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I haven't followed this board for very long so this may have been brought up. I wish not to be redundant but, this is a valuable improvement. I live in Phoenix, Az and drive Pontiac powered vehicles on the street, strip, tow and even in my boat. Our summers are among the most intense there are.
About 15 years back while trying many ideas to improve cooling the Real Pontiac I found something that helped. I drilled a 5/16" hole in the block and in both heads. The location was directly above the center head bolt on the lower row. This is a hot area on the Pontiac where the 2 exh ports are next to each other (except Ram Air V). Pontiac actually did this at the factory from 1955 until about 1959 or 60 (another virtue of the early motor). For some reason, Pontiac stopped drilling out this hole. This was the same time Pontiac dumped the reverse cooling. This modification improves water circulation at that critical area and will also help extend the life of head gaskets under extreme conditions. Most head gaskets actually already have the hole in them including the popular #1016. To perform this improvement, use the gasket as a template and center punch it. Then use a small, high quality drill and slowly drill it through. The first hole is the hardest, be careful not to catch the bit and snap it off in the block. I have well over 200,000 miles on different Pontiac engines with this modification. Steve Barcak www.pontiacheaven.org Real Pontiacs only......NO corporate nonsense! |
I haven't followed this board for very long so this may have been brought up. I wish not to be redundant but, this is a valuable improvement. I live in Phoenix, Az and drive Pontiac powered vehicles on the street, strip, tow and even in my boat. Our summers are among the most intense there are.
About 15 years back while trying many ideas to improve cooling the Real Pontiac I found something that helped. I drilled a 5/16" hole in the block and in both heads. The location was directly above the center head bolt on the lower row. This is a hot area on the Pontiac where the 2 exh ports are next to each other (except Ram Air V). Pontiac actually did this at the factory from 1955 until about 1959 or 60 (another virtue of the early motor). For some reason, Pontiac stopped drilling out this hole. This was the same time Pontiac dumped the reverse cooling. This modification improves water circulation at that critical area and will also help extend the life of head gaskets under extreme conditions. Most head gaskets actually already have the hole in them including the popular #1016. To perform this improvement, use the gasket as a template and center punch it. Then use a small, high quality drill and slowly drill it through. The first hole is the hardest, be careful not to catch the bit and snap it off in the block. I have well over 200,000 miles on different Pontiac engines with this modification. Steve Barcak www.pontiacheaven.org Real Pontiacs only......NO corporate nonsense! |
...does a 5/16 masonry bit drill it like butter?
I will look into your idea. meanwhile, My 2 headgasket breaches occurred after 12 years, yet within 3 months of each bank. Passenger between CYL 2&4...nice dry gasket burn-through. Driver bank between CYL1 and valley...wet, ugly engine-destroying antifreeze contamination. My cooling trick has been to replace the Waterneck with a Y-branch. Half-Inch Stud "tbdET/1xxMPH/1.xx 60foot/28"/3.54:1/10"/469 #48/Flat HYD/DualQ-Jets/Offyl/3xx0Lbs 11.00/123MPH/1.50 60foot/29.5"/4.10:1/10"/469 #48/FlatHYD/DualQuad/Wenzler/3250Lbs 12.00/112MPH/1.61 60foot/26"/3.31:1/10"/469 #48/FlatHYD/Q-Jet/Torker/3650Lbs 12.70/103MPH/1.71 60foot/28"/4.10:1/12"/469 #48/FlatHYD/Q-Jet/Torker/3950Lbs" |
If you simply hand drill with a regular 5/16" bit it is hard to keep the hole location accurate. You may want to predrill with a small bit first or use a split-point bit to keep the bit from wandering. Doing it in a drill press would be the best way. At least invest in a new bit.
http://fiedlerh.home.att.net/ |
What kind of temperature change are you actually reading when this modification is done correctly???...Robert http://forums.performanceyears.com/g...n_rolleyes.gif
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I may have been slighly unclear as to the procedure. First, I use a smaller bit to start the hole, then the larger one. A 3/8" hole may work even better. This modification improves water circulation in this hot area of the Pontiac. There are other things I do also to help but, I have done this to every engine I have put together along with friends in the last 15 or so years. Easily over 200,000 miles on this modification in all applications- street, strip, marine (boat), towing, stock car. Steve Barcak www.pontiacheaven.org
Real Pontiacs Only.......No corporate nonsense! |
First off, welcome aboard Steve.
I've actually cruised your web page in the past, and enjoy it. I'm getting ready to pull my existing heads, and replace them with higher flowing / compression heads. I like your suggestion, since my heads have been worked over pretty heavily, any additional cooling is a plus Let me make sure I'm reading your post correctly. I should be able to drill a new water passage in both my block and heads. I'm pretty good at figuring out exactly where the drilling needs to go from your description But do you by chance have any photo's of exactly where? |
.... a dull-looking masonry bit can be an eye-opener.
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I guess I don't understand as well as I thought I did.
I just finished comparing my #16 heads with the gaskets. Every available water passage in the gaskets coincide with the water passage holes in the heads. Is there a specific year that this would apply to? Granted I haven't pulled the existing heads off my 69 428 block yet. So maybe the difference is specific to the blocks? |
Half inch, I think the "Y" adaptor is a good idea as it promotes more even cooling on both side of the motor.
In my situation with what I have already developed, there are no further needs to improve as of now. What I do works well. The GTO actually will run at about thermostat temp on the freeway (75 mph) on a July 115 degree day with A/C on, with 4 people in the car and pulling my boat to Lake Havasu for hours. There are some other things I do too. Yes, the block and head will both need to be drilled, 4 holes altogether. How would I post a picture here? pics can be helpful when explaining something or, you could call or email me. 480-899-7873 mornings and early afternoons are best. Another thing, I have learned that 1972 and newer heads cool better, but, you all may already know that too. Steve www.pontiacheaven.org |
Steve, you can post a pic using the "post attachment" feature in the options section at the bottom of each reply screen. The pic size has to be small however.
http://kurtspontiac.homestead.com/files/bbaker.jpg |
Marty, Not all brands of head gaskets have the hole. I know the fel pros do. I've seen some that do not, try a fel pro gasket.
Brian, thanks for the info on pics. Steve |
Probably the longest time for a thread to be resurrected, but...
Steve, where's the pic? Thanks. |
there is a much more recent post with several pics and Im not sure but I think Steve put them on his website as well.
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You may find this helpful. http://www.pontiacsafari.com/EngineCooling/index.htm
You can see the "421" cooling mod existed long before the 421. (it was std in the early blocks thru 59) BTW look carefully at the block drillings of the 1960 block.(1st year of the "new" cooling scheme) They took precautions to ease cooling loads and insure cooling on the exhaust side of the head. They didnt want overheating problems. Suspect it created longer warm up times as the reason for opening up some holes again. With the water holes blocked just below the intake crossover on the deck you cut down on cooled water "shortcutting" from the front of block and right back out the crossover. |
Yep. When you order head gaskets from Cometic, just tell them you want the '421' mod and the hole will be in the gasket.
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was there not a article with picture,s some time ago in PY forums area?? Also showed where to drill the block deck surface area??
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Standard gaskets already have the hole you just use it for a template. "421" mod was actually in production motors long before the 421. The 55-59 reverse cool scheme had those holes. In 60 they went conventional cool. 60 blocks arent drilled quite the same as 55-59 or the later blocks either.
Check this link carefully. http://www.pontiacsafari.com/EngineCooling/index.htm BTW heres another cooling link you might find interesting... http://forums.maxperformanceinc.com/...d.php?t=583733 |
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Decided to bring this almost 20year old thread back to life here and NOT in the Race section, which has an older thread as well. Im not building a drag car here. Im just starting to do the math and work on a 1970 Firebird 400. This engine I hope to use in the Silver State Classic . This means roughly 100 mph, for roughly 100 miles in the Middle of Nevada. And I want the AC on..... With a suit and helmet and gloves, and a hot passenger, its a must for this rookie effort. Many cars run this at well over 200 mph in their bracket. SO, Before machine work gets done, I wanted to take advantage of Steve's knowledge and advice and make sure I run COOL. If I lived in AZ, Nevada, Calif, or Texas, or Florida etc, I would do this on every Poncho motor.
First is to block off the 3 coolant holes in the front, which forces the coolant to the rear of the block, where it can better cool and maintain a even temp throughout the block and up through the heads, especially the Middle exhaust area. Tools needed : 1. 3/8 drill 2. LETTER Drill Bit "R" This is specific to the tap and plug you need. Easy to find, but Not a home depot. A fastenal can get ya one, or ebay. 3. 1/8-27 NPT Pipe Tap. 4. 3/8 drive 12 POINT socket ( or a Tap handle that does 3/8 taps) 3/8 drive short ratchet. 5. Cutting oil 6. 1/8 NPT Pipe Plug ( Allen drive 6 required) The 3 plugged per side are NOT all uniform in size due to casting, rust, etc. Some drill easier than others. Use cutting oil and drill on Slow. Start the tap and then use oil and go back and forth with it Slowly. Some tap easier than others due to casting thickness and original size. I used my tap to the end of taping threads, so my plugs were below block. They are snug and tapered, they will Not move once they are finally installed. I will drill the much discussed ( racing section) center hole when I get a a couple high quality drill bits. https://forums.maxperformanceinc.com...2&d=1645941466 https://forums.maxperformanceinc.com...3&d=1645941477 https://forums.maxperformanceinc.com...4&d=1645941488 https://forums.maxperformanceinc.com...5&d=1645941500 https://forums.maxperformanceinc.com...6&d=1645941513 |
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more pics of this below. More when I get my drill bits for the center block and heads.
https://forums.maxperformanceinc.com...7&d=1645942104 https://forums.maxperformanceinc.com...8&d=1645942116 https://forums.maxperformanceinc.com...9&d=1645942126 https://forums.maxperformanceinc.com...0&d=1645942138 https://forums.maxperformanceinc.com...1&d=1645942147 |
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