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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: plowking_90 on March 09, 2008, 06:05:02 pm
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i have a stall converter in my truck not sure on what size. i have a 350 with around 350 hp, motor is approx. 6 years old. i have eldelbrock performer intake, eldelbrock 650 carb with a miled cam, roller rockers, turbo 400. when im driving the truck it has no power i usualy run 36 inch super swampers and put 31 inch bf goodrich for the winter. it wont even spin the 31's, you would think it would be a rollerskate.......... i changed cap, rotor, plugs ,wires, fuel filter what are some other things i can look for to get my power back. maybe some carb.adjustments, timing, i bought the truck like this 1 year ago and im trying to work all the bugs out for this spring (MUD SEASON) and summer cruising
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What gears are in the diffs ?
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i did the turn the wheel thing to calculate the gear ratio and i think its a 411 not possitive though, but even if it was stock gearing i have 350 hp it should be like butter on my tires with the 31's
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Plowking, Start with the basics. Do a compression test, is the engine is sound working condition? Then move on. Where is the timing at? Does the distributor advance with engine RPM? What do you have for fuel pressure? Is the cam degreed in correctly & so on. If you bought it this way you may need to "dig in" a little to find out what the last guy did or did incorrectly. You may have some mis-matched parts (low compression/cyl. pressure) that you can not fix without knowing what is in there. Good Luck, Lorne
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gear ratio.
I ran into that in my monte carlo. Had a nice motor that came from a 76 truck would scream in the truck, had 2.11's in the car and it sucked. I put in a set of 3.42's and a shift kit and stall brung it right back.
Taller tires bring the gear ration numbers down further.
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what is the gear ratios these trucks came with mine is a 1980 1/2 ton lwb
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You probably have 2.73's lol
Put it in low range and see if it has sack.
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how hard??? and how much money am i looking at for better gearing front and rear?
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What's your plans for this truck ? D/D (daily driver) W/T and M/T (work truck mud truck)
Look in some of the Off Road forums and you might find a set of diffs ready to go.
A set of 60's could cost about 2k +/-
Dana44's would last for a while, But they have there week links when off-roading a full size truck.
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it gonna be a daily driver mud truck so it dosnt have to be special gearing but im gonna check again to se what i have for gearginf then ill go from there ill post my gearging tomarow to cold to deal with it right now
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Well summit or jegs has ring and pinion sets for like $140-160 or so.
I think I'd get 3.73 or bigger for a mud truck or daily. If you put in 4.10's time you slap on 33's it take it down to like 3.73 or so I think maybe less. For real torque and power you could get 4.56's or something along those lines.
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Plowking, Start with the basics. Do a compression test, is the engine is sound working condition? Then move on. Where is the timing at? Does the distributor advance with engine RPM? What do you have for fuel pressure? Is the cam degreed in correctly & so on. If you bought it this way you may need to "dig in" a little to find out what the last guy did or did incorrectly. You may have some mis-matched parts (low compression/cyl. pressure) that you can not fix without knowing what is in there. Good Luck, Lorne
Plowking, Start with the basics. Do a compression test, is the engine is sound working condition? Then move on. Where is the timing at? Does the distributor advance with engine RPM? What do you have for fuel pressure? Is the cam degreed in correctly & so on. If you bought it this way you may need to "dig in" a little to find out what the last guy did or did incorrectly. You may have some mis-matched parts (low compression/cyl. pressure) that you can not fix without knowing what is in there. Good Luck, Lorne
i agree in your list i saw no vacuum advance diaphragm, i had a 68' 327, it seemed gutless... it maxed out a 3500 rpm. thats not right. so i pulled the hose for the vacuum advance diaphragm and sucked, i could suck air like nothin', so changed it. $10 two screws and 15 min. later i had a easy 6000 rpm and what seamed to be triple the power, thats my opinion.
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^ That sounds kinda like my truck. I should check that out on my HEI to see it's doing anything. Should be a strong suction in that tube when i take it off the canister?
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If it's hooked to manifold vacuum yes.
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I have 3 hoses attached to the front of my Edelbrock carb. Big one in the middle goes to my PCV valve, another one goes to my vacuum canister and the other small one flanking the PCV hose connects directly to a hard line from my tranny (I presume for my vacuum modulator).
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What do you mean flanking your pcv hose? ??? you can hook it up either way. I prefer manifold vacuum at idle to vacuum advance. You should have vacuum at the modulator also.
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I mean I have 3 ports on the front of my carb. Big one in the middle and two on either side of it. I keep hearing about timed/non-timed and ported/non-ported vacuum ports. I have no idea what means what, but I'm wondering if the ports on the carb make any difference.
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Ported or timed means there is no vacuum at that port while the throttle plate is closed. When the throttle plate opens it exposes that port to manifold vacuum then receiving a vacuum signal. So it only receives vacuum when the throttle is open.
The other port is manifold vacuum.
The large front port is for your PCV like you have it.
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Ahh I see. Well I just learned something new. Thanks!
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i did the turn the wheel thing to calculate the gear ratio and i think its a 411 not possitive though, but even if it was stock gearing i have 350 hp it should be like butter on my tires with the 31's
how are you so sure you have 350HP? No offence but just wondering how you know this for a fact. If you did the driveshaft rotation, versus wheel rotation, calculation, and came out with something close to a 4.10 I would believe it. Have you checked your vacuum advance? I had the same problem on my 78', the advance diaphram was bad so no power at all.
What year is the truck? What transfer case do you have? What kind of RPM does it turn at around 60MPH? Your positive, 100% sure the 4wheel isnt engaged?
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Hey Vile, does it matter which kind of vacuum the modulator is seeing? I downloaded the Performer owners manual and the passenger side port is ported and drivers side is manifold vacuum. I know you said it doesn't matter too much about the vacuum advance canister, but does it matter for the modulator? I suppose it shouldn't since vacuum is available at both ports as soon as the throttle is opened eh?
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Transmission vacuum modulator should have manifold vacuum
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Cool, thanks for the info.