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Where did I go wrong?

O

OneLeft

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Okay my Blazer is an 89, and I live in Jefferson County, so I need to pass the smog test, Grrrrr! I built an engine and I am a little unhappy about the outcome. Here is a description as best as I can type it.....

4 bolt main smallblock
.030"+ flattop pistons
Ballanced
cast iron centerbolt heads
valve job and stainless valves
Comp Cams Xtreme Energy roller cam (lift .480/.487 dur @ .05 = 206/212
Comp Cams valve springs
GM roller lifters
Crane Gold Race roller rockers (1.5)
Cloyes double roller timing set
Edelbrock Victor Series water pump
Edelbrock MPFI
MSD billet small cap HEI distributor
MSD coil
MSD Offraod Ignition System
MSD Super Conductor wires
AC Delco plugs
K&N X-treme air cleaner assembly
Thorley Tri-Y headers
3" Y-pipe
3" Flowmaster 2 chamber muffler
an engine oil cooler with GM thermostatic bypass/adapter.

The tranny is a 700R4 built as bomb proof as can be. The gearing is 4:56 and the tires are 36" TSL Super Swampers. I barely slipped past the smog test, it runs okay, just had hoped for it to be a little stronger. I have thought about running a smaller exhaust to build a little more back pressure, and having the chip re programmed. Any other suggestion?
 
Just guessing cause I ain't there to hear and see it run. Is it setting any codes? First thing I would do is readjust the rockers, you would be suprised how much power you can lose there. Next I would verify the timing. The next thing I would do would be contact Edelbrock and discuss the situation and see if they think that the fuel map needs to be recalibrated. Other than that, it sounds to me like you have a very solid combination that should be producing plenty of torque. Have you considered swapping to Vortec heads? Good luck! Just my $.02

'85 K5 : Run it til it breaks, then fix it and go again!
 
I am far from an engine gurru, but I'd think if you got a stock chip, then you should call <a target="_blank" href=http://www.fastchip.com>fastchip.com</a>... they did the chip for me on Jedi Mind Trick, and when I do a 383 I'll have them do the chip for that too... I'd think a custom chip would get a LOT more out of the engine.

<font color=blue> Jeff - may the force be with you</font color=blue>
<a target="_blank" href=http://coloradok5.com/gallery/Jeffs-Stuff>http://coloradok5.com/gallery/Jeffs-Stuff</a>
 
The heads I have are the stock 89 TBI 1.94 heads. I had a multi angle valve job done. Are the Vortec heads a lot better than the TBI heads? I have thought about going with some aftermarket aluminum heads, like Edelbrock or Trickflow, but those are pretty costly.
 
The Edelbrock MPFI comes with either one of two chips. One is for to use with cast iron heads, the other is for to use with their aluminum heads. I will contact those guys about a chip and see what they say.
 
I'm told the vortec heads give you some of the best bang for the buck if you're looking for power. There have been a couple of write-ups in the fourwheeler mags lately with positive results.

Smitty
 
I believe TBI heads are some of the worst ones performance wise GM put out. Yes, Vortec heads ARE that much better. But with all your mods, I'm a little surprised you aren't getting better performance than you say you are. Theres maybe something wrong or missing from that equation.

Dorian
My tech/links page: <a target="_blank" href=http://www.dorianyeager.com/index2.html>http://www.dorianyeager.com/index2.html</a>
No anti-theft measures on your truck? No pity when its stolen
 
I'm assuming the vortec heads would not accomodate the MPFI though... it requires different intakes.

you might wanna try some other head though (and if you get a custom chip it is $150 everytime you change something so I'd do heads before you get a custom chip)

<font color=blue> Jeff - may the force be with you</font color=blue>
<a target="_blank" href=http://coloradok5.com/gallery/Jeffs-Stuff>http://coloradok5.com/gallery/Jeffs-Stuff</a>
 
If it requires a different intake, then I would need to go for some good aftermarket heads. Does anyone have any expierence with Edelbrock or Trickflow? I would need to be able to use my existing roller rockers as they were not cheap.
 
Randy you forgot to mention that you're only getting around 8 mpg on the road with that setup.
shocked.gif
That's totally crappy mileage for a 383. I've got a pretty heavily modified TPI on the 383 in my K5 and it still gets 13.5 mpg on the highway.

I also thought that you said something the other night about a wierd stutter/vibration from the engine at certain times since you added the Edelbrock MPFI setup.

I think about any of the aftermarket heads will outflow the stock TBI heads. The Vortec heads provide excellent flow and power for the dollars spent, but if you add in another $200-300 for an intake that fits the Vortec heads, then the price isn't that great after all. I suppose if you're building up a stock engine, where you'd probably want a better intake anyway, then it wouldn't matter much. But if you already have a good intake then buying another one would up the ante considerably. But since you have the Edelbrock MPFI I guess you have to stay with a head that is compatible with that intake.

<font color=black>HarryH3 - '75 K5</font color=black>
<a target="_blank" href=http://www.angelfire.com/super/ThunderTruck>www.angelfire.com/super/ThunderTruck</a>
It's a great day to be alive...
 
Your right, I am getting a studder/vibration, but I do not believe its related to the MPFI. I used the MPFI on the original engine for about a year and didnt have that problem at all. The gas mileage problem is partly contibuted to my lead foot. I like to get up and go. :-) The other factor I believe it the tranny. I have had the tranny built with a lock up valve that keeps the converter locked up all the time. This keeps the clutch packs from slipping as much and makes it last longer. The last 700R4 went for the better part of 175,000 miles. I dont know for sure, thats my theory. I do know that something just isnt right. I think I might opt for the edelbrock heads, since I am running the Edelbrock MPFI. But the $1300 price tag.......

Good thing I am gonna win the POWERBALL tonight!
 
The TBI heads aren't that awful. They kick butt compared to the even cruddier carb heads, but that is about it. That is probably the worst cause of bad performance. I would try getting an aftermarket head like GM parts new HP FI heads, specfically designed to these trucks... otherwise get the Edelbrock TBI heads and you will be a happy camper. The vortechs are an awsome bang for the buck, but won't work w/ this setup as far as I know.

-Mikey
1987 Chevy K5 Blazer- 350 TBI
<a target="_blank" href=http://coloradok5.com/gallery/captcrunch>http://coloradok5.com/gallery/captcrunch</a>
 
Would you happen to know a part number for the GM HP FI heads that would work with the TBI style intake manifolds? Or maybe how much a set of those heads would cost?
 
Is this the one?

12480092

Cast Iron High-Performance Head (Large Valve)

This cylinder head (casting P/N 3991492) was originally installed on special high-performance small-blocks such as the 302ci Z-28 and 350ci LT-1. It is popularly known as the "fuel injection" head because it shares many features with previous high-performance Corvette heads. This head has straight spark plugs, 3/8" screw-in studs, pushrod guideplates, and heat riser passages. The 64cc combustion chambers are machined for 2.02" intake valves and 1.60" exhausts. Seats are not heat-treated.

Technical Notes: The Cast Iron High-Performance Head (Large Valve) does not include 3/8" studs or guideplates.
 
I'm no engine guru either, but 3" exhaust sounds awfully big for a small block. I have a friend running a built 454 that only runs 2 1/2", and restriction is non existent. You may consider a 2" or at largest a 2 1/4" set up.

God has a hard on for Marines, because we keep Heaven chock full of fresh souls!
 
On that 454, are those dual pipes? Being in an emissions controlled area, I am required to keep my (1) cat-converter. I believe the collectors on the headers are 3", so I had the y pipe, cat and muffler all done 3". It does sound quite healthy, but I have actually thought about going down in pipe size a little. The little bit of backpressure will add torque. Right?
 
<blockquote><font class="small">In reply to:</font><hr>

. I have had the tranny built with a lock up valve that keeps the converter locked up all the time. This keeps the clutch packs from slipping as much and makes it last longer.

<hr></blockquote>
This is probably the problem your having right here!!!!! The TC needs to un-lock to allow the motor to "spool" up a bit before it locks up. You need to have the TC where it can be manually controlled or automatically controlled weather it be vacum, speed, electronic or what ever. But if in FACT your TC is staying Locked up ALL the time oyur robbing yourself right there. Also if its locked all the time, how do you keep the motor running while idling with it in gear????

What is and what should never be....
<a target="_blank" href=http://www.nashvillek5.freeservers.com>www.nashvillek5.freeservers.com</a>
 
I asked the same question when I was talking with the man who built the tranny for me. I cannot remember the exact way he described it to me, but I will do my best. I do know that the life of the average 700R4 is less than 100k miles. The first one he built for me went for almost 175k miles until I blew up the pump.

Okay, I lied! Haha! Sorry. Ya know how us Texas born Colorado people are! Ya only gotsta tell me about ten times before I can psyfer it all out.

I just talked to Mike at AC Transmissions. He re-explained it to me. The lockup valve hydraulically provides for lockup in 3rd and 4th. On the 89, the original control for this is not the best, so they went for the valve. He also refreshed me on the 10 vain pump and tighter clutch packs.
 
SO when your going down the road say in third and you want to pass someone and you give it more gas does the converter unlock adn give you higher RPM's until you reach a steady speed then it locks back up?

What do you mean by the "original" way? On the 89 the computer would control the lockup the same as my 90.

What is and what should never be....
<a target="_blank" href=http://www.nashvillek5.freeservers.com>www.nashvillek5.freeservers.com</a>
 
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