Pro-Gram Engineering Caps for a 401

Since several guys have asked questions about aftermarket main caps I have decided to make a post about them and show photos. Yes, Pro-Gram Engineering still makes them in batches and depending on when you try to obtain them it can be from today to six months from now depending on supply and their production schedule before you will get them. My most recent order last spring took 6 months to get the rear cap, so if your planning an engine around a set order asap and see what happens. I am a dealer and still have to wait 2-3 days for them to return my calls. Very nice people, however not big on expedient communication. Cost wise the rear cap cost almost as much (78.3%) as all 3 center caps do. The front cap is the most reasonable obviously do to ease of manufacturing. So the bottom line do we need all 5 caps or not? Who really knows on a factory iron block. I look at it as if your lucky in life you get to play with toys 50-60 years and your done. If it makes you feel better having 5 really nice billet main caps on your block whether we really need them or not who cares. I for one sleep better at night knowing that I have done everything possible to give my iron block every advantage I could. Now the eye candy for your pleasure gentlemen.

motorhead_1 wrote: say, those are pretty.  they came with the hardware? not going the stud route to give your engine every advantage?

Yes they came out of the box with the outer bolts you see in the photos. Of course I will obtain the proper ARP studs when the time comes. Yes, the engine will get every advantage. I even have a warm wool blanket over it in the garage. LOL

Rebel Machine wrote: The rear cap must be something recent. I got a set minus the rear from another forum member. Wish the rear was available then. I'm not making insane horsepower so I think I'll be okay (shooting for 650 HP).

Hi, glad you made good use of them... at the time of purchase back in 2004, directly from Pro-Gram, I questioned about the rear caps, which I could have bought at the time of order. He told me that the rear main is strong enough, and that front and rear caps were more for a complete look and serious all out performance engines.

The stud kit was important for all builds. As it does strengthen the rear and front cap when secured.

I weighed the limitations of a 70 390 block, which can use them, but won't have enough register to secure from rocking. Though having extra splayed cap screws should act like heavy duty dowl pins at the center, which is better than stock on the 70 390. Figured adding dowl pins will be good enough with a stud kit for my use, so the deal was to sell to a member in need.

Also, I noticed the new kits are bare metal, not black... though both look great!

PS about the front cap... I got it thinking to chamfer the front edge to allow oil to pass the front pan lip. Many complain about not enough clearance. Figuring the new cap can take some trimming and be stout enough for keeping it strength.

Edited by 304-dude - Jan/16/2019 at 8:01am

Like most things, it would be interesting to hear people's thoughts about the power level where you would consider stepping up to these.

WesternRed wrote: Like most things, it would be interesting to hear people's thoughts about the power level where you would consider stepping up to these.

For for long term bearing wear with NOS, Turbo, or Super Charger usage into 7000+ RPM use. If fully blown 6-71 they are a must for bracket racers.

Since I changed my plans on using NOS, because it produces instant power and will probably brake my input shaft before seeing any main cap issues.

I may give it a try with a super charger on the mild side of the RPM range, no more than 6500 RPM for a few fun attempts, but will be street driven setup. Thus no need for such caps, though I did have them for my build plans, but realistic side of things, they were better served on a bigger build or a more serious use.