I finally got it done. My '88 Formula is now a Formula 400.

• Original-- L03 "E" engine -- 305
• Now-- '77 400 SBC, bored 0.030" over for 406
• Most of the other details are in my sig.

After cam break-in, several short test runs, and finally its first commute to work, here are the early results and first impressions. Almost totally non-scientific, but that's half the fun.

• In low gear, punch it at any RPM and it'll "light'em up." Pretty impressive, considering it's a 3.08 posi.
• A hard launch pushes the RPM's to red line almost instantly, with tires screaming. Gonna hafta buy some slicks if I even hope to test it on the strip.
• From a stop, almost impossible to kill it by letting the clutch out too fast without enough throttle.
• 0-60? Hah! On an interstate entrance ramp, it's over 90 before you can blink.
• Hard to hold it at the speed limit without cruise control. It definitely wants to RUN.
• Can cruise around easily at 40 mph in top gear at about 1100 RPM. (0.61:1 overdrive with 3.08 rear).
• The lopey, hard-to-tune, ill-mannered 305 would run upper 12's. But it doesn't even compare to this smooth-idling beauty.
• The throttle response is so sharp, I'll have to install an aftermarket cruise control. The factory cruise really surges badly. Unless one of you has a "fix."
• No problem pulling up a hill at 55 mph on 2-lane highway.
• The '416-casting heads, even ported and polished, may be too low-flow even for a 5300-rpm red line. It seems to run out of pull about 4500 RPM. Could be injector sizing or WOT tuning, though. I'll know for sure after fine-tuning the computer. (I wanted to try these first, before spending big bucks on a set of aftermarket heads. But I'm definitely open to this possibility. When the budget will allow, that is.)

Gas mileage report will come after a tank or two.

Quarter-mile results in the spring, after the strip opens.

If anybody is considering this swap (or a 383 which is similar), I'll gladly answer any questions. (The biggest challenge was the flywheel and starter, dealing with the different starter mounting, external balance, and flywheel fit.

Anyway, this is one SWEET machine now. Now I can start on cosmetics.

 

Nice.
i've wanted a 400 after meeting quite a few people that have them in their thirdgens.

 

I just found me a 400 for $400. Machined, balanced with 5.7 rods, hyper pistions, and unknown heads. Only needs to be assymbled, and rings, bearings, gaskets. Im getting axious to tear into my car this week lol.

 

Congrats, Habu!

You've definately built something for torque. Small cam, small primary headers. What are you using for an intake manifold? I seriously doubt the 416s are limiting you - the 416s will outflow any stock 400 head - those headers will first. They're small for a performance 305, okay for a torque 350, but way too small for a 400.

May your T5 last through the winter so it can spill its guts on the track. . .

 

The cam choice was made in talking with CompCams, and telling them I wanted torque, torque, torque with a red line 5300-5500 rpm. Their tech nailed it for me. I was actually looking at a smaller cam than this one.

The headers are so small because of budget. I already had them on the 305, so I'll use them 'til they start to rot.

The intake is a dual-plane Holley ProJection TBI w/ EGR (#300-49). Holley lists its performance range as "Idle - 6000 rpm." I chose it over Edelbrock 'cuz it had 2" bores to fit the 454 TBI unit. Edelbrock's bores were smaller, so I'd have to have them bored out. Plus I heard that their TBI manifold wasn't much better than stock.

The only little problems I'm having is tuning. I think it's going lean at WOT and high RPM, and it has a flat spot at all throttle positions from 1700-2000 rpm.

Other than that, it's seriously sweet. One more totally subjective performance statement: "It passes slower traffic like a motorcycle!" At least, shift down to 4th to pass and it easily matches or beats my 1500 Gold Wing, which is a high-12's machine.

 

Oh! I forgot to mention-- I'm open to a head upgrade, to something with modern kidney-shaped chambers, probably aluminum, for the increase in power and fuel economy.

The "recipe" I based the build on was from a 400 small-block build in a magazine's article that I found on-line. Danged if I can remember the issue right now! Anyway, that build made 430 ft-lbs and 360 horses with iron wedge heads, and 530 ft-lbs 430 horses with modern aluminum heads. Their cam was a step bigger, so if I get the heads, this one should make that torque with a little less horsepower.

Then it probably will be "bye-bye T5."

 

I got my 400 fully assembled, for $500. I couldn't believe the luck, but since it was very low mileage since the build, and I saw what the guy had built to replace it (a 350), I started looking for what was wrong with it.

I found two things--

First, it had a cam that was pretty strange. When I degreed it, I found it was WAY too big for the compression he had (about 8.5:1). As I recall, it degreed out to 270/274 @ 0.050 and 300/309 advertised (measured @ 0.004"). Definitely an "old school" grind with slow ramps.

Second, when I drained the oil, I saw that it was slightly used, obviously recently changed. But when I removed the oil filter, it was empty. Clean and dry. Hmmm..... I opened the main bearings, checked them visually, used some Plastigauge. They were fine. Almost like new. Then I opened a rod cap. Bingo! The rod bearings were seriously slammed on the top half. The engine had been run without oil pressure. Thankfully, it was brief. The rod journals miked out perfect, so I put in new rod bearings, checking with Plastigauge just to be sure. The cause of the oil pressure loss was the oil pump shaft had disconnected from the distributor shaft. Apparently, whoever assembled the motor before failed to firmly snap the locking sleeve together.

It'll never run without oil pressure again. On an '88 TBI, if the oil pressure drops, the fuel pump shuts off.

Anyway, for the price you got it, be sure to check EVERYTHING as you put it together!

 

If you are wanting to upgrade the heads, I would look at Dart Iron Eagle 180s. They flow better than GM Vortecs, have 2.02/1.60 valves, have a 180cc intake runner to keep your torque up, can be had with 64 or 72 cc kidney bean shaped chambers, and come setup for about .525" lift out of the box. They would be a great upgrade over your 416s.

I put 325 to the wheels with a pair of 180s on a 355 with a PRODUCTION LT4 camshaft.

 

I also want to put a 400 in my 83 trans am. Does it bolt in or do you need different mounts? If I do need new mounts where do I get them? Thanks

 

Bolts right in. You'll need a different flexplate/flywheel.