If anyone is wanting to tuck an inside computer under the hood, a trailer weather proof battery box is a slick way to mount it and protect it. The come in a lot of sizes, and the medium sized ones could be tucked back under the fender where either the overflow tank is or the washer tank is. They make new smaller, trick looking bottle to replace those with anyway.

 

I have roller rockers installed under my powder coated L82 valve covers. They only needed to have the drippers cut off.

 

Is there a common clearance problem? My roller rockers fit fine under stock LT1 center bolt valve covers.

 

Well it has been Almost three full months with the TPI in the Corvette. I'm still very happy with it.
I have about 300 miles on it since the Swap, and have had no major issues. The low end torque is alot of fun. The City fuel milage has been an average 14.02 mpg. I havent taken it on any highway runs of significance to get an accurate measurement of Highway mpg.
The only glitch I have found is that when accelerating very hard I sometimes will get a check engine light, and trouble code
I haven't found the cause, but I think it may be a faulty module that controls the ignition timing when detonation is detected, or it is a faulty wire to the Knock sensor. I'll figure it out and post my findings.

DR.Jay

 

That used to happen to a buddy's truck, a TBI truck. He had it checked out and it was an EGR code. He was thinking it had something to do with the EGR system was not getting good readings when the throttle was too far open.

I always suspected an O2 sensor, but I think if you read your codes you'll have a better understanding.

 

I've put my Snapon scanner on it, and it's the same code every time it happens. The code the scanner reads indicates the problem has something to do with the Knock sensor,or Electronic Spark Control module.
During road tests with the scanner plugged in I can't get the car to act up, and doing all the tests for troubleshooting everything checks out fine.

I think I'll replace the module with a new unit since the one in the car is 20 years old, and who knows what it has been through.
Hopefully it will cure the problem, if not I'll just live with it, as it is more of an annoyance issue at this point.

 

DrJ, I find you fuel economy rather disappointing, when I installed a stock TPI on my original L48 some 12 years ago the car doubled it fuel economy....literally with the muncie and 336 rear it got 24 on highway, cruising at 4000 rpms...80 mph..... and around town got an easy 18-20.....

now with a more hotrod roller engine, and still only 355 ci....the thing with overdrive automatic gets about 14 or so around town....not too pleasing......what sort of engine you have under your TPI??

especially the cam....I have a ZZ9 TPIS cam....

 

Off hand that would seem a good idea, but it's not....reason is because of condensation, the moisture would be very hard to block on a home built basis.....which is why I like computers inside the pass compt....

need to breath, you get temp inversions and high humidity in that box and it's got no where to go....

 

Did you ever figure out anything with the air filter?

I'm putting a speed density TPI set-up on mine and I'm thinking about going with just a conical K&N filter mounted directly to the throttle body but I heard they were kind of noisy.

Then I seen this cold air set-up on TPIparts.com's website and was wondering if there was enough room to mount this securely.

 

Just a shot in the dark, could putting too much teflon tape on the knock sensor alter its performance and cause your trouble code? If you used too much teflon tape you may have insulated it too much from actual knock. Some folks will do this intentionally to isolate a hopped up motor from "hearing" false knock from headers, big cams, and roller rockers. I know they can also be sensitive to the correct installation torque. If it's torqued to tight, it can give erroneous - too much - knock count.
The replacement knock sensor on my Impala SS came with a dab of teflon sealer on the threads so I couldn't mess it up.

 

I was disappointed with the milage also, but the figure I gave was for around town milage, and I was enjoying the new found bottom end alot.
On the most recent fill up with me not driving it so hard, and mostly mixed driving city/highway. I filled up 10.23gal @ $3.03 a gallon for 93 octane, and drove 205 miles since last fill up:
205miles/10.23 gallons used= 20.03 miles per gallon or .0499 gallons of fuel used per mile = $0.151 per mile sorry i was on a role.

The second thing is that i'm not sure what work has been done to the engine. It is not origional. it is a 350ci 4 bolt main block out of a '79 1 ton and up truck. When I bought the car the previous owner told me the engine only had about 2000 miles on it since it was rebuilt. It seems to have a non stock cam in it from the lumpy idle it has, but I could be wrong. I also have larger injectors in it (the stock 305 ci are 19lbhr) to compensate for the extra displacement, but that shouldn't matter since the ECM regulates fuel flow based on load.

My best highway milage withgout digging up reciepts for the carb was I think just short of 18mpg, and the worst was around 13mpg.
I am also thinking that some of the improvement might be the summer fuel formula, but what do I know?

 

Sorry to reply so late, but post #72 in this thread is where I explained what I did for the air filter, it isn't pretty, but it works, and that is what counts. I'm not sure if the one from TPI parts would work or not.
Are you going to use an electric fan or mechanical? I think clearance might be an issue with the mechanical fan, and a cone filter, but im sure some of the others will chime in.

 

Some time ago Matt/DB sold me a rubber flex/corrugated hose for my TPI TB into a 3.5 inch round input....I found a pipe just recently that was 3.5 inches and bent 45* so for up over....and got some time ago a kit from a hotrod shop for two aircleaners into a Y pipe of 3.5 inch diameter....so upon getting that up/over 45* pipe just this afternoon, it's all installed.....I had cut the rad support right in front of the input so it's ~2" offset to pass side....I also had to oval the over top tube and cut it to fit the air cleaners/housing/tube.....

so far, it's in there and working....NOW, having said all that....I have a grafted on BB hood scoop and so was free to cut out the under hood plastic for clearance....in fact, i'ts about all cut out....so have a huge opening for air to rise through.....

TOTALLY UNCOOL if a rad hose EVER busts......

instant death on the windshield.....ask me how I know....been some 30 years, but it did happen to me LONG time ago....in a land far far away...

 

MrVette - Do you have any pics of that setup you can post? I'm curious how you used all that stuff and what you made.

 

No problem,

I actually ended up going with a 90-92 speed density set-up so after it was said and done I went with one of those K & N conical breathers.

I have a dual spal fan set-up, no mech fan plenty of elbow room now.

I do have one question....what did you do for the throttle cable? I bought a TPI f-body cable but the end that connects to the firewall is a little bigger in size so that means I'll have to enlarge the factory opening some. Plus the cable is a little too long, it will still work, just will be curled a bit in the engine compartment.

One more question, did you re-use the stock upper radiator hose? The TPI set-up puts the thermostat housing at a weird angle and the stock hose is a little too long. I'm thinking of trimming it.

I bought a steel braided flexible hose but it's a hair too short and the huge clamp covers look funny on the short tpi thermostat neck....it's a little too small for the hose too begin with and I'm afraid it'll leak.

 

1) I used the throttle cable off the '87 camaro. I trimmed the cable to fit the hole, and rivited it to the fire wall. I did this since if If I ever had to go back to carb I wouldn't have to repair the fire wall.

2)I used the upper radiator hose from a '87 Camaro with a 350 ci engine. The 305 uses a different hose that will not have the proper bends. The problem that you then run into is that the stock Vette radiator upper inlet fitting is to large. So I used the new radiator out of the donor Camaro, and fabbed up a lower hose using the orrigional lower Vette hose, and the lower Camaro hose, and a splice to get the angles correct.


I can post pics if you need of the cable, and hoses if you need, and even part numbers. Just send a PM to me before 10am CDT as I will be Going to a Memorial Day Event/ WWII reenactment for the weekend.

 

Hey Thanks for the reply, I would like to see a close-up of how you riveted the cable to the firewall. I didn't think of that.

I don't think I'll be able to use the camaro radiator hose, I just bought a new aluminum radiator. I think I'll try to figure something out on a flexible hose from autozone. I wanted to try and get my car fired up this weekend.

 

double post

 

I used the same thing when i did my tpi but didnt rivet it just filed it and snapped it into place but used a upper 96 caprice radiator hose and trimmed it and fit fine.
And when i removed it from my 73 and installed it in a 80 vette i did the same thing and fit fine.

 

I used a '90 C4 cable. The sheath was the right length, but I had to shorten the cable with a hood cable stop. I have an F-body cable in my truck, but it is really long. I used an '88 TBI cable in another project and it looks like it would be about right for a C3.

On mine I used an '89 IROC upper hose and I have a Griffin radiator. I do have C4 serpentine belt setup. I used that on my truck as well and it worked well. On another project I used a '77 Pontiac hose. You can go to a good auto parts store and peruse their hose selection if you ask nicely sometimes.