Home 1968 Shelby Cobra GT350, GT500 & GT500KR My 1968 Shelby Cobra GT350 Finding an Engine Builder

Finding an Engine Builder

I called Dan Mattila, a local club member, has an auto shop in Fridley. I told him about the knock. He said he needed the car to diagnose the problem. Dan sent his flat bed tow truck to pick it up. He very quickly called me back and told me I had at least three cracked piston skirts, a common issue on high mileage 302’s, plus a loose timing chain and some leaking exhaust header gaskets. I gave him the go ahead to fix it. More than a month later, he still could not give me a date as to when my car would come back to me. Car show season starts the first week of June. He picked up my car in early April. After about two months into this, I went to his shop to work out a plan. I was shocked to see that my car had been setting outside during an unseasonably wet April and May. My car had not seen rain for 30 years. If it is going to rain, I didn’t drive it. We did not work out a solution, Dan could not give me a delivery date. I had the car picked up and moved back to my garage. It was worse for wear sitting outside in the monsoon rains. My new Master Cylinder was covered in rust.

Time for Plan Two

I called a number of local shops and got lots of referrals. What I discovered is almost all of these shops, who can rebuild a Mustang engine. focused on newer versions of the 5.0 with fuel injection and a computer. If this block were trashed that is what I was going to do, put a 1985 or newer 5.0 in it. In fact I talked to Mattila about one he had built that was available. 450+ HP, roller cam, aluminum heads. If my block was shot that was the option.

I also became aware that I needed to be an expert at Ford 302 engines when I talked to a builder. This should be the last time I have to rebuild this engine so I might as well make it count and get best results.

I talked to a local auto shop that did my oil changes and such. He told me he worked with a shop in St. Paul that did engine rebuilding. I had my car moved to his shop, he pulled the engine out so it could be picked up by that rebuild shop. Then Dan, the engine builder, called me and we talked about my engine.

First thing Dan, my new engine rebuidler, asked me is why he had my engine? I told him about the knock and 3 cracked piston skirts. He had taken it apart already. He told me there were no cracked pistons. But it did need rebuilt. It had two bad head gaskets. The block and crank were fine. What did I want to do with this engine? I told him it had not been opened since 1982 so I wanted to replace things that should be replaced like bearings. I also told him I’d like a stronger engine with 350 HP. That number was very possible. But what was it going to take and what was it going to cost?

At the minimum, my engine needed new head gaskets, But if I’m opening the engine up I might as well check to see what is worn and what is fine. And I might as well see what it would take to make it more awesome, right? I already knew a lot about these engines. But with Google at my keyboard I dug into options, parts and what other people have done. I spent a lot of time really digging into what makes the 1968 Ford 302 tick.

One of the key questions in any old car build is what you intend to use the car for? I wanted a performance street car. That’s what it was from Shelby American. But I wanted a dependable ride with some impressive performance. The Shelby tweaks to it were exactly that. The rear end had a 3.89 gear, great for performance and winding the engine out quickly. The stock Cobra intake was a dual plane designed for good low end torque. I had Tri-Y headers on it already which are also good for low end torque. Torque is what you want to increase on a street car. The torque of your car is what you feel in the seat of your pants. The hi-po 289 engine had solid lifters which made it a high winding small block. The max HP came at the top end RPMs. I was not going to be hitting high RPMs with this car very often, I needed the HP and torque to max out in a lower RPM range. And of course all these parts need to work together efficiently. I opted for staying with hydraulic lifters.


  • That 5.0/302 block is the same block that has been used from 1961 until 1995. The modular 4.6 was introduced in 1996. So that means ALL those aftermarket 5.0 parts will fit this block. But all those parts will not work together. The 5.0 engine has evolved a lot over the years. In 1985 Ford went with Fuel Injection and a roller cam. My 68 engine has a flat tappet valve train with a carb. (Although this older technology has evolved, too.)
  • These blocks are often referred to as Windsor engines. The engines were manufactured in Windsor, Ontario. Cleveland blocks were made in Cleveland, Ohio. This label was first used to differentiate between the 351 Windsor VS Cleveland. It’s used now to refer to the 5.0L 302 engines built there.
  • The first choice was whether to stay flat tappet valve train or go to a roller rocker & cam. Both valve trains would fit my application. However, to go roller cam was going to be about $1000 more than flat tappet. Lot of advantages to a roller rocker & cam valve train. Dan, the builder, wanted to stay with flat tappet with roller tips on the rocker arms. He was the expert. (In hindsight, even though Dan wanted to say with flat tappets, I would have taken roller rockers more seriously.)
  • The pistons were the stock, original pistons with 100,000 miles on them. We didn’t replace the pistons in 1982. The engine builder wanted to go with flat top, forged ICON aluminum pistons with dishes in the top for the valves. So that is what he installed. Click here for info about these pistons.
  • Next question is what to do with the heads? The stock heads limit the capabilities of the engine. Those heads were designed for about 250 horsepower. If you want more power, the heads needed to allow the engine to breath better. An auto engine is an basically an air pump. Air comes in and exhaust goes out. Make that process more efficient and the horse power goes up. Larger ports allow more air in and exhaust out. The second thing is to clean up the air flow inside the ports and runners. That was Dan’s suggestion, he wanted to clean up the runners and port those stock heads. But with what he was going to charge to do the original heads, I could add a couple hundred dollars and pick up some Edelbrock aluminum heads that were already polished, ported with bigger valves. You can get aluminum heads pretty reasonable today. I looked at all the head options. What I discovered is many of these aluminum heads are manufactured in China and tooled here in the US. I wanted American aluminum heads which narrowed down the selection to Edelbrock. (Read about the specs on Ford 302 heads.) (Read about the Edelbrock Aluminum heads I put on this engine.)
  • The other aspect of the heads is the combustions chamber volume and the resulting compression. The design of the head chamber area directly affects the size of the combustion chamber of the pistions. My builder wanted to keep the compression low enough to be able to run 91 Octane fuel.
  • What about the intake? The intake manifold directly impacts the flow of air and fuel into the cylinders. My car has the original Aluminum COBRA intake on it. This is an Offenhauser dual plane, hi-rise intake made to Shelby specs. I told the builder I wanted to keep that on the engine. It turns out Shelby American had the intake designed to give this engine more low end torque. Dan said he would clean up the ports and flow of that intake.
  • I had a Holley 600 cfm 4 bbl carb on it. Not the original carb but it did come from that period of time. (My car came with a Ford Autolite carb which I have long since replaced and lost.) They couldn’t get that carb to perform properly. Dan told the shop not to install the engine with that Holley carb. To get my car back a week or more faster, I bought a new Holley Brawler 4 bbl with an electric choke, per Dan’s instructions, from the Carb Shop. (Pat at the carb shop told me I didn’t need a new carb. To bring my old carb back to him and he would rebuild it. But it was going to be a couple of weeks before we would get it back. The shop doing the installation had been storing my car inside for over a month. He wanted it out of his shop and convinced me I would like a new tech Holley Brawler.)
  • The other piece of this conversation is to make all these parts work together. I am trying to get some pretty serious horsepower from thje engine. That means every piece needs to considered and “matched” to work best. Add to that, one potential surprise buying aluminum heads. Will the existing intake and exhaust headers bolt up to the heads? Edelbrock assured me the heads I picked would bolt to the intake and exhaust headers. We know the stock ones would. Everything bolted up fine.
  • My car had a set of Try-Y exhaust headers on it. If you have a Ford small block, a good set of headers are a must. These Tri-Y headers were designed for lower end torque rather than hi end RPM horsepower. Headers are a must on a small block Ford. Restrictive exhaust forces the engine to use power to push the exhaust out. The right size headers and exhaust make it easier for the exhaust to leave. Tri-Y refers to the design and have proven to be the best choice for small block Fords.
  • You also want to know if the transmission and rear end would handle more horsepower from this engine. This car came from Ford with a bulletproof 4 speed Toploader. I had it rebuilt with all new gears some years prior to this. That transmission will easily handle 400+ HP.
  • The rear end is the a Ford with a 3.89 set of gears. That Ford rear end will more than handle 350 horsepower.
  • What about the braking or the suspension? Making the car go faster is great but can the rest of the car handle it? In this case I have already rebuilt all those parts or upgraded them. The entire suspension has been replaced and the car lowered an inch. And it has Wilwood 4 piston disc brakes on it. I’ve seen other owners to put a hot engine in their car with poor stopping and handling which is a potential disaster looking for a place to happen. I did it the opposite, brakes and suspension first then the engine rebuild. A fast car is great but not if you can’t get it to stop.