TheAMCForum.com Homepage
Forum Home Forum Home > The Garage > AMC V8 Engine Repair and Modifications
  New Posts New Posts RSS Feed - 304 Power and Potential
  FAQ FAQ  Forum Search   Events   Register Register  Login Login

Click for TheAMCForum Rules / Click for PDF version of Forum Rules
Your donations help keep this valuable resource free and growing. Thank you.

304 Power and Potential

 Post Reply Post Reply Page  123>
Author
Message
Rambler Mexicano View Drop Down
AMC Addicted
AMC Addicted
Avatar

Joined: Mar/05/2011
Location: Guadalajara
Status: Offline
Points: 850
Post Options Post Options   Thanks (0) Thanks(0)   Quote Rambler Mexicano Quote  Post ReplyReply Direct Link To This Post Topic: 304 Power and Potential
    Posted: Sep/20/2016 at 3:40pm
Some AMC models I would like to own in the future if I have the chance are the 1977-1979 AMXs, 1978-1979 Pacer coupe, 1974-1975 Gremlin X Rallye and 1974-1975 Hornet Rallye X .

The main feature of these models is they were available with the 304 V8, that'd would be the engine of choice to buy any of them. I could opt for a factory 360 V8 in both Hornets but that would extremely rare and highly unlikely to happen.

In regards to accessories and appearance I'm with the crowd that supports full originality without being a purist. But in regards to the mechanical department, that's another story.

I always like to make cars better performance-wise. That's what I've done to my current car (1981 VAM Rally GT with a 282 six), all original parts and looks but I threw in dual exhausts, flat pistons, reduced the height of the head, ported head and intake manifold, performance carburetor, performance distributor, etc.

Canadian/American-made AMC cars with V8 engines (not available in Mexico) mostly get the following treatment, the 304s (and 290s) most times get removed (and discarded) in favor of 343/360 or 390/401 units.

In my case, I would like KEEP all 304s BUT would like to build them into higher performance units. I'd keep the 360s and 401s for higher performance models (AMX, Javelin) and heavier larger sized models (Rebels, Matadors, Ambassadors).

It would have been cool for AMC to offer a dual-exhaust, four-barrel, four-speed version of the 304 like they did with the 1966-1969 290 V8s. When the GEN-3 engines were introduced they opted instead for a 2-barrel version of the 360, but, alas, no four-speed in this one. The 1979 AMX was the only time the 304 had a four-speed transmission.

If I build a 304 from the ground up with performance parts (heads, cam, pistons, four-barrel intake, four-barrel carburetor, ignition, headers, dual exhausts) what results can I expect from it performance-wise?

Does anyone have 0-60 and quarter miles numbers on customized/modded 304 units?

I'm Not planning to BORE OUT any of the engines (at least so far), but I rather ask the PROs and CONs of such a decision first.

How much can a 304 block be bored out? Are there differences between blocks through the years? Most of the ones I'd be working with are the 1974-1979 units.


In regards to the added power of the engines and how could that affect the transmissions, my plans would the following.

I am mostly a STICK driver myself, I'd rather get floor-shift manuals on the Hornets, Gremlins and 1979 AMX, but I'd keep the automatics on the Pacer and the 1977-1978 AMXs.

I know the 1977-1979 SR-4 four speed manual is not a performance transmission and is practically nothing more than MARGINAL in regards to high amounts of torque. I wouldn't keep the 150-T three speed manuals either. I would have them swapped in favor of five speeds (WC T-5, AX5, AX-15) or Hurst linked four-speeds (T-10).

As for the A998 TorqueFlyte automatic, medium duty unit, how would it stand out against a highly modded 304?

Would you recommend swapping it for a very-high-torque A727 unit?

The A999 models used in Eagles, higher torque resistance than the A998, can be used as an alternative to the A727?

Thanks in advance for any information you can provide.


Edited by Rambler Mexicano - Sep/20/2016 at 3:48pm
Mauricio Jordán

Cuando no se es una empresa famosa se deben hacer mejores automóviles.
- Vehículos Automotores Mexicanos S. A. de C. V.
Back to Top
304-dude View Drop Down
AMC Addicted
AMC Addicted
Avatar

Joined: Sep/29/2008
Location: Central Illinoi
Status: Online
Points: 8706
Post Options Post Options   Thanks (0) Thanks(0)   Quote 304-dude Quote  Post ReplyReply Direct Link To This Post Posted: Sep/20/2016 at 3:56pm
When I did my simple bolt on mods to my 73 304, it livened up well. mostly because dual exhaust an better intake with a 650 cfm carb. Adding a cam would even bring more power. I think if you put more effort into torque around 4500 RPM would be more beneficial than trying to get 300 hp out at 7000 RPM. It weighs as much as a 360, and has smaller valves and pistons. Over boring won't do much and stroking is to costly compared to obtaining a 360.

If you do want to run 300+ hp, a 100 shot of NOS would do the trick and you don't have to run high octane or go to radical with the build.
71 Javelin SST body
390 69 crank, 70 block & heads
NASCAR SB2 rods & pistons
78 Jeep TH400 w/ 2.76 Low
50/50 Ford-AMC Suspension
79 F150 rear & 8.8 axles
Ford Racing 3.25 gears & 9" /w Detroit locker
Back to Top
Traveller View Drop Down
AMC Addicted
AMC Addicted


Joined: Feb/26/2011
Location: Idaho
Status: Offline
Points: 1014
Post Options Post Options   Thanks (0) Thanks(0)   Quote Traveller Quote  Post ReplyReply Direct Link To This Post Posted: Sep/20/2016 at 4:07pm
The 304 is an under-rated engine in my opinion. It's a solid performer with some upgrades. With a Performer 4 barrel manifold, some work in the heads and a better piston choice, it can be quite a good engine. The engine can be overbored (a lot) in relation to the other blocks. .125 is not a problem usually, but it needs to be sonic tested.   The factory said max overbore was .155, but I'd test any block first due to core shift and corrosion over the years.

The 998 is the same trans used behind the 360, and you won't have quite the peak torque with the 304. It can be built to take a lot of power.   

So, just depends on budget. How much do you want to spend?

I have a 325 incher in our blue car making over 300HP, and it's a hoot to drive.   Just need to do a couple things with the front end to make me happier and I'll take it to the track.   I run a 4 speed auto made from the 42RE Jeep case. I run the 3.54 rear gear, and the RPM is 2600 at 80MPH on the freeway. About 2000 at 60MPH.

As far as times, hope to know that in October. Trying to get the front end stuff done the next couple weekends so I can take it to the track.   My 360 powered Hornet runs 13.50-13.70, and the blue car feels faster. I'm crossing my fingers.

I'll probably post times once I have them.
Back to Top
tufcj View Drop Down
Supporter of TheAMCForum
Supporter of TheAMCForum
Avatar
Supporter of TheAMCForum

Joined: Jul/10/2007
Location: Watkins, CO
Status: Offline
Points: 3409
Post Options Post Options   Thanks (0) Thanks(0)   Quote tufcj Quote  Post ReplyReply Direct Link To This Post Posted: Sep/20/2016 at 4:23pm
I had a 304 in my mud-bogger Jeep. It was bored .030", rods shot peened, 10.5 forged pistons. Balanced. Heads were polished/ported with bronze guides and 1.94 and 1.50 Chevy valves. Don't remember cam specs, but around a 290 duration with a .500 lift. Edelbrock Torker with a Holley 600. Easily revved to 6500. I never had it dyno'd but it was easily 300HP. Lots of people thought I was running a SBC conversion until I'd open the hood.

Bob
tufcj
69 AMX
74 Javelin AMX
67 Rogue

If you need a tool and don't buy it...
you'll eventually pay for it...
and not have it.
Henry Ford
Back to Top
uncljohn View Drop Down
AMC Addicted
AMC Addicted
Avatar

Joined: Jan/03/2013
Location: Peoria AZ
Status: Offline
Points: 5388
Post Options Post Options   Thanks (0) Thanks(0)   Quote uncljohn Quote  Post ReplyReply Direct Link To This Post Posted: Sep/20/2016 at 5:22pm
I would have no problems deciding to build a 904 transmission or a 998 for a street performance AMC V8 engine of any size. And my preference would be the later versions with a lock up torque converter and I would have a 2200 rpm stall lock up converter installed at the bare minimum.
By the by, any size includes a built up I-6 which I have done and put so far 50,000 miles on with out the slightest inkling of a problem with it.
As to a 304? Unless I had a specific reason to build one, my preference would be a 360!
70 390 5spd Donohue
74 Hornet In restoration
76 Hornet, 5.7L Mercury Marine Power
80 Fuel Injected I6 Spirit
74 232 I-6, 4bbl, 270HL Isky Cam
Back to Top
purple72Gremlin View Drop Down
AMC Addicted
AMC Addicted
Avatar
Charter Member

Joined: Jul/01/2007
Location: Illinois
Status: Offline
Points: 15846
Post Options Post Options   Thanks (0) Thanks(0)   Quote purple72Gremlin Quote  Post ReplyReply Direct Link To This Post Posted: Sep/20/2016 at 6:27pm
I put a performer /edelbrock 650 and dual exhaust/ stock manifolds in a 1979 AMX. this car has a 998, and 2.87TG.  It had a bit better driveability.  but on the track, it was no faster.  I have another 1979 AMX, but this one is completely stock and has the SR4 4 spd. 2.87s open,  I want to put a Holley Z intake on this one. and duals with free flows. I very seriously doubt Ill drag race this one.    based on my experience, the small bore is the big limit on making good power.   a 360 has the same stroke and it runs rings around the 304, and the 360 also responds to mods better too.   Ive had 3 cars that came with 304s.  2 1979 AMXs, and one 1972 Gremlin. 
Back to Top
53w View Drop Down
AMC Apprentice
AMC Apprentice


Joined: Sep/14/2010
Status: Offline
Points: 231
Post Options Post Options   Thanks (0) Thanks(0)   Quote 53w Quote  Post ReplyReply Direct Link To This Post Posted: Sep/20/2016 at 6:59pm
Stock 304 Rods and rod bolts are weak link. Without addressing that problem must stay in stock rpm range.
Back to Top
Ken_Parkman View Drop Down
AMC Addicted
AMC Addicted


Joined: Jun/04/2009
Location: Ontario
Status: Offline
Points: 1477
Post Options Post Options   Thanks (0) Thanks(0)   Quote Ken_Parkman Quote  Post ReplyReply Direct Link To This Post Posted: Sep/20/2016 at 9:25pm
The 290/304 have tremendous potential and can make some serious power. The heads are very good stock and shockingly effective prepared right, and if you want they can rev fine. For example they are a far more capable engine than a 302 Ford, and look at what people think of those. If you want real proof look at something like Garrett Ghezzi's SS car with a 290, one of the fastest traditional SS cars there is for running under index.

The only problem with a 304 is a 360 is the same physical size, weight, and fit, and has 56 more inches. A little better parts availability, but that really does not matter much. You just can't argue with 56 more cubic inches at the same cost, weight, and installation; bigger is always better. It will make more torque and power, and deliver the power at a lower rpm. That's why almost everyone will suggest a 360 or 401, although a 401 is a lot harder to find and takes more money. Just tell them it is a 304, no one will ever know. Unless there is some rule requiring a 304 a 360 is a better plan as it is more cost effective for power.

But the 304 is a terrific engine.
Back to Top
Buzzman72 View Drop Down
AMC Addicted
AMC Addicted
Avatar

Joined: Sep/15/2009
Location: Southern IN
Status: Offline
Points: 2112
Post Options Post Options   Thanks (0) Thanks(0)   Quote Buzzman72 Quote  Post ReplyReply Direct Link To This Post Posted: Sep/21/2016 at 6:33am
In a "run what you brung" world, the 304 should be acceptable for a performance build. Do you hear the Ford guys telling the novices to ditch the 302 and build a 351? Not as often as AMC folks dismiss the 304. And in the Ford universe, there are a lot of built 302's.

Aren't the 304 rods the same as the 360 rods? Same deck height block, same journal diameter, same piston pin diameter, same length. So why are we telling folks the 304 rods are inferior?

My questions about the 304 concern how much overbore, if any, is necessary to install larger-diameter Chevy valves. Can you use the 1.84" Chevy intakes without boring the block? The stock AMC heads start out better than stock Chevy heads, except for valve sizes.



Buzzman72...void where prohibited, your mileage may vary, objects in mirror may be closer than they appear, and alcohol may intensify any side effects.
Back to Top
304-dude View Drop Down
AMC Addicted
AMC Addicted
Avatar

Joined: Sep/29/2008
Location: Central Illinoi
Status: Online
Points: 8706
Post Options Post Options   Thanks (1) Thanks(1)   Quote 304-dude Quote  Post ReplyReply Direct Link To This Post Posted: Sep/21/2016 at 6:53am
Most built 5.0L have boost of some sort. Having thicker walls helps on the 304. Having smaller valves good boost will compensate. So, dollar spent should be on bolt on stuff. A turbo and NOS should get 450 HP on a stock built motor, with a nice mid range cam on pump gas. Building a stock 304 is too costly in HP return over grabbing a 360 and living with stock head setup. Stock 360 heads flow better by valve size, no machining needed. So how it all depends on how you want to spend your money. The Ford guys may stroke kit an engine, but most will bolt on performance of some kind as it is not just easier, just plain cost effective for the gains.
71 Javelin SST body
390 69 crank, 70 block & heads
NASCAR SB2 rods & pistons
78 Jeep TH400 w/ 2.76 Low
50/50 Ford-AMC Suspension
79 F150 rear & 8.8 axles
Ford Racing 3.25 gears & 9" /w Detroit locker
Back to Top
 Post Reply Post Reply Page  123>
  Share Topic   

Forum Jump Forum Permissions View Drop Down

Forum Software by Web Wiz Forums® version 12.03
Copyright ©2001-2019 Web Wiz Ltd.

This page was generated in 0.078 seconds.
All content of this site Copyright © 2018 TheAMCForum unless otherwise noted, all rights reserved.
PROBLEMS LOGGING IN or REGISTERING:
If you have problems logging in or registering, then please contact a Moderator or