FAQ |
Members List |
Social Groups |
Calendar |
Search |
Today's Posts |
#1
|
||||
|
||||
Waking up a '75 TA 400 with a budget of 2k
Car already has true duals no cats. Everything else is stock.
I think it's only 7.6:1 compression to ratio. I know it is a 557 block. I think 3:23 rear gears, not positive. Cam, Carb rebuild, headers, different iron heads?? 185 hp now. 2000. Budget. |
#2
|
|||
|
|||
Personally if car is going to be a driver and currently runs decent, I would put my effort into tuning the ignition, carb dialed in, brakes being perfect and spend the rest on gas driving it and enjoying it. Agree it’s fun to enjoy more power but I enjoy reliability and efficiency while driving it all the time
|
#3
|
|||
|
|||
Not sure if those cars had retarded cams. Maybe a timing set.
__________________
"At no time did we exceed 175 mph.” Dan Gurney's truthful response to his and Brock Yate's winning of the first ever Cannonball Baker Sea-to-Shining Sea... Still have my 1st Firebird 7th Firebird 57 Starchief |
#4
|
||||
|
||||
Stick or automatic?
__________________
1964 Tempest Coupe LS3/4L70E/3.42 1964 Le Mans Convertible 421 HO/TH350/2.56 2002 WS6 Convertible LS1/4L60E/3.23 |
#5
|
||||
|
||||
|
#6
|
|||
|
|||
I went from a 9.1 cr 48 headed ping crazy engine to a 7.7 cr 6x4 headed no ping engine. I found it more enjoyable to drive. Even with a bad cylinder it had more power than the run of the mill dd's today. Has a cam close to but not quite a 068 or Summit 2801. Had an rpm with 750 vac. Now with new pistons at 8.2 cr and a modified stock intake with Qjet both done as per Cliff. From what I've read here, other than the compression being a bit low, that seems to be close to the go to set up for a good daily street engine.
__________________
Frank M. 75 Firebird 68 Firebird 400 RAIII 66 Chevy II 461 Pontiac in AZ Last edited by tooski; 02-05-2024 at 12:28 AM. |
#7
|
||||
|
||||
I would swap on a fresh set of 6X-4 heads to bump the compression up by a point or so. Mill them as much as .030” but no more so the intake still fits. Keep the stock intake.
Swap in the Summit 2801 cam and a good quality lifter set, Johnson Hylift. Make sure the heads have new springs that match the cam. A good timing chain set that’s the factory link style, available from NAPA I’m pretty sure. Find out for sure what gears you have before settling on a cam. If you have 3.08 gears I’d suggest toning down the cam to the 2800. Have the distributor reworked by a good shop that can put a performance curve in it. Carb reworked with the proper jets and rods and of course a high quality rebuild kit from Cliff. If it’s in need of baseplate bushings have that done. I would skip the headers but upgrade to 2-1/2” all the way to the mufflers if it’s not already. Make sure your mufflers aren’t restrictive. The second-Gen T/As have poor ground clearance already without making matters worse by running headers.
__________________
1964 Tempest Coupe LS3/4L70E/3.42 1964 Le Mans Convertible 421 HO/TH350/2.56 2002 WS6 Convertible LS1/4L60E/3.23 |
The Following User Says Thank You to b-man For This Useful Post: | ||
#8
|
||||
|
||||
If it's a 4 speed car it likely has 3.23 gears, good compromise gear. The compression ratio is 7.8 to 1, and it is lowered by the 45 degree bevel cut on the outside edge of the pistons.
If you wanted to swap to 350 heads it would be easier to get smaller combustion chambers, rather than changing pistons, in the low compression Pontiacs of the mid 70 raising compression 1 full point is only going to gain maybe 10 HP. That's a lot of money/time/effort for 10 HP. There are easier gains to be made with cam change to something close to the 068 cam, and headers, a reworked Q jet, and a good timing curve into the distributor. Basic hot rod techniques that will keep you within you 2K limit. The added efficiency will also gain fuel mileage, and smiles per gallon. FWIW I had my own garage during the late 70s and early 80s, I used these techniques all the time on customer cars, many were the smog era T/As. For those of you that werent around there were only 2 choices of gasoline at the time, 87 unleaded, and 87 regular leaded, so raising compression was a waste of time, you'd just get detonation with the crap fuels we had available at the time. I'm fully aware that there are premium fuels now that we didn't have back then, but 3% gain in power, for one full ratio of compression on a 300 HP engine, is 9 HP, big deal. Marginal gains, for a rather hefty investment. I did try to run more compression, and was rewarded with broken pistons, and rings. I just resigned myself to keeping the compression low, and making the engines more efficient. Gaining efficiency with low restriction exhaust, richen up the carb slightly, and bring the timing in at a good rate. Mild cams that were efficient, and the cars would respond very well to these modifications. You don't need a cam that will rattle the windows when you're running relatively low compression, under camming is the key so you don't bleed off compression with overlap at street RPM. An H pipe connecting the head pipes in the vicinity of the rear of the transmission will also increase low end, and mid range on a low compression street car. I know there will be a bunch of naysayers, but headers will help much more than RA exhaust manifolds in this type of an engine. This was my recipe for the TAs of that era, I hope it is of some help to you. |
#9
|
||||
|
||||
Start off with a simple 40 minute long change that cost you nothing!
Open up the rear of your shaker scoop
__________________
Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs! And he was not talking about 1/8 or 1/4 mile ETs! 1) 1940s 100% silver 4 cup tea server set. Two dry rotted 14 x 10 Micky Thompson slicks. 1) un-mailed in gift coupon from a 1972 box of corn flakes. Two pairs of brown leather flip flops, never seen more then 2 mph. Education is what your left with once you forget things! |
#10
|
|||
|
|||
Raising just compression will provide more torque from idle to redline increasing efficiency everywhere
Raising just size of camshaft will soften lower RPM with rise in power mid / top therefore decresing efficiency at low RPMs on a dyno graph that raising the curve or tilting the curve ideally for max fun you want to do both but if limited raising the entire curve is preferable
__________________
If your not at the table you're on the menu A man who falls for everything stands for nothing. |
#11
|
||||
|
||||
I forgot to mention I do have a set of 72 350 2v heads, 7k3 heads, and 62 heads .
|
#12
|
||||
|
||||
Then have your 62 heads rebuilt top to bottom and run a 068 cam or better yet a high lift version of it.
You want to get the lift up to .470” to .490”. Then re-jet your carb .
__________________
Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs! And he was not talking about 1/8 or 1/4 mile ETs! 1) 1940s 100% silver 4 cup tea server set. Two dry rotted 14 x 10 Micky Thompson slicks. 1) un-mailed in gift coupon from a 1972 box of corn flakes. Two pairs of brown leather flip flops, never seen more then 2 mph. Education is what your left with once you forget things! |
The Following User Says Thank You to steve25 For This Useful Post: | ||
#13
|
||||
|
||||
Quote:
https://forums.maxperformanceinc.com...d.php?t=855368 Stan
__________________
Stan Weiss/World Wide Enterprises Offering Performance Software Since 1987 http://www.magneticlynx.com/carfor/carfor.htm David Vizard & Stan Weiss' IOP / Flow / Induction Optimization - Cam Selection Software http://www.magneticlynx.com/DV Download FREE 14 Trial IOP / Flow Software http://www.magneticlynx.com/DV/Flow_..._Day_Trial.php Pontiac Pump Gas List http://www.magneticlynx.com/carfor/pont_gas.htm Using PMD Block and Heads List http://www.magneticlynx.com/carfor/pont_pmd.htm |
The Following User Says Thank You to Stan Weiss For This Useful Post: | ||
#14
|
||||
|
||||
Quote:
The 6X-4 was a 350 head, on the smaller bore 350 engine (with the specific 350 pistons) those engines made 7.6:1; When the 6X-4 was placed on a 400 engine, you would see more compression. IIRC the 77-79 6X-4, with those multi-relief (ect) slugs, the compression was a smidge above 8.0:1; If your engine had better slugs, you had a little more than that yet. Quote:
The less valuable 7K3 combine large valves with 8.2:1 (with the good earlier slugs) - I believe that they are the same combustion chamber size as the 6X-4. I believe that the #62 heads will have an exhaust cross-over mismatch to your factory intake - so if you run those, block the cross over - that's not too hard to do. The 1975 5C-7 or 8 have the same combustion chamber size as the 6X-8 - which is larger than the 6X-4. Honestly, I'd look at the heads you have, and which ever ones look better, I'd pop them on - unless they obviously need a rebuild; A head rebuild could break your bank right there. I used to run heads as pulled off all the time with no issues. According to my Pete McCarthy book, the 1975-400/mt engine still received the 067 cam - and that's a decent cam, so I'd leave it alone, unless you have your heart set on a cam swap.
__________________
1970 Formula 400 Carousel Red paint on Black standard interior A no-engine, no-transmission, no-wheel option car. Quite likely one of few '70 Muncie three speed Formula 400's left. 1991 Grand Am: 14.4 @ 93.7mph (DA corrected) (retired DD, stock appearing) 2009 Cobalt SS: 13.9 @ 103mph (current DD; makes something north of 300hp & 350ft/lbs) Last edited by unruhjonny; 02-05-2024 at 11:49 AM. Reason: typo and missing info |
#15
|
||||
|
||||
Quote:
|
#16
|
||||
|
||||
Id probably be happy with 275 hp. Sounds doable on a budget.
|
#17
|
|||
|
|||
I had a 79 400 spare engine I used when my 455 self sestructed. It had 7.5 CR. I used a Holley Performer with the stock Q Jet, Cheap headers, Summit 2800. It ran really great and used 87 octane gas.
__________________
1979 Trans Am WS-6 .030 455 zero decked flat pistons 96 heads with SS valves 041 cam with Rhoads lifters 1.65 rockers RPM rods 800 Cliffs Q Jet on Holley Street Dominator ST-10 4 speed (3.42 first) w 2.73 rear gear __________________________________________________ _______________________________ 469th TFS Korat Thailand 1968-69 F-4E Muzzle 2 |
#18
|
||||
|
||||
__________________
1964 Tempest Coupe LS3/4L70E/3.42 1964 Le Mans Convertible 421 HO/TH350/2.56 2002 WS6 Convertible LS1/4L60E/3.23 |
#19
|
|||
|
|||
That's a great 400 build that I never saw before B-man! Love it!
Thanks for sharing it! Dennis |
The Following User Says Thank You to SD455DJ For This Useful Post: | ||
#20
|
||||
|
||||
Quote:
371 hp from a stockish W72 with basically just a bump in compression (unless I missed something). That's awesome. Although that sounded like a fairly meticulous build (not that yours wasn't) so maybe it's the little things that add up. Anyway, it's cool to see that you can pep those things up without going crazy. If only I knew that back in the day...
__________________
70 TA, 467 cid IAII, Edelbrock D-port heads, 9.94:1, Butler HR 236/242 @ .050, 520/540 lift, 112 LSA, Q-jet, TKX (2.87 1st/.81 OD), 3.31 rear https://youtube.com/shorts/gG15nb4FWeo?feature=share |
Reply |
|
|