Bruce Charles

Got a question for the experts. I'm building my first LT-1 and all is going well until I realize that the "vent" tube from the back of each head is clogged completely closed. Previous owner mixed Dexcool A/F with Prestone and got MUD. Banjo bolts are beyond repair. I have looked everywhere and it seems that General Motors has deemed this an "obsolete part". Is this tube necessary for normal operation? If it is, is there anywhere it can be found? - I would need the tube assy, seals and banjo bolts. I have completely rebuilt the engine, had the radiator rodded and flushed, flushed the heater core as well as I could with it still in the car. I want to do this right, but if it isn't needed I would be more than happy to leave it off. I'm not going to race this car (at the strip), it will really be more of a weekend cruiser. I would also like some suggestions on fuel system upgrades. I upgraded the Cam slightly from stock and added beehive springs, roller rocker arms, melling oil pump with 25% higher output and some shorty headers. Should I step up the fuel injectors and/or throttle body? I want to continue to operate on 93 octane pump gas, and keep the cost reasonable.

Injuneer

Strongly recommended that you install the steam pipe from the back of the heads. It allows you to get trapped air out of the system (air + Dex-Cool = sludge) and keeps the rear-most cylinders from experiencing hot spots on the heads and possibly detonating.

Some people have converted that line to -AN fittings and braided S/S line.

Check Shoebox's site for part numbers. I know he has the seals on there. Not sure about the tube and banjo bolts.

slick1hunting

I couldn't find banjo bolts for it either but mine were still able to be cleaned up and used. As said above you should keep it in operation. I almost went the braided lines myself but my parts were usable. There are writeups on the conversion if you search. There were a few people who pluggged them off running around too saying they hadn't had problems and I will add a yet to that. One person used a high temp rubber hose but I was leary about that myself. Could always check a few salvage yards and ebay. Ebay had a couple listings back when I was checking around.


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shoebox

You could easily convert it to the 95+ steam pipe assy that is still available from GM with all the seals and bolts. Hawks Third Gen has the bolts and seals.

slick1hunting

^^^^ the price there was comparable to what I had saw on ebay last year. As for the other questions you may want to add the specs of your cam and if you are planning on having the pcm re tuned. I will leave it to more experienced people if bigger will help with the tb and injectors but will say good flowing injectors do make things run better so getting yours cleaned may well be worth the expense. The tb I would steer away from the aftermarket if you go bigger and get a ported stock one because the aftermarket doesnt use the iac passages like the stock unit without modification. Many people dont notice but its proba ly because they are not monitering the data and since it idles ok and runs fine are none the wiser. When you moniter the data you can see large fuel corrections and often big splits in fuel corrections. Much of that can be tuned out but it usually takes changing the tune at least a couple times. Fuel system upgrades - my guess you are still ok but a common one is the racetronix with hotwire kit (thats what I did). If you do change out the pump I am a fan of cutting the trap door.


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slick1hunting

I am far from an expert more like know enough to know I dont know enough. The other two guys know there stuff. I forgot to ask what brand roller rockers you went with(and ratio) and if you provide your cam specs might include what ratio its based upon. The reason I ask on the rockers is because I found out the ones the guy who built my motor put on are often reported with failures(proform).


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Bruce Charles

Thanks for the info...The only reason I was considering replacing the injectors and TB is because of mileage - (160K). Are there rebuild kits available for the stock TB? Where can I get my fuel injectors cleaned? Since I upgraded the cam and springs, I just assumed that I would have to have the pcm re-programmed. I have been rebuilding engines for a while, (mostly diesels) - this is my first fuel inj. gasoline motor - and it's mine.

Bruce Charles

Don't have the cam specs on me, but it is a Comp Cam with Comp stamped roller tip rocker arms

slick1hunting

Hopefully others can give you insight if bumping up the injector size and tb size would benefit you over stock( thats why I asked on cam specs a generization may be helpful like very similar to hotcam). The guesstimated hp level would help point to injector size increase or not (plus if you plan on anything in the future like port the heads). I am guessing the power level might dictate weather porting your tb or getting a ported tb would be beneficial. I would assume you could get rebuild parts but dont know and also dont know what if any parts are prone to wear or failure.. Cleaning injectors can be done at various places with a couple different methods but if it were mine I would mail them off to one of the places that really checks them out. An online search for that will yield a couple of the big players and their service. Since you do plan to reflash the pcm(good choice) having bigger injectors may be a better choice. Good luck and hopefully someone can give a more definative answer than I.


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englundjd

can you go on comp cams website and link us the cam you have? most likely wont need to get new injectors or a bigger throttle body if the cam is mild as you say. With any upgrade past bolt-ons you need to get a tune. some will argue that a tune is nessesary with headers.

does your car have an aftermarket catback? that would gain you horsepower and really help the car breath with that new cam

is your car an auto or manual transmission? stock rear gears?

if your car has stock gears then you could look into swapping in some 3.73's (auto) or 4.10's (manual) ... they will give you a good boost in performance

also if auto, a good 2800-3600 rpm stall would get you off the line quicker.