[Formulajones]

For 70 ramairIII, Sit back and enjoy

http://www.youtube.com/watch?v=KWR0I...yer_detailpage

http://www.youtube.com/watch?v=89Ltz...yer_detailpage

http://www.youtube.com/watch?feature...&v=qQ6oBEnthg4

[tjtjwdad]

Originally Posted by Formulajones

For 70 ramairIII, Sit back and enjoy

http://www.youtube.com/watch?v=KWR0I...yer_detailpage

http://www.youtube.com/watch?v=89Ltz...yer_detailpage

http://www.youtube.com/watch?feature...&v=qQ6oBEnthg4

Happiness is watching a Pontiac 400 outrun the legends.

[Formulajones]

Here I found an old glossy running my car. I remember this race and the car in the other lane, but don't remember the year exactly.
The 97 bird is a procharged LT1 that should be making twice the power I am. My stocker put a hurt on him The firts 60 foot was everything, this is about mid track trying to run me down, he didn't get it done. The race was at Kil-Kare back when the TA Nats used to have drag racing and made it worthwhile going.. Several people enjoyed watching my bird run and one of them shot this photo. Somehow they got in touch with other people that knew me and a few weeks later this photo was in my mailbox. I thought that was pretty cool. Enjoy, photobucket won't keep it up for long....

[johnta1]

Great pic!

But they let you run with window down?

[Formulajones]

Normally no, I had forgotten to roll it up and I wasn't reminded. I realized it after the green. I was in the process as I went down track when I had a free hand.

[2manyT/A'S]

Originally Posted by Formulajones

Here I found an old glossy running my car. I remember this race and the car in the other lane, but don't remember the year exactly.
The 97 bird is a procharged LT1 that should be making twice the power I am. My stocker put a hurt on him The firts 60 foot was everything, this is about mid track trying to run me down, he didn't get it done. The race was at Kil-Kare back when the TA Nats used to have drag racing and made it worthwhile going.. Several people enjoyed watching my bird run and one of them shot this photo. Somehow they got in touch with other people that knew me and a few weeks later this photo was in my mailbox. I thought that was pretty cool. Enjoy, photobucket won't keep it up for long....

Alright.....give us the lowdown....

[Formulajones]

I'll let out some tricks I did. I didn't however exploit the rules to the full extent because this was still primarily a street driven car (and still is).

I didn't go with the allowable 1.5 compression bump or the max allowable bore either, and elected to keep this a pump gas motor. So it's right on the edge, although finicky, so I mix 3-4 gallons of race gas on race day to be safe. Pump gas on the street.

.030 over with a forged TRW flat top that is NHRA legal (hence legal in pure stock as well per rules) and assentially isn't any real difference from the factory flat tops. Block is zero decked. Standard ring package used. So again I didn't exploit the rules here which actually allow the much thinner (ie: less friction and weight) 1/16" ring package if you wish. That's how most aftermarket pistons come nowadays anway.
I wanted durability and long lasting, that was the thought process, so the standard "thick" ring package was used.

Heads are bone stock 1970 ram air III castings (no porting allowed) They were milled .010 to ensure flatness and a good seal. Afterwards they CC'd at 74. Stock OEM valves used, nothing necked down for flow or anything fancy like that. All new seats and guides, springs etc...Only deviation from stock is a nice multiangle valve job, which is allowed per rules. Compression came in at 10:1.

Camshaft is stock melling blueprint ram air III. Melling at the time had more accurate lobe profiles and was the favorite among the pontiac guys years ago. Only deviation in the valvetrain is BBC rocker studs (larger diameter for more stability, not that important however with stock spring pressures) but more importantly I gain complete adjustability and can set preload. Camshaft is installed advanced to increase cylinder pressure and give me a slight boost in low end torque (you'll see why in a minute)
Intake, carb, distributor, manifolds, all stock correct casting numbers.

Trans and rear have never been out of the car. 400 turbo, stock 40+ year old everything and never rebuilt. Stock 12 bolt and 3.31 gears. More gear allowed but again, primarily a street car so I gave up some ET, Car could use 3.73's. Cam advanced for a little more grunt to get the car moving with the mild gear.
All stock springs and shocks (oil filled shocks on the front for more movement) and front sway bar frame mounts spaced down slightly so as not to crush the bar with the bushings to allow the bar to move freely, however still hooked up per rules. Pinion angle shimmed and set to 4*, to give zero angle under load for best transfer of HP. All stock original 40 year old suspension bushings that are in fine shape but "broken in ". That's really it for suspension tricks and as you can see from the pics, the car is effective at transfering weight to the wheels and hooks up nicely, a breeze to drive on stock rubber.
Exhaust is the allowable 2 1/2 inch setup with a stock style transverse muffler as the rules state.
Lots of tuning on dyno with a wideband and tweaking at the track, makes 301/355 at the rear wheels.

I gave up HP on the engine build for streetability, and didn't exploit many tricks. Engine built 16+ years ago and still running as the day it was built some 50,000 miles later. Not raced much in the last several years however.

[Formulabruce]

Originally Posted by Formulajones

I didn't go with the allowable 1.5 compression bump

Block is zero decked.

Heads are bone stock 1970 ram air III castings (no porting allowed) They were milled .010 to ensure flatness and a good seal. Afterwards they CC'd at 74. Compression came in at 10:1.
Camshaft is installed advanced to increase cylinder pressure and give me a slight boost in low end torque (you'll see why in a minute)

Breaking this down a bit....having done this same thing before.... Don't take offense, just trying to justify your results..
1. Seems the CR did get bumped.. which IS logical in this build.
2. Decking the block , Read below a bit from Jim hand on how Both decking and lowering timing because of it, can and does change the CR.
3. Heads. Stock heads are 72 cc, how does one slice off 10K and get 74 cc?
4. Advancing cam to "increase cylinder pressure" >> Fact>> Does Increase the CR....
Im NOT being critical, just stating that what you did do had a huge effect on performance which deviated alot from stock. ( I do like it, I did it, and I didnt like the CR at "dynamic" of 10.5) but I wasnt drag racing it much.
Read some of Jim Hands comments on block decking and its effects...
Quote >>Jim Hand "Deck Height or Deck Clearance:

This most important step consists of measuring the distance from the assembled piston tops to the surface of the block deck (deck clearance), and milling as necessary. The general feeling is that the total quench or squish distance should be about .040". The quench distance is the compressed thickness of the head gasket plus the deck clearance. As most of our Pontiac head gaskets compress to about .042", that means we want about 0 deck clearance. The quench area is the flat part of the piston that would contact a similar part of the head if you had .000 assembled quench height. In a running engine, the .040 quench height decreases to a close collision between the piston and the cylinder head. The shock wave from the near collision drives air at high velocity through the combustion chamber. This movement tends to cool hot spots, averages the chamber temperature, reduces detonation and increases power. The shock wave also provides better fuel/air mixing, and this allows the fuel to ignite better and burn faster. A faster burning fuel charge means less timing is required for optimum power output. An example of this--after running my 462 for years with a factory deck height of about .020, we set the deck to 0. There were no other significant changes to the engine (new rings and bearings, but same cam, heads, intake and exhaust systems). The optimum timing setting prior to the change was 34 degrees - that provided the fastest MPH and quickest ET. After the change to 0 deck, the optimum timing using the same Amoco gas changed to only 30 degrees total mechanical. Not only did the lowering the deck RAISE THE CR by several tenths of a point, but by retarding the timing 4 degrees, we were later able to INCREASE the CR even higher due to the optimum lower timing setting. " END Quote<<

[Formulajones]

Originally Posted by Formulabruce

Breaking this down a bit....having done this same thing before.... Don't take offense, just trying to justify your results..
1. Seems the CR did get bumped.. which IS logical in this build.
2. Decking the block , Read below a bit from Jim hand on how Both decking and lowering timing because of it, can and does change the CR.
3. Heads. Stock heads are 72 cc, how does one slice off 10K and get 74 cc?
4. Advancing cam to "increase cylinder pressure" >> Fact>> Does Increase the CR....
Im NOT being critical, just stating that what you did do had a huge effect on performance which deviated alot from stock. ( I do like it, I did it, and I didnt like the CR at "dynamic" of 10.5) but I wasnt drag racing it much.
Read some of Jim Hands comments on block decking and its effects...
Quote >>Jim Hand "Deck Height or Deck Clearance:

This most important step consists of measuring the distance from the assembled piston tops to the surface of the block deck (deck clearance), and milling as necessary. The general feeling is that the total quench or squish distance should be about .040". The quench distance is the compressed thickness of the head gasket plus the deck clearance. As most of our Pontiac head gaskets compress to about .042", that means we want about 0 deck clearance. The quench area is the flat part of the piston that would contact a similar part of the head if you had .000 assembled quench height. In a running engine, the .040 quench height decreases to a close collision between the piston and the cylinder head. The shock wave from the near collision drives air at high velocity through the combustion chamber. This movement tends to cool hot spots, averages the chamber temperature, reduces detonation and increases power. The shock wave also provides better fuel/air mixing, and this allows the fuel to ignite better and burn faster. A faster burning fuel charge means less timing is required for optimum power output. An example of this--after running my 462 for years with a factory deck height of about .020, we set the deck to 0. There were no other significant changes to the engine (new rings and bearings, but same cam, heads, intake and exhaust systems). The optimum timing setting prior to the change was 34 degrees - that provided the fastest MPH and quickest ET. After the change to 0 deck, the optimum timing using the same Amoco gas changed to only 30 degrees total mechanical. Not only did the lowering the deck RAISE THE CR by several tenths of a point, but by retarding the timing 4 degrees, we were later able to INCREASE the CR even higher due to the optimum lower timing setting. " END Quote<<

Actually, my compression ratio is lower than "advertised", which is key when looking at the rules. Since these engines never actually had their "advertised" compression ratios in reality, which I explained above. That's what I was trying to get accross. I could have built a 12.25:1 engine if I wanted to, but I chose to keep it pump gas friendly. I could have done all the tricks we are talking about starting with a 12.25:1 engine and been within the rules. I gave up about 8-10% of potential HP with this engine, but,,,I'm not running $8 a gallon gas either.


Zero decking the block, which I do on all my builds, does raise compression, however my main reason is for tighter quench, which as you read Jim Hand touched on. That tight quench promotes swirl and mixture in the chamber which fights detonation. Again detonation is my main concern since this was a pump gas motor.


Not all stock heads will CC at 72. I've been over this before in past posts. They vary give or take a few CC's. 72 is just a number that GM tossed out but I've found with many castings that this number is not set in stone. Mine actually CC'd at 76 after new seats and valve job done, with an extended tip spark plug. Valves were not sunk (that hurts flow ) Then they were milled .010 and CC'd again, came in right at 74CC. This actually worked out in my favor however to keep my compression ratio down a tad, because the overbore and deck bumped it slightly.


When talking compression we have to talk about dynamic and static. Advancing my camshaft didn't increase the static (or advertised) compression ratio. What advancing the cam does is change the dynamic's of the engine, or increasing dynamic compresson (creating more cylinder pressure) by closing the intake valve sooner. It's not exactly the same thing but they do affect how the engine runs. I'm more or less changing the power band of the engine to put it in simple terms. It's just a tuning tool.