Pulled the plenum, now what?

[scholtmj]

Pulled the plenum for the first time with the intent to replace the coils, spark plug wires, spark plugs, starter, serp. belt and fuel injectors (FIC). My car has an idle around 1k rpm and it spits black soot out the pipes (and on to the back bumper) even when driving around with modest foot control.

Some observations:
1. Strong smell of gas
2. Air box to IH hoses are VERY hard
3. Plenum runners and IH's are NOT ported
4. All vacuum lines have hose clamps or zip ties installed (Vette Doctors most likely)
5. Secondaries move but I'm not sure I'd call it 'freely'
6. Pretty dirty for only 17k miles!

Some questions:
1. How much HP will I pick up by porting the top end on a 368 motor?
2. What's the part # for IH fuel injector gaskets?
3. Is there anything else I should replace while I'm in there?

[ittlfly]

I'm just courious about the strong smell of gas, black soot etc... did you happen to use a scanner to check your O2's readings before you tore it down? I'm just wondering if they are scewed to the lean side or not even working properly. Just a thought.

[tccrab]

Looks like original Multec fuel injectors. Suspect the smell and soot is a injector stuck open.
Were any of the plugs fouled?

Really surprised that a 368 didn't have at least port matching.


Did the previous owner live on a dirt road?
It's remarkably dirty under there.
My '90 with 11k miles looks almost new by comparison.

TomC
"Crabs"

[scholtmj]

Originally Posted by tccrab

Looks like original Multec fuel injectors. Suspect the smell and soot is a injector stuck open.
Were any of the plugs fouled?

Really surprised that a 368 didn't have at least port matching.


Did the previous owner live on a dirt road?
It's remarkably dirty under there.
My '90 with 11k miles looks almost new by comparison.

TomC
"Crabs"

I'm glad your motor looks new! Your pictures are going to help me put everything back where it's suppose to go when I'm done!

None of the plugs where fouled but they looked pretty dark. The first owner autocrossed this car for 14k miles in Michigan (best roads in the USA!), the second owner was an older guy who didn't care much for cleaning...I'm just getting started.

I don't think soot would be a byproduct of a lean condition, more due to running rich which points to bad fuel injectors. I don't have a scanner to check the O2 codes but I didn't have a check engine light on either.

[ittlfly]

ie: If there was a vacuum leak, the exhaust gases would be scewed to the lean side. The O2's would report that condition to the ECM which in turn would fatten up the A/F mixture causing a rich condition.

[scholtmj]

Originally Posted by ittlfly

ie: If there was a vacuum leak, the exhaust gases would be scewed to the lean side. The O2's would report that condition to the ECM which in turn would fatten up the A/F mixture causing a rich condition.

Ah, I see what you meant.

Pictures of ports with Jerry's gasket for reference:

[tccrab]

Originally Posted by scholtmj

I'm glad your motor looks new! Your pictures are going to help me put everything back where it's suppose to go when I'm done!

Under the plenum:

Close up:

Plenum with Jerry's gasket:

Injector housing with Jerry's gasket:

I'm not seeing very much difference in size between your ports and mine.
But on mine there is clearly a casting ridge inside the injector housing that doesn't appear in yours. It doesn't look like they removed much material, just polished out the rough stuff.
I would bet there's a good 25-50hp waiting to be discovered in your top end.

Your Cam covers look much better than mine. Mine are getting darker and darker.
This winter I'm sending the top end up to JeffVette for a P&P & powder coating, in his bright sliver. Was going to do it this last winter, but replacing the transmission ate up last years upgrade budget. I had the 2nd gear synchro catastrophically fail, it was cheaper to replace than to rebuild. *sigh*



TomC
"Crabs"

[scholtmj]

Originally Posted by tccrab

Under the plenum:

Your Cam covers look much better than mine. Mine are getting darker and darker.
This winter I'm sending the top end up to JeffVette for a P&P & powder coating, in his bright sliver.
TomC
"Crabs"

My cam covers are actually polished (just very dirty like the rest of the motor). It makes sense to get the top end re-ported and up to date so I'll do that while it's apart.

Can you get a better shot of the injector housing and plenum ports?

[LGAFF]

I have a set of IHs ported to 36MM if interested, they are ready to go on an exchange basis.....