nm9stheham
Well-Known Member
As a point of reference, the shallow flat area in the heads is around .090" deep on stock castings. With that step being about .030" high, that seems right for the KB243's, but I don't have any to doublecheck for you.
My engine is on a stand right now. If I rotate it over will there be a way for me to see the bottom of the piston? If so I can give it a go since the oil pan is off. I would still need to remove the lifters before turning it over then the metal shield on the bottom.As a point of reference, the shallow flat area in the heads is around .090" deep on stock castings. With that step being about .030" high, that seems right for the KB243's, but I don't have any to doublecheck for you.
So based on your statement, if I change out my cam I need to change the lifters also?Yep you can see right up to the piston bottoms. Good call to remove the lifters! Or just look up underneath with a flashlight....
IMPORTANT!!! Keep track of the lifters and EXACTLY where they go. Once they are run any little bit with the cam, they 'wear in' with the individual cam lobes, and cannot ever be switched from lobe to lobe. If you swap lifter positions by mistake, it will destroy the cam lobes.
I knocked over a box of used lifters the other day where they were kept in order just a coupla weeks ago and some got jumbled... they all went right into the trash can.
Yep you can see right up to the piston bottoms. Good call to remove the lifters! Or just look up underneath with a flashlight....
IMPORTANT!!! Keep track of the lifters and EXACTLY where they go. Once they are run any little bit with the cam, they 'wear in' with the individual cam lobes, and cannot ever be switched from lobe to lobe. If you swap lifter positions by mistake, it will destroy the cam lobes.
I knocked over a box of used lifters the other day where they were kept in order just a coupla weeks ago and some got jumbled... they all went right into the trash can.
So based on your statement, if I change out my cam I need to change the lifters also?
Message received.ABSOLUTELY. You MUST change the lifters with the cam.
I just poked my eyes around and I can't see any markings on the bottom side of the pistons. I advanced the crank and couldn't see any marks.Yep you can see right up to the piston bottoms. Good call to remove the lifters! Or just look up underneath with a flashlight....
IMPORTANT!!! Keep track of the lifters and EXACTLY where they go. Once they are run any little bit with the cam, they 'wear in' with the individual cam lobes, and cannot ever be switched from lobe to lobe. If you swap lifter positions by mistake, it will destroy the cam lobes.
I knocked over a box of used lifters the other day where they were kept in order just a coupla weeks ago and some got jumbled... they all went right into the trash can.
Message received.
Well, they were only /6 lifters after all...You could have had them resurfaced.
Here were my compression numbers back in August. I didn't do #5 or #7 due to the header.
Driver
1 141
2 135
Pass
1 140
2 140
3 135
4 132
What is chasing 1 point going to net me?
Also, wouldn't mulling the head down just decrease the volume of the heads and negatively effect the amount of flow?
Just to make sure, will I be able to see the cam specs without pulling the cam out if I pull the timing gear off?
Here were my compression numbers back in August. I didn't do #5 or #7 due to the header.
Driver
1 141
2 135
Pass
1 140
2 140
3 135
4 132
Ok. I'm going to order the XE268 or 262 today, the kit with lifters.Yes, that is in the neighborhood of the high 8's or low 9's for SCR. Which is what this has been about, and the DCR is likely where this has been point all along: it's in the high 6 to low 7 range. We have a 340 with a true 10.0:1 SCR that shows 159 psi average at 2400' of elevation. DCR is in the low 8's; it spins the rear tires in an early A body with half throttle, 3.55. rear gear, and a 600 or 675 carb: torque out the wazoo.
What you have in this case it a pretty common situation: moderate SCR at best and a low DCR due to a large-ish cam. The result is well known: poor low end poop, but it winds out at the high RPM's great. Where you say that you want to go is known territory too: raise the SCR to get the wider torque band extend to the low RPM's and make sure you keep the cam small enough to not kill it down low. With something like the 268 sized cams, you get into that sweet spot. You can do other combo's but this one is like falling off a log to get to work decently.
40 HP? Don't get caught up in HP here; that is NOT what you are after based on what you want to do the get the low RPM performance up; you are after torque. Getting the SCR with a thinner head gasket and some milling will really pay off here. THEN you keep up the DCR with the smaller cam. It is gonna make a world of difference.