Pulled the plenum, now what?

Originally Posted by scholtmj

Vette Doctors did it in the 90's but I don't have any information on the specs from them.

You mean Kirchoffer did the work.

You are probably missing about 15-20 hp from a current 368. You have headers on the car?

[LGAFF]

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

[scholtmj]

Originally Posted by LGAFF

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

Have you done any plenums?

Jeff,
I didn't know Kirchoffer was part of the Vette Doctors... Should I assume the tuning could be improved as well?

I do have headers, Corsa, Samco intake hose and SLP blackwing intake.

Originally Posted by scholtmj

Have you done any plenums?

Jeff,
I didn't know Kirchoffer was part of the Vette Doctors... Should I assume the tuning could be improved as well?

I do have headers, Corsa, Samco intake hose and SLP blackwing intake.

He is not really part. Vette Drs farmed the LT5 work to him. Tune and porting could be improved.

[LGAFF]

I have done plenums......my dyno run was recently posted at 391(see LT5 sound), I have also done karterdon's, CCMANOS, and my own. I am working on another plenum for my car right now(the 90).

Plenums do not take as long as the IHs.

[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"

[Paul Workman]

There is some hp to be had, based on your pix. These are some "work in progress" shots I took last spring. I patterned them after Pete's and Mark H's work. (I guess it would be considered "modern" with regard to the porting for a 350 ci engine - lots of input from Pete n Marc n Ryan n Locobob n Lee)

Pete's ports are BIG, and Marc H said I really couldn't go too big, especially on the plenum. Tho I used a 36mm ball gauge to guide the burr, after drum sanding and then flapping, the snap gauge showed I was between 36.5 and 37mm throughout. Or, to put it another way, I had to trim the gaskets with a razor blade...



I extended the porting into the heads by coning the port to the base of the valve guides; almost 3". This shot is a primary(?) port, and the ball is a 36mm.



This is a primary port "in progress"...



And this is a secondary port after it too was coned to the valve guide and sanded.



From what I understand, most just port match the heads on a top end P&P. But, the transition is very abrupt that way! So, I did the math and came up with a bit over 2.75" "minimum" for a 33 to 36mm transition - which just fit the length of the head's runner up to the valve guide. So...It should be interesting to see what it makes on the dyno.

P.

[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.

[scholtmj]

Made some progress over the weekend. Pulled injectors, IH's, coil packs, alternator, compressor - ready to get to the starter and clean the V. I was surprised at the size of the secondary ports in the head. Compared with Jerry's gasket, they look slightly larger than 37mm.



Injector housing from the bottom:





Old fuel injectors:


"V" looks cleaner than I expected:


Should there be oil here?

[A26B]

Originally Posted by scholtmj

Made some progress over the weekend. Pulled injectors, IH's, coil packs, alternator, compressor - ready to get to the starter and clean the V. I was surprised at the size of the secondary ports in the head. Compared with Jerry's gasket, they look slightly larger than 37mm.

For reference, engine drawing show secondary port dia to be 36.54mm dia with a 30deg chamfer, which would make the dia slightly larger at the mating surface. Injector Housing gaskets are made with 36.5mm port size for all ports, primary & secondary.