New everything... not enough oomph

Status
Not open for further replies.

Wagon1979

Not-quite-so-new-guy
Sep 15, 2017
7
8
3
79 Wagon - Love my wagon, but I've dumped so much money into the car and it still doesn't have that "holy sh... this car is fast" feel. I mean it's a stout daily driver, but I expected more I guess. Here is the build list and all of it is new with about 800 miles on the new motor & trans to date.

GM 350/290 hp crate long block (Camshaft lift is .450 intake / .460 exhaust. Camshaft duration at 050 is 222 degrees intake and exhaust. Lobe centerline is 114 degrees)
Replaced GM 76cc heads with Aluminum Promaxx 2169 Heads : 185cc intake - 64cc chamber - 2.02 intake/1.6 exhaust
1.6 rocker arms
Edelbrock rpm air gap intake
Holley 670 street avenger carb (plugs say jetting is spot on)
Hooker headers - no cat - glasspacks 2.5in all the way back
New TCI Street Rodder TH350 Trans
original 2.73 gears in back (Don't really want to change as I'm on the highway alot)
initial timing is 14deg at 650rpm
solid motor mounts

I feel like I have to be making really decent horsepower and the motor feels strong, but it just doesn't have the oomph that I would expect from this build. Is it wrong to assume I should be more impressed if i'm getting 10-13mpg or is it the weight of the car that's making it somewhat lackluster? I know I'm going to read alot of "change the rear gear to 3.73", but I really can't do that and go even lower than 10mpg as this is my daily driver.

Drove around (slowly) for a year with the original 200cid v6 and this is way better, but the $$$$ to fun ratio I'm at is disappointing.

Any thoughts?
1117171621.jpg
 

DRIVEN

Geezer
Apr 25, 2009
8,062
14,479
113
*CENSORED*
As you predicted...gearing.
A 200-4R and 3.73s would really wake it up and probably increase mpg a bit.
 
  • Agree
  • Winner
  • Like
Reactions: 5 users

axisg

Comic Book Super Hero
Jul 17, 2007
2,685
2,354
113
YYZ
Gearing will make it a little faster off the line and the OD will def help with the MPG.

The 290 hp crate is a wonderful improvement over stock and is great for a cruiser but with the advances of late it doesnt seem to be enough to keep up with the newest of mini-vans with a load of snot nosed kids in tow. LOL
My car at appx 375+ hp, premium fuel and in full street trim, with A/C / stereo / my fat *ss etc... pulls off a 14 sec flat 1/4 mile.

In comparison my wifes DD v6 camry pulls a 14.2 in the 1/4 and will eat my Monte for lunch off the line while pulling off 25 mpg.

But, what would I rather drive every day ? Monte hands down

In short, some gearing will definately put some sport in it, and let you squeal some tires, make some smoke, maybe even pull you back in the seat. But it wont feel very fast doing it unless you add a couple hundred HP to the mix. Enjoy what you have :)
 
  • Agree
  • Like
  • Winner
Reactions: 4 users

Wagon1979

Not-quite-so-new-guy
Sep 15, 2017
7
8
3
As you predicted...gearing.
A 200-4R and 3.73s would really wake it up and probably increase mpg a bit.

As much as I want to do that, I can't as I figure that would put me to 6-8 mpg and I would be cruising at 32-600
Gearing will make it a little faster off the line and the OD will def help with the MPG.

The 290 hp crate is a wonderful improvement over stock and is great for a cruiser but with the advances of late it doesnt seem to be enough to keep up with the newest of mini-vans with a load of snot nosed kids in tow. LOL
My car at appx 375+ hp, premium fuel and in full street trim, with A/C / stereo / my fat *ss etc... pulls off a 14 sec flat 1/4 mile.

In comparison my wifes DD v6 camry pulls a 14.2 in the 1/4 and will eat my Monte for lunch off the line while pulling off 25 mpg.

But, what would I rather drive every day ? Monte hands down

In short, some gearing will definately put some sport in it, and let you squeal some tires, make some smoke, maybe even pull you back in the seat. But it wont feel very fast doing it unless you add a couple hundred HP to the mix. Enjoy what you have :)


I tell my wife every time she asks why I work on the car so much, "I'm just trying to make this car faster than your 96 civic coup (no mods)".... and she gets 28mpg. I'd still rather drive the wagon.
 

Texas82GP

Just-a-worm
Apr 3, 2015
7,981
18,676
113
Spring, Texas
As much as I want to do that, I can't as I figure that would put me to 6-8 mpg and I would be cruising at 32-600.

I think you are overlooking that the 200-4R is an overdrive transmission.
 
  • Agree
  • Like
Reactions: 6 users

DRIVEN

Geezer
Apr 25, 2009
8,062
14,479
113
*CENSORED*
^^^This^^^
With a 200-4R and 3.73 your effective ratio is 2.50 compared to your current 2.73 which will give you much better acceleration and a lower highway RPM. Win - win.
In fact, if you went to 4.10s it would have the same cruise RPM that you have now.
 
  • Agree
  • Like
Reactions: 3 users

64nailhead

Goat Herder
Dec 1, 2014
5,659
1
12,059
113
Upstate NY
You main issue is that cam sucks according to what I found about it. 291/287 duration and 222/222 at .050". Yielding a hydraulic intensity of 69/65 which is an old school technology and design. The cam is yielding a sub 7:1 dynamic compression ratio. Great for a turbo build, terrible for a daily driver with a tall gear.

Your head swap put you near 9:1 SCR. Picking a cam that yields a 7.5-8.5 DCR will increase your performance and mileage dramatically. Also a cam that is made to operate in the range that you intend to drive, and designed to operate with a TC and final drive ratio that you have. And of course fuel economy.

Your second issue is gearing.

Here's your choices IMO : cam swap; cam swap and TC swap; cam swap, TC swap and final drive ratio change. Based on your mention of not wanting to swap the trans and rear gear ratio leaves the 1st or 2nd option. How concerned are you about fuel economy?

If your car were mine and I had to stick with the long block, trans and rear gear, then I'd grab an XE268 cam and throw a quality (not off the shelf) 3000 stall converter at it and have some tire roasting fun. Fuel economy on the highway should stick pretty close to 10.

If fuel economy was the only concern the XE250 or XE256 cam.

All of these cams raise your DCR into the 7.5-8.0:1 range - acceptable.

My two cents :):)
 
  • Agree
  • Informative
  • Like
Reactions: 8 users

Injectedcutty

G body LS mafia
Nov 24, 2014
6,057
22,807
113
Louisville, KY
If the cam swap does come along, I happen to have a brand new in box Comp 268XFI cam and lifters that would be a great upgrade. What Jim and the others have stated already is the cam in the crate motor is lackluster, especially with the heads you swapped out.
 
  • Agree
Reactions: 2 users

online170

G-Body Guru
Oct 28, 2010
726
319
63
I have a wagon with a basically stock, 80s truck 350. I think it's maybe 250hp if I'm lucky.

Its snappy and feels really fast but in reality it's not that quick. But the feeling is there.

It has headers, rpm intake, 750cfm DP carb and a 268cam. T5 manual with 4.11gears. I can cruise on the highway at about 2000rpm. Gets pretty awful mileage but I can do better with a different carb if i wanted to.
 
  • Like
Reactions: 1 user

Wraith

Royal Smart Person
Jan 13, 2013
1,599
4,747
113
DFW, TX
I built a Bu back in 03' with a new crate ZZ4, built TH350, 2500 stall, Edelbrock 750, and 3.73 gears and I would get 18mpg highway. You have a mismatched combo. Mine felt like a slug with 2.29 gears, after the 3.73/posi swap the first time I jumped on it I about wrecked it. Gears would make a huuuuuge difference.
 
  • Like
  • Creative
  • Agree
Reactions: 3 users
Status
Not open for further replies.

GBodyForum is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to amazon.com. Amazon, the Amazon logo, AmazonSupply, and the AmazonSupply logo are trademarks of Amazon.com, Inc. or its affiliates.

Please support GBodyForum Sponsors

Classic Truck Consoles Dixie Restoration Depot UMI Performance

Contact [email protected] for info on becoming a sponsor