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motor problems..need help.. not enough power!!!!

RootBreaker

RootBreaker

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Boy oh Boy.. it is such a nice feeling to have the truck back on the road... Well sort of a nice feeling...
GAS price is up and my truck MPG is DOWN more than 1/2!!!!

anyhow... I have serious motor problems... Can anyone assist?

Here is my delema..
do I
1. replace the cam and intake
2. buy a 350hp crate motor (350 4bolt)
3. drop in a stock used 454??

Ok this is what I have..
1991 Caprice police 9C1 350 2bolt
1987 stock Z-28 intake (used to be TBI)
hydraulic roller lifters
supposedly 195hp / 350ftlb torque

Well I am getting about 4.5mpg!!! for that might as well put in a 454!!!
For some reson the truck cant get out of its own way...

I laid 2 - 8 foot posi marks outside of my friends house in first (not granny gear)

If I start out from a light... the motor tachs to 5000rpm quick...
shift into 2nd and floor it.. I can actually count to about 8 seconds till it is time to shift (approx 4500rpm)
then shift into 3rd and floor it till my needed speed (required speed is felt and speedo not used as it is not accurate)

So
If I go with choice 1 what cam should I put in?
the motor is a hydraulic roller so I believe I have to stay with that? if so what size, lift, duration???


If I go with choice 2 it is obvious as they can be had from GM for about $1200 with a warranty

If I go with choice 3 it is a used 454 complete.. remove my motor and drop this in for $1000

ASSISTANCE ANYONE!!!!
P.s. I dont have the $$$$ for choice 2 or 3 and will take time to get it but if it is the best choice then that is what I want..


I am trying to get around 10mpg.. that is why I didnt go big block in the first place...I want the truck to make a trip to NY or Maryland, Bloomsburg PA..... but if a BB gets me 8mpg and there is no other way for me to get any better with a small block then hey.....
 
If you're getting 4.5 MPG you need to do some tuning. Don't change a thing until you figure out why your mileage is so horrible and fix it.
 
First welcome to the world of the wide ratio 4spd. The 4spd will probably never feel great on the 2-3 shift, the ratios are just too far apart.

I could be wrong but I don't think the $1200 crate motor is the 350hp version. I was thinking those were a grand (or more) more than that.

I'm a BBC fan so my vote is for the 454 BUT (not trying to be negative) it wont usually happen for $1k. Unless you find a good running motor with ALL the brackets, bolt and pulley's CHEAP (don't forget exhaust, possibly a radiator, flywheel, etc) you will have a hard time staying inside that budget.
 
I wouldn't be surprised if your timing was off and the carb needed tuning. Even a gutless 305 should be able to squeak out 10 mpg in that thing. So I'd also say find the problem and deal with that first before spending a ton on something you prolly don't need.

Rene
 
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(required speed is felt and speedo not used as it is not accurate)

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Do you have a GPS unit or something ? How can you actually know your mileage ? Not trying to tick you off , but you need to get the speedometer and odometer working , and drive around normal for a full tank before you figure your mileage /forums/images/graemlins/k5.gif /forums/images/graemlins/k5.gif
 
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(required speed is felt and speedo not used as it is not accurate)

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Do you have a GPS unit or something ? How can you actually know your mileage ? Not trying to tick you off , but you need to get the speedometer and odometer working , and drive around normal for a full tank before you figure your mileage /forums/images/graemlins/k5.gif /forums/images/graemlins/k5.gif

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I appreciate all the replies... I dont get ticked off.. I GET EVEN!!! just kidding..

I have been to my moms and know the miles I went. My speedo may not work on my truck but I do know the miles I went. When I get home I am going to go and fillup the truck and get the exact gallons and do the exact math...
anyway.. I know my timing is off... guess I need to get the timing fixed...


so what should it be? 10degrees before 0?

I was having a problem where when i set the timing to 10 before 0 it was idling at 2800rpm.. so I found the high idle screw on the carb and turned it down... but for some reason she idles at 800rpm now... I start driving and when I pull up to a light and put it in neutral it revs back to 1500rpm.. mash the gas and it will go back down to 800...
anyone know why that is happeneing???
guess that is my first part....

I took the carb out of the box and put it on and have only adjusted the high idle.. maybe should adjust everything else /forums/images/graemlins/whistling.gif


all in all I guess is 4.56's with a manual trans and 38" (theoretically 38") tires adequite? also am I dreaming of 10mpg?

also I can get a 454 used with 50-60k miles complete and drop in for $1000 already found one.. but I didnt originally go big block due to want to take the truck for long rides and get 10+mpg vs 8 or less (which is what I have now)
I am planning on getting 2 winches so that will get me out if I get stuck due to not having a big block /forums/images/graemlins/peace.gif
 
That idle up and down thing sounds like linkage or choke . Some carb cleaner and an exploded view to make sure the linkage is working allright /forums/images/graemlins/k5.gif /forums/images/graemlins/k5.gif
 
4.5 MPG??--thats almost gallons per mile!.I've had 3 454's do better than that--even my 74 K20 with 4.10 gears got 12-14 mpg in daily driving.You must have something way out of whack,timing,carb choke sticking,maybe a restricted exhaust(catalitic converter plugged??)--or the brakes dragging??.If you are swapping motors,the big block is no worse on gas than the small blocks,the ones I had were slightly better on fuel than the 350 they replaced,so dont think the bigger motors are always gas hogs--in stock form at least,they arent.But I bet you could at least double the mileage your getting now with the present motor,unless it needs a valve job or major repairs. /forums/images/graemlins/crazy.gif
 
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If you're really looking for mpg wouldn't keeping the pedal out of the rug the first step? I say try drafting its working for me!

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That is my point.. the motor cant get out of its own way so you must mash it... I dont have carpet.... but I have to constantly mash it.... well we will find out later.. Im going RIGHT NOW to fillup to double check my gallons used last night... im assuming 7 as it is on 1/2 tank now.. but we will let the pump tell me... still it is 35 miles that I drove... /forums/images/graemlins/thinking.gif
 
aight I was crying wolf.... I just went and filled her up... took 5 gallons... not too bad I guess.. still 7mpg. better than 4.5

so I also noticed why I thought it was worse... I thought when I filled it up that the fuel gauge went beyond full so 1/2 tank was 9 gallons... and it was a bit before 1/2 thus 7 gallons... well it is full now and the needle is before the full mark... not even touching the line....
so tomorrow I am going to adjust the carb by setting the timing, choke, fuel mixture and floats... hopefully I can get better... also maybe if I dont mash it all the time I can squeeze 10mpg... we will see....

more to come so stay tuned.. but I believe I should still get a different intake though...get rid of this 305 z-28 intake.... Sunday someone may be coming for my dirtbike so that will help!!!
 
Chevy gas gauges are strange , each one is different . Mine reads from past full , all the way to empty ( although I keep off empty after the only time I ran out LOL ) . And they are not linear , they read slower from full to half than they do from 1/2 to empty /forums/images/graemlins/k5.gif /forums/images/graemlins/k5.gif
 
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Chevy gas gauges are strange , each one is different . Mine reads from past full , all the way to empty ( although I keep off empty after the only time I ran out LOL ) . And they are not linear , they read slower from full to half than they do from 1/2 to empty /forums/images/graemlins/k5.gif /forums/images/graemlins/k5.gif

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guess that is why having a dual tank is nice.. always keep at least 1/4 over there... just in case.. I dont like letting my tanks go dry either... expecially since now I have a electric pump.. but will do it just once to see how far down the guage goes... /forums/images/graemlins/whistling.gif
 
[ QUOTE ]
Chevy gas gauges are strange , each one is different . Mine reads from past full , all the way to empty ( although I keep off empty after the only time I ran out LOL ) . And they are not linear , they read slower from full to half than they do from 1/2 to empty /forums/images/graemlins/k5.gif /forums/images/graemlins/k5.gif

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Mine reads past full all the time. I think it may be a bad ground... you guys got any advise??? (sorry for the hijack)
 
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Chevy gas gauges are strange , each one is different . Mine reads from past full , all the way to empty ( although I keep off empty after the only time I ran out LOL ) . And they are not linear , they read slower from full to half than they do from 1/2 to empty /forums/images/graemlins/k5.gif /forums/images/graemlins/k5.gif

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Mine reads past full all the time. I think it may be a bad ground... you guys got any advise??? (sorry for the hijack)

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Bad ground, yes.

Back on topic....

I'd advance your timing and check your carb out. You should be able to get at least 10 MPG. When I was driving on the road with 4.10s and 38.5s I was getting 11 mpg.
 
actually over at camaroz28.com they are saying that the camaro intake is a spreadbore and if I do not have an adapter plate that kicks down from a spreadbore to a non spreadbore that there is a HUGE vaccuum leak.. IS THIS TRUE!!! may be my biggest problem....
 
I'd have to look at the intake, but that is most likely true.

You need an adapter to put a holley carb on a spreadbore intake.
 
If you have a factory spreadbore intake, how did you get a Holley bolted on? I know on my Edelbrock intake the front studs are in a different place for a spreadbore than they are for a squarebore.

The biggest thing that helped my acceleration is to advance the timing, as Tim already mentioned. When I first installed my rebuilt motor I was disappointed in the acceleration. I took the timing way up and it was a big improvement. Right now with the Qjet I'm running the timing at 16* (@5000ft elevation). I'll bet with the Holley you could stand a little higher initial timing than a Qjet. You don't want to get too carried away, or you total timing will be too high. I wouldn't want the total timing higher than 50*.

Also as a side note the idle not coming down can be a symptom of your timing needing advanced.
 
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Also as a side note the idle not coming down can be a symptom of your timing needing advanced.

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That's not true. Idle not coming down screams vacuum leak.

Idle too high might indicate overly advanced timing though.
 
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Also as a side note the idle not coming down can be a symptom of your timing needing advanced.

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That's not true. Idle not coming down screams vacuum leak.

Idle too high might indicate overly advanced timing though.

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I will check tomorrow... I believe over 12* it pings like a mofo... so she aint going to go up more than that...

also yeah i guess I gotta look cuz I dont remember but I possibly did put the adapter plate on to run a holley on my truck... but if I remember correctly it is identical to the manifold meaning that it is just a big gaping hole... I wonder if there are spreadbore and non spreadbore adapters for holleys.. I will call the speedshop tomorrow...
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