Standard heads vs Stage 1 - Good data to share

Thought I would share some data with the masses on my recent head swap. While not a surprise, nor news to most here, it’s a little unusual in that it is a true apples to apples real life comparison of the value of fairly modest airflow improvements in the 455. Essentially the only thing changed was swapping the standard valve heads with freshened ported stage 1 iron heads.


The starting point was a ’71 455, bored .030, with stock bottom end, full groove mains, ’71 small valve heads with very minor cleanup done, 10:1 forged SpeedPro pistons, and an original KeneBell C118 cam. KB valve springs and pushrods and stock stamped steel rockers. Bear in mind, this thing is as old school as it gets, since I built it in 1984 when I was young, poor and much less wise. While never measured, guesstimate on CR was about 9.25:1 with the larger chamber ‘71 heads and felpro blue gaskets. Upgrades in the last 30 years were only in oiling and ignition and lots and lots of fine tuning with the 800 Quadrajet and ignition. So it now has a TA front cover, custom tuned Qjet, and MSD 6A with a billet distributor. Fuel delivery is an Aeromotive pump and regulator with a 3/8 tank pickup and ½ line to the motor. The race weight of the car was about 3850-3870 and the trans is a 11” switch pitch slightly reworked in front of a race prepped Kenne Bell TH400. Rearend is 3.73 12-bolt. Small MT Drag radials now but I have run almost every kind of tire including old M&H racemasters all about 27” tall. Traction has never been much of a problem. With this combo and decent air typical ¼ mile numbers would be 12.6’s at 104-106 mph. Air temps in the 70’s. One cold night it did go 12.49 at 109, but I think air temp was about 49 degrees!


I got a nice set of reconditioned, ported 1970 stage 1 heads from a board member last summer. Good numbers. At .500 lift / 28” water- intake flows 271, exhaust 192. Not huge, but definitely an improvement!

I did the swap over the winter, replaced the cam bearings with the new TA grooved bearings, but kept everything else on the motor exactly the same. Same carb tuning, same ignition curve. Everything. I did lighten the car with a set of Weld wheels and slightly lowered the rearend to improve suspension geometry. I run the HR sway bar in the rear and slightly raised adjustable top links from Art Morrison. Race weight now is 3840, per the scale at the track.


Finally got to the track last week. Once I fixed the issue of running out of fuel at half track (add more gas to the tank! Needs at least ½ tank now), with comparable air at about 70F, I pulled off a 12.02 at high 112 mph. Wow, was I surprised! Dropped 60’ from 1.79 to 1.73. Doing the math indicates +68HP at the wheels with just the head change and slight compression bump. On the right day, with enough fuel and good 60’, high 11’s are an easy goal, but I only ever wanted this car to go 12.0’s!! Life is good. Next step, install the Autogear M23 4 speed!

 

That's awesome! Should be a blast with a 4-speed too!

 

Pat glad these worked for you, thanks also for giving me the text update. Glad they ran well enough to give you a good surprise, normally surprises at the track come from the other end of the spectrum.

John Z did a great job on these heads and I loved them, I wish I could has kept them but just needed the funds to put the current project in play, but if you ever don't have a need for them let me know, maybe I can get them back.

If there is anything else I can help you with just ask. Till later enjoy the new found power.......

 

Awesome Results!
Did you use the same type head gasket and rocker arms?
any differences in combustion chamber size?

 

Same head gaskets = Felpro blue. Same rocker arms - stock steel. The 71 small valve heads have a significantly larger chamber than the '70 stage 1 heads. Don't know the volume.

 

Those heads had been cut to clean up, once when I first had them done, once during the freshen up b4 I sent them out. I think if I recall those heads were 68cc b4 this last freshen up, I don't know his much they cut off this last time. I know I slightly bent 1 exhaust valve when the stk connecting rod failed, so I replaced all of them b4 listing. Still have the other 15 valve.

 

The factory measured the difference between the untouched 70 455 small and large valve heads at 16 horsepower.

 

There is nice tid bit there

 

I remember that 16 HP figure. That figure didn't consider the higher lift cam and slightly ported heads on the OPs motor. And, his baseline used '71 heads with more chamber volume. He probably has headers too. But, I agree, 68 HP is an awfully high number with just the head change.

 

The stock difference is 360 versus 376 horsepower according to Dennis Manner, the Buick powertrain engineer that designed the 455.

 

Do you recall whether that was on a production engine or a blueprinted one? Didn't NHRA factor the Stage 1 to 400?

 

Well what I can tell you is these head's were run on top of my 464, my car is 3850 with me in it, on 9 inch tires we ran 11.0s and 10.90s. We ran 2 cams on these heads, a postons gs110 and custom comp cam with more lift and duration, near .570 lift and 250ish duration @ .050.

When we hurt the bottom end I had a bone at 430, had 30k or 40k, I didn't change rings, bearing, didn't touch the timing cover, the oil pan nothing......use felpro blue gaskets put these heads on, used our same ported sp1, same 950 prosystems carb with the same jetting, my same 2 1/8 tube ta headers, same trans, same 4.10 gears. Cam was a small crower grind very similar the the gsca hem killer.......that motor ran low 11.30/high 11.20s this is a no spray car. So I fully believe that with some tinker time the OP will find another tenth or more.

When I first was running in low 13s upper 12s I put on a set weld rims and pulled my stk steel wheels off, I gained almost nothing. I was positive that the lighter weight wheels would had got me a tenth or something.......nope

 

I heard D. Manner say this in person a couple of times. This was the Buick factory differential between the two engine variants tested by the same dyno under the same conditions. So, for purposes of the 16 hp differential, it would not matter whether they were both blue printed or production. I assumed that they were both production engines, especially since you see so much speculation on the internet that 70 stage1 production engines made over 400 horsepower. Today we know from a lot of testing that production engines never seem to make anywhere near 510 ft lbs of torque.

[Please note that above I originally mistakenly posted 350 versus 376 horsepower when I meant to post 360 versus 376 hp for the 16 hp differential. I have since corrected this above.]

 

Whoever ported those heads knew what he was doing. Goes to show that porting really turns on all the other mods you have done.

 

I have a set of boh that would be good candidates...Just not the time to do it though

 

John Zaruka from parma ohio did the port work, we'll he lived in Parma then don't know if he still does

 

Sorry john, never could spell your last name right