72 340 engine

-
H

hockeydad1189

Well-Known Member
Joined
Aug 3, 2011
Messages
60
Reaction score
0
Location
mass
hi i just bought a 73 duster with a 72 340 it was rebuilt it has a upgrade cam specs unknown, it was built to 71 specs,it has a 70 intake and exhaust manifold, a carter afb carb ,it has a steel crank the heads are 72 j heads.my question is if i do a compression test what numbers should i be looking for any guesstimates on hp and tourque
 
Compression, 120 to 240 lbs--depending on cam and compression ratio.

Power between 250 to 400 hp

We really need more info, like what is the compression and how much vacuum does it pull at 1,000 rpm
 
i have a question on air filters i currently have a stock air cleaner, i have a hood with two scoops with air passage to top of air cleaner i am wondering if iwould be better with a k n extreme flow air cleaner set up . i would like to know if it is worth the money and does it make any real difference
 
Welcome to FABO, hockeydad1189.
Yes, K and N filters are worth what they ask and perform as advertised.
 
i just did a compression test the car had been run about 20 minutes before the test the lowest reading was 165 the highest was 180 is this considered good, normal or low and how does this relate to compression numbers 8.5,9.0,9.5 ??? thanks jim
 
That is up there. I had a stock 8.5:1 340 that had 100 lbs comp and my stock 10.5:1 340 was 150-155. Of course that all depends on your cam.
 
just looking at the intake on my engine the number is 3462848 it is a 70 casting number i am wondering if this is a good intake , or i would be better off with a after market intake. and if so what is the best one out there i want a dual plane
 
Its not bad, how happy are you with the performance? The intake does very little, its the overall set up. Sure going from a 2bbl to a 4bbl sure helps but it has a 4bbl right now. Switching to say Edelbrock RPM intake will pick it up around 15 hp or about 2 car lengths farther ahead in the 1/4 mile...3 car lengths max I would expect. A carb swap might give you more gain, the old Carter afb on it right now is a nice carb but a new Edelbrock AVS tuned right would pick it up at least 15--20 hp. Or a Holley DP but I like Carter/Edelbrock for the street--motor seems to idle better--I run dual 500 Carters on my 340, Got a old rare Edelbrock intake.

One thing about that 1970 intake is those holes under the carb, if you put a 750 Holley on it, the front holes are a tad too small and you need a 1/4 spacer to raise the carb up. Aftermaket intakes don't have those 4 holes, just wide openings so heck a Holley 850 would bolt right on with no spacer needed
 
My 340 has 198-205/cyl compression test ,on a 1970 340 10:5.1 pistons lunati 60403 cam air gap intake . The was not a huge difference when I switched intake from stock .The 1970 intake is dual plane , even bore , 1971 0r 1972 went spread bore I think . The Carter is a good carb
You should get between 300 and 400 HP depending on cam pistons and if the heads were worked on
 
hockeydad1189 said:
i have a question on air filters i currently have a stock air cleaner, i have a hood with two scoops with air passage to top of air cleaner i am wondering if iwould be better with a k n extreme flow air cleaner set up . i would like to know if it is worth the money and does it make any real difference
Click to expand...

I say no , seen enough real world tests and internet test , not paid for by K N and the air filters are not good I M O
.http://www.nicoclub.com/archives/kn-vs-oem-filter.html

http://www.bobistheoilguy.com/airfilter/airtest1.htm
 
out of all the after market intakes edelbrock performer ,air gap or weiland which is better i use the car for mostly street driving what size carb should i be using. do intake spacer really make a difference outside of cooling fuel
 
The stock intakes are not bad for a mildly built engine but man are they heavy. I would swap to an Edelbrock RPM just to get rid of that weight.
 
There is a lot of advice on intake manifolds floating around here. Has anyone actually tested any of these manifolds?
 
it would be good to see some comparisons on all the different ones out there to see if they really make a big difference
 
Intakes are designed for different purposes, so first you need to figure out what your main use is. Just an extreme comparison, a tunnel ram would work great on a race only car but would suck on the street. Unless you're running FI on it like DVJCuda.
 
it is for the street mostly,it will be a dual plane i will be putting on a new carb either a edelbrock avs or holley? i just wanted to know if it would be worth the money, if the hp gain is noticeable
 
I don't think manifold change will give any noticeable hp gain in your situation. But like 340sFastback said I would just change it to get rid of some weight, and it would look cooler too. I would look for an LD340 cause I like the looks of those on a street car. Or an Edelbrock Performer RPM if you want a newer look.
 
hockeydad1189 said:
it is for the street mostly,it will be a dual plane i will be putting on a new carb either a edelbrock avs or holley? i just wanted to know if it would be worth the money, if the hp gain is noticeable
Click to expand...


Sounds like I would leave it alone. Oh sure, you could save 30 lbs max, big deal, IMO. You gain a few HP but be lot of work yanking that heavy intake off and swapping it.
 
IQ52 said:
There is a lot of advice on intake manifolds floating around here. Has anyone actually tested any of these manifolds?
Click to expand...

So, it looks like the answer is no.

Buy whatever dual plane is in your budget, that you think looks good, and don't look back. I have tested stock cast iron manifolds against aftermarket aluminum ones and they all work better than the stock ones. But I have never done a test on small block Chryslers that would be applicable in your situation.
 
The factory 340 intake isn't too bad, large ports no really big negatives until you get in to the EGR years. Its too bad the factory did not offer a dual carb option, yes they did have the 6 bbl but it doesn't clear without a hood scope in most car.

If you got the time and money Edelbrock RPM intake is a very nice intake and don't rule out the old single plane Holley Street Dominator which offers a very low profile and great low--mid range power with its small intake ports...I still swear the Holley intake pulled better than the RPM after 5,500 when I did the swap. The RPM was better taking off from a stop.

I'm running the old Edlebrock dual carb intake on my 340, love it and would not change it ever unless I went with the W2 heads, I got an old water heated Holley W2 intake sitting in my basement if I ever get my hands on some good W2 heads--or if China finally starts making and selling them cheap one day
 
dodge freak said:
The factory 340 intake isn't too bad, large ports no really big negatives until you get in to the EGR years. Its too bad the factory did not offer a dual carb option, yes they did have the 6 bbl but it doesn't clear without a hood scope in most car.

If you got the time and money Edelbrock RPM intake is a very nice intake and don't rule out the old single plane Holley Street Dominator which offers a very low profile and great low--mid range power with its small intake ports...I still swear the Holley intake pulled better than the RPM after 5,500 when I did the swap. The RPM was better taking off from a stop.

I'm running the old Edlebrock dual carb intake on my 340, love it and would not change it ever unless I went with the W2 heads, I got an old water heated Holley W2 intake sitting in my basement if I ever get my hands on some good W2 heads--or if China finally starts making and selling them cheap one day
Click to expand...

Yes the old holley street dominator was great on a 318 , had one on my 318 and it was a big improvement over cast 340 intake . That and a thermoquad and it screamed , from idle to 5200 it ran great , best 318 intake imo
 
You must log in or register to reply here.
-

Back
Top