Double Roller Timing Chain vs Gear Drive

[Bluedog]

I'm doing due dilligence on various engine options for a cobra. What are the pros and cons of using a double roller timing chain as opposed to a gear drive? Also, if I used a double roller timing chain is there any preference of a mechanical over a hydralic mechanism? Your input is highly appreciated!

Bluedog

[427sharpe]

The dbl roller chain is a basic hammer. Solid, reliable, quiet and well proven. The gear drives CAN be very noisy, but they do give you almost unlimited adjustment much easier than a chain. Some will fit behind a stock timing cover, but there have been problems with the guide buttons wearing a hole thu the cover. Pete Jackson gear drives are in particular quite noisy---sounds louder than an old supercharger! As for solid or hydraulic lifters....the solids will give you more rpm because they will not 'float', but they also require more fiddling to stay in adjustment. If you want all out power, and don't care how often you have to adjust valves, than solids are for you. If you want to DRIVE the car, spend as little time as possible under the hood, than go hydraulic. In a Cobra, almost any motor with decent power will give all the power you want. Remember that most '427 Cobras' actually came with 428's, just like the one in grandmas TBird (if she drove a Police Interceptor ). There is a reason Ford put more 428's in street cars than 427's! I would recommend the you go with a roller cam, either way. If you get an older block, there are plenty of conversion kits out there to put in a roller cam. The roller cams use much stronger profiles, for better all-around performance.

[blykins]

For what it's for, I would just go with a double roller. I did for my 425 SBF. Cloyes offers a really nice chain (hex-adjust) with several different keyways for various cam-timing options. Very nice.

You may get a little horsepower increase with a gear drive, as chains are the most inefficient ways of coupling. But for a high-performance street engine, a chain is perfectly fine. You would probably get a lot longer life with a gear drive...but you probably wouldn't notice it until you hit 100k miles or so.

Also, most gear drives are noisy. I think you can buy quiet ones now, but the regular ones sound like roots-type blowers.

As for mechanical vs. hydraulic, I have no idea what you're talking about. Can you clarify?

[blykins]

Oh duh...after reading Sharpe's reply, I guess you're talking about valve-train.

I suppose you're asking about mechanical/hydraulic instead of flat tappet/roller tappet though, right?

You can buy either style in either hydraulic/mechanical. The only real drawback is that hydraulic lifters have to be pumped up. Not that this causes a problem, but when you're doing your engine build you will have to check piston-valve clearance and cam degree. This is a lot easier with a mechanical lifter, as a hydraulic lifter will collapse as you put pressure on it and give you false values...i.e. your cam will show up as .400" lift instead of a .480" , etc.

Does this help?

[Excaliber]

Hydraulic vs mechanical

Yeah, not applicable to the cam shaft gearing/chaining at all. Must be a reference to the camshaft itself, hyd or solid lifters? Which has little or nothing to do with how the cam is driven.

The OLD Chevy 6's had a fiber cam gear driven by the crankshaft iron (steel, whatever) gear. The fiber was quiet and long lived. I bet most gear drives available today are metal gears, helical cut (angled teeth for smooth gear mesh) and noisy at best! Straight cut teeth on the gears would be REALLY noisy, but stronger (think FULL race application only)!

Ernie

[Bluedog]

Sorry for the confusion, I was talking about the valve train and kinda lumped everything together. Thx!

[blykins]

Hey bluedog...

What are you leaning towards? BB or SB? Big cubes or small cubes? Maybe that will help us make a little more wise and logical decision on your question. There are different combos for different engines and applications.

[Bluedog]

At this juncture, I'm leaning towards a stroked 427 aluminum block Clevor produced by Fontana Automotive. It basically has the best features of a Cleveland and Windor in one lightweight block. For example, it incorporates the Cleveland's 2.75 inch main bearings, oil pump and wider oil pan (for maximum crank-throw clearance), plus the Windor's superior oiling system, taller deck height (9.5") and greater cam to crank spacing. Basically, this block rocks! The only downside it that it's $3750 which is a little pricey!

Bluedog

[blykins]

I'm a little confused. A clevor is usually a Windsor block with Cleveland heads. Are you using a Windsor block, or is it one of the new Dart blocks? I think Ford Racing offers a Winston Cup block that has 9.500" deck heights plus the smaller main journals.

I guess it all depends on what you wanna do. Are you wanting to build a strictly race motor? If so, there are other combos that you can go with that can save you a little money.

If you're wanting to go with a street engine, you can save a lot of money....

What's your intention with the car?

[Bluedog]

My future cobra will be mostly used on the street but occasionally at the track. I'm heavily considering a JBL. No, I'm not planning on using the Dart block or a Windsor with Cleveland heads. In 1985, Joe Fontana designed and built a "real" Clevor engine block out of aluminum having the best attributes of the Windsor and Cleveland as I stated in my earlier message. Clevors are still being manufactured today. It's surprising how many people have never heard of them giving their performance characteristics. The engines are typically found in sprint cars, track cars, and Panteras. They are designed for up to 1,500HP...like the Shelby 427 block. Fontana Automotive has a real nice brochure on their Clevor blocks. Call Joe and he will send you one. They are located in Gardena, CA.

Bluedog

[blykins]

I'd get a brochure, but it would only cost me money...hehehe...I'd end up wanting one.

I've heard of some custom blocks, but the only Clevors I've ever seen were Windsor blocks with Cleveland heads. Oh well.....

I have a nice little engine that I built for my Cobra. 351W punched out and stroked to 425ci. It made 484hp and 500 lb-ft with a somewhat mild cam and a 750cfm Demon. Compression was 10.3:1. It should be plenty.

If you're wanting a race motor and you are thinking about spending that kind of money on a block...there are probably some alternative routes that would be less expensive.

Like I said earlier, you can go to Ford Racing's webpage and look at their 351W Winston Cup blocks. They have the smaller main journals, 4 bolt mains, and you can get them with either a 9.200" or a 9.500" deck height. They would be a lot cheaper (I think they're somewhere in the $2000 range) than the block you're thinking of using. You could use a fairly large bore (4.125") and a shorter stroke to get 427ci....that would give you some rev-ability. To top it off, a set of Yates heads would be nice...they would be my choice for a hi-po engine of that price bracket. Bare heads are $1200 each. But they flow really well. The guy that dyno'd my engine had a 347ci stroker (out of a 302) with those heads...titanium valves, etc...and with some pretty high compression and a wild cam, it made 715hp at 7800 rpm. Not too shabby.

I can't really justify spending that much cash on an engine myself though...the only racing that I'll be doing is some pretty mild SCCA stuff. However, I've spent approximately $8500 in my engine not counting the clutch/pressure plate and the blowproof bellhousing.

It was my first build though, and I researched everything...and I'm really happy with the results. I used the best parts I could find for that caliber engine...Main cap girdle, Eagle H-beam rods, Eagle ESP 4340 crank...Victor Jr. heads (custom assembled by me )...etc. I didn't skimp anywhere. I even bought a bore mic so I could mic the bearings down to .0001". No plastigage here.

Anyway to make a long story short, if you're building it yourself, it could be a 2.8L V6, and it would make you proud. It was just totally awesome to hear that thing fire up the first time and not throw any rods through the block. No leaks, really good oil pressure...no metal in the oil filter. It was a good day for me.

I did run out of carb though...I have a 750cfm Demon, and the EGT sensors showed that the cylinders were running a little lean. Turned out, even though we got it really rich on the idle circuit, it still wasn't running too rich even with 88's and 98's in the carb. I could have used a bigger carb I think. There's probably a lot more potential in that engine...but it's good enough.

I'm sure you'll be happy with whatever you decide to do, and there's a lot of knowledgable people on here to help you along the way. You're in good hands with this group of people.

BTW, check out my pics...I have a few posted on my engine build.

Brent

[Bluedog]

Blykins, sounds like you have a really nice engine. I went to the car show today in Pleasanton and saw the mother of all carbs. It was a Holly having 1150 CFM...it was huge. Add this Holly to your setup and you will have a rocket ship. Glad you mentioned that you liked Yates. I'm considering Yates heads. The only problem is major chassis modifications are needed for it to fit in a JBL. The headers drop straight down from the heads with the Yates. Check out JMARSEY's masterpiece JBL using a 302 and Yates heads. Also, notice the "extra" effort required for this work of art!

Bluedog

[Mr.Fixit]

My future cobra will be mostly used on the street but occasionally at the track
Basically, this block rocks! The only downside it that it's $3750 which is a little pricey!

A $3800 engine block for a street car? Are you nuts?

Forget the timing gears, run a chain.

[65 Blur]

When I was doing research for my engine I ran across the same question. The double roller was the easy choice.

The cost / benifit for the gear drive was not there, and if you are not careful, there are issues with crank harmonics transmitting to the valve train with the gear.

Roy

[Jack21]

It's tough to make a mental transition from your typical 3600 pound street machine and a 2400 pound Cobra until you're actually driving one. You don't need to go overboard on a 600 HP monster engine to have all the power you need on a mostly street driven Cobra. Gross excesses are not required, or even desirable. Build your engine slightly on the conservative side. You, and it will have a happier relationship in daily living with each other. Build it hot, and you build it tempermental. Not a happy situation.

Check the SVO Catalog, and you'll find the weight savings for an aluminum block (120#), and an iron block (195#) is simply not worth the extra cost in $$$, and reliability for street and ocassional track use. Use a well seasoned production block, and spend your money on good bottom end ARP hardware holding it together.

Gears vs chain on the street. Remember when (and likely still today) when the cam gear was sintered iron or cast aluminum, and the gear itself was nylon, or plastic. For a mostly street and ocassionally track use, the double roller chain from Cloyce or any of the cam vendors will more than suffice. The gears will last forever, and the chain will get replaced with rings and valvegrinds.

Retrofit hydraulic roller cams (and roller rocker arms) are a definate "Go for it" if you have the budget. Well worth the extra $$$! Makes your engine think it has grown an extra 50 ci. Tip. Have your valve springs oil retentitive coated for cooling. They'll last longer before needing replacement. Keep the duration where you realistically expect to use the motors' power band. 220 - 225 I, 220 - 235E regardless of lift. Good street manners, and awsome torque when the tach hits 3000.

Most will disagree with me on this point. Don't use aluminum roller rocker arms on a street engine. Use steel. Specifically, Comp Cams Pro Magnum steel roller rockers. They last forever. (Actually, they don't last forever. Comp Cams recommends you send them back for a rebuild when the engine is down for rings and/or valvegrind). Aluminum rockers are a throw-away item for replacement every racing season.

The nemisis of the Ford Windsor engine, 289, 302, 351 has always been in the breathing department. Chuck the stockers in the dumpster. There is nothing you can do to help them. Aftermarket is the way to go. Roush, TFS, Edelbrock, AR, and others make vastly superior heads for the 351W motor. 2.02/1.60 is the minimum valve size for a 351 size motor. 393 stroker, look to upping that to 2.08/1.60. (The Aussies, where the 351C is well supported, have a C3V aluminum head for this motor. 2V ports, 4V valve sizes) (Some BBC folks have this combination on their street 454's via Dart - awsome mid range torque).

What I have come to hate about Fords! The starter, the distributor, the alternator, and the power steering pump. With a Cobra, you have a choice. Summit sells a Powermaster starter, new, that's 1/3 the size and weight, and lasts forever. $160. Distributor. The MSD is a Delco distributor on a Ford stalk. Get one. Likewise for a Delco alternator. Change the brushes every 100,000 miles, and bolt it back in. Likewise for the Saginaw PS pump. Keep it full, and filtered, and it will outlast the car.

OK. I'm off my soapbox. Mr. Fixit, anything to add?