# Cam question



## PontiacDave (Jun 9, 2009)

Quick question.....is anyone running a CompCams XE268H? I have the cam and lifter set new in box. It came with the purchase of my car and I want to try it but am a little hesitant. My engine is a 389, 0.030 over, 670 heads, 067 cam, everything else is stock with around 10 to 1 compression. My car is a '65 GTO 4-speed (wide ratio) and 3.36 posi. Any input would be appreciated.


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## Too Many Projects (Nov 15, 2008)

By comparing the specs, the 268 should be a good cam for your combo and improve performance noticeably. The torque range will move up slightly from the 067 but is still spec'ed by comp as starting around 1600; good for a manual trans car. Due to the tighter LSA, it will have a slightly rough idle.... You will need to check for adequate pushrod slot length in the head and rocker arm travel at the pivot ball for the higher lift. You can also go to a 1.65 rocker for even more lift.
Put it in......:willy:


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## Rukee (Feb 8, 2007)

Be carefull with the 1.65 rocker arms, they may force the pushrods to contact parts of the head. I couldn't use them on my 389 heads.


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## geeteeohguy (Feb 2, 2008)

The pushrods should be ok with the 1.65's on the 670 heads due to the guideplates the 670 heads have. I've never run 1.65's myself, so I don't know much about 'em. I DO wonder what pistons you used in the 389 that are compatable with the '67 heads you're running: the valve angle is different and it shouldn't work with stock pistons....they'd hit.


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## Too Many Projects (Nov 15, 2008)

Actually Jeff, it's the slots in the casting that Comp Cams recommends checking for clearance issues and also the slot in the rocker for bind on the stud. Pontiac's weren't known for high lift factory cams and anything over .450 should be checked for bind. Of course that doesn't include the ram air heads as they were made for more lift.


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## PontiacDave (Jun 9, 2009)

I am aware of the piston differences between the 389 and 400 pistons...the valve reliefs are a different size and different location. I did not rebuild the motor, it was done by the previous owner so I have no idea what he used. I swapped in the 670 heads. It had #77's before (I still have them boxed away for safe keeping). When I first put them on I had no idea of the different valve reliefs....the valves and pistons have not touched. I already purchased the correct valve springs from CompCams and now realize they are not a direct drop in. My machinist says the valve spring boss needs to be machined down to make them work, which means removing the cylinder heads. Is that true? this whole thing sound like a lot of work and I am unsure it would even work (valve/ piston clearance) :confused Thanks for all the input....last thing I want to do is damage my engine.


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## Too Many Projects (Nov 15, 2008)

PontiacDave said:


> I am aware of the piston differences between the 389 and 400 pistons...the valve reliefs are a different size and different location. I did not rebuild the motor, it was done by the previous owner so I have no idea what he used. I swapped in the 670 heads. It had #77's before (I still have them boxed away for safe keeping). When I first put them on I had no idea of the different valve reliefs....the valves and pistons have not touched. I already purchased the correct valve springs from CompCams and now realize they are not a direct drop in. My machinist says the valve spring boss needs to be machined down to make them work, which means removing the cylinder heads. Is that true? this whole thing sound like a lot of work and I am unsure it would even work (valve/ piston clearance) :confused Thanks for all the input....last thing I want to do is damage my engine.


Yes, the heads need to be machined for the spring seats. It could be that the valves could hit the pistons with a higher lift cam. The only way to know for sure would be to pull the heads and measure clearances with clay to see if they have room to go further. Either route you take from here, it's a bit of work and screwing around.  If it runs now, I would be tempted to leave it.


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## geeteeohguy (Feb 2, 2008)

I agree with Mitch on that one.l If it runs fun now, leave it alone and concentrate your efforts elsewhere on the car. You may have a piston/valve clearance problem with more lift. The 77 heads you removed were stock '65 GTO 389/421 heads. The 670's are '67 GTO 400.


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## geeteeohguy (Feb 2, 2008)

Runs FUN? I meant FINE. Sheesh...........


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