I built a 400 with a 428 crank with 3" mains, Edelbrock heads from Kauffman ported to 320/260 Comp Cams 286R roller, Meizere water pump, Carillo rods, Wiseco pistons, Victor intake, Barry Grant 1050 Dominator, 1 3/4" headers. 3.90 gear, 12 bolt.
618 HP. Ran mid 10's, couldn't hook.
Weak point is the block. Some say yes, others no. Nickle content/hardness issue. I have never built or grenaded a latter (post 71) block, but I have heard stories. Would stick to no more than 500 at the flywheel for the 75, but I would make sure someone who knows how to build a Pontiac builds it.
It can be done, sure, but reliability and streetability is the question. You will need to make at least $2000 of suspension upgrades and at least $1000 in a good trans and convertor. Then you have a braking issue. After that, the rear end? You need a rear and differential (axles too) to withstand 500 HP. Add another $800 in wheels and rear tires for that 500 HP to make traction. Then you have another in the $500 aluminum radiator to cool the beast.
Yes, 500 HP is nice...618 HP was great until I snapped an axle, couldn't stop, overheated, was all over the road, split the transmission case. Yes, I planned on driving the existing components to failure, but that was stupid and foolish. The tow bills were $450 and the embarassment of a broken down 67 was as embarrasing as getting stood up on your wedding day. Not recommended, and definately not a boost to my ego.
The worst was fathers day, 1999. Driving to the track, I 96 by the Wixom Ford plant. An 80 year old lady gotmy attention during a backup in construction and said "your dripping". I was running 240 on the gauge.
Talk about being owned...
Si Vis Pacem Parabellum
1967 Starlight black PMD Engineering 400 Auto 1968 Alpine Blue 400 4 speed 1968 Verdoro Green 400 HO 4 speed 2013 1LE 2SS/RS Inferno Orange Camaro.
How about starting with a 455 block for more cubes? Mine just has aluminum E-heads, roller cam, stock crank, stock rods, runs on pump gas. My target was 500 hp.
Dyno'd at 490 HP at about 5200 rpm. The only thing holding it under 500 is the non-RPM Edlebrock intake manifold. I wanted my carb at stock height so I could run an aftermarket Ram Air setup.
While I have a 3.55 4-pinion nodular 8.2 rear which is pretty beefy and dual OEM traction bars (on a TH 400 car), I'm just never going to put slicks on it. Even if the drivetrain could handle it, I would probably twist the body
If you don't already have a copy of Jim Hands Pontiac engine book, get a copy.
2012 Mustang Boss 302 #1918, Competition Orange. FGF replacement 2006 Mustang V6 Pony, Vista Blue. Factory ordered. 2019 BMW X3 (Titled to the wife, but I'm always driving it for her. So I'm claiming it) Old projects, gone but not forgotten: 1967 FB 400, original CA car. After 22 years of work, trashed by the guy who was supposed to paint it. I had to sell it. 1980 Turbo Trans Am 1970 Mustang fastback, 351C 4Bbl, auto 1988 Mustang GT, 5 speed 1983 F-150 4x4, built 302 1994 Chevy K2500 HD 4x4, 454 TBI
Banshee's right. Been thru it myself. Once you get good traction, all the factory parts start breaking. It will twist the body and crack the the upper windshield pillars and w/shield itself. So figure frame connectors, HD u-joints, healthy trany, 4 pinion rear end with aftermarket axles to start with. The 75 block will handle 500, but must be done right. "Balanced" light wieght rods and pistons help. Power is in the cylinder heads, so get good performance ones to start with. It can be done with off the shelf parts.
We havent purchased Jim Hand's book yet but is on our list. Maybe we should aim a little lower on the HP. Our convertible may not handle that much even with frame upgrades.
You will sacrifice manners and streetability with 500 HP. You will likely need to run a minimum of 104 octane, maybe 100 at altitude.
IMO, stick to a well built ported aluminum head motor with 10.5 to 1 compression and a roller cam for pump gas. Should get you 375-400 at the flywheel.
Another IMO, The car will not be fun to drive. Vacuum will be minimal unless you add a can.
Unless you plan on racing the car, 500 hp is too much for a street cruiser without extensive mods. 400 hp is a little too much without modest mods.
I once did a little homework at the shop about 5 years ago.
Stock rebuild, stock heads, detuned for pump gas. All machine work done, pump gas 250-275 HP 9 to 1. Comp Cams valvetrain, SERDI cut, TP bore/hone, stock rods/ARP. balanced, assembled. Cost $2400-2800 with your core.
Stock rebuild advertised compression usually 330-350 hp (10.5 to 10.75) same cost, Just changed pistons (cc's) and cam. 96-100 octane.
Rebuild for street strip. 350-400 hp. changed cam to moderate roller, changed to E heads (stock) Add another $2200 for aluminum heads, but deduct $700 for the stock head rebuild cost. So actually add $1500 for total cost of roughly $5000.
Rebuild for strip, Ported E heads, girdles, 6000 series valves ($2800) Carillo rods ($750) Wiseco pistons ($850) 428 crank/machine ($500) gapless rings $190, CC pushrods $200. o- ringed block.
Engine cost $8300 total, turn key. 10 second motor.
Si Vis Pacem Parabellum
1967 Starlight black PMD Engineering 400 Auto 1968 Alpine Blue 400 4 speed 1968 Verdoro Green 400 HO 4 speed 2013 1LE 2SS/RS Inferno Orange Camaro.
We havent purchased Jim Hand's book yet but is on our list. Maybe we should aim a little lower on the HP. Our convertible may not handle that much even with frame upgrades.
Great question Doug. Jim Hands book is a must. As fas as the engine. Do it once. Dont wish you had spent another 500 or grand more. But on the flip side . You have to be happy with what you have. There is someone always with more $$$$$$$$$$. Read the combo packages in the back pg 120 to 133. Awesome info.
I have a pretty stock 400 with a little modification...probably 275-300 hp...its a convertible w X brace... I dont drag race it ,but drive it fairly fast 80-90 mph most everywhere...no need for more hp for me....I get to the places we go as fast or faster as the guys w more hp...plus I can use mid grade gas....
if I had too much hp, I`d probably get ticketed plus probably twist the h$ll out of the car
Our goal is an engine we can run on pump gas, reliable so we're not constantly tuning and has some get up and go when you stomp on it (would like to know we can smoke the tires). Our 75 rebuild just dosent have the HP we expected (maybe 200hp at best). Since were trying to do this car right, we feel we should spend a little more on the engine and get the HP a bird like this deserves. In hindsight we would have started with a better block. But at the time we didnt know a thing about engines (not that we do now either
just get a cam and heads...Banshee can tell you how to do it fairly inexpensively... I have a 72 400 , it had 7J2 heads, and I got some 5C , milled to to 88 cc, runs good...have whatever cam came in it...650 Holley ,and even 2.56 rear end...I can smoke the tire (right rear only...lol), I use pump gas, mid grade...
