My GS350 now has a 70 SF coded 455 +.40 overbore with forged 10:1 TA1621-A pistons and a few other upgrades. The stock 70 iron heads were refreshed to like new and I added a TA284-88H cam with an SP1 intake. All of the oiling mods were done to the block as well as timing chain upgrade and TA headers into true dual 3” exhaust completes the package. All of the other rotating assembly parts were refurbished or replaced with the build. I’ll add that the stock rod size remains. I mated this to a 2004R transmission with a 9.5” lockup torque converter that flashes to 3k and have an 8.5” posi rear with 3.73 gears and a 28” tire. Holley 850 DP carb and HEI distributor are up top and overall, the engine runs fine. The issue is I thought I’d be satisfied with the (engine shop quoted) 425HP/550TQ but I think I want to go further. At WOT, the car pulls hard from off idle all the way through but falls flat at about 5000rpm. I have been considering purchasing TA SE stg1 aluminum heads, but have no experience with this. Their site claims ~50hp bump in head swap alone out of the box. Does this seem right? My desire is to be able to rev higher and continue to make power through 5500-6000rpm. Will this head swap achieve this without swapping my cam? Note:I have stock rockers and adjustable pushrods for my valvetrain duty. Are roller rockers necessary? Or should I just slap some aluminum heads on and run it like this. Any guidance is appreciated. cheers friends, Duke
Duke, How is your fuel delivery? Make sure you aren't losing fuel pressure at higher RPM. That would make it stop pulling. The answer is, yes, the aluminum heads will absolutely give you a big bump in performance without changing anything else. The only thing you should do is bump your compression up. You can do that by milling the TA heads .040" as I had Greg Gessler do with my TA heads. Do you know your SCR?
I would think if you went that route you would want more cam to fully use the extra flow the heads have at higher lift number . More lift will be pushing the factory rocker arms
The engine I bought my GS with was a 462 with untouched Stage1 heads, a KB 118 cam, MT headers with 2 1/2" exhaust. Switch pitch transmission with 3.42 gears. Best was 13.22@ 101 MPH. SCR was 9.4:1 Added TA heads, and went right into the mid 12's. Eventually went a best of 12.20 @ 110.65 MPH with the Q-Jet and SP1 intake, and 12.11 @ 111.98 MPH with the 1000DP carburetor.
better heads make more power. But if you want to rev more then you need a cam change. TA 413 makes a BBB think it is a small block chevy
Interesting, any idea how much fuel gets burned in 1/4 mile at 450hp? Just seems like the bowls would have enough for at least one pass even with a marginal pump. I have heard of the large quantity the Top Fuels dragster burn however.
What bowls? The itty bitty fuel bowl in a Q-jet? Even the Holley fuel bowls don't have enough fuel for a 1/4 mile pass with a stock engine.
I always try to race w a minimum of a 1/2 tank of gas. You sound like you may have a fuel issue. What is your total timing and when is it in by. What valve springs used and what pressure are they set at. I’d fix what I have before investing in new heads. You appear to have a nice street combo. With potential to very low 12s depending on where you are.
I’m currently overseas with work, so I don’t have access to all my files to confirm but if I remember correctly the SCR was 9.8:1. Pistons were ~.30 in the hole after the clean up cut was accomplished at the machine shop. Transparency, I could be off here but I’m 90% % sure I’m close if not spot on. I don’t have a fuel pressure gauge viewable in the car to monitor while driving, but I never suspected a fuel starvation issue. It’s worth looking at for sure and I’ll will get that confirmation prior to throwing parts at it. The stage 1 fuel pump and eccentric cam are new for this build and I expect them to be serviceable. I will definitely look at my bowls and make sure they are set right with the proper amount of fuel viewable in the glass window, etc. I like the thought of the added power aluminum heads bring to the table, and kicked around a cam swap just to change things up a bit. I thought the 413 was a good choice but was concerned about stock rocker arm fatigue with the added lift. Also considered the 290-94H. I’m a fan of the lope for sure.
valve springs are the TA 1435 stage 1 but I don’t know the spring pressure settings. I’ll have to get my prettier half to email my engine build sheet when able. timing is 34* all in by 2400rpm based off “the wizards” guidance in the power timing thread. Again, I need to get under the hood to confirm that, as it’s been a while since I set it. No way I can talk her on to how to confirm that for me from Afghanistan. Lol! I’ll be happy to get the dang build sheet emailed!
At an extreme, the car will nose over, but if you are borderline, it might feel like it doesn't pull as hard.
In general. One of the things I noticed the most when I swapped on the aluminum heads were how hard it pulled all through the RPM range. Night and day.
Duke, get home safe. Most importantly. why it noses over would need to be looked into. Lot of good info here. But I would want to know why it noses over before spending close to $3000. The heads will pick you up. But you need a baseline to work from. And there is a repair needed. Maybe tach is off even? When you get home. Put some laps on it and start there. Enjoy it. Sounds like a fun combo.
