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  #16 (permalink)  
Old 03-01-2011, 04:49 PM
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Quote:
Originally Posted by 350chevyrob
ok heres the story on my truck i had a stock 5.7 tbi in my truck and did a cam ,head,intake,and crab swap the heads are

world sportsman II heads 200cc runners 2.02 1.64/64cc

comp cam 4x4 X4270H 270/274 480/498 @111

intake with 4160 750 holley

now after getting it to run right i took it out to test drive it and there's no power .motor rev's up and sounds good but it's worse than the tbi setup i had on it before .so i noticed a ticking sound coming from the valve cover.i think i have a collapsed lifter or didn't set the rockers arm right.so i was going to do a compression test to see if i'm losing compression in any cylinders.
so i question is about what psi should i be in when i do the test??

thank you rob
This will not make any bottom end power, the heads are huge for a 350 the cam fairly long and the valves large not to mention the 750 Holley, you're going to have to wind this up. If you're running an automatic with a stock stall converter the engine is going to bog out of the hole as it's held to the lower rev range this cam needs more stall.

Lots of good parts but it's going to take some sorting to get this up to its potential.

Lifters are an increasing problem, seems nobody can make a good set any more. ID the ticker then R&R it and start over.

Bogie

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  #17 (permalink)  
Old 03-01-2011, 04:58 PM
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so your saying that it won't make any power ?
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Old 03-01-2011, 05:09 PM
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Did you change the distributor? I dont think the factory TBI distributor will provide proper timing when running open loop.
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Old 03-01-2011, 05:13 PM
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before i built this motor i had a 388 stoker in and pretty much did the same thing with how i set it up with the dizzy and it ran great .i have a 4l60e in my truck and i made a TPS bracket to mount on the side of the carb to run the tranny .i never had a problem with the dizzy not firing right .it made great power with the 388 in .just having trouble with this bish LOL
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Old 03-01-2011, 05:18 PM
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heres some pics of my setup

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Old 03-01-2011, 06:16 PM
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Quote:
Originally Posted by 350chevyrob
so your saying that it won't make any power ?
I'm saying two things:

1) The power band will be at pretty high RPMs, this is because the flow capacity of the carb, the ports and the valves is quite large so at lower RPMs the velocity in the induction system will be low such that the late closing intake valve of this cam will blow much of the mixture out of the cylinder as the piston rises until it gets enough RPMs to where the incoming mixture velocity can overcome the reverse pumping forces of the piston. This pushes the torque peak toward the RPMs of the horsepower peak and softens lower RPM power. Also an associated problem with this if you're running an automatic is the need for a higher stall converter. This works like a slipper clutch allowing the engine to rev up into its power band before loading it.

2) You have a lot of good parts, but some of the selections like the 200cc ports and big valves are overkill on a 350 that doesn' turn 7000 RPM. They can be tamed but it takes a lot of time and testing to get there.

There is a point where it's hard to tell if the engine's power issues are the result of tuning or of large capacity components working too far from their best solutions in terms of displacement and RPM. There is a lot of work after putting the parts on an engine, the further the part selection gets toward high performance the more the work is involved in getting them settled down.

You've hit into one of the reasons the Vortec head is so popular for hot street and certainly off road 350s, because they offer a significant power boost without resorting to large cams, big ports and valves. So they are much happier when mated to an engine that runs from idle to 6000 or so RPM. Your big port and valve choice of heads will take some extra work to get them working their best.

I would ask if you know the static and the dynamic compression ratios of this engine. The both compression ratios against the cam timing is very important to getting all the power you paid for, again because of the big ports, valves and cam timing the compression is used to restore power lost to the reverse pumping effects. So knowing the deck height, thickness of the head gasket, and the volume of the piston's dish is important to computing the compression ratio. For the dynamic CR you need the point where the intake valve closes as well and the rod length. you can play with the numbers at this URL. http://www.kb-silvolite.com/calc.php


So I don;t know if this is a tuning issue or whether the power band is just higher than you realize. But first you need to understand what you've got for compression ratios, that will lead into what the timing needs to be both in terms of how much but also when it comes in. You need to figure out the mixture ratios, it's unlikely the Holley is correct out of the box.

Bogie
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  #22 (permalink)  
Old 03-01-2011, 06:50 PM
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Hi
Here's an accurate way to adjust the valves. The lifter must be on the heal of the lobe to get an accurate adjustment. To accomplish this you split the firing order, 1843 6572 now with #1 Int. at full lift, #6 Int. lifter is on the heal of the lobe ready for adjustment etc. etc.
Rich

#1 cylinder Intake Valve at full valve lift .... Adjust #6 Intake Valve
#8 cylinder Intake Valve at full valve lift .... Adjust #5 Intake Valve
#4 cylinder Intake Valve at full valve lift .... Adjust #7 Intake Valve
#3 cylinder Intake Valve at full valve lift .... Adjust #2 Intake Valve
#6 cylinder Intake Valve at full valve lift .... Adjust #1 Intake Valve
#5 cylinder Intake Valve at full valve lift .... Adjust #8 Intake Valve
#7 cylinder Intake Valve at full valve lift .... Adjust #4 Intake Valve
#2 cylinder Intake Valve at full valve lift .... Adjust #3 Intake Valve
Now The Exhaust
#1 cylinder Exhaust Valve at full valve lift .... Adjust #6 Exhaust Valve
#8 cylinder Exhaust Valve at full valve lift .... Adjust #5 Exhaust Valve
#4 cylinder Exhaust Valve at full valve lift .... Adjust #7 Exhaust Valve
#3 cylinder Exhaust Valve at full valve lift .... Adjust #2 Exhaust Valve
#6 cylinder Exhaust Valve at full valve lift .... Adjust #1 Exhaust Valve
#5 cylinder Exhaust Valve at full valve lift .... Adjust #8 Exhaust Valve
#7 cylinder Exhaust Valve at full valve lift .... Adjust #4 Exhaust Valve
#2 cylinder Exhaust Valve at full valve lift .... Adjust #3 Exhaust Valve
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  #23 (permalink)  
Old 03-01-2011, 06:56 PM
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Quote:
Originally Posted by richard stewart 3rd
Hi
Just buy one lifter & put it in. Use some break-in lube, it will be fine.
Rich
Quote:
Originally Posted by 350chevyrob
yea i call the mechanist at napa at he said the same thing.
This goes against everything I've ever read regarding flat tappet (assuming you're not running rollers) cams/lifters. You should never swap out a flat tappet lifter once it's been run.
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Old 03-01-2011, 07:16 PM
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H
Remember when Rhoads V D L came out?
Many people have put Rhoads variable duration lifters‎ in without changing the camshaft without problems. I've don it myself. I put a whole new set of lifters in 2 different SBCs that sounded like machine guns when they came down the street. Why
Because that is what I was being payed to do. (Of course that was before this crap oil there passing off now) neither car had a problem.
Rich
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  #25 (permalink)  
Old 03-01-2011, 10:19 PM
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Quote:
Originally Posted by 350chevyrob
before i built this motor i had a 388 stoker in and pretty much did the same thing with how i set it up with the dizzy and it ran great
Not using an advance curve on the street gives away power and economy. That looks like an HEI w/o any type of advance. If that's the case, you really ought to be using an earlier large coil-in-cap type HEI (w/o computer control required for an advance curve) like used in the '74-'80 cars and some trucks through '86. You don't have to use the in cap coil, there are caps to adapt it for an external coil like you now have.

Good luck w/using a new lifter on your cam- you may need it.
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  #26 (permalink)  
Old 03-02-2011, 04:44 AM
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Quote:
Originally Posted by oldbogie
I'm saying two things:

1) The power band will be at pretty high RPMs, this is because the flow capacity of the carb, the ports and the valves is quite large so at lower RPMs the velocity in the induction system will be low such that the late closing intake valve of this cam will blow much of the mixture out of the cylinder as the piston rises until it gets enough RPMs to where the incoming mixture velocity can overcome the reverse pumping forces of the piston. This pushes the torque peak toward the RPMs of the horsepower peak and softens lower RPM power. Also an associated problem with this if you're running an automatic is the need for a higher stall converter. This works like a slipper clutch allowing the engine to rev up into its power band before loading it.

2) You have a lot of good parts, but some of the selections like the 200cc ports and big valves are overkill on a 350 that doesn' turn 7000 RPM. They can be tamed but it takes a lot of time and testing to get there.

There is a point where it's hard to tell if the engine's power issues are the result of tuning or of large capacity components working too far from their best solutions in terms of displacement and RPM. There is a lot of work after putting the parts on an engine, the further the part selection gets toward high performance the more the work is involved in getting them settled down.

You've hit into one of the reasons the Vortec head is so popular for hot street and certainly off road 350s, because they offer a significant power boost without resorting to large cams, big ports and valves. So they are much happier when mated to an engine that runs from idle to 6000 or so RPM. Your big port and valve choice of heads will take some extra work to get them working their best.

I would ask if you know the static and the dynamic compression ratios of this engine. The both compression ratios against the cam timing is very important to getting all the power you paid for, again because of the big ports, valves and cam timing the compression is used to restore power lost to the reverse pumping effects. So knowing the deck height, thickness of the head gasket, and the volume of the piston's dish is important to computing the compression ratio. For the dynamic CR you need the point where the intake valve closes as well and the rod length. you can play with the numbers at this URL. http://www.kb-silvolite.com/calc.php


So I don;t know if this is a tuning issue or whether the power band is just higher than you realize. But first you need to understand what you've got for compression ratios, that will lead into what the timing needs to be both in terms of how much but also when it comes in. You need to figure out the mixture ratios, it's unlikely the Holley is correct out of the box.

Bogie
i agree with your post.its like saying bigger is not always better.

when i was looking for heads i keeped in mind that i still have the 388 i want to rebuild and put some good heads on.and i kind figered that the heads where going to be a lil over kill on the 350 i'm try to put it on.

but your right!! on alot of aspects of your post.it will take alot of tuning before it is going to at it's best and some detuning lol

i'm just a guy how love's to wench and make something my own .even if it's not right .this is how i learn


well didn't get it all back together last night so i'm going to start working on at the crack of dawn.just a few odds and ends i need to button up
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