Q&A / Tech

Ask Away! with Jeff Smith: Waking a Stock Small Block with Simple Bolt-Ons

I have a 302-cubic-inch small block Ford engine that I’ve inherited from a friend. It’s an older carbureted engine that I think is stock – it still has a 2-barrel carburetor. What kinds of parts should I buy like a four-barrel carburetor and maybe a big cam or something to make more power? I’m relatively new at this, but a couple of friends will help me remove the worn out inline six out of my ’69 Mustang and replace it with this V8.

E.S.

Jeff Smith: Sounds like a great little project. First, we will assume that your engine is in good shape. If the engine has sat around for a long time, the first thing to do would be to change the oil and filter and remove the spark plugs. Next, I’d recommend pressure lubing the engine to get oil to all the bearings, lifters, and rocker arms. Pressure lubing an engine is not difficult, but it will require you to remove the distributor and then drive the oil pump with a suitable hex drive. You can buy this drive from ARP (PN 150-8801) but you can make one out of an old Ford distributor shaft that will drive the hex so you don’t have to spend the money for something you might only use once.

The key is to get oil to all the critical components. Next you might want to squirt some oil in each cylinder. This will help the rings seal. Then you can do a simple little compression test to make sure all the cylinders are actually working. The actual cranking pressure isn’t as important at this point as is making sure all the cylinders are balanced with near equal pressure.

Assuming you have good cylinder pressure, we now have an engine that’s probably in decent shape. If you have a dead cylinder, no amount of tuning or parts will help if the engine has problems.

Before we get too deeply into this, let’s talk about horsepower potential. With stock heads and cam and a decent intake manifold, carburetor, and headers, you’re looking at making between 250 and perhaps 275 horsepower. In order to make 300 horsepower you’re going to have to have better cylinder heads and a mild camshaft. We only mention these numbers because inevitably one of your friends will spout off about making 400 horsepower.

That’s certainly achievable, but the reality is it will take a good set of aftermarket aluminum cylinder heads, between 9.5 and 10:1 compression, a fairly stout camshaft, headers, a good dual plane intake, and probably a 650 or 750 cfm carburetor to produce that much horsepower. It sounds like you might just be happy with a few mild bolt-on upgrades that don’t require you to tear into the short block – like changing the cam. So we’ll stick to simple bolt-ons.

You didn’t mention what year small-block this is but we’ll assume it is an engine from the late ‘70s – for grins let’s say it’s from a 1976 Granada. That engine with a 2-barrel carb made a stunningly weak 134 horsepower with 8.0:1 compression. Not exactly a barn-burner for power but then you get what you pay for, right? Assuming the engine’s in good shape, there are several weak points in these ‘70s engines centering on the soft compression and poor exhaust port flow.

So let’s start with the simple stuff first. The best way to wake up any stock small block Ford is to improve the exhaust flow. Early, stock small block Ford Windsor heads are notorious for weak exhaust ports and restrictive exhaust manifolds.

This makes a set of headers nearly mandatory to improve breathing. This may sound counter-intuitive but everyone tends to focus more on the induction system than the exhaust. But our experience consistently reveals that even a stock 2-barrel engine will respond to a higher-flowing exhaust system. By reducing the backpressure in the exhaust system, this pulls more spent gases out of the cylinders, allowing the engine to make more power.

Headers come in a variety of configurations. The most popular are the long-tube four-into-one style headers. These style headers improve low-speed response because the longer primary tubes increase torque. The down side to long-tube headers is that by placing the header collector underneath the floor pan, ground clearance can be an issue. Intermediate length headers are shorter and use a smaller collector that bunches the tube together before the primary tube turn under the floor pan. These headers are still an improvement over stock manifolds, but they do sacrifice a bit of low-speed torque. They are much easier to install, so keep that in mind as well.

Another advantage to intermediate headers is their low cost. We found a set of Patriot Clipster headers that would fit your Mustang (PN H88433-B). These come with a three-bolt exhaust flange that can be welded to a 2 ½-inch dual exhaust system that would really complement the headers. Coated headers look nice for a long time but will probably cost more money.

Next on the list would be to upgrade the intake and carburetor. The stock 2-barrel Autolite carburetor is a descendant of the Holley but the flow numbers are nothing to get excited about. We’ll assume this carburetor will deliver roughly 300 cfm, but it might be much smaller depending upon the size of the venturis. The best move is to upgrade in a good streetable four-barrel dual plane intake manifold and a small four-barrel carburetor.

Here you have quite a breadth of selection opportunities. The trick for this engine is to not get caught up in all the horsepower hype. Two excellent choices would be the Edelbrock Performer intake or the Weiand Street Warrior. Dual plane intakes are the ideal choice for a mild street engine where this style intake really improves low and mid-range torque while still delivering decent top-end power. Ignore all those guys who lobby for a single plane intake to make any power. Single plane intakes offer shorter intake runner lengths that sacrifice low-speed torque to make top-end power. We’ve seen these intakes on a mild street small-block lose 30 to 40 lb-ft of torque against a good dual plane.

As for a fuel mixer, this small engine would respond very well to a 600 cfm carburetor. There are plenty of really good carbs to choose from. We’ve had good luck with all three of the ones we’ll suggest. In no particular order are the Edelbrock Performer 600 cfm carb, the Street Demon 625 cfm carb and the Holley 600 cfm vacuum secondary carb.

The Edelbrock with the electric choke is Edelbrock’s mileage version of this carburetor line. The Edelbrock carb offers one small advantage that it shares with the 600 cfm Street Demon that we really like. Both carburetors offer a small cover that allows quick access to the part throttle primary metering rod. Loosening one small screw allows access to either the metering rod or the primary power valve spring. By changing metering rods or the springs, you can tune your carburetor for both part-throttle and wide-open throttle (WOT) metering. With the Holley, you must remove the float bowl. This isn’t a big deal, but it usually requires changing the bowl gasket as it might tear when removed for the first time.

The third carburetor is the Holley 600 cfm which is the electric choke version of the standard 600 cfm Holley. This carb also incorporates the Ford automatic transmission kick-down linkage which the other two carbs do not. I would hazard a guess that all three of these carburetors would deliver similar power numbers.

There’s far more to go into if we want to get into making more power, but it would be challenging with your engine’s stock 8:1 compression ratio. One of the best ways to make more power and better fuel economy is with compression up around 9:1 to 9.5:1. There’s a reason that all the late model engines now are running between 10 and 11:1 compression ratios. It really helps.

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13 Comments

  1. @dear jeff small block ford: you forgot that the clevland based 302 found in the 69 mustang is different to the 302 windsor found in the 79-92 mustangs and are two different engines. so tuning them is completely different like chalk and cheese. espsially as you can a 302C into a 351C by changng the internals. CHI 3v heads availible the clevland can can be stroked upto a 393ci if you want EFI you can bolt on the carb based efi system. you also forgot to mention when changing from 6 to 8 cylinders to change the differential and use the v8 shocks and springs.

    • Wow. Amazing that you don’t have a clue what you’re talking about yet you felt you needed to show your ignorance while calling out Jeff.

  2. AnalogDan Wilson says:

    I’ve been building 351 Cleveland engines for street and strip for about 40 years so naturally I’m a believer in the heads ability to make substantial amounts of power due to their superior design over the limited Windsor production heads.

    Jeff Smith’s excellent reply to the question covered the preparation of a used engine for operation and the options available for building more power.

    The person asking the question stated that they are new to building performance engines so it’s best to keep it simple and most of all, accurate.

    Regular production 1969 Mustangs built in the States did not come with Cleveland style 302 engines. The only exception would be the rare Boss 302’s offered in ’69 and ’70. They have 302 Windsor engines with Cleveland style 4-V (venturi) cylinder heads and the heads wouldn’t be practical for a standard 302 build because of the rare availability and high cost.

    The 302 Cleveland heads were produced by Ford in Australia but never available on U.S. production Mustangs. There are a couple of reliable sources in the States for the 302C heads and because of their quench style combustion chambers, they are desirable for performance builds.

    The CHI 3V aluminum alloy Cleveland heads were also mentioned. CHI heads and intake manifolds are excellent examples of aftermarket parts available for use on production Cleveland blocks or any of the aftermarket Windsor blocks. The CHI 3V or 4V heads can be used with one of the modern Cleveland specific reproduction blocks from tmeyerinc.com or mmeracing.com for a stroker build close to 500 cubic inches for a naturally aspirated “small block” Ford capable of over 1000 horsepower !!! That’s kinda hard to imagine but a similar alloy Cleveland build for the Engine Masters Challenge made 932 peak horsepower with only 444 cubic inches of displacement and NO power adders. That’s 2.09 horsepower per cubic inch of the most penalized, restricted and totally banned engine in sanctioned Motorsports history….the Ford 351 Cleveland !

    That has nothing at all to do with a budget 302 Windsor build…but the thought of an all alloy 500″ Cleveland in my ’70 Mach 1 brings on a state of sustained euphoria

  3. I have a 302 I took it out of a 87-89 f150 it is bored .30 over it has roller lifters roller rockers and I was told it has a mild cam with a high rise intake and shorty headers it is EFI I have a 750 holly carb to put on it I know I’ll have to swap a couple things to do it bit I’m putting it in my 2003 f150 supercab long wheelbase with has a limited slip rearend what size would the motor be classified as and will it bolt to my transmission that’s in the truck it had 5.4 engine not sure on what the stock trans would work or would I need to swap it as well and how can i tell what generation it is it probably sounds crazy but this is what I have and need my truck going 2 months ago when the oil pump went out in in the 5.4 and I was almost 2 hours away from home with over 10grand in tools in the truck in a very bad part of jackson mississippi coming from the hospital from visiting my wife witch had been parilized from neck down when she lost control of her 97 camaro convertible and flipped it and broke here neck I sure could use the help or the advice on what I should do thanks

    • Andrew McGee says:

      Get another 5.4L. The PCM in the ’03 will not talk to a Windsor small block without alot of electronic work. Probably possible, but you’d pay more trying to get the 301 to work than just getting a 5.4L.

  4. Lucky Chuckie says:

    What about exhaust and muffler? What should we use?

  5. I have built a 95 5.0 ltr with e303 cam gt 40 heads performer intake and edelbrock carb all brand new and msd ignition . Cant get 1-4 -6-7 to fire there is spark but no fuel can this new carb b scrap !

  6. This may be a stupid question but I have been looking at installing and edelbrock carb myself on my 302. Does it matter that it is a four barrel when the stock intake manifold has only two openings?

    • In order to use a four-barrel carburetor you will need a four barrel manifold. There are plenty of options from Edelbrock, Holley, and many others to choose from. Be sure to choose what is called adual plane manifold – these are best for mild street engines. On a small-block Ford, this does not require the distributor to be removed which makes the job much easier. Also choose a vacuum secondary carburetor and preferably with an electric choke.

  7. Gary D Shaffer says:

    I have a 67 289 out of a falcon Futura sports coupe that I rebuilt with all new internal guts. The heads and block have been decked it’s got hydraulic lifters. it’s got an Edelbrock dual-plane aluminum manifold with a 600 CFM Holley carburetor and Hedman headers. The problem I’m having is it keeps fouling plugs when I take them out I can pour gas out of them and that’s after running pretty hard. it’ll run really good for about 3 or 4 minutes and then it’ll start missing. I’m running brf 42 spark plug should I be running something else?

  8. D.J. DeForge says:

    You probably have fixed this by now but here goes, I suspect a high float boat level caused by a sticking or leaking needle and seat or a a leaking power valve diaphragm. Alternatively the power valve may not be installed properly. These are the items I would check first.

  9. On the question of small block Windsor engines no one ever talks about the 289 cid. In 1974 I owned a 1967 Ford Falcon sports coupe with 289 2 barrel carb. It would run a respectable 130 MPH. I thought it was an awesome small block engine

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