 240K subscribers Subscribe 63K views 1 year ago WESTECH PERFORMANCE GROUP LOW BUCK, GT40P 5.0L HEADS-CHEAP &. What you are trying to do is to increase the amount of airflow through the engine in order to make more power. Also, you'll need to get a steel distributor gear to replace the iron gear that is currently on your distributor. JUNKYARD GT40P HEADS-ADD 30+ HP TO YOUR 5.0L (FOR FREE?) Yes Mr.Smith, your column here at OAC adorned with extreme performance without power adders, or all Engine as its known, from a superior pushrod Small Block featuring almost all USA sourced modern components with the familiar smell of Ford Blue. The HP DIFF column on the far right lists the horsepower difference between Test 1 and Test 3. Just make sure it is a roller cam. Where they differ is the combustion chamber size. We will go into more detail on the head mods in a later story in Junkyard Builder, so watch for it. Even with a stock Mustang 5.0 cam makes good power. The GT40P cylinder heads had a small combustion chamber ranging from 58-61cc while the GT40 heads had a 63-66cc combustion chamber. GT40p heads peak horsepower was [email protected] with 363ft/[email protected] The worked 351 heads showed peak . Stock 1989 5.0L HO pistons will work if you can find them. Runs well. $169.50. made more power everytwhere and 40 hp is respectable. Ive been building ENGINES for 40+ years. You can use the stock roller lifters with any size cam you want. We didn't increase the valve size, although we did have to add Manley valves to get the proper spring-installed height. Jeff Smith has had a passion for cars since he began working at his grandfather's gas station at the age 10. AFR 165 Heads | Have options for pedestal mounted rocker arms or stud mounted rocker arms. Real world data seems to show that GT40 or GT40P cylinder heads, assuming no other mods on your Foxbody, are good to add anywhere between 20-40 HP (over stock heads). Commonly referred to as Explorer heads, GT-40P iron castings are found on current 5.0-equipped Explorers. GT40, GT40P, would be great factory heads. Not when you can buy a set of Promaxx or AFR Enforcer heads for $1000, that already have decent hardware included. Not *as* good as the GT40p heads, but I'd prefer to not have to worry about exhaust fitment issues, or have a narrow range of what I can work with. Im running stock GT40 heads with stock 4.000 bore on cylinders and a Lunati cam with 256/262; Duration @ .050 (Int/Exh): 213/219; Gross Valve Lift (Int/Exh): .483/.499; LSA/ICL: 112/108. 1.7 shaft rockers and beehives. 68 XR7 & 68 M-100. i've got a short block started, and i recently came across a set of GT40P heads for FREE ( love family members). Compare. On the power side, we selected 400 hp as an impressive but reasonable output for our small-block 5.0L Ford. When building an engine there is a lot to take into consideration. Boy, were we surprised with the results. The reason this new generation of Ford engines make a ton more power is they also enjoy fantastic cylinder heads and four valves per cylinder. We heated the bottle to 950 psi and hit the button at 4,500 rpm. I just read about this build on the corral.net. Test 2: Changed to the smaller of the two Lunati camshaftsno other changes. According to his data and verified dyno tests with an EFI 302, you can go above this level if you port the stock, lower intake manifold, or upgrade it altogether. Theres many options available for a little more power. well i finally did my first ever carb build, ive always been an EFI guy Black 1985 GT: 408w, in the 6's in the 1/8 mile. Holten runs the factory fan, but he had removed it when he ran the 12.63. ford 302 sbf gt40p v8 cast iron complete cylinder head and head bolts and head gasket set. 1 - 7 of 7 Posts. Different years can have different combustion chamber sizes but ffor the most part there will be no performance increases by going with 302 heads. A mild porting with gasket matching will be very good. Seriously though if you're not planning on an all-out attack for HP, I'd consider a forged piston out of Probe's SRS line-up. Joined: Sun Mar 15, 2009 9:31 am. It runs smooth but seems lazy. Yeah, except those. a) ain't early and b) aren't 289 heads. And have discovered something that I dont think anyone else knows. 97% Positive Feedback . If the head bolt holes are 1/2" or slightly larger, ARP makes the washers and can be sourced from Ford Racing or ARP through a speed shop or Summit, Jegs and PAW among others. The entire front accessory drive and timing chain cover must be removed, along with the distributor and intake manifold. Yeah, out of a bolt on upgrade, you'd probably be looking at 260-280rwhp ish with supporting mods. The Fora platform includes forum software by XenForo. Here a comparison of different heads on a 302: I'm very happy with my GT40P. Build Thread 1965 Fastback Project "Racesteed". Now we know why Dennis Hilliard of Central Coast Mustang is so high on these heads. Not sure about that but got some pictures of the cast iron explorer manifolds on a 302. JavaScript is disabled. Once the headers are in place, then you can consider if you still want more power. Yes- thank you. We also discovered some issues with the GT40P heads that required changes, so we added valves from Manley that eliminated the exhaust-valve rotators and allowed us to set the proper valvespring installed height. As you might expect with more duration, the idle quality dropped significantly but was still able to make 11.5 inches of vacuum at 980 rpm. The 302 uses smaller 7/16" head bolts and your "P" heads may or may not require the step washers. After we installed the heads and with the fan off, he ran a 12.46 at 107.9. There are several actions that could trigger this block including submitting a certain word or phrase, a SQL command or malformed data. Step 1. They work, but present their own challenges. Ford offered a performance head that was a stock part on 1993-1995 Mustang Cobra models and pre- 1997-1/2 Ford Explorers and Mercury Mountaineers equipped with the 5.0 L engine called the GT-40 head (casting ID F3ZE-AA). GT 500; Posts: 8496; Location: Brisbane . The GT40P heads had a small combustion chamber ranging from 58-61cc while the GT40 heads had a 63-66cc combustion chamber. These are some of the best castings Ford ever produced for this engine, and are still fairly cheap and available used. There's not a lot of reson to use 351 heads later than '75 since they essentially identical to 302 heads except for head bolt holes. The results were a major increase in power throughout the entire rev range, with an increase of 60hp at 4500rpm through to a peak of 279hp at 5800rpm. $139.99. The longer duration created a slight loss of torque below 3,300 rpm compared to both previous cams, but beyond that mild loss of power, the bigger Voodo out-powered its smaller cousin, cranking out a peak torque of 355 lb-ft at 4,300 (a gain of 7 lb-ft over Test 2) and charging to a peak horsepower of 376 at 6,000 rpm. We also added a veteran Ford magnetic pickup distributor and used it to drive an MSD ignition system. *** 65 Mustang 351C 4v, AOD, 4.11 gears *** 66 Galaxie convert big block. If you can get the mentioned GT-40 heads with studs for a good price, that would be good for you. I'm wondering how these heads will interact with the paxton 1220 sl supercharger I'm trying to put on. Mar 23, 2004. It took him and yours truly eight hours from start to finish, using air tools and a lift to gain access to the header flanges. fuel injection system . After graduating from Iowa State University with a journalism degree in 1978, he combined his two passions: cars and writing. Someone does make the Tri-Y's headers for the early Mustangs using the "P" heads. This one added another 10 degrees of duration over the smaller Voodoo cam, along with 0.020 inch more intake valve lift. i know a guy who used to build race engines so he has all the right tools, how much would it help to get the heads ported and polished or anything else he could do to them. We bolted the Ford to the dyno with a set of 158-inch long-tube headers and an 18-inch collector extension to help the low-speed torque, then we fired up the small-block. All Ford Mustangs | Model Specific Forums, GT-40P Heads - 5.0 Mustang & Super Fords Magazine. Motor is going into a Ranger. Stock heads with a fresh 3-angle valve job, shorty headers, T5, 4.10s, stock Explorer intake and stock '88 GT short block with 140,000 miles on it and an E cam in it. This is just a quick overview of the changes that need to be done. So I've got the motor and heads already for my maverick project. If you know him, ask him. I ran the Speed Pro L2488 pistons and it had me around 9.9 compression with a .041 head gasket, Now I had GT40 heads milled .020 and so that's just a guess on the CC. That's fantastic for the minimal investment we made. Once you get into the FoMoCo aftermarket aluminum GT40s though, all bets are off. The GT40 heads have thermactor holes built in to connect to the EGR/smog equipment whereas the GT40P heads use an external EGR connective system. T5z and 3.89 9" TL rear. These are some of the best castings Ford ever produced for this engine, and are still fairly cheap and available used. I'll save the effort and lighten my front end by 50# with aluminum. I had a set of 69 302 heads I ran for a while . Hey Motorheadty,Like your comments,question for ya,I have a 92 convertible,just bought a 5.0 out of a 94 gt that was just freshened up top end,gt40p heads w/new springs etc for the new E303 cam,new FRP roller lifters,Crane 1.7 rockers,hardened push rods,double roller timing set,all put on a bottom end w/104000 miles,needless to say previous owner pulled said engine after 800 miles and now building a 351,I pulled engine down my machinest,putting forged internals in and bolting everything back together,I want to run about a 150 shot N2o,and iam going carb,wondering which intake would be best w/the 150 shot,heard that dual planes might not be the way to go? Small Block V8 (221, 260, 289, 5.0/302, 5.8/351W) - GT40P heads? I don't need tons of power to enjoy the car. many thanks to all you eco-hippies giving me dirty looks and helping me feel llike an overall badass rebel. The spark plug issue is almost a non-issue. Let us explain. You'll also have to use your 289 timing chain cover since it has a hole for the oil dip stick and fuel pump. I plan on running a AFM b31 cam too which has relatively small duration for the intake valve. I have heard this rod bolt weakness myth for years but have yet to have a single problem with them in any of the SBF engines I have pounded on for the last 30 years and there have been lots of them. Within a few hours of his discovery, the engine was sitting in the back of his truck on its way to a new home. I am sure you have increased the bore size and possibly even the stroke a bit and spin it up pretty high in the RPM range. Even with relatively small valve sizes of 1.85-inch intake and 1.46-inch exhaust, the P-heads flow much better than previous. Ported Hurricane Single Plane and custom 750 HP. But the part about a cam replacement possibly being a labor intensive undertaking is correct. Manual trans. Aside from the cost of the nitrous itself, this setup should cost you little more than a stock rebuild using all brand new parts. A solid 300-325 hp should be plenty and that's with good drivability and reliability as well. Cloudflare Ray ID: 7a2e2d95dedea1e4 For a better experience, please enable JavaScript in your browser before proceeding. For all of us interested in Gt40p heads. Mac and Ford Motorsport both make a GT40P spacific header. could the gear of off the oil pump drive(i know they're DIS), for the explorer motor be used on his dizzy? He'll have to get a gear for his distributor. Thank You. The car weighs #2835 with driver. For this reason, we're not sure what kind of boost the GT-40P heads will give. Shop by category. Similar to regular GT-40 heads, the biggest difference between the two is that the P-heads feature a revised spark plug angle which extends the plug into the combustion chamber, putting the flame front close to the absolute center of the chamber, resulting in a smoother combustion process. I have a 5.0 from a 1992 Mustang in my 65. In addition, the cam timing was designed for torque, with duration somewhere around 190 degrees at 0.050 with roughly 0.450-inch lift. Nice to see actual dyno results instead of "butt dyno" guesses. I'm also have the regular GT40 heads on my current build. Instructions on porting the GT-40p heads here. Not to mention, they will run circles around GT40P's out of the box. Go for it if you get them super cheap and can get headers/manifolds super cheap as well but otherwise I'd say it's a waste of time and money. One benefit gt40P head will have over other 80's-90's model heads, including the gt40 head, is that it has a smaller combustion chamber much like the original 289 heads. In less than an hour, we were ready to test. The GT40 and GT40P cylinder heads are highly sought after, but how do they stack up against other cylinder heads, and is it worth it to upgrade the Fox Body's stock heads? K.S. Anythoughts? Everything fits, use the stock rockers and pushrods. SBF FORD Aluminum Cylinder Heads 302 /351w 190cc 62cc 2.02 /1.60 For ROLLER CAM. Because its all been done time after time after. We compare the GT40s to modern cylinder heads as well as other heads from the era. These engines came with the GT40P head, which even with its small valves, offers really good performance. In review, we rescued a used 5.0L Ford from the boneyard, ported the heads, added a cam, carburetor, intake manifold, and headers, and pulled an amazing 376 hp out of the mix. 302 .030 over with; Scat Forged Steel Rods, SpeedPro pistons and rings . Tim's junkyard refugee survived the beating and we had a bitchin' story. Would have liked to see a comparison done on the same short block using a set of decently-ported early non-Thermactor iron heads Tracy Blackford, 65 Mustang FB, 331 built with 289 H beam rods and 383W piston, 282S cam, self ported '70 351w heads, Dougs Tri-Y headers. REMANUFACTURED FORD 302 5.0 COBRA GT40 CYLINDER HEADS. The specs are a conservative 212/218 degrees of duration at 0.050-inch tappet lift but offer a really nice 0.512-inch valve lift for both the intake and exhaust. Assemble the rotating assembly with a stock 5.0L crankshaft, a set of 5.0L rods and the specified pistons with stock-type rings. We then dyno'd the car without the fan to get some consistency and were rewarded with a peak of 316 hp at 5,500 rpm, and 348 lb-ft of torque at 4,000 rpm. AFR 165cc 58cc Heads. Yea. Per a UEM tech support email I have the Icon IC736 is supposed to be good for GT40 heads when I asked about it. Slover primarily focused on the exhaust side of the GT40P heads. are you twisted331 also? Do you guys have part numbers for the spring kits? . Generally expect with a good cam, intake, roller rockers and a good ignition system to see around 300-350 max rear wheel horsepower, depending on what type of dyno you use. Our recommendation would be, rather than change the camshaft, you might want to look into adding a set of long-tube headers and a dual exhaust if the engine is not already so equipped. Can anyone give me a little feedback about a '99 Explorer 5.0, and tell me if it's my answer. Shop by category. the springs are new stock oem ford. Find many great new & used options and get the best deals for FORD GT40p 4 BAR HEADS IN GOOD CONDITION w/ONE BOLT BROKEN at the best online prices at eBay! They are more expensive than standard head gaskets, but they also do the job and are worth the additional money. Long tube headers are a terrific idea, but you need to open up the exhaust side. I need that part number too! Maybe I'll think about a cam swap? Required fields are marked *. 68 Mustang GT/CS Highland Green, PS, PB & Console, C Code w/C4 & 3.55 8 rear, If you aren't using the GT40P's stock, with maybe a spring upgrade and valve job, they aren't worth it anymore. Plus you will need to drill all the head bolt holes out as the 351W uses larger head bolts. SBF engines are modified constantly. Holten's best time is a 12.63 at 105.9 mph, and if we gain the desired result he will be right in the thick of things in Trophy Stock competition. GT40s have 64cc chambers. Install a set of 1.7:1 roller-tipped rocker arms on the heads. The engine was only rated at 215 hp, but it at least had 9.0:1 compression. 69-70 302 heads (the ones with the heart-shaped combustion chamber) Any early 289 heads for the chamber size (but you'll have small ports & valves w/all that CR) Flat Ernie, Aug 27, 2011 SHARE POST #8 fordfan289 Member from indiana correct me if Im wrong but cant you use 351c heads and get the same thing as a 302 boss. The Edelbrock Performer RPM is a good choice, but Holley, Weiand and Ford Motorsport also have similar offerings. A forum community dedicated to Ford Mustang owners and enthusiasts. A LOT of them do it these days. We gained 45 hp and 40 lb-ft of torque. The only one that's close, is #7. However, since Holten's car has an E303 cam, we didn't want the pistons and valves becoming too close, so we chose the 1.6 rockers. All in all, the addition of GT-40P heads to any 5.0 Mustang is a worthwhile venture, especially if you're on a budget (aren't we all) or shooting for the Trophy Stock title. The reason for this is that we're actually replacing mildly worked E7TE heads. If I remember right, non of the GT40P's (later models) had the thermactor smog provisions. I'm running BBK un-equal length shorty's, and I'm able to get all the plugs in, tight, and all plug wires on. These are some of the pictures I have showing the Explorer manifolds. These are a great head but do need some machining mods to make they really work well. (A starter is a motor, windshield wipers use a motor,electric windows use motors) Any one uses that terminology in my shop will be corrected once, only once. The GTp heads are like GT 40's with smaller combustion chambers and the spark plugs are relocated for a more efficient burn. Take the assembly to a machine shop to have it balanced and install it in the block. Well also assume that this engine is running stock exhaust manifolds. The factory heads have a boss for the exhaust valve that restricts flow through the exhaust port. For additional insurance, we also added a set of ARP head studs, which are stronger and offer better thread overlap than factory bolts, which helps prevent pulling threads out of a used block. Im new and Im currently building a 302 on a budget and want to raise compression without milling heads but by pistons and I want to get close to 10:1. Calculating pushrod length With the engine reassembled, we boxed up our second camshaft and headed for Westech's dyno. Actually, making around 240 to 250 hp with a near-stock Windsor 302 will feel pretty good. Most of the time, GT-40 heads are worth a good 20-40hp over stock heads. This is what I recommend to everyone who is doing a budget 5.0 build. Central Coast Mustang sells GT-40P heads at a great price, making them a viable alternative in a market flooded with performance head choices. Skip to main content. Im a different animal. This is not a criticism but instead consider it to be more of a heads-up. These are Ford iron GT-40P heads. Install a Ford Motorsport E303, X303 or F303 cam, or any of the similar units from Indy, Lunati or your favorite manufacturer. There are caveats to this plan, however. . Not bad for off the shelf parts and a stock shortblock. Yank a motor out of the junkyard, clean it up, add a camshaft, intake, and a carburetor, and see how much power we can squeeze out of it. JavaScript is disabled. Ive bought wrecking yard SBFs and put 20 lbs of boost to them and spin them to 7000 and made 500 HP with several of them. I am very happy too. Joined . #2::: Get advice from a reptile engine builder with experience(first flag for me is when somebody refers to an ENGINE as a MOTOR! MAC is the only manufacturer of these headers, and the parts we installed fit like a glove with no problems whatsoever. Gt40 heads/intake from a jy explorer, leave the . 302 explorer short block with roughly 80k miles GT40's from a local u pull n pay ($97) weiand x-celerator trick flow stage 1 cam 650 holley double pumper car made 322/329 SAE . Test 1: 750-cfm carburetor, dual-plane intake manifold, and stock camshaft. The GT40 & GT40P heads had a few differences that are note-worthy, the most importantly being the bump in compression. JEGS High Performance. You will have to address the 50 oz balance of the 5.0 engine by getting a 50 oz flywheel. Richard Rowe has been writing professionally since 2007, specializing in automotive topics. I have a 432 HP non Hi Po 289 I built. Many years ago, a friend bought a used 2001 Mercury Mountaineer 5.0L that was equipped with a set of really decent GT40P style iron heads. Smith began writing for Car Craft magazine in 1979 and became editor in 1984. I have managed to get 402 horse power from a 289 hipo natural aspirated. Both swaps made more sense when parts were readily available at the bone yard for cheap. Compare. E303 Cam advanced 4 degrees. With no other changes we gained 25 hp using factory iron heads. Headers and a camshaft will help but the engine really needs aftermarket 3/8 inch connecting rod bolts and aftermarket cylinder heads. Beyond the engine's amazingly good appearance, Moore had a couple of good reasons for choosing this engine. Come join the discussion about performance, production numbers, VIN decoders, modifications, troubleshooting, power adders, DIY tutorials, and more! A forum community dedicated to vintage Ford Mustang owners and enthusiasts. If you go with a diffrent cam, make sure you change springs, The Trick Flow kit comes with everything for around $130. We did a quick search for hydraulic roller cams and landed on a COMP camshaft that looked promising. The cost of a new set of standard replacement roller lifters is very affordable at major retailers like Summit. Save narve00 If you can find individual flanged headers like the obsolete MAC headers had, those worked really well with GT40P's. I'm new and I'm currently building a 302 on a budget and want to raise compression without milling heads but by pistons and I want to get close to 10:1. Finally, we exchanged the Explorer's EFI manifold (which is a pretty good manifold in its own right) for an Edelbrock Performer RPM Air Gap intake and a Holley 750-cfm HP-style carburetor.