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I just got myself a ZZ4 that is practically new, before installing it I want to increase the power to around 400-450hp and same in torque.
I would also look on getting the Fitech EFI on it at some later stage
The problem is that I have no clue about heads, cams and what carb to get so can somebody help me on this
The car is a '75 with AT and I will need good vacuum for my power brakes.
Thanks for any help
Without an appropriate set of lower rear gears any engine upgrades you plan to make will be a waste of time and money. The high horsepower engines achieve that high horsepower at a higher rpm and that's why lower rear gears are necessary.
I just got myself a ZZ4 that is practically new, before installing it I want to increase the power to around 400-450hp and same in torque.
I would also look on getting the Fitech EFI on it at some later stage
The problem is that I have no clue about heads, cams and what carb to get so can somebody help me on this
The car is a '75 with AT and I will need good vacuum for my power brakes.
Thanks for any help
To leverage real power out of the ZZ4, the heads have to go. Unfortunately, the heads they use have pretty tight combustion chambers and most of the good aftermarket stuff is looser - meaning your compression ratio will drop.
AFR 195s and a mild roller cam (high 210s low 220s) will get you to 450 hp as long as you have decent compression ratio. It will also make good torque.
Gearing does help with forward acceleration, but I've been in plenty of tall geared cars that are quite fast. A lot of faster cars use VERY tall overall gearing to avoid shifts in the q-mile.
Thanks for the info, well as a matter of fact I have the rear end open and am considering changing the gears to 3.55 or 3.73 for now to use with the TH400.
Later I am going to put a 200r4 under it, when the funds are back up :-)
Thanks for the info, well as a matter of fact I have the rear end open and am considering changing the gears to 3.55 or 3.73 for now to use with the TH400.
Later I am going to put a 200r4 under it, when the funds are back up :-)
A TH700 has a very fast first gear, with a 3.73 that will give you 11.2:1 in first gear. A good street car, is 10:1
Plus the huge drop going from 1th to 2th gear (43% drop) will give you "slow" 2th gear/huge drop in RPM.
A TH2004R with a 3.73 will give you 10.1:1 and the gear "layout" is better going up the gears compared with TH700
For me, the TH2004R with 3.73 is the best solution. Also because it is a easy install, compared with TH700
You can obtain a sound running engine even using the factory heads on the ZZ4. Yes, you can obtain more power using AFR's or other aftermarket heads but its going to cost you. I purchased my ZZ4 back in 1998 and modified it back 2003 on a limited budget, so I can't give you every detail about my build but I'll do my best. Below is a chassis dyne run showing rear wheel horsepower and torque, so you have to ratio it up to compare to your 400HP number. Depending on what ratio you use for a manual transmission I figure I'm somewhere between 385-400 net HP.
List of modifications:
Lightly ported cylinder heads to remove casting flash, bumps, smooth down the walls, and thin down the area around the valve guide. Nothing real aggressive, didn't increase volume, didn't even port match the intake, just got rid of the obvious flow restrictions.
GM's LT4 "hot cam" (~ 0.545" lift), but didn't buy the whole kit
MANLEY 221423-16 NEXTEK valve springs for LT4 - Single Spring without Damper, Ovate Wire, 1.255" Outer Diameter, .830" Inner Diameter, Seat Pressure 115 @ 1.750, Open Pressure 350 @ 1.175, Coil Bind 1.100"
Manley 23634-16 Titanium Valve Spring Retainers, 7 Degree, 1.255 in. Outside Diameter, .830 in. Inside Diameter
I'm sure I'm forgetting a few things but that is most of it. You'll have to measure the installed spring height & shim them to fit correctly. Also, you will need to measure the correct push rod length, and buy the correct length pushrods. I think I ended up with standard length push rods, but I'm not sure anymore and can't find the part number I used.
If you don't feel comfortable installing custom hardware onto your existing heads, then probably go the AFR route as mentioned earlier.
One more thing, since you are running an automatic transmission, you'll need to upgrade the torque converter with a higher stall to match the powerband of the new engine configuration.
Thanks for the info, well as a matter of fact I have the rear end open and am considering changing the gears to 3.55 or 3.73 for now to use with the TH400.
Later I am going to put a 200r4 under it, when the funds are back up :-)
Be sure to match the camshaft with a stall converter. I would go with afr 195's which are a hair large for a 350'' but give you room to grow to a 383'' or a 400'', xe276hr and the low rise team g intake, should hit the 450 mark. That cam shaft would probably want 2400 to 2600 rpm.
You can obtain a sound running engine even using the factory heads on the ZZ4. Yes, you can obtain more power using AFR's or other aftermarket heads but its going to cost you. I purchased my ZZ4 back in 1998 and modified it back 2003 on a limited budget, so I can't give you every detail about my build but I'll do my best. Below is a chassis dyne run showing rear wheel horsepower and torque, so you have to ratio it up to compare to your 400HP number. Depending on what ratio you use for a manual transmission I figure I'm somewhere between 385-400 net HP.
List of modifications:
Lightly ported cylinder heads to remove casting flash, bumps, smooth down the walls, and thin down the area around the valve guide. Nothing real aggressive, didn't increase volume, didn't even port match the intake, just got rid of the obvious flow restrictions.
GM's LT4 "hot cam" (~ 0.545" lift), but didn't buy the whole kit
MANLEY 221423-16 NEXTEK valve springs for LT4 - Single Spring without Damper, Ovate Wire, 1.255" Outer Diameter, .830" Inner Diameter, Seat Pressure 115 @ 1.750, Open Pressure 350 @ 1.175, Coil Bind 1.100"
Manley 23634-16 Titanium Valve Spring Retainers, 7 Degree, 1.255 in. Outside Diameter, .830 in. Inside Diameter
I'm sure I'm forgetting a few things but that is most of it. You'll have to measure the installed spring height & shim them to fit correctly. Also, you will need to measure the correct push rod length, and buy the correct length pushrods. I think I ended up with standard length push rods, but I'm not sure anymore and can't find the part number I used.
If you don't feel comfortable installing custom hardware onto your existing heads, then probably go the AFR route as mentioned earlier.
One more thing, since you are running an automatic transmission, you'll need to upgrade the torque converter with a higher stall to match the powerband of the new engine configuration.
Out of curiosity what do you figure you've got into the heads? you did real good, 325 horse at the rear tire is no joke, but the op needs help on selecting parts for which he admits the lack of knowledge, cleaning up the intake runners might be a little more than his skill level or willingness to learn can take or maybe he can, but either way real impressive what you got out of it.
A TH700 has a very fast first gear, with a 3.73 that will give you 11.2:1 in first gear. A good street car, is 10:1
Plus the huge drop going from 1th to 2th gear (43% drop) will give you "slow" 2th gear/huge drop in RPM.
A TH2004R with a 3.73 will give you 10.1:1 and the gear "layout" is better going up the gears compared with TH700
For me, the TH2004R with 3.73 is the best solution. Also because it is a easy install, compared with TH700
How is an 11.2 to 1 1st gear a problem? And yes, the span between 1st and 2nd gear is larger than desired but how is that a problem when the whole object of a street driven car is to go from point A to point B. If the span between 1st and 2nd gears is really bothersome you can change the planetary to get a 2.84 to 1 1st gear.
Out of curiosity what do you figure you've got into the heads? you did real good, 325 horse at the rear tire is no joke, but the op needs help on selecting parts for which he admits the lack of knowledge, cleaning up the intake runners might be a little more than his skill level or willingness to learn can take or maybe he can, but either way real impressive what you got out of it.
Thanks for the compliment. This engine has treated me real well over the years.
Porting ~$30, did it in my garage
MANLEY 221423-16 NEXTEK valve springs - $184
Manley 23634-16 Titanium Valve Spring Retainers - $144
Manley 13091-16 7 Degree Locks - $44
Manley Race Flo Stainless Steel Valves - $152
ARP rocker studs ~$100 (don't have receipt)
Valve spring shims ~$25
So in total I've got about $700 in the heads, which at least back in 2003 was a lot less than any good aftermarket aluminum cylinder head. Now days you can get good aluminum heads quite a bit cheaper. One thing nice about the ZZ4 heads having only 165cc intake runners is that they do provide really nice street manners with plenty of low end torque.
It did take me quite a bit of reading up on cylinder heads, port design, porting techniques, etc. before I went that route. Plus I ended up buying a valve spring micrometer and push rod length checkers which added a little cost to my build. I just wanted to give the OP an option other than going all the way to completely new heads. I can see the appeal of going that route however.
Last edited by Jason Staley; Jan 18, 2016 at 06:26 PM.
Thanks for posting- nice article. It's interesting that, once they put a high performance dual plane intake on, the double pump Holley produced 20+ HP and 16 lb/ft of torque over the vacuum secondary Holley. Then the head swap just blew it wide open!
A TH700 has a very fast first gear, with a 3.73 that will give you 11.2:1 in first gear. A good street car, is 10:1
Plus the huge drop going from 1th to 2th gear (43% drop) will give you "slow" 2th gear/huge drop in RPM.
A TH2004R with a 3.73 will give you 10.1:1 and the gear "layout" is better going up the gears compared with TH700
For me, the TH2004R with 3.73 is the best solution. Also because it is a easy install, compared with TH700
I have a 700r4 and 3.70's, winds up quick, but not an issue, if I'd built the engine to wind up to say 7000 rpm I would have went with 3.90. If I shift above 5500 from first to second it goes from a chirp to spin, but not uncontrollable. I'd heard that 10 to 1 formula and wondered about it, but went 3.7 and happy with the gear.
1. How is an 11.2 to 1 1st gear a problem? And yes, the span between 1st and 2nd gear is larger than desired but how is that a problem when the whole object of a street driven car is to go from point A to point B. 2. If the span between 1st and 2nd gears is really bothersome you can change the planetary to get a 2.84 to 1 1st gear.
1. I didn't mention anything about a problem?
2. Or buy a TH2004R
I have a 700r4 and 3.70's, winds up quick, but not an issue, if I'd built the engine to wind up to say 7000 rpm I would have went with 3.90. If I shift above 5500 from first to second it goes from a chirp to spin, but not uncontrollable. I'd heard that 10 to 1 formula and wondered about it, but went 3.7 and happy with the gear.
Don't would feel the RPM drop from 1 to 2 gear?
I mean, shifting to 2 gear, your RPM goes "way" down.
I'm sure more then 10:1 in 1th gear is fine with autotransmission, I think (I don't know) that it is more a "problem" with a manuel transmission.
Help on ZZ4 power upgrades
