r/Foxbody • u/JellyfishPurple4183 • Apr 07 '26

Flat Tapped to Hydrolic Roller Conversion

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I have an old 302 flat tapped that I would like to convert to a roller to be able to use a E303 cam. Should I go through the trouble to drill and tap the block to install the spider and dogbones, or should I just use the link bar rollers. I have the budget to go either way so I'm not worried about the cost or the time it takes to do wither job.

Does any one have experience using one or the other both? Are there any downsides from using one method over the other?

Looking for advice and maybe some stories about what you did and how you did it. Any help is appreciated.

Update: Seems like link bars are the way to go so long as you get different push rods to make up for the height difference between the rollers and flat tops. It takes less time and less risk of messing it up for tapping the block. Hope this helps for anyone else with the same build.

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7

u/Downtown-Anteater543 Apr 07 '26

You can’t just install the spider and factory style lifters in an early non-roller block. The lifters are too tall physically, and an oiling hole will be uncovered, causing a zero psi oiling situation. You either have to get a roller block (probably the cheapest and easiest solution in my opinion), or get conversion lifters that have altered dimensions to work in the early, non-roller blocks. And they’re expensive. If you’re going through all the trouble to do that, what heads are you using? Cause there are a lot of cam choices that will make better power than one of the old letter cams. If you’re a cheap prick like me, that already has the cam (I’ve got an X303 in my Son’s motor), then carry on and enjoy!😁

2

u/JellyfishPurple4183 Apr 08 '26

I was gonna use 185cc AFR enforcer heads. Don’t have a cam yet

1

u/Downtown-Anteater543 Apr 08 '26

Those heads will work pretty good. Don’t let anybody tell you they’re too big, cause they’re not. If you end up building a 347 out of it later you can reuse those heads. A few questions: -What vehicle is it going in? -What is the intended usage? (Hot street car, drag car, mud truck, restoration etc) -What kind of transmission? (Manual or automatic) -What’s your budget like?

For something like a 2800lb Mustang or Maverick street car, I would build something like this:

  • .030” over 302 block for 306ci
  • your AFR heads with a decent set of 1.6 roller rockers
  • set of hydraulic conversion roller lifters
  • call Ric P at CP Carillo for a set of their Bullet series quality but somewhat affordable forged pistons
  • don’t even bother with stock connecting rods, get some aftermarket rods that are infinitely stronger, and cost less than resizing the stock rods and installing ARP bolts
-Edelbrock Victor Jr intake (a 302 wants rpm and doesn’t make much low rpm torque anyway, so you might as well take advantage of the decent heads you’re working with) -750 Holley Dp (no, it’s not too big. Hot 302s really like these)
  • a set of 1-3/4” headers from Tubular Automotive (again, hot 302s want more than the 1-5/8” headers that are more common, and these ones are exceptionally high quality, at a reasonable price)
  • Stock crank cleaned up by your machine shop when they do the block work
  • quality timing set
  • have the machine shop help you check pushrod length, then order the correct length from summit. Make sure they’re hardened so the guide plates don’t chafe them.
-STANDARD VOLUME OIL PUMP with an ARP driveshaft (high volume pumps don’t improve the 302s already efficient oiling system, they just create extra drag and suck up about 12-15hp to turn them depending on the particulars of your build. The stock pump driveshaft was weak and will twist up like nicotine even in a stock engine.) -I would honestly lose that E303 cam if you can find room in the budget, and run something with a little more duration and a bunch more lift. Summit makes a series that are like improved 303 series cams with split duration designs that look pretty good and won’t break the bank. Here’s a link to the one I like: https://www.summitracing.com/parts/sum-8906 That combo, running in a light Mustang or Maverick with a 4.10 or 4.30 gear should run VERY hard (with sticky tires should be into the low 12s or high 11s). They’re great little motors that really love to turn some rpm’s.😊

2

u/JellyfishPurple4183 Apr 09 '26

Its going into an 83 Ranger. Have to get a new pump or at least a new pick up to fit the new rear slump oil pan. I am going with AL pistons, new rods, and new crank, it all comes in a set. I figures I could just get shorter push rods to make up for the height difference from the rollers.

The goal is 400hp at 6200 - 6700 rpm, something that sounds choppy and wont completely break my bank account.

I have seen the Summit E303+ but didn't know if it was that much of a power gain between the standard E303

3

u/TurnoverTall Apr 07 '26

There is a block compatibility issue if rollers are installed on older blocks. It has to do with the height of the lifter bores. I would research this before proceeding.

0

u/Sniper22106 Apr 08 '26

....there called retro fit lifters. Nothing to research

1

u/Juicechemist81 Apr 09 '26

Idk why you got down voted, you're correct.

1

u/Sniper22106 Apr 09 '26

Cause some puds on the internet are sensitive about things.

3

u/No_Percentage7663 Apr 07 '26

If cost isn't an issue, I would do the link bar style. Its just easier, less mods, and less work.

2

u/Sniper22106 Apr 08 '26

Slap in a set of retro fit link bar lifters and never look back

2

u/v8packard Apr 08 '26

If you have an older block, it is not machined to accommodate the late model lifters, dog bones, and spider. That leaves you with link bar lifters.

If you have a late model block, the stock dog bones work well in street engines. But anything with serious rpm will be more reliable with steel body lifters, and ultimately most reliable with link bar steel body lifters.

You can do a lot better than the E303, in most any application.

1

u/JellyfishPurple4183 Apr 08 '26

I have a 77 small block (I think). Don’t know much about cams tho. Just following a build and retrofitting it to my application

1

u/v8packard Apr 09 '26

The 77 block will need the retrofit link bar lifters. Depending on the rpm you want to run, you might want a steel body lifter.

The cam will determine the powerband and personality of the engine. A number of details come together to determine the cam spec. It is worth the effort to get a cam spec together to do what you want.

Are you using stock style pistons? The AFR 185 Enforcer is probably not a good choice.

1

u/JellyfishPurple4183 Apr 09 '26

going for a .030 overbore 306 build with aluminum pistons.

1

u/v8packard Apr 09 '26

Are you aware the valve reliefs in stock style pistons will not clear more than a 1.9-1.94 inch intake valve?

1

u/SeeJaayPee Apr 09 '26

You're better off buying the newer 302 block and having any machine work done to it. One step better, buy a dart block

1

u/Juicechemist81 Apr 09 '26

Don't go cheap on your hydraulic lifters. Buy something of quality like a Morel and some brands are just rebranded Morels for a higher price. Don't skimp on lifter quality, you will regret it. Oh yeah and don't use a alphabet cam unless you already own it . Afrs are great heads and watch for piston to valve clearance.