“While I’m this far….?”

Another update:

On the stock valve covers, I had to do a lot of material removal on the inside & pinched the breathers to get them to fit. I only tightened the valve cover center bolts to 5nm instead of the 8 or 9nm torque spec because of all the material I removed, to be safe.
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I had a break in the AC bracket & used the Alumaweld from Harbor Freight to fix it, worked well. The red line is roughly where the crack was at before hand.
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Porting & polishing was done from the throttle body all the way into the head an inch or two. Since it was the original TPI intake & heads, the goal was to clean it up, get rid of any blockage & straighten the air flow in the intake base a little bit through porting.
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I also opened up these gaskets some to match the porting I had done.
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Here you can see how well the plenum to runner tubes fit.
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I didn’t go too far into the head since they weren’t removed but gasket matched it an inch or two in.
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Intake side was in need of porting to match the gasket. The pic shows how off things were on the original casting before any porting.
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At the bottom of the plenum’s entrance ports one can see the finished product.
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Before:
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She came together nicely, thankfully I had bagged & tagged everything.
I guessed at the timing, distributor positioning & was close enough that she started just fine. I had no speedometer & found it to be the VSS (vehicle speed sensor). I had to use one from a 92 Corvette & change the plug, it worked perfectly. I put 75 miles on her then decided to check the timing. It wasn’t as close as I thought, it was -4 degrees retarded. Stock timing is 6 degrees advanced so 10 degrees in total she was off. Once the timing was fixed I also replaced the IAC.
I took her out & she honestly surprised me for how well she was now running with the timing correctly set, dramatic improvement. She’s running very strong now & I’m going to look at getting a performance PROM for her next.

One last thing, I went with 5w30 Synthetic oil & oil pressure actually look good even with the cam bearing wear I found. However I plan on changing to 5w40 Synthetic because I’m not going to be able to keep my foot out of it now!
 
thanks for the update and posted pictures, the pictures look like you've improved the intake air flow from stock ,
and should as you suggested see some benefits,
chevy did a decent job designing the tuned port intake but it was designed for a 305 displacement,
and they never changed , the runner or port size when they installed the TPI on the 350, so the ports and runners are restrictive.
increased air flow rates mandate increased fuel, so larger injectors , and a better fuel pump might be required to gain the full potential benefits,
and of course a restrictive stock exhaust can make much of the potential gains very difficult to achieve.
theres a good deal of related info linked below to read through,
info you can use, but keep in mind every choice is a compromise,

and while you can easily double the stock hp/tq, its not dirt cheap to do.




http://garage.grumpysperformance.co...ive-are-the-stock-tpi-engine-components.1509/

http://garage.grumpysperformance.com/index.php?threads/c4-corvettes-fuel-system-info.67/#post-37351

http://forum.grumpysperformance.com/viewtopic.php?f=32&t=1401&p=8895&hilit=start+sequence#p8895


http://garage.grumpysperformance.co...ey-grumpy-do-i-need-bigger-injectors.5583/#po

http://garage.grumpysperformance.com/index.php?threads/calculate-fuel-injector-size.1200/#post-4041

http://garage.grumpysperformance.co...easonably-effective-tpi-combo.1060/#post-2031

http://garage.grumpysperformance.co...-other-efi-intake-manifold-info.431/#post-530


http://garage.grumpysperformance.com/index.php?threads/ideal-tpi-build.12203/#post-76070

http://garage.grumpysperformance.co...-stock-tpi-engine-components.1509/#post-74581

http://garage.grumpysperformance.co...rger-intake-runners-l98-tpi.13785/#post-72541

http://garage.grumpysperformance.co...lay-switch-locations-and-info.728/#post-66935
 
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I hear ya on that slippery slope of more & more mods & naturally how it all must work together to get the most from it and it’s not cheap either! I have always loved the look of the TPI even though it’s long runners kill power over about 5k. Therefore knowing I wanted to keep the TPI intake I made only a few changes & chose the mild TPIS cam; 220/220 duration & .427/.427 lift w/112 lsa). The addition of the 1.6 rockers brings the lift up to .456/.456 intake & exhaust, so a nice bump over the factory cam.

I still have other things I can do to help improve performance from here; get a performance PROM, headers & exhaust work, relocate the intake air Temp sensor, cut MAF sensor screen out, & install an adjustable fuel pressure regulator for tuning. I probably should have just pulled the heads when I was as far into her as I was to do full head porting, a valve job & install a thinner head gasket. However I was getting tired of working on her & opted to save that for a possible future 383 build.

I would also like to remove the air pump & egr system as it would definitely clean up the mess of clutter on the engine but I really don’t like the look of the aftermarket air pump replacement pulley setup. One thing I still am searching for an answer on is how much more can I go with the static timing, beyond the factory recommended 6 degrees of advance?
 
from experience Id suggest you don't exceed about 8 degrees advance, at idle, and take the time to accurately map, your ignition timing curve,
and verify TDC is accurate. its the air and exhaust flow, injector size temp sensor accuracy, not the initial 6-8 degree advance that much more important to the power curve,
your total advance will need to be modified and checked, and generally falls in the 34-37 degree range and needs to be all in by about 3200-3800 rpm, this obviously varies with the combo used. fuel octane, cylinder head design, and use of aluminum, or cast iron, coolant temp, air temp, oil temp, even spark plugs used and the gap set, all effect the engines ideal ignition advance

chart3e1.jpg





 
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