I've seen lots of debate over the EFI engines and my '96 was really tired with 260K miles on it. Gas mileage was horrible, even for one of these big blocks. Decided to overhaul it. Amazingly the cylinders were able to be honed so we just re-ringed, new bearings, cam and timing chain kit, heads done at local machine shop with proper springs for the new cam. Thought I'd share some pictures of the gasket matching we did to try and gain a little more from it. You must be careful on the exhaust side because the water jacket is closer than you would think. If you grind the lower part of the port even with the gasket, you will be in the water jacket...

 

These EFI heads are really choked down on the exhaust side. But every little bit helps.

 

Didn't want to use headers, so did some port work on the exhaust manifolds too.

 

I have some big port 79 heads if u feel like going with a carb to get some real power outa it!

 

Thanks davistr, but it is actually back together and on the road with the EFI. This truck weighs within 100lbs of my old '79 and has same axle gear ratios, so I have a pretty good base line to compare it to. I am pleased with it and feel that if it were a stick shift like the '79 was, they would be very comparable. There was some tinkering to get the timing right and make the computer happy. It didn't want to idle and took the computer some time to adapt. The only fault code it is throwing now is low EGR flow. I cut the pipe at the valve and welded it shut, but left the vacuum and electronic plug in place to make the computer think it was still working...

 

Intake manifold and heads were gasket matched as well. Took the injectors out and cleaned them good. Reinstalled them with new service kit (o-rings and collars).

 

So the big debate was cam profile and I decided on an off the shelf grind from Comp Cams. It was bought in kit form with timing set, springs, keepers and locks, part number K-34-226-4. This is the cam profile that was used in my '79s 460 and ran great. The lobe separation is 110 degrees and is actually not computer compatible. But the profile is mild enough at 265/275 duration and 484/510 lift, I tried it. Here is what we had to tinker with to get it straightened out:

1. The truck didn't want to idle at first and required some tinkering with the idle screw (I know, factory set, don't touch). We actually used an Auto X Ray hand held scanner with real time to make sure we didn't change it enough for the computer to see a change in throttle position.

2. The truck does throw low EGR flow code on a regular basis as mentioned above, due to the valve being capped on the exhaust pipe side.

3. The truck seems to idle a little rough and rich when the temperature is down around zero or less until it gets some temp in it. It has a new O2 sensor in it, and it is factory replacement quality (Bosch). I'm not sure what, if anything can be done about this. I suspect it is due to a combination of the bigger exhaust profile on the cam, and the lack of EGR causing the engine not needing as much fuel when cold as it did stock.

4. The truck runs best with the base timing set at 14 degrees when it is empty, but we had to back it down to 12 because of spark knock when loaded with a car trailer.

5. Gas mileage is in the mid 8 range, about the same as my old '79.

6. My biggest complaint is the transmission tries to go into overdrive early now that the motor pulls better. On our back, rural roads, it is just annoying. I just run the truck with the overdrive off now unless we are getting on the highway.

 

Nice job!!

 

Try a custom valve body. I don't know any others besides the punisher valve body, however, the lightning guys swear by it, and there aren't many people who know an E4OD like Paul. Email him @ lightning2fast@aol.com

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