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Username Post: 93 K1500 5.7 Cam help needed (roller to flat tappet?)        (Topic#349478)
Skribble93 
Poster
Posts: 20

Reg: 02-03-18
02-03-18 06:22 AM - Post#2723175    

Hi everyone I recently ran into a bit of a snag trying to figure out an aftermarket cam for my truck. It is a 93 K1500 4x4 5.7. The issue is the motor is 2 into 1 the block and internals are from a mid 90's vortec and the heads & intake are the original tbi from 93. My problem is trying to find a bit milder roller cam and lifter kit that is fuel injection and ecm friendly the few I have found are not computer compatible but found several flat tappet ( as to be expected) but am unable to progress as far as information on either a good reasonable priced roller set or if I can go backwards and run a flat tappet although I would rather not. The motor is stock minus the usual headers and dual exhaust and upgraded cap, rotor, plugs and wires. It has a shift kit to help towing wise being it's used to pull trailers and such and does a lot of hauling scrap, round hay bales and anything that will fit. Just looking to give it a bit more oomf without breaking the bank. Any info is greatly appreciated.

If it's to loud your to old

93 K1500 Z71 step side 5.7 shorty headers and 2 1/2in straight pipes. 3in body lift and leveling kit.


89 K1500 4.3 rotted frame dubbed parts rig


 
1983G20Van 
Super Senior Member
Posts: 3695

Loc: Bedford, Texas, USA
Reg: 11-13-02
02-08-18 09:54 AM - Post#2723749    
    In response to Skribble93

  • Skribble93 Said:
Hi everyone I recently ran into a bit of a snag trying to figure out an aftermarket cam for my truck. It is a 93 K1500 4x4 5.7. The issue is the motor is 2 into 1 the block and internals are from a mid 90's vortec and the heads & intake are the original tbi from 93. My problem is trying to find a bit milder roller cam and lifter kit that is fuel injection and ecm friendly the few I have found are not computer compatible but found several flat tappet ( as to be expected) but am unable to progress as far as information on either a good reasonable priced roller set or if I can go backwards and run a flat tappet although I would rather not. The motor is stock minus the usual headers and dual exhaust and upgraded cap, rotor, plugs and wires. It has a shift kit to help towing wise being it's used to pull trailers and such and does a lot of hauling scrap, round hay bales and anything that will fit. Just looking to give it a bit more oomf without breaking the bank. Any info is greatly appreciated.



Maybe clarify what you mean by milder. Its practically impossible to go with a milder cam than what came in the Vortecs. The only cam I can think of that is smaller is the 305 TBI peanut roller cam and thay cam is a dog. It only has .350/.385 lift and the duration is tiny. I have a 305 Vortec in a Tahoe that has a flat tappet cam. I used the flat tapper cam because I was able to go with a signifigantly larger cam without having to change the springs or retainers. With the parts I had sitting around the shop I was able to put a new cam and lifter set in the engine for around $100. I only have about $600 into the whole engine that I completely resealed as well as put new rings and bearings in. With a 218/218 @ .050, .454/.454 cam cut on a 110* LSA I killed off a little bit of low-end power for a big boost in the mid-higher rpm range. With a converter that stalls in the ~2,500 rpm range the little 305 gets right into its powerband and pulls as strongly as its larger 350 brother. Where the 350 with a stock cam is nosing over the cammed 305 is just waking up.


1983 G20 Van, 350 TPI, Ported 906 Vortecs, Edelbrock 3817 Base, ASM oversize runners. Reed Custom Roller cam, 700r4, 12 bolt with 3.08 gears, Doug Thorley Tri-Y headers, true duals


Edited by 1983G20Van on 02-08-18 09:58 AM. Reason for edit: No reason given.

 
Skribble93 
Poster
Posts: 20

Reg: 02-03-18
02-11-18 09:48 AM - Post#2724030    
    In response to 1983G20Van

I have run stage 1 and 2 RV cam's in older carb 350's and in a 305 tbi but they were flat tappet setup's the only vehicle I had with a roller cam setup was an old cutlass but I bought it that way so I never messed with it much. I tow and haul hay a lot with the truck and just want to give it a bit more power in the lower gear range but as you said the stock cam is already pretty beefy I have thought of putting an older 350 in it and just switch everything out to carb and call it a day but really do not want to give up the slightly better mpg just for a bit more torque and rougher idle plus already changed the motor once not something I enjoy much on a lifted truck lol.

If it's to loud your to old

93 K1500 Z71 step side 5.7 shorty headers and 2 1/2in straight pipes. 3in body lift and leveling kit.


89 K1500 4.3 rotted frame dubbed parts rig


 
scrambldcj8 
Senior Member
Posts: 2326

Loc: MA
Reg: 04-06-03
02-12-18 05:53 AM - Post#2724138    
    In response to Skribble93

  • Skribble93 Said:
on a lifted truck lol.



Curious, what size tires and what gear ratio are you presently running. Possibly a lower gear ratio will be more beneficial than a milder cam swap? Often times with a lower ratio such as 4.10 even in a stock truck/stock size tires.....low rpm grunt and fuel mileage actually improves



 
Skribble93 
Poster
Posts: 20

Reg: 02-03-18
02-12-18 05:32 PM - Post#2724187    
    In response to scrambldcj8

Tires are stock 265/75/16 just mud radials and ratios are stock as far as I know of.. I'm leaning more towards abandoning changing the cam and adding a tb spacer and having the heads redone with slightly bigger valves.

If it's to loud your to old

93 K1500 Z71 step side 5.7 shorty headers and 2 1/2in straight pipes. 3in body lift and leveling kit.


89 K1500 4.3 rotted frame dubbed parts rig


 
CowboyTrukr 
"7th Year" Silver Supporting Member
Posts: 3926
CowboyTrukr
Loc: Salt Lake City
Reg: 06-20-09
02-12-18 08:59 PM - Post#2724209    
    In response to Skribble93

Honestly, save yourself the $30 for the spacer. It doesn't work.

Greg

'95 K1500 Z71 EC Short Step 5.7L+0.040/NV3500
'00 Explorer XLT 4.0 V6 Auto
'94 K2500 5.7 NV4500 ECLB - SOLD

"The only thing necessary for evil to triumph is for good men to do nothing" Sir Edmund Burke


 
1983G20Van 
Super Senior Member
Posts: 3695

Loc: Bedford, Texas, USA
Reg: 11-13-02
02-13-18 04:47 AM - Post#2724228    
    In response to CowboyTrukr

1" oval, open center spacer combined with a 2" bore marine TBI unit, hypertech powerbowl and modified air cleaner was very noticeable for me.

1983 G20 Van, 350 TPI, Ported 906 Vortecs, Edelbrock 3817 Base, ASM oversize runners. Reed Custom Roller cam, 700r4, 12 bolt with 3.08 gears, Doug Thorley Tri-Y headers, true duals


 
65_Impala 
Very Senior Member
Posts: 4003

Reg: 12-29-02
02-13-18 12:54 PM - Post#2724273    
    In response to Skribble93

How did you make the roller cam engine run well with the TBI system?

Are you trying to change the cam without doing any tuning?

There are LOTS of roller cams that will work well with the TBI once you tune it.

A roller cam will always make more power than a flat tappet. Switching the current roller cam you already have to a flat tappet in an attempt to get more low end power doesn't make any sense.



 
1983G20Van 
Super Senior Member
Posts: 3695

Loc: Bedford, Texas, USA
Reg: 11-13-02
02-13-18 01:15 PM - Post#2724275    
    In response to 65_Impala

  • 65_Impala Said:
How did you make the roller cam engine run well with the TBI system?

Are you trying to change the cam without doing any tuning?

There are LOTS of roller cams that will work well with the TBI once you tune it.

A roller cam will always make more power than a flat tappet. Switching the current roller cam you already have to a flat tappet in an attempt to get more low end power doesn't make any sense.



I can answer your first question. I have built several 350 TBI engines with similar stock GM cams and never had an issue getting it to run well on the stock GM tuning. The factory TBI cam is 194/203 @ .050 on a 112 LSA. The Vortec cam is 191/196 @ .050 on a 111 LSA. The F/Y-car LT1 cam is 201/208 @ .050 on a 115/116 LSA. I had a 1996 LT4 cam 203/210 @ 0.05 on a 115* LSA with 1.6:1 rockers in my old G20 and ran it for thousands of miles with the stock chip from a 1992 G20 van. I have also put a L98 roller cammed Caprice 9C1 engine in a Suburban and it also ran well. ALL of those were done before I was tuning and worked with the stock chip. Just played with the base timing and fuel pressure until I got it running at its best at WOT. Usually around 13.5-14 psi fuel pressure and about 4-8* BTDC on the timing.

1983 G20 Van, 350 TPI, Ported 906 Vortecs, Edelbrock 3817 Base, ASM oversize runners. Reed Custom Roller cam, 700r4, 12 bolt with 3.08 gears, Doug Thorley Tri-Y headers, true duals


 
Skribble93 
Poster
Posts: 20

Reg: 02-03-18
02-20-18 06:02 AM - Post#2724960    
    In response to 1983G20Van

As 1983G20 said it runs fine on the stock tune. All that was done was I removed the vortec heads and intake and put the TBI intake and heads on it I just had to use the vortec push rods due to them being a different length. There was a couple sensors that had to be swapped out and one on the vortec that just sits unused being it was a newer motor and of course different setup. While sorting out another issue I did confirm the block is from a 98 truck so 5 years newer. I think I am going to look into the throttle body swap as suggested and leave well enough alone for the cam ordeal though have learnt the hard way if the insides are working fine don't mess with it something usually goes wrong lol. I appreciate all the info and suggestions very much. And if anyone was wondering by chance I'm for the most part self taught when it comes to mechanics a lot of watching and learning growing up and trial and error on my own my dad is a GM ASE certified mechaninc and recently retired (said 43 years was enough to many computers involved now lol) so he has helped teach me a bit through the years but tries staying out of my projects as much as he can and says "you in your 30's now figure it out". Thanks again for all the input though guys

If it's to loud your to old

93 K1500 Z71 step side 5.7 shorty headers and 2 1/2in straight pipes. 3in body lift and leveling kit.


89 K1500 4.3 rotted frame dubbed parts rig


 
scrambldcj8 
Senior Member
Posts: 2326

Loc: MA
Reg: 04-06-03
02-26-18 04:44 AM - Post#2725638    
    In response to Skribble93

What gear ratio (see label in glove box if it hasn't faded yet)?

A swap to 4.56 might just get you the low end "oomph" you're after and won't break the bank too much.....especially if you're ratio is now a 3.42.

IMO, on stock a 1/2T with 265's I think 4.10 ratio is ideal and w/OD it doesn't kill fuel mileage (in some instances it may actually improve). If the truck is called into haul duty all the time, I would not hesitate to go 4.56.....depending on load and distance of course.

PS, Lower ratios also tend to make these trannies last a bit longer by taking off some of the "stress".



 
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