installing comp cam...ran into problem help - Third Generation F-Body Message Boards

benin360 · 10-05-2009, 02:42 PM

i got a comp cam and lifter set for my 91 z28 305 5sp. the cam ratings are at
Advertised Intake Duration 280
Advertised Exhaust Duration 280
intake valve lift 480
exhaust valve lift 480
lobe separation 110
i was looking around for a long time asking many questions and i came to this one. but i got into my motor to install it and i then realized there were roller lifters..... this is a flat tappet cam/lifter set. i could not afford the roller. the roller lifters are about .5 inch taller then the tappet lifters. will this affect the lift or anything? please help

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mikesz1984 · 10-05-2009, 04:25 PM

i dont beleive it will affect the lift, but you will need to get new push rods for the motor. The push rods from the roller lifters will be to short.

vetteoz · 10-05-2009, 06:03 PM

Quote:

Originally Posted by mikesz1984

but you will need to get new push rods for the motor. The push rods from the roller lifters will be to short.

Roller pushrods are 7.200" ; flat tappet are 7.800" long

benin360 · 10-05-2009, 06:32 PM

my buddy just got a set of 7.794" will those work? he said he would give them to me? or would those not work?

flaming-ford · 10-05-2009, 10:12 PM

i would say that would do fine ,but you will just have to test fit them to make sure you have correct alignment.

benin360 · 10-05-2009, 11:24 PM

ok cool. they fit i checked. one last problem lol. ran into a few. the plate that holds the old cam in place. it does not fit the new one. what is this called and where do i get one that fits? thanks for the fast response guys. much appreciated.

chevymec · 10-05-2009, 11:36 PM

With a flat tappet cam you wont use the plate. IIRC you will also have to get a new timing set because the factory roller cam has a lip that goes in the retainer plate.

benin360 · 10-05-2009, 11:49 PM

so what is gonna hold the cam in place?

benin360 · 10-06-2009, 01:05 AM

info please

vetteoz · 10-06-2009, 03:01 AM

Quote:

Originally Posted by benin360

so what is gonna hold the cam in place?

A flat tappet cam has a "angle" ground on the cam lobes so the pressure of the lifters drives the cam back into the block.

A roller cam cam has a flat lobe for the roller lifter wheel so there is nothing to stop the cam walking forward out of the block .The factory used a cam with a grove in the front so a retainer plate could hold the cam in

vetteoz · 10-06-2009, 03:04 AM

Quote:

Originally Posted by chevymec

you will also have to get a new timing set because the factory roller cam has a lip that goes in the retainer plate.

And the cam timing gear has a different bolt pattern

chevymec · 10-06-2009, 08:06 AM

Cam gear has the same bolt pattern.

vetteoz · 10-06-2009, 08:20 AM

Quote:

Originally Posted by chevymec

Cam gear has the same bolt pattern.

Holes for the cam gear bolts on a flat tappet cam are out where the retainer grove is on a HR cam.Bolt pattern and pin are moved in on HR cam to allow for groove.
Put the two gears side by side or try a flat tappet gear on a roller cam; you will see the difference.

stroker_SS · 10-06-2009, 11:40 AM

Here i am ready to drop about a 1000 bucks to have a roller set up in my Flat tappet block, and i see all these people using FLAT TAPPET CAMS in there ROLLER BLOCKS. ARRRRRRRRRRRRRRRRRGGGGGG.

Rant off.

chevymec · 10-06-2009, 01:16 PM

Quote:

Originally Posted by vetteoz

Holes for the cam gear bolts on a flat tappet cam are out where the retainer grove is on a HR cam.Bolt pattern and pin are moved in on HR cam to allow for groove.
Put the two gears side by side or try a flat tappet gear on a roller cam; you will see the difference.

Ill have to check that out. I never noticed a difference.

JakeJr · 10-06-2009, 11:45 PM

Actually, flat tappet cams can be either what we refer to as "front walkers" or "back walkers", depending on the how the block was machined at the factory.

Handling the "front walkers" is usually done with a thrust button. Those come in three basic variations; plastic, aluminum and roller types. I prefer the roller type since I've seen the plastic type wear excessively and have seen the aluminum type actually drill through the timing change cover.

Handling" back walkers" is done with a bearing placed between the cam gear and the block. Cloyes makes a timing chain set that is already machined to account for the thickness of the Torrington bearing and even comes with the timing chain set. It's a simple bolt on. The best type is the three-piece Torrington bearing.

Hope this helps.

Jake

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