425/409ER
Well Known Member
Sounds like a engine that wants more compression.
Now, that being said, try smaller rpm shift changes.
You are right about needing more compression, but when I short shifting the engine the ET slows down.
Sounds like a engine that wants more compression.
Now, that being said, try smaller rpm shift changes.
Sounds like a torque engine that needs taller gears.
Is this a hydraulic cam?
How tight of preload on the lifters?
Can't you loosen them and get more RPM?
I bet you would be surprised what some bigger heads would do.
Many of the Pontiac guys have gone just as fast(torque type motors like this one) dropping the ratio. Heck one guy with a fairly street friendly Trans Am is deep 11s with 3.08s!
That said I run a Hoposier 30/9 radial slick(the "short" 29.5) on my Trans Am so I did not have to pull the 4.11s when I went to the 455 from a 400.
Interesting. I'm building a drag car using a 1990 Firebird or third gen body. Got the roll bar in it already from previous owner, but I need to make a couple mods to make it easier to get in and out of the car. Interior is gutted, no heat or AC. Going to run a built 350 for the first season then spray it with a 150 HP shot for the second season if I can get a rear end swap. Eventually want to drop a built Pontiac 455 in it or maybe get the aluminum AII pontiac block. Current rear end is the 10 bolt 7.5" rear with posi and 4.56 gears, those start to break at around 450 Ft lbs of torque. Transmission is a TH 350 with 3500 stall converter. Car is not going to like the highway at all with the 4.56, but when I swap the rear gears I'm thinking 3.73 with a 700R4.
What is your goal for the car?, a 350 is a great power plant for a 3rd gen. Putting a Pontiac engine can be done but it's a lot of work and nobody makes headers for that body. Using a 700r4 with 3.73 gears would be a way better choice that 4.56's on the street.
Initially get the car reliably in the low 10's. I don't want to mess with all the NHRA tech inspections you get into when you get under 10 seconds. After I get there with the SBC I want to see if I can do it with a more unique motor like the Pontiac motor all naturally aspirated. All this while keeping the car street legal in the loosest of terms. The lights are going to work, but the interior will be gutted except for driver and front passenger seat. A gauge package and roll bar. No extra comforts in the car like AC or heat. I will probably have to baby it from a start to keep from squealing tires at every stop sign and stop light. I would love to get it reliable enough to maybe do a power tour or something like it in the future.
Actually I found a company that makes custom motor mounts to put a poncho in the third gens using the stock SBC V8 frame towers. They keep the poncho lower in the body to alleviate hood clearance issues. The same company also makes a special set of headers for the conversion.
That's pretty cool you can get headers and mounts for the Pontiac engine, makes the swap a whole bunch easier. To go low 10's will not be too hard with the 350 if you are going to spray it. My 9 to 1 358 went 10.04@136 with a 200 shot a few years ago and it was nothing fancy. You will most likely bust that 7.5 with a ton of power so that would be the thing I would get before doing and NOS shots. One thing that will keep it going for a little while is not to make the transmission shift real hard.