First let me say that I am a long-time subscriber and really enjoy your magazine. I have a vexing problem that I can’t figure out and I hope you might have some ideas.

I have an ’81 Trans Am with the WS6 option, including the factory four-wheel disc brakes. The brake system works fine. I’ve upgraded the brake hoses to braided lines and the rotors are cross-drilled. I’m running Performance Friction carbon-fiber brake pads. The car was originally equipped with a 301 four-barrel Pontiac engine and a Turbo 200 trans. It now has a ’77 Pontiac W72 400 and Turbo 350.

My problem is the left rear valve cover clears the brake booster by less than ½-inch. I’m building a 455 that will require taller valve covers due to roller rockers. I have been told that this was a one- or two-year-only brake system. I have considered the following solutions:

1) A smaller aftermarket booster/master cylinder, but I have no idea how to figure out what size I need and what size master cylinder I would need. The car is “showy,” so a chrome or polished unit would be good but not necessary.

2) A hydro-boost system. This would give me the room I need, but would clutter the engine compartment with hoses and is not very nice-looking. I used to own a Chevy Astro Van with a hydro-boost system and the brake feel was not very good, although the system worked fine.

3) Manual disc brakes. I am sure there is a formula somewhere for the length of pedal arm I would need. I am an experienced welder and fabricator.

Any other ideas or OEM booster swaps?

Michael Dinan - St. Louis, MO


Rocky Rotella responds:

Michael, thank you for your loyalty to HPP. We certainly appreciate it.

Firebird brake-booster dimensions varied with the model year, and engine and rear-brake application. As you’ve learned, ’81 is rather unique. Its brake booster, master cylinder, and proportioning valve do not directly interchange with previous years, so finding alternatives may be somewhat difficult.

A larger brake booster used with the 301 in your ’81 Firebird wasn’t an issue with the short-deck engine, but it can interfere with the driver-side valve cover on a standard-deck Pontiac engine, such as the 400 you installed. I strongly advise against reengineering or mixing-and-matching the components of any vehicle’s brake system. You need to know you can rely upon it when you need it most.

Firebird brake-booster dimensions varied with the model year, and engine and rear-brake application

There are a few different options, and it sounds as if you’re on the right track with your ideas. I don’t know that you need to go to a hydro-boost system or manual-effort brakes, however. The most complete and easiest solution is to purchase a complete kit from one of the many brake companies that offer such products. It will include a small-diameter booster, the correct master cylinder, calipers, and the associated hardware for proper operation. It doesn’t sound as if you need all that, however, since your Firebird was originally equipped with a rear-disc-brake setup, and it’s in excellent working order other than the brake-booster interference issue.

Many of the same companies that offer complete kits also offer individual components. Classic Performance Parts (www.classicperform.com) is one that sells its brake boosters individually, and in various diameters and dimensions to fit within a cramped engine compartment of a typical hot rod. I would contact its technicians to determine which, if any, of its boosters might work with your existing factory components. I suspect you’ll be able to find something smaller that will bolt into place and provide you with a similar amount of pedal effort without compromising braking performance.


Block Shock

About five years ago I completed a restoration of an ’80 Trans Am. I rebuilt a 400ci Pontiac engine, had it bored 0.030 over; installed forged pistons, ARP studs and bolts; had the stock rods re-sized; installed a Crane Blueprint cam (068 specs), stock No. 13 cylinder heads, Harland Sharp roller rockers, an Edelbrock Performer intake manifold, a Holley 750 carb, and Hooker headers. All the parts were balanced before assembly. I also used a TCI torque converter, Turbo 400 transmission, and 3.73 gears.

I love the torque, the sound of the turbo mufflers, and the tire smoke. It makes an old man (closing in on 60) feel like an 18-year-old again, back when I owned a ’70 GTO.

I just finished reading about building Pontiac blocks in the April ’13 issue. You can imagine how I felt when I realized my block is a #500557. The machine shop that bored my block said they didn’t remember a 400 Pontiac block being as light as this one. Now I know why.

I’ve driven this car about 6,000 miles since it was completed, street driving with occasional burnouts and 5,000-rpm shifts. Should I look for a different block and put my parts in it, start from scratch, or keep driving it as is? I figure the engine must make around 400 hp. Thanks for any input.

Jim Seymour - Harrisville, NY


Rocky Rotella responds:

Jim, there’s no question that the mid-to-late-’70s 500557 block casting simply isn’t as beefy as its predecessors or the 481988 casting that was revived for the T/A 6.6 in ’78. As you read in the April ’13 issue, its cylinder walls and main saddles (or bulkheads) were thinned considerably to reduce casting weight. It was just one of many attempts Pontiac engineers made in that era to shed overall vehicle mass and improve fuel economy.

The lack of material and the rigidity issues it creates makes the 500557 susceptible to failure when combined with a long-stroke crankshaft, high-speed engine operation (above 5,200 rpm or so), and/or a combination producing more than about 400 hp. Many have successfully used the 500557 up to that level and even slightly more over the years. I personally don’t recommend exceeding the 400hp mark simply because I feel the block is incapable of reliably enduring the operational characteristics associated with it.

Assuming your particular 500557 block was in excellent reusable condition and was rebuilt properly, I don’t suspect you’ll have any issue at your current performance level or with the way you’re driving it. I certainly don’t suggest boring it any further, and wouldn’t recommend any additional modifications to dramatically increase performance. If that’s your goal, then I highly suggest beginning a new build using a better foundation. But it sounds as if you and your machinist paid close attention to the details, and that should yield reliable engine operation for years come. So continue enjoying your Pontiac just as you have. I don’t believe you have anything to worry about.


Restricted Access

I need your opinion on my street/strip 461. I’m going with a Comp Cams solid-roller with the company’s Endurex lifters. Do I need restrictors with these lifters? The experienced race-engine builder who did the bottom end and spec’d out the cam said restrictors weren’t necessary. Butler’s catalog says this lifter requires restrictors or restricted pushrods. The bottom end is complete. I hate to take it apart, but I want it right the first time. Your opinion on this would be much appreciated.

Denny Drone - Via Internet


Rocky Rotella responds:

Denny, that’s an excellent question that many hobbyists ask. However, I’ve found the answer is rather complicated, and ultimately application and builder specific. Let me explain why.

Generally speaking, pressurized oil lubricates an engine’s rocker arms while the oil flowing from them carries heat away from the valvesprings. In a Pontiac V-8, that oil is commonly delivered to the top end through the lifter and pushrod. The greatest concern when using a mechanical (or solid) lifter in a Pontiac block is the volume of oil that passes through it. Pontiac engineers designed its new V-8 for ’55 to deliver a relatively high volume of pressurized oil to the lifter bores for proper hydraulic-lifter function.

When Pontiac selected a mechanical camshaft for its Super-Duty engines of the early ’60s, the solid lifter it developed had a very small feed hole intended to reduce the amount flowing to the top end just enough to keep the rockers lubricated and the springs cool. When that factory-designed solid lifter disappeared from Pontiac’s parts catalog, many companies began creating their own by modifying a typical hydraulic lifter. The internal plunger was replaced with a fixed piece to effectively create a solid unit. The oil feed hole in the lifter body was, however, permanently sized for hydraulic operation.


Over the years, I have found that the preferred method of effective oil restriction when running a mechanical cam in a Pontiac V-8 seemingly varies by builder and/or cams


Engine builders and hobbyists quickly found that because oil flow through these modified hydraulic lifters wasn’t restricted, the oil pump could deliver oil to the top end quicker than it could flow back to the sump during a full throttle blast, potentially starving the crankshaft of vital lubrication, ultimately ending in fatal bearing damage. Tapping the block’s lifter bore holes to accept a ¼-inch-diameter set screw with a restriction—measuring around 0.040 inch—drilled into it proved an effective solution that remains common even today. It’s also a modification that must be performed with the engine completely disassembled so the block can be properly cleaned of any metal filings associated with the tapping process.

Another suitable solution is using special pushrods that have a smaller diameter hole in them, which provides the lifter with a generous amount of oil but limits flow to the top end. Savvy camshaft manufacturers such as Comp and Crower have since developed specific solid flat-tappet and roller lifters for the Pontiac V-8 that reduce oil flow. It lessens but doesn’t totally eliminate the need for lifter-bore restrictors in the block. The solid-roller units are among the best available today and are a popular choice with professional Pontiac builders. These special lifters and restricted pushrods can be combined or used independently, depending upon the application.

Over the years, I have found that the preferred method of effective oil restriction when running a mechanical cam in a Pontiac V-8 seemingly varies by builder and/or camshaft manufacturer. Some feel no restrictors are required, while others prefer using restricted lifters and/or pushrods. While that may seem contradictory, both answers are absolutely correct because of the wide array of variables involved when building engines. I contacted a couple of knowledgeable and experienced Pontiac engine builders and asked their thoughts on installing a solid-roller camshaft into a Pontiac V-8.

David Butler from Butler Performance in Leoma, Tennessee, believes there are too many variables to make a blanket statement that fits every application. He tells me the position of the lifter’s oil feed hole in relation to the lifter bore hole, the diameter of the lifter’s oil feed hole, lifter-bore clearance, oil-pan capacity, and the intended application are all factors he considers when determining the best method of oil-flow restriction for a given engine. Additionally, aftermarket aluminum heads typically do not drain oil back as quickly as original iron castings, so oil pooling can be an issue, and that adds to the consideration.

Though Butler has successfully used all types of solid-roller lifters, he most commonly uses Comp Cams equipment in the engines he builds. Since Comp’s lifter for Pontiac V-8s generally flows a greater amount of oil than what’s required for adequate top-end lubrication, Butler tends to prefer limiting oil flow with restricted pushrods, particularly in high-rpm engines and/or those with a very aggressive roller camshaft with high valvespring pressure, where additional lifter oiling can increase the lifespan of the roller wheel. He added that he uses lifter-bore restrictors in applications in which bearing wear issues are a concern, and he has found it an effective solution.

Dave Bisschop at SD Performance in Chilliwack, British Columbia, commonly uses Crower solid-roller lifters in his engines simply because he’s most comfortable with them. He typically doesn’t use lifter-bore restrictors in the engines he builds because, for him, the Crower lifter adequately restricts oil flow through the lifter body, and the roller wheel’s needle bearings rely upon the pressurized oil for effective lubrication. Bisschop feels that less oil flow than what’s available from the Crower lifter can potentially lead to rocker-arm damage and premature valvespring wear, and if oil control still seems to be an issue, he then uses a restricted pushrod for limitation.

As you can tell, there isn’t a simple one-size-fits-all answer to your question. Each engine builder machines and assembles their engines differently and that can ultimately affect the outcome, regardless of what components are used. Without knowing all the details of your particular build, it’s difficult for me to make a suggestion, but I’m confident you’ll find adequate oil-flow control is possible using a quality restricted pushrod, and that will eliminate the need to disassemble your engine to install lifter-bore restrictors.

Your best bet is to contact your favorite professional Pontiac builder and carefully outline the details of your particular combination, however. He or she can provide you with the best solution for your application based on their experience, and that will certainly keep your Pontiac operating as reliably as possible.

Email questions to tom.demauro@sorc.com


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