Nick89TA

I picked up this 77 vette a few weeks ago, with a 350, single turbo, water injection, and auto trans. Here is a picture of the engine.



As of now, it is giving me a little trouble, like stalling on me when I hit the brakes. It also seems to lack a little power down low. I may try and convert this thing to a drawthrough TBI, possibly a blow-through TBI (Holley Pro-jection or commander 950). Or, I may just start saving up for an MPFI system... I'd appreciate your thoughts on how to make this thing a little quicker ;-) Thanks all!

No5.0

Check valve going to brakes working?

ATOMonkey

How often does the compressor wheel need to be replaced? I know that it doesn't like fuel hitting it.

JAYDUBB

Too many places to have vacuum leaks. I count 5...

1- carb mount
2- turbo inlet
3- compressor housing-to-backing plate area (maybe)
4- compressor discharge
5- plenum at intake manifold

And thats just the inlet track!

Not to mention intake manifold gaskets, vacuum lines, etc.

Is the power valve ruptured?

What did you pay for this car? Maybe the previous owner let it go for cheap due to the problems youre having.

Give you some advice...

Leave the turbo where it is. Rotate the compressor housing and point the discharge and point it up or at about 10:30 (45 degree to the left). Mount the carb on the manifold (after you get it rebuilt and modified for blow-through). Fabricate an intercooler setup and install it on the car. Go have fun with it.

If you dont have room for the above mentioned setup then point the compressor at 2:30 (45 degree to the right), get one of those Paxton carb enclosures (or Vortech), run a tube from the turbo to the carb enclosure, get it tuned, and have fun.

Draw-through-carb setups went out in the early eighties, right along with break-dancing, poppin and lockin!

LOLOLOLOL!!!

Nick89TA

To tell you the truth, I have no idea. I got the car about a month ago. The turbo on the car is an old rajay 300 EE i beleive. I hear these are good to about 350 horse, so I think I may be in the market for a new turbo that can handle the power when I do a head/cam swap.

Jaydubb, I was actually thinking the exact same thing, because that way i can run an intercooler, and not spray fuel through my turbo. I know this isn't an ideal turbo setup, but I thought it was a good starting point. My current carb is an 800 cfm holley 4011(spread bore) I know I have to install nitropyhl floats for blowthrough, is there anything else i need to do to the carb? Thanks

Jester

Thats a pretty slick setup....very nice.

There is nothing wrong witha drawthrough systems. They're not hard on the turbo, the carb, or anything moreso than a normal boosted setup. The only problem is no intercooler, and blowing PV's ocationally. I know a guy that has been running one on his daily driver for 10 years with hardly any problems.

I would leave the setup alone. Maybe update the Holley a bit...that thing is ancient. Maybe replace the turbo with a bigger one if you need to.

As for your problem, check on the checkvalve for the power brakes..I don't see one in the pictures. might wanna run the brake line (if thats what I'm seeing) to a port on the manifold instead of on the carb.

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"American made baby. 100% American iron. The muscle among the masses. My hero. Yep, you can take your ergonomically designed, space age, computer controlled, 4 door, cup holding map lighted split double wishbone split fold down retractable cargo covered moon roof piece of transportation and keep it. For I have felt the thunder. And I know the difference!"
JSP Motorsports
ICON Motorsports

JAYDUBB

Call Brad Urban at the "Carb Shop" in Ontario, California. They may be on the pricey side but they know their doo-doo and their stuff works!

Ummm... Jester? Buick, Chevy, Pontiac, and Ford gave up on draw-through-carb turbo setups. Nuff said...

PS... Does anyone even make a draw-through-anything setup anymore? How about Gale Banks?I dont think so. Hell, the Europeans dont even do that anymore. And screw the Japs!!!

fast86

Yes, You break problem is becasue there is no check valve in your break vacum line.

I have a simlar system for my car but I got ride of the car. So if anyone wants a turbo system like above for any small block chevy cars. You can by mine for 800firm. All stainless steel pipes and adapters! And a stainless Steel Down Pipe and Crossover!
Let me know!

Jester

They didn't give up on draw through systems, they gave up on carbs period. They stopped making draw throughs when they went to fuel injection.

No OEM company (to my knowledge) ever made a blow through setup.

No one aftermarket company ever made a blowthrough turbo system either. There were supercharged ones..but I'm not sure those are made anymore either.



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"American made baby. 100% American iron. The muscle among the masses. My hero. Yep, you can take your ergonomically designed, space age, computer controlled, 4 door, cup holding map lighted split double wishbone split fold down retractable cargo covered moon roof piece of transportation and keep it. For I have felt the thunder. And I know the difference!"
JSP Motorsports
ICON Motorsports

Guido

Fast 86, Do you have any photos of the header section of your system? Im interested in seeing how it looks. Not so much purchasing but looking.

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-86 IROC
11.31 @ 120.2 mph
-=ICON Motorsports=-

fast86

Guido,
I don't have any pic's. I can try to get some! The way it set up is the one Passager side has a stock cast iron manifold and on the drive side there is the cast iron manifold turbo. And there is a Chromed Stainless steel pipe (Like a U) that runs under the car and attacts the to togther.
The one thing that I like about this kit is that the Cast iron manifolds seal So Nuch better then those steel headers. And they it's Very heard to crack the cast iron exhaust manifold unlike the Heads as well!
Turbo is E10 type which flow 900fcm so it's good to 500rwh.

Nick89TA

Thanks for the info fast86. I know this may seem like a dumb question, but where would I get a check valve, and how would I go about installing it?

As for pictures of the exhaust set-up Guido, here is the picture of the U-tube I have under my car, it sounds pretty similar to the system fast 86 is describing

JAYDUBB

Thank god!!

Well, there were plenty of blow through setups made by the factory. They just werent carbed. Oh BTW, Chryslers early turbo cars(Lancers, Daytonas, Omnis) were draw through, but with EFI instead of carbs.

Gale Banks used to make a blow through carb turbo setup for our beloved 3rd gen. And most supercharger companies sell supercharger kits that are no where near as difficult to install as a turbo "kit". Oh... all of the centrifugal blower kits are blow-through kits. Both the carb and the EFI kits are blow-through. I dont think Paxton, ATI, Vortech, or Powerdyne would be foolish enough to try a draw-through carb setup these days.



[This message has been edited by JAYDUBB (edited August 14, 2001).]

JAYDUBB

Does it idle fine before you hit the brakes? Do you have a vacuum gauge? If so, what is the reading before and after you apply the brakes?

Personally, being a car AND a diesel truck mechanic, I think you have a vacuum leak. The check valve is only there so that in the event the engine cuts off, you can still stop the car with some vacuum assist. The check valve holds a little vacuum in the booster so that you can stop the car. Unless the check valve is physically cracked on the exterior, I dont see this being the problem.

Since you say that the car is already running like crap, I'm willing to bet my money that the problem is one of the following;

1- Huge vacuum leak (like I mentioned in my first post).
2- Poor state of tune.
3- Carburetor is shot.
4- Low compression(?).
5- Any combination of, or all of the above.

First, I'd check for any vacuum leaks. Then I'd do a compression test and a leak down test. Then I'd tune it up and get the carb rebuilt. Hell, the carb may have a blown power valve! One hiccup and...

Stop going with guesses. Time to get your hands dirty!

Nick89TA

Well said JAYDUBB! After takin my friggin MCATs this weekend I will be a free man, and I'll be able to get nice and comfy with my tool set and a can of GUMOUT

JAYDUBB

LOL!

JERRYWHO

You found a old martin turbo kit. The strange thing is on that set up is the reed type valves under the carb to bypass the turbo at low speed and than flap shut under boost.

Please let me know if it has them.

Jerry

Nick89TA

Yeah, I have spoken to somebody else about the kit, and they told me about those valves too. I haven't taken the carb off yet, I may do that this winter. I have heard that the opening/closing of those valves can be modified with some springs...
mmmmm, more boost...

Nick

Lionsden

My brother had one of these on a 78 Corvette. The system really worked nice. Sounds like you need to go the tune up route like others here have mentioned.

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Dan

crazeinc

fast, I'm kinda interested in your turbo kit. I'm a little hesistant on the price though with the performance that these guys are talking about, but maybe you can convience me differently. Possibly a trade + cash or something. Let me know and pictures as well if you have them.

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1990 GTA
-355 carb'd, nicely reworked '64 vette heads, 2500 stall, 4.10's, other small things.
-Alston SFC's, Eibach Pro-kit, Koni's all around
-100+ nitrous shot
-Cruising in style with leather and nice stereo.