I don't believe break in had anything to do with it. If it isn't broke in within about 10 minutes it's never gonna be. From what you've listed it appears that the new engine has just plain old heads on it...not even as good as the old Vortec's?

The cam has a good bit of duration...but who knows if it even has 8.0 compression? If not..then the cam isn't helping low end at all..along with the heads.


A true 300HP 350 will spin the tires for sure..but again..those gears are going to want to go 6500+ rpm and that 300HP 350 isn't going to be happy up there. I'm assuming it's a hyd flat tappet also?


JIM

 

Isn't a 4:56 rear end good for about a blocks worth of Corvette use? Would it even be good on the latter parts of a quarter mile strip run given the rpm limits of the engine?

After or while you are fixing the engine issues you might want to consider putting a different rear end ratio in that thing unless one or two block runs of the car is your thing.

If 4:56 wont spin the tires, there sure are other issues. I think my stock L48 four speed with a 4:56 would melt the tread off the tires versus my 3:36 rear end which I'm actually much happier with as I drive it on the highways.

lance

 

I do not even clain to know what parts work and do not which is the reason i went to a shop to build it. They are the professionals and i valued their opinion. The same can be said when someone brings me the specs they want on their new computer. One of my techs will discuss with the customer what the end goal of the machine is and taylor the system around those needs.

 

So could my problem be the gears and stall? Should i go back to 2.73 ? and stock stall? Could this be my whole problem? If that is the case i know i cannot just buy a ring and pinion 2.73 i need the whole rear end. I bought this one out of a 67 for my old one and $100 to put it in.

southern indiana is alot of cornfields and dragracing not much in between(almost literally).Medium expressway driving(just to a show) and maybe fun at chandler speedway (test and tune only)........That is the whole purpose of this never ending project.

Btw when i do need to get a new rear end whomever wants it can have the old one with the 4.56's (local pickup)

 

If you really want to have a nasty quick and fun little street toy, you're going to have to go into that engine. That's a 14 sec at best....15 sec usually engine. High 13's if you have everything perfect. That means all your old stuff will walk away from it no matter what. A 350 can go pretty good..but it needs compression, cam and heads to do it.

Know anyone that needs a nice stock little engine and you can sell it to them and build another one? I know that sounds crazy at this point. If we stick with that one, we can do something with heads and cam to let it breathe. If the bottom end seems sound then let's just add some power to it. We'll have to be careful with the cast pistons and who knows what crank is in it.

You surely don't want to go to the 2.73's if quick acceleration is what you are after.

Do you have any hot rod buddies who can ck it over for tune? Like carb opening all the way (very common problem), timing curve, compression test etc?

JIM

 

Jim,

As dumb as this sounds if that is what i need to do that is what i will do......I work on computers Everyday ALLDAY and these cars are my release. I have never claimed to know what i was doing just enjoy doing what i can. fyi i picked up a 66 mustang GT Pics Here . Last year With a full out race engine (guy claimed 10sec car) which is just sitting in my ever expanding garage waiting for me to break(umm restore). I also have a 90Iroc,02 WS6,and 08 Aveo DD.

But corvettes come back to me from the long lost days in highschool. I always had posters on wall and dreamed i would have one. When i finally became successful enough in life to make that happened i jumped in head first and never looked back.

If i made a bad decision with Jasper 350/300hp then i will have it removed and find someone who can build an engine that will run. In all honesty i probably wouldnt know the difference between 300 and 450hp just wanting a fast launch and a 9sec 8th mile car. I know people said i could expect 13 or 4 so what do i need for 9sec 8th mile track not 1/4 as wendy hollow is bowling green which is the only close 1/4 mile track is a 2hour drive.

 

A 9.0 1/8th mile is barely a 14 flat 1/4 mile. You *could* do that with 300 real flywheel HP but that means no losses with manifolds, headers, water pump, accessories etc etc. I'm guessing your weight is in the 3400-3500 lb range with driver?

You could easily put together a 12 sec or even 11 sec very streetable Vette with the right motor combo. 10's gets pretty pricy and a little tougher to do with a smallblock.

I'd look into a 383-427" smallblock. We just did a Dart SHP 400" *crate* buildup where you buy the shortblock and heads you want and screw it together with the valvetrain you want. We dyno'd it and it made 540-555HP depending on intake we had on it and runs all day on 93 octane. The beauty of a deal like that is YOU get to screw it together and learn how it all works and the fancy machine work is all done.

There are quite a few ways to go...but the average crate motor is NOT going to be the fastest or most powerful. They are just put together like any other stock motor with a few upgrades. Having one built by someone who knows what they are doing can really make for some fun!

Either way..we can help you out. The current 350 isn't the end of the world, I just worry about longevity if we start making some real power. If 14 flat is all you need..then you already have something pretty close.


JIM

 

Discovered what i think is my main engine problem. The Holley 600 Street Avenger electric choke was somehow closing when car got hot and would cause it to die........after car would sit for hours choke would close and i could drive home.

 

God give me your vette for a month or so and 9000 bucks and I will build you a car that would scare the living crap out of you. LOL it will do a whole lot more then light the tires!

 

First, are you absolutely sure your trans is starting in first gear?

Second, given your past experience with having a shop build an engine from the parts bin, why not buy a factory crate engine complete with warranty?

I mean no disrespect with this statement but a lot of folks have suffered your same fate because they are in, as Jay Leno eloquently puts it, 'the more money than brains club.' There is a lot of bad advise floating around, even on this forum. You would do well to have a modicum of engine-building knowledge to glean the wheat from the chaff. Otherwise your past history is sure to repeat itself.

 

Many moons ago I experienced a couple situations similar to the one you're in now...it sounds to me by the number of cars that you have that you have the room AND the $$$ to rebuild an engine at home. After experiencing a couple of these disasters myself at the hands of unsavory, unscrupulous jerks who were taking every dollar I threw at them and laughing their asses off as soon as I was out of earshot I decided to attempt rebuilding an engine myself. It ran better and cost WAY less than anything I ever paid anybody else for and best of all I understood everything about why it did what it did, good OR bad. I'm not an expert now by any means but at least I have armed myself with enough information to keep from getting ripped off, and by the sound of this thread these guys can see you coming a mile away. My best advice to you is to put some of the intelligence to work that you used to learn so much about computers and commit yourself to fixing this problem yourself-go buy an engine hoist ($200 max), a stand ($50 max), a torque wrench, ring compressor, and a few other tools, then pick up "How to Rebuild" and "How to Hotrod" Your Small Block Chevy, read them both, and GET TO WORK. As long as you insist on giving away your money in order to solve your problem (Lack of knowledge)you're just going to find yourself broke...my $1.380

 

Expanding a little on what 427 Hotrod was saying: Using the common conversion factor of (1/4 mile ET / 1.58) = 1/8 mile ET, you need to be capable of 14.22 in the quarter to run 9.0 in the eighth mile. If you have 300 hp, 4.56 gears and 2,600 rpm stall converter, all you might need is a little set of drag radials. Just get the car tuned properly.

 

I'm not a expert w/auto trans but, i've raced alot of C-1 and C-2s with 4.56 gears { all with 3 or 4 speeds } and engine HP should not be the reason you can't spin your tires. From a dead stop, i can spin my tires on my L-48 3.08s w/auto.I would question your choice of T-converter. Running 4.56 gears will more than likley cause wheel hop and alot of broken parts.

 

[QUOTE=Golden;1577870121]
I don't have much experience with high stall converters but those I've driven are crap if you just mash the throttle from idle, this isn't how they're designed to work, the shop should have explained this to you.QUOTE]





Crap ? Can you explain (or anyone) how they are designed to work. Why wouldn't you be able to spin the tyres with a high stall converter? Anyone got a theory. I would have thought just the opposite. Step on the gas with one foot and one on the brake. Your engine 'spins' up to the rated convertor speed. So a 3000rpm stall would take you higher on the torque curve. Wouldn't it?
Anyone?

 

If he can't spin the tyres now - why does he need drag radials?

 

I bet gwank is on the right track. I bet your engine with all the good parts never made it back to Jasper. I bet some other core motor made it back to them. I've been to the plant there. They are basic engines.

 

i wouldnt be surprised either. Right now i dont even care about weather or not it will burn the tires cause it wont and probably never will. My biggest problem is the car still will not stay running even with the new engine. I dont want to call these guys or pay them another dime and have been advisied against going to the dealership.

Even with "hot wire" off the carb choke it still gets closes when it get hot and car will die. Can pump it and start back up but will dye when you put it in gear. the only reason i thought this was choke was beacuse when this happens and i remove air cleaner the butterfly was 80% closed. another idea could this be a "heat soke" issue on the starter as their is no heat shield with those massive headers.

 

Go to holleys web site they sell a dvd on carb tuning. Summit and jegs also sells the same one. pretty simple to adjust the choke. the rest of the carb tunning info is informative and is there to watch over and over again untill you get the carberator working right. If it were me i would drive the jasper engine until i saved enough money to build or buy a motor putting out in excess of 450 of 500 horse. I agree with every one else about you getting ripped off twice, but this should be the learning experience that dosen't let this happen again. jmo. Oh and have fun with your project.

 

With the hot wire off, the choke is going to stay most of the way closed. The electrical input is what heats up the choke element and opens the choke plate.
Maybe your choke wire isnt getting proper voltage. A closed choke will certainly result in the car not wanting to rev freely.

I dont think I have seen mention of the timing curve. Has it been set up for performance?
Proper ignition timing can make a world of difference in how an engine performs.

 

This is such a painful thread to read. I feel for you and wish that you get this resolved ASAP. Here is what I would do if I was you. Join your local Corvette club, go to a car show, meeting, etc and seek their advice. There are many a guys with significant knowledge that would love to take a look at it and see if they can help you get it going or at least tell you where to go to get it running.

You are now part of a community. My advice to you is to get to know those within it. I think it's your best bet out of this mess!