Major upgrades! Any ideas on hp gains?

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4mulaSvaliant

4mulaSvaliant

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Hey guys long story short I had 318 heads on my 360, older edel. manifold, headers, and to my recent amazement 1 7/8" duals out the back.

Story with that, had a 318 for the build that turned out to be cracked. Too bad I had the heads rebuilt already. So on a High School budget the heads were ran on a 360 block a managed to dig up.
As for the exaust, it was a graduation gift that was inexpensive, effective, and much appreciated, but as I measured it today I was amazed at how small it is. Especially considering this used to run 14 flat w/ the exaust on. (not way fast but it is a seriously sufficated 360 here! lol)

Now for the upgrades: Rebuilt Jheads (nuttin' special)

2 1/2" exaust with a cross pipe and those typical turbo muffs

Unfortunately I have to put the ED 318 intake back on for the moment but it will be moving on as well.
But with the stock J heads vs. the stock 318 heads and the 2 1/2" with cross pipe vs. the 1 7/8" strait pipes w/ cherry bombs, what are your guys' bets for HP gains and Torque gains?

I think maybe bout 40 hp or so? let me know guys! lata'
 
I think that your torque will go down as the ports are larger, and the HP will increase but how much is anybodys guess, 40 HP and being stock? If I had to guess I would say 15-20 with full exhaust. But this is IMO.
 
I think if it has a stock camshaft, not much unfortunately. You removed exh restriction, and added some port volume (both of which I dont consider bad...) but you didnt change the control for all the airflow. The cam. If it has some soert of small cam, I dont think you'll feel that "night and day" difference Unless it's mostly emotional. Last two items, swap that intake, and swap ina cam. And you'll be having that night and day feeling.
 
I agree w/ moper, that intake will be the next restriction to be removed. You need to consider the whole package for any changes to be effective. Unfortunately, (or, fortunately, depending on POV ) it could be the beginning of a long list of mods to come. After changing the cam & intake , the carb may be next , then to take advantage of those changes, tourqe conv. & gears ,and so on.... Then you'll find that you want to go faster, and a 360 will sound like a good ideal....
 
I forgot to say I have a "mild cam" already, but yes I do understand that the intake will still be restricting me pretty badly. I have a 904 so I am going to stick with a dual plane manifold. I have not decided which one Ill be running yet. Ill be driving this on the street mainly. I say "mild" because I know when I built it 10 years ago I sat down with a knowledgeable guy and figured what i needed based on what it was going to be used for. So I remember its not stock, but I had the J heads in mind when Building it. As for the carb I have a 1405 Ed, i think that is a 500/600 cfm carb. If I have to go bigger there Ill do so. Thx guys
 
Well, depending on the cam, I'd say you've probably added 20-30hp with what you have. Maybe more depending. So figure in the 250-260hp range witht he intake as a possible limiter, or possible torque maker.
 
depends on the cam too................

specs?

What cranking compression is that thing running? can you check it?
 
Well my mind has gotten the better of me, or maybe experiance is setting me strait here.
I have decided to hold off, putting the heads on. Reason being, I think I was misled. I know they are 72 360 J heads, I ran the numbers and they have an obvious "J" on them. But were I think I was BS'ed was, he told me that they were a fresh rebuild. This was about 8 years ago (my car has been sitting while I collected parts while in the Navy). Well I bought them thinking they would just be slapped on and go! Upon further inspection over the last several days I noticed there was some glass beads holding a valve open (it has been sitting on the valve seat for bout 8 years now, aswell as Im not sure where esle the beads may have found a home. Also I see there is a decent amount of carbon in one or two of the really hard to get areas in the valve chambers. All this leads me to believe that I have been played! I am sure you all get the same impression! I think they were old and were bead blasted to be sold as new.
So like I said I think my experiance is getting the best of me because I decided to get them checked out before I put them on.
Aside from that I dont have the correct intake for that combo right now and Id rather do it all at once, so Ill wait to get the intake and then just do a top end swap!

Plus I have to say I like the torque that it has at the moment! Thx guys talk to ya lata'
 
Wise choice. Never, ever, pay for sand or glass beaded complete heads someone says are "ready to run if they were blasted while assembled. If you see the burnishing on the keepers and valve heads. Run away..
 
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