BIG BLOCK CHEVY 300cc OVAL PORT ALUMINUM HEADS BY PROCOMP
FULLY ASSEMBLED, FOR USE WITH HYDRAULIC ROLLER CAMS UP TO 620 LIFT.
119cc COMBUSTION CHAMBERS
This sale is for a set of heads (2 heads).
Our user id is: skipwhite, and our store name is whiteperformance1. You may have noticed other sellers using a similar name offering similar products. These other sellers have capitalized on our name as we see it, and many customers searching for us will inadvertently find them, thinking we are one in the same company. There is only one "Skip White." We are the original premier seller under this name since approximately 2003. We have no other names, nor are we associated with any other company regardless of the similarity in the name or location. Our official company name is Skip White Performance. Please see the article in the lower part of this ad for a more detailed explanation.
The Procomp bbc heads are perfect for 427, 454, 496 and 540 street/strip engines. These are what we use on our 505 and 555 bbc engines. They will produce up to 680 hp with the proper cam and intake manifold on pump gas. This is an outstanding trouble-free set of heads. Fully built, ready to install.
Valve Opening CFM Valve Opening CFM
0.050 31 0.050 27
0.100 66 0.100 57
0.200 125 0.200 112
0.300 194 0.300 152
0.400 255 0.400 192
0.500 296 0.500 219
0.600 310 0.600 240
0.700 323 0.700 257
0.800 335 0.800 271
Test Pressure 28"
In the lower section of this ad you will find valuable information on how these heads perform when used with various engine sizes and cam combinations in street rod form. Please read the complete ad before purchasing.
Fully assembled with premium PBM race grade valves, Melling springs, Comp retainers, viton valve seals, spring ID locators, high grade Comp Cams 10 degree locks. The hardware setup in these heads is for use with hydraulic roller cams. Below is a detailed breakdown of the hardware used in these heads. We do offer these heads set up for all types of cams. See our other listings.
heads are not suitable on 396 or 402 engines that have the less then
4.250" bore size. With the larger 2.250" intake valve on the BBC OVAL heads, it can interfere with the cylinder wall. These heads are well
suited on 4.280" and larger bore BBC engines. The recommended
compression would be from 9.8:1 to 10.5:1 with pump gas, taking
advantage of the aluminum castings.
Valve size 2.250 and 1.88. These heads have the correct seat diameter to allow use of these valves.
We know of many sellers of aluminum high performance heads that claim to use good hardware. Chances are they don't know the difference between low grade and high quality hardware. Failure to follow proper assembly procedures and the use of low grade hardware are what cause most problems. Good quality hardware and proper installation can determine how well the heads will function and hold up under hard use.
SEE OUR OTHER LISTINGS FOR THE REC. PORT VERSION.
Please note: Due to a high volume of sales at this time, these heads may take up to 3 business days to complete and ship. Please let us know if you are under a time constraint with this order, and we will do our best to accommodate your request.
These are true multi-purpose heads for street, drag race, and power boat applications. This set is an excellent upgrade over OEM cast iron heads on your big block engine. We honestly feel there is not a better set of heads for the price. These heads are tried and proven. The intake runner volume is 300cc, and the combustion chambers are 119cc.
You can reduce your engine weight by around 100 lbs. with the use of aluminum heads. You can also increase your power up to 250hp over an OEM 454 engine, depending on choice of cam and intake manifold.
We do our own assembly on our heads. See details below about our hardware and assembly procedure.
We also offer variations of these heads for use with all types of cams. Be sure of what type cam you plan to run before purchasing. Read the ad completely before purchasing.
The horsepower gain from the weight reduction of aluminum heads alone is noticeable, not to mention the fact that aluminum heads will allow you to run a bit more compression without the risk of detonation. The benefits are many to running aluminum heads. The most expensive cars in the world all run them. There are no drawbacks!
Tech support is available. We are confident that we offer the best advice in the business.
We also offer these heads in bare form, as many customers have selected a machine shop of their choice, as well as their own hardware. We hope you will check out our other listings for the many other items we have available.
Here is a rundown on the hardware used in these heads and the assembly process.
PBM Competition Series Valves.
PS824 forged high temp stainless. 10% reduced weight. Hardened keeper groove.
We use what we consider to be the best valves on the market: the Competition series PBM backcut valves. These valves are considered very high quality. Do a search on this brand of valves and you will find them to be very highly rated.
PBM has three different series of valves. These are the top line. The backcut feature reduces valve weight by an average of 13 grams per valve. This weight reduction of approx. 208 grams for the complete set has a great effect on acceleration, deceleration, and will extend valve train life. The valve spring compression and rebound action will remain stable at a higher rpm with the use of reduced weight valves. The instability of a valve spring at high rpm is known as valve float. This is very damaging to the heads, and valve train components.
The backcut feature is not be mistaken for an undercut. These valves have both features. Backcutting is an additional radius put on the head of the valve to increase the flow numbers and reduce valve weight. The flow increase is usually around 3-6 points on the flow bench, and possibly more, depending on the initial flow rate of the heads. According to one of our machinists who built Winston cup engines for 15 years, the exhaust valves had an additional radius cut on the outermost edge that allowed a better escape of the exhaust gas. This cut on the exhaust valve is in addition to the backcut feature.
The Competition series is made from a much higher temp alloy than most other stainless valves. There are at least three levels of stainless valves on the market, excluding those used in very high level racing such as pro-mod. The PBM Competition series is compared to the highest level of those three.
Notice in the picture below the concaved face of the valves. You will only see this on high end valves. Most other valves are either flat faced or have a dimple in the center.
The pictures below show our PBM valves installed in set of CNC'd combustion chamber heads. This is not actual combustion chamber of the PC heads. The pictures are to show you the valve face design.
Pictured directly below in the first pic. is the PBM competition valve, and the other pic. is of our conventional style valve. It was difficult to show the back-cut feature in the picture, but note that the valve that is hand-held (PBM) has a third radius cut.
These valves are swirl finished, back-cut plus undercut style, and have a very well designed lock groove. The exhaust valves have an additional feature: a blunt face on the outermost edge to assist in the elimination of exhaust gases. Low temp valves will fail with ease under the right conditions. High temp valves are not just for those running to extremes; they are essential for all carbureted engines. Should your engine lean out for any reason, the combustion temperatures can rise in an instant. Carbs that are not working as they should (and all carbs have their moments) can cause a lean condition and you will most likely not know this is happening.
Using a low grade stainless valve on a BBC engine will cause problems sooner or later. If you're running a blower, your valves must be of the highest grade stainless. Marine engines require a premium valve due to the fact they are run at high rpm (usually 85% of max rpm) for long periods of time. This sustained high speed is more than any standard stainless valves can take, and not just due to the heat. The stems must be perfectly designed and constructed with high end alloys. These valves are used in many 800 hp BBC engines. You simply can't do this with low level stainless valves, or they will fail.
Melling High Performance Dual Springs.
Our Melling springs are 1.46 diameter, with an inner spring and internal damper. Others are using springs that are much smaller in diameter. Smaller diameter springs may be in the correct spring pressure zone, but they usually have a shorter life. Melling springs are made in the USA. All of our engines using the Procomp BBC heads use these springs. Spring failures are near non-existent.
10 Degree machined valve locks.
We use only Comp Super 10 degree machined locks. Our head builder noticed the low grade locks on the market fit more loosely than he felt they should, not to mention the possibility that they were made of inferior metal. He envisioned the engine being much more prone to dropping a valve at high rpm. Using these locks, coupled with our PBM valves, we have yet to have an engine drop a valve due to a valve lock failure.
Comp Cams retainers # 75740-16 and Comp Cams ID locators Part number: 4771-16
Our Comp Cams retainers # 75740-16 and Comp ID locators # VTH-4771-16 are made from 4130 chromoly steel. These retainers have a perfect fit with the Comp valve locks. We have used these on all of our engines for many years, and have had zero failures.