Big Block ????

Ok I am new here but I am looking for an answer to a problem.I was suppose to be buying a throttle body big block for my 1993 chevy c3500 truck that had a small block in it,but when I got there to pick it up the guy was bolting a throttle body intake on the motor that had a quadrajunk on it that I later found out was a reman crate motor I asked him if there would be any problems with doing this he and another guy said no so with doubts I still picked it up giving them the benefit of the doubt,so I dropped it in wired it up and it would not idle and when we got it to some what idle it was surging then dying and when revving it was back firing and dying out.so I called the guy and he said it was the computer so after a week of hunting I found one ordered it got it in and hooked it up still the same problem.I am pretty sure it is the camshaft causing the problem because it isn't the right lift and duration for a throttle body motor.Please help me answer this question so I can get the problem solved.
Thank You in advance


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No one has any in put as to why this beast won't idle????

You haven't really asked a question. You told us you were buying a TBI, but the guy was bolting on a Qjet intake, and your engine won't idle. Those are three completely unrelated issues.

We have NO idea what the problem is.


are you buying the engine, or the TBI?

You can't put a Qjet on a TBI intake. I think you misinterpreted.


Punctuation is huge. That is one big run-on sentence, and while I'm sure it made sense to you, it is a big jumble for us.

Might be a number of things.

IMO, you should have PASSED on a deal that you were unsure about.

It sounds like you know a little about engines, etc. So you might have asked yourself, "Why is this guy installing (at the last minute) the TBI on an engine that was running a Q-Jet?"

And you might then have realized that the guy's trying to dump this engine by telling you what he thinks you want to hear.

To figure it out, start w/the basics- spark, fuel and compression.

From there, see what codes have been set.

With a degree wheel and a dial indicator you will be able to tell whether or not the cam's computer friendly. It doesn't take much cam to throw off the PCM.

I agree with colbalt327.If the cam is not computer friendly you are going to have promblems.One fix would be to find a good engine builder in your area and take it to them.It sounds like you are in over your head,no offense.

"You haven't really asked a question. You told us you were buying a TBI, but the guy was bolting on a Qjet intake, and your engine won't idle. Those are three completely unrelated issues."

No. I said I was suppose to be buying a throttle body big block for my 1993 chevy c3500 truck that had a small block in it.

So that would tell me that the truck had a small block in it, and I wanted to change it to a throttle body big block.

"You can't put a Qjet on a TBI intake. I think you misinterpreted."
DUH I think you miss read.

but when I got there to pick it up the guy was bolting a throttle body intake on the motor that had a quadrajunk on it

That would tell me that the motor had a "Q-jet" on it and the guy had unbolted that intake and was bolting a throttle body intake on it.

"Punctuation is huge. That is one big run-on sentence, and while I'm sure it made sense to you, it is a big jumble for us."

I didn't know that Punctuation was such a big deal but I will try better.

jc I think you should go to hotrodding basics. These guys in the engine forum are all cut throat hotrodding professors. They teach at their local universities on hotrod etiquette. I know what and what not to ask these guys. You'll learn hang in there, but hell just go back and proofread your post and you will be like" dang I said that?".

Thanks guy's for the input. (cobalt327) (1pistol)
Yah I should have passed on the buy,but I wasn't sure about it my self.
They were under the understanding that in early years of the throttle boby big blocks, chevy bolted throttle body's on the same long blocks.So with me not knowing much about a big block it was worth a try.But knowing about small blocks it tells me that the camshaft isn't right for that set up.I was just looking for a conformation on that theory or some other suggestions.

P.S. 1pistol I'm too hard headed to be in over my head I'll figure it out one way or the other LOL. Thanks for all of the help.

Yah I left out a lot for a Professor but some one with a little common sense could figure it out LOL

Do you have the big block injectors and computer on it? I don't think the smallblock injectors would flow enough fuel for a big block..The smallblock computer timing curve and injector pulse wouldn't be right either.But I could be wrong I have been before..good luck

Yes Sir
The motor came out of a 1990 chevy suburban with a Q-jet on it and he bolted a 1993 or newer intake and throttle body assembly off of a 454 on the motor.Dropped it in and it wouldn't idle.Then we thought it might be the computer so I found a computer for a big block and put it in the truck and it wasn't much help at all.The only two things that hasn't been eliminated is (1)cam & lifters (2) old and weak fuel pump.
Thanks for your in put any in put will help.

Have you checked to make sure the distributor is not in 180 degrees out?

Have you disconnected the check timing connector while setting the timing?

Yep,I know what you mean.My wife told me that I was hard headed when she signed the divorce papers.I believe her.

Yes Sir
I have been all over that motor.And had two other mechanics double check me.Still the same.

LOL She'll get over it