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'90 K5 - Project Betty - LS3 Swap for a DD/Offroad/Utility Build

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That engine will make that power level easily with the heads cleaned up and a cam change but the problem will be TBI. Its an outdated system and burning chips for them is expensive and has limited adjustabilty. You may be better served with an aftermarket EFI system. More adjustabilty and versatility but you are stuck with that makers parts whereas a stock TBI system is everywhere. If it were me I would do a nice flowing valve job, roller rockers, good oil pan and do a real good set of headers and free flowing exhaust from the heads back. Probably put you over 350 ft-lbs easily and run very well.

Now i have built a few big blocks now and can say that carbed these engines are very forgiving. With exception of their weight are perfect for off roading because the torque is just right where you need it and it doesnt have to work hard at all. Another option is a good dual plane manifold and a SMI or JET quadrajet tuned to your needs with a nice idling cam and good head porting woud really wake that engine up. Also what port heads are on it now? Everybody $hits on oval port heads but i think they are just ticket for most off roaders needs.
 
It has the peanut port (small oval ports), which as you implied are better for low end torque, and hp restrictive upwards of 4500 RPM. I am thinking they are probably going to have to go to get above 400 hp, however demon engines did do this build ( http://www.carcraft.com/techarticles/ccrp_1010_cheap_big_block_chevy_engine_build/index.html )

I have gotten a decent amount of suggestions about moving toward a quadrajet set up. I understand that a carb is easier to set up, but wont I lose appreciable mpg's, driveability at inclines (had an 86 k10 with a 350 and 750 CFM eldelbrock carb that nearly got me sunk on a steep boat ramp once), and I have heard complaints about carbs being more temperamental at start up.

Are these legitimate concerns? Or can these issues be resolved with the right carb?
 
No your problem is you used a AFB style carb. A quadrajet is a whole different animal. I run mine routinely up some really steep stuff and it is like i am on flat ground. http://www.4wheeloffroad.com/techarticles/off_road_carburetor_review/index.html
Yes an EFI will net you more fuel economy and a little better maners than a well tuned quadrajet but my quadrajet runs real well with none of the setup hassle of the TBI especially if you dont have all the parts for your engine currently.
 
IMHO it will be more trouble then its it worth for TBI because:
1. Its an old system
2. Chip burning for your application is a PITA just ask buefchris (spelling?)
3. Not as adapatable.
4. Needs to be custom if you plan on changing the cam and using the TBI (TBI engines dont like anything but the factory cam)
5. The OP doesnt have the computer, TBI or harness to make it work. All added expenses on top of what needs to be done to make it work with a cam swap.
 
1. TBI is much newer technology than a carburetor.
2. I could drive two hours to Lincoln and have a dyno tuned chip burnt for it for a few hundred bucks and I am in Nebraska....
3. It is self adapting. Not screwdriver adapting.
4. The engine in my 1988 V10 Suburban a cam from a 95 LT1 (it previously had an LT4 Hot Cam in it). No changes were made to my PROM. It ran fine. The LT4 cam wa a bit much, but the LT1 cam runs quite nicely.
5. He has a factory TBI vehicle. That has a computer, harness and throttle body. 454 throttle bodies are all over for sale for less than a new carburetor.

Martin
 
Computer and harness are different for small and big blocks. He be better served getting the whole factory harness. A burnt chip has no other adjustability other than what it is programed with. You cant tune on the fly. Chip doesnt work gotta burn another one, idle is too low, gotta burn another one, got a stumble at 3k because the fuel curve is off, burn another chip. Etc..TBI works great when stock not so much when not. You dealing with OBDI tech yet expecting OBDII adjustability. Just look online you cant find the amount of OBDI tuners like you used to. Its obsolete. Carbs are as well but they are so low tech and fool proof. That is there advantage. I agree if he is going to rebuild to stock spoec but just mildly port the heads he can definetely get away with it. But if he goes with a lumpy cam it aint going to work worth a darn with stock components even with a chip.Stock components just cant keep up.
 
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I was one of those diehard carb guys... i still work on hundreds of quads annually.. i'll take EFI any day of the week..

f*ck all that chip burning bs.. megasquirt can do just about anything ya want performance-wise for cheap...
 
i wouldn't even consider trying to use a reworked GM ECM with the nasty TBI'd 383 I'm gonna do.. not that it can't be done, but Megasquirt just seems to cut to the final chase when ya know the cam specs are gonna be a ummm, "challenge"....
 
Okay, I know we will get to the bottom of this now that I got some of the elders on talking.

1. I have been chatting with Brian at TBIChips.com, and he suggested that 400+hp and 500 ft/lbs is impossible via TBI (talking engine dyno numbers, not rear wheel hp). I sited this article http://www.carcraft.com/techarticles/ccrp_1010_cheap_big_block_chevy_engine_build/index.html
I know that it is not TBI, but you can get 750 CFM out of a modified TBI right? It is not like the article refers to a double carb set up.

2. I do not mind using aftermarket to get the job done. Can I get a consensus that the megasquirt is the way to go?

3. Up until a week or two a go I was the proud owner of an IS-F, so I am familiar with what hp feels like in a car with a race focused tranny and rear end. However, the K5 is a ****-ton heavier (I know low-end and mid-range torque is more important for weightier vehicles than sport cars), the tranny and rear is what it is, do I need to replace the peanut port heads to get this girl to move? Or will the torque/HP curve presented in this article suffice for pushing this fatty down the highway?

I would like to know that if I spend the time and PITA to set up TBI that I will get more power or MPG than a well tuned quadrajet or some other carb.
 
side note

I went to true duals several months ago, and did not think twice about where the o2 sensor was placed. To be honest with you, I still dont know (I am out of town on business, and cannot check).

Can it be positioned on one side of the exhaust, or does it need to be in a H or X pipe?
 
One side of the exhaust is fine. That is how it is from the factory.

Martin
 
336871 Heads

Picked up some new to me heads in hopes they will work on the gen 5/6 454 with the special felpro gasket.

I did not want to go to rectangular ports in effort to preserve some low end torque.

Picture will not upload, do not know why.
 
I just read through. Nice build. I was going to saw I have a set of 781 large oval heads sitting around. Just put the square port 990s on the 454 in my car. But looks like you picked up a set already. :thumb:
 
454 vs 496 Stroker

Demon, thanks for thinking about me, but even if you were willing to give those heads away for free, it would have to cost a fortune to ship them. I (like an idiot) went to pick them up prior to ranger games, and was a little to dressed up to get greasy. I tried to keep the heads out and away from my body, and ended up throwing my back out. So that has already slowed down my stagnant build. I honestly thought I would have a 5.13's and custom aluminum dash by now. Oh well hopefully the mig and pipe bender will be here before summer, get the engine done and 5.13's in by year end.

Question for you and the BBC gurus. I know that a 454 is one of the best way to get low buck hp and torque, however since I am going to have this thing apart, shouldnt I just go to a 496 (or 489 or whatever, might just bore it .03 over so I have another bore out of it)? I know I will have to get a new crank, rods, and pistons (seen complete kits for around $1500 that are balanced), but I was probably going to need new pistons for hp and I am not sure how likely it would be that crank or rods would need to be replaced.

http://www.superchevy.com/technical..._chevy_big_block_build/weiand_water_pump.html

Looks like from the simulations I have ran on Virtual Engine Dyno (if anybody has any custom databases they wouldn't mind sharing, I would appreciate it) suggests that I would not necessarily increase horsepower, but should give me 50-110 ft/lbs (at the fly wheel) during the lower end of the power band.

Since I have not been getting much done other than gathering parts, here is some pics of of the wife and I having fun at the ballpark.

200346_719676191169_18806355_37730699_8152627_n.jpg

196555_719676171209_18806355_37730698_275803_n.jpg
 
TBI/Vacuum/Engine Help

My k5 occasionally suffers from what I have heard referred to as the "lean stumble". It dies at idle when at a stop light or something after being warmed up. Cranks right back up and runs fine. Happens probably less than 10-5% of the time.

I am going through the usual culprits, egr, fuel pressure regulator, fuel filter, and I am going to try to test the trouble codes when I get home tonight. I have ordered an ALDL cable and scanner so I can start getting more involved with my TBI setup, but that is not really what this post is about.

While googling this problem I came across a couple of pics like the one below. I have this bladder thing and the linkage, but no spring or arm to connect the throttle linkage to the bladder. I do not know what the bladder thing is and cannot find what it is called in any manuals so I can google it.

Any help would be appreciated.

Thanks

TBI Question.jpg
 
Buying a 1st gen

I doubt I will get a ton of response on this since I have not done much with my blazer recently to generate interest. We are trying to move, work, etc everybody has excuses I know.

However I have 5.38's coming, a Detroit for the rear and a Powr Lok Posi LSD for the front.

I was thinking, is this the truck I really want since I am spending so much money on these axles? Then it occurred to me that everything I had done (other than the ORD weld in steering box brace and rear shackle flip kit) can be moved to another vehicle. Dana 60's F&R, crossover steering, springless kingpins, XJ steering shaft, etc. I could swap those out and still have a running 90 TBI to sell to recoup the cost of the 1st gen. The 1st gen can run like ****, because my next project is to finish the 454 build.

I started making a pro's and cons list and this is where I need help.

Pro's.
1. Older more desirable vehicle
2. Start fresh, less wiring/vacuum bs from factory to deal with
3. No emissions bs
4. Full convertible (also con)

Con's
1. Lots of work
2. Extra unnecessary expense
3. Want an auto, would have to change out the manual or 3 speed auto since I do highway driving.
4. Full convertible (I live where it is 90 degrees half the year, some shade is nice sometimes, plus rain). Taking the top on and off is a PITA so my blazer is almost always topless

Remember I like to offroad, but do use the truck as reason to build and work in the garage, and the wife likes to take it happy hour or just for sunday strolls as well.

Thanks

(this post has not been proof read)
 
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