well, at first i was just going to re-ring my current, low-quality/compression pistons

then last night i saw a deal for a set of sealed power pistons and rings for $80

they stated the comp ratio was 9.53 with 64cc heads

all else being the same, the comp ratio is about 10.25 with 58cc heads

i figured thats probably pushing it with iron heads, but i figured:
1. its an EFI (tpi) motor
2. i will keep the EGR active the help prevent detonation
3. i can always cut back timing advance a little
4. gives me a good excuse the use sunoco 94 octane

now my REAL question is:
how are chevy 350 pistons attached the the rod?
with pressed in pins?
OR
with C-clip pins?

this is my first small block build/rebuild, but i am willing to bet they are pressed in pins


my second question which is off topic is:
how do i hook up a oil pressure sending unit to a 1978 block?
the one that was one there seemed to get in the way of the TPI manifold......
so can i use a sending unit for say a 1991 350? or is the block machined differently for the two?

thanx for your help

 

pins are pressed unless someone changed them over to floating pins and that isn't likely. if the oil sender doesn't clearthe intake use a el or nipple to move it where you have access to it.

 

I was running 89 octane happily w/ my GM 58cc Vette heads and flat-top pistons...even more happily on 93 octane but the 89 was enough to keep the spark retard to ~2deg max.

The trick is to run the right thickness head gaskets. Go too thick trying to lower the compression, and you have excessive fuel/air in the quench area which makes the engine more prone to detonation than if you ran thinner gaskets and got more compression. See the Vizard books for details, great reading.

I was running FelPro 1003 head gaskets at the time, 0.039" compressed thickness. I'm going to SCE 0.031" copper head gaskets this time w/ my AFR 58cc heads. Given that my piston is 0.015" below the deck surface @ TDC, this gives me a 0.046" piston to head clearance which is as close as I'll get without decking the block again or going even thinner on the head gasket (no thanks).

 

If the 58cc iron heads you are planning to use are 305 heads
you would want to upgrade the valves to 1.94 x1.50 at minimum.
To do this you have to sweep out the chamber so the valve clears the chamber wall. This removal of material will enlarge the cc of the chamber a little. When done right your final chamber cc will be 60/61 cc. not to worry. If then you really want a finished chamber size of 58cc then a minor clean up cut to the decks of the heads will straighten up the deck and reduce the chamber a
little.

 

i'm assuming i remove the pins with a hydraulic press then?

please correct if i am wrong, or tell me if i am correct

 

i mite actually switch to better heads (read: AFR's) when i can actually afford them, for now though the 305 heads should do the trick

 

oh yeah, i almost forgot

how much HP/TQ is a stock crank good for

i am not looking for high RPM usage as this motor is going into my daily driver

i just want to make sure the stock crank can withstand approx 400 ft. lbs. (and its not like i am going to be beating the hell out it all the time either)

 

A stock 350 cast crank is a lot tougher than you think.
There are only a few things that will break a crank.

Detonation is the biggy. As long as the crank is not cracked now
and you assemble the motor right, it will take all the abuse
you're likely to throw at it. If it passes a mag test, use it.
My buddy runs a stock cast 400 crank in his 9 sec nitrous
406 700hp na/1000 hp squeezed.
He's broke a few parts over the years but never the block
or crank.
I've run a cast crank in my motor for over 6 yrs. No problems.
You'll break a rod, even an aftermarket rod way before you break a stock crank.

 

 

well, i mainly asked about the crank cuz i dont want people to think i'm cheapening out on the bottom end

i'm guessing the stock rods should be ok for what i have in mind then

i did some playing around with dyno2000 and found out that the compcams XR258HR would make more power than the ZZ4 cam in my combo

if anybody wants to recomend another cam for me, here are the motor specs:

350 shortblock
flat-tops with 10.25:1 compression
416 305 heads (which will hopefully be fitted with 1.94/1.60 valves)
basically stock TPI (for now)
24 lb. injectors

 

Sounds fine especially on a basicly stock TPI motor with
near stock gearing and converter.
Let the Ported heads and plenum/runners make the power
and cam it for torque. You might want to order that cam on 112 deg lobe centers to better suite the TPI computer.
Get in touch with Comp Cams either by email or phone,
They'll advise you on the best choice.
These ported heads, like most ,like valve lift. Some 1.6 rockers might be worth a look if your buying rockers. The pushrod slot in the head will/may need to be elongated for 1.6 rockers.
If you go this route be sure to use good valve springs as the valve train will have high acceleration rates.

10.25 finished cr would be the absolute highest I go on this TPI motor with these heads.
By the time you've swept out the chambers to unshroud
for the new 1.94 x1.60" valves your chamber volume should be closer to 61/62 cc's which likey will be a + in the long run.
Trouble with increased compression is once you reach the threshold that the fuel octane will allow, detonation results.
Then the motor is always running @WOT with knock sensor induced ignition retard.
What octane fuels are availble in your area, that you'll buy and run?

 

yeah, i think i am just going to use the 416 heads on this engine, i feel confident enough to attempt to port them myself, and they sound pretty decent flowing-wise when you put larger valves in them

what valve springs am i going to need for either of these 2 hi-lift camshafts?

and 94 octane really is available in my area, atleast it was when i last checked a few monthes ago, i think only sunoco and amoco carry 94 octane though

if not, 93 octane is still availble everywhere else

and in the future i might consider dumping the stock TPI manifold for a stleathram.........thats a ways off though

 

At minium I would go with what is recommended for that grind
from the catalog. Or a spring of equal specs. If the budget will allow it, might consider upgradeing to a medium 1.44" dia. sized spring ( machining required).
Like I said, get in touch with the Cam Company itself. They are the experts.
They have a vested interest in getting your combination right the first time, and are more than happy to help.
Ordering a roller cam on a different lobe center usually doesn't cost any more, and they can ship it right to your door or to the gear head shop you're dealing with.
Getting the camshaft and valvetrain right will put you ahead of the guy who just picks one from the Summit book and throws it in.
Don't be shy at all to get in there and home/port these heads.
Ya can't hurt them, no real rocket science to it, just time consuming. But worth the effort in grins when ya mash the pedal.
With a good honest effort you'll end up with 90/95% of what a pro can get out of them, maybe better...

Note: the stock exhaust spring seats are machined deeper
on the 305 heads to allow for the ex rotator. If your going to eliminate the rotator and use a stock retainer in its place, you should shim up the spring seat to get the right installed height.
I'll make it easy for ya. For a installed height of 1.72" to 1.73"
usually just right add a .015,.030,.060 (black, silver, copper)spring shim to each exhaust spring pocket on assembly. You can buy these from any automotive supplier/builder for cheap. {8 of each} On the intake side for 1.72" installed height just reuse the oil shield under the stock intake retainer.

Measure your stuff.