I've read a lot in this forum and i need some advice as i am still learning about TPI.

I built a 383 TPI motor for my jeep YJ (700r4 tranny) and it falls on its face (doesn't make power) after 3300rpm's. My father-in-law gave me the engine (needed assembled). I added the speed density TPI. I had the center bolt holes machined to fit the older heads. When i put the engine together i checked the head number (14022801) and they are 305 heads 1.72/1.5 58cc and all along he told me they were 350 heads. I think the heads are the major problem as most of you probably will say. I found another set of heads at his garage from a 350/400 (462624) 1.94/1.50 76cc and would like to try them. Is it worth swapping heads and then work on getting chip calibrated right for the engine? I installed 30lb injectors and had the chip programmed for the cam. I am also having problems with knocking/detination probably because the of comp ratio which i do not know but i'm sure it's high. I ran 104 octane and the knocking went away. I posted this in a off-road forum but you guys are the experts here so let me know what you think i should do. I would like to provide more engine specs but i don't know all of them.

Comp Cam
12-206-2
212 int/212ext 0.440 lift

My jeep is built for off-roading and does get driven on the street. I am not looking to get high horsepower/torgue out of the engine but would like to get good perfomance.

Help

 

So far a guy replied in another forum saying that the bigger heads would help but are probably cracked and they are crappy late 70's smog heads.

My fuel map will need to be adjusted once i figure out which heads i am going to use.

The lobe seperation on my cam should be 112 to 114 for fuel njection. The cam i have now is to tight at 110.

 

Choking off at 3300 to me says something is wrong with the tune. Although it could all be detonation induced. The stock TPI likes to peak at 3200-3400. Take the bigger head, it will lower your CR back to a level compatible with your cam.
I'd assume you have the 12cc dish pistons. The next bigger dish isn't very common. And if you have flat tops, don't drive it again till you swap heads. With the 12cc dish and 58cc heads your in the 10.5 to 10.9 cr range. You want about 9-1 with your cam. You'll have to go to a thin head gasket to do it.
Depends on your deck height. Assuming .020 then the .015 gasket for 9.2 cr.

You've got plenty of injector. The cam is fine for a 383 even with efi. The main reason for going with the 114 is to make tuning easier. You don't have to do it. And a 383 will run better with a 110 or lower. Especially with your small cam.
You might look into the DIY-Prom board. Look up top at the sticky posts first. Doing your own chips is the best way in the end.

 

It's probably the tune being way off... too much fuel.

 

Those heads are a major issue. They didn't breath well on a 305...
I'd agree w/ you're own statement. Change the heads, and get it tuned properly. - Take the 462's and have them pressure check at a machine shop. They shouldn't charge much, and you could do that before making any decisions. Then you'll know if they're racked or not. Also, have the machinist give 'em a good old once over. A good machinist can identify any major problems before you spend money...

 

Any good recommendations for aftermarket heads that won't break my bank account for my engine?

I'll start searching, but thought i would ask.

 

Pro topline
and World products are both considered budget heads. You can find them on ebay.

 

Even a good set of 083's(350 center bolt) w/ some half-assed porting. You'll see a good improvement in power, and they'll work well for what you're doing.