[Rafe LORHO]

Hello everyone and a little "bonjour" from France.
It's been a while since I last wrote something on this forum.
I have been busy nevertheless, putting together my '77 Bandit Trans Am.
Here's the engine build-up:
403 block (reworked with oil restrictors etc…)
330 steel crank
Custom flat top ROSS pistons
Reworked 4A heads – ported, polished, crossover filled etc…
ENGLE JM 22-25-10 camshaft driven by a gear drive and pushing roller rockers
OFFENHAUSER 360° inlet manifold
HOLLEY 4 barrel projection
HEI with 50000 volt coil (yes the HEI fits the OFFY – with a couple of mm ground off the back of the manifold)
Headers running into 3" PYPES dual exhaust

After completion, the motor fired up but ran very badly. It seemed that the compression was way too high for normal fuel. The compression readings were all in the 200 to 225 psi range. Only certain cylinders wanted to work and the spark plugs were getting fouled up on the non-working cylinders. It wasn't very easy to see which cylinder would work as they all seemed to stop after a certain time… only coming back to life after changing the plug. (By the way, the No. 4 cylinder seemed never to work and its partner, the No. 3, had a lot of trouble as well.)

Having not had much success getting it to work, even after changing the spark plugs for platinum tipped ones (I have a lot of experience with small turbo charged European engines so I know what it takes to make it burn under pressure!), I took the reluctant decision to lower the compression ratio of the engine. The heads were taken off and I reworked the combustion chambers.
The resulting compression of the engine is now exactly 160psi on all the cylinders. Each combustion chamber is now 95cc.
However, the engine still doesn't want to run properly – merde!!
Please take note that there are no engine workshops in my part of the world like you have in the States. So asking for a flow test or other operations on a V8 is met with a blanc expression! They weren’t even able to re-bore the block so I could use off the shelf pistons – hence the custom pistons made to fit the existing bores. Luckily, the block was not worn.


So here's the problem:
The engine fires on the back 4 cylinders only (cylinders 5, 6, 7 and 8) while idling.
There is no acceleration when you open the throttle and you have to pump it to get up in the revs.
Cylinders No. 1 and 2 will run from time to time judging by the colour of the plugs but they seem to foul up nevertheless.
Cylinder No. 3 and 4 just don't work, period! No matter what plug I use, it comes out clean. The tops of the pistons are still shiny when you look through the plug hole.
When the engine is running, I get horrible back fires through the inlet manifold below 2500rpm. As the revs increase (above 3000rpm) the engine will run a little better and can go up to 5500 to 6000rpm but there isn't really that much power.

The engine was set up with a clock gauge – everything is spot on:
Cam adjusted to 8° before TDC as in the ENGLE specs.
Ignition at 35° mechanical advance with 15° vacuum advance to give 50° at half throttle/under load. (I've tried a range of settings at WOT from 30° to 39° but it makes no difference while I can't get all 8 to fire!!)
It goes without saying that the spark plug wires are all new and have been permutated from working cylinders to non working cylinders just to see – no change as far as the non working cylinders are concerned. As I have said before, I've tried just about every type of spark plug available.

As for the fuel, I've run it lean, run it rich, high fuel pressure, low fuel pressure etc… The back 4 cylinders can be burning perfectly and the front ones still won't work.

One thing that is strange is that I've very little intake vacuum – not even enough for the power brakes. (I had to add a vacuum pump to get back my brakes!)
Now the ENGLE cam was sold as a "hot muscle car cam" "good power and torque" "recommended for power brakes". However, the lack of vacuum was noticeable even before I redid the heads for the second time.

Is it the OFFY manifold at fault? (Of course there are no leaks – I'm not that dumb!)
Would a more conventional dual plane 180° manifold be needed?

Has anyone ever had the same problems?

Please help me.

Thanks,
Rafe