TBI to Vortec heads issues

[chowderhead72]

I have recently installed a set of Vortec (062) heads on my 1990 k2500hd. I also used the GM Performance intake manifold that allows the use of my original TBI system but now I am having issues. My brake pedal is hard as a rock at idle and the engine will not run smoothly no matter how I set the timing. The power is improved but my milage has gone to hell (5-6 mpg). The intake came with an instruction to add a pipe from the exhaust manifold to the intake manifold, I was unable to figure out how to do this as I have no ports in my exhaust manifold. Please advise.

 

Intake manifold: http://www.jegs.com/webapp/wcs/stores/serv...11935&langId=-1

 

 

Heads: http://cgi.ebay.com/ebaymotors/ws/eBayISAP...TRK%3AMEWN%3AIT

[Mr. Smith]

First off with the EGR. You will probably have to get a left side exhause manifold for a vortec. On the left front of the manifold you have the fitting for the EGR. Get the EGR pipe from a donor at a yard for a vortec as well. Otherwise you will have to cobble up something that may be more trouble than it is worth.

 

 

Sounds like the timing is off a tooth or so on the distributor and possibly vacumn leaks. What is your vacum at idle?

 

I have recently installed a set of Vortec (062) heads on my 1990 k2500hd.  I also used the GM Performance intake manifold that allows the use of my original TBI system but now I am having issues.  My brake pedal is hard as a rock at idle and the engine will not run smoothly no matter how I set the timing.  The power is improved but my milage has gone to hell (5-6 mpg).  The intake came with an instruction to add a pipe from the exhaust manifold to the intake manifold, I was unable to figure out how to do this as I have no ports in my exhaust manifold.  Please advise.

 

Intake manifold:  http://www.jegs.com/webapp/wcs/stores/serv...11935&langId=-1

 

 

Heads:  http://cgi.ebay.com/ebaymotors/ws/eBayISAP...TRK%3AMEWN%3AIT

 

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[chowderhead72]

First off with the EGR. You will probably have to get a left side exhause manifold for a vortec. On the left front of the manifold you have the fitting for the EGR. Get the EGR pipe from a donor at a yard for a vortec as well. Otherwise you will have to cobble up something that may be more trouble than it is worth.

 

 

Sounds like the timing is off a tooth or so on the distributor and possibly vacumn leaks. What is your vacum at idle?

 

 

Vaccuum was very low; I have routed the vaccuum (direct from the tbi to the pcv, intake and power booster) is now up to snuff (breaks work again and it runs a little better) Still has the low and mid stumble and the horrible gas milage (4-5mpg) Would the non-functional egr cause this or do I have the valves too tight? Both?

[Mr. Smith]

First off with the EGR. You will probably have to get a left side exhause manifold for a vortec. On the left front of the manifold you have the fitting for the EGR. Get the EGR pipe from a donor at a yard for a vortec as well. Otherwise you will have to cobble up something that may be more trouble than it is worth.

 

 

Sounds like the timing is off a tooth or so on the distributor and possibly vacumn leaks. What is your vacum at idle?

 

 

Vaccuum was very low; I have routed the vaccuum (direct from the tbi to the pcv, intake and power booster) is now up to snuff (breaks work again and it runs a little better) Still has the low and mid stumble and the horrible gas milage (4-5mpg) Would the non-functional egr cause this or do I have the valves too tight? Both?

 

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It sure sounds like a very bad vacumn leak. I would start spraying carb cleaner arounf the TBI base and all fittings to see if the idle improves. I would also relook at the timing, since you have said you checked it. What is the vac at idle?

[chowderhead72]

The timing is advanced a few degrees to smooth out the idle. With the timing set at the mark it runs horrible. I do not have a vac guage but it seems to be pulling alot of vacuum.

 

Ps: I sprayed brake cleaner everywhere and no change in idle. Internal leak?