High Comp 120cc Build

samIam

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So it about time for me to lay out what I've got for a project. My 84 Coupe will be getting a new motor this winter and I'm just about to the point of assembly so I figure I better get some pics out to the pros before I move forward.

The block is 1975 I think. Its 30 over, lined honed and decked. I did the line honing because of the new studs and I plan on higher rpm though I'm not sure as to how high because I haven't got a cam made yet. Also have the oil balance line from Marty, just feeds the drivers side rear galley. Did the mods to the oil pump also. Deburred the whole block.










The rotating assembly has been balanced with the new forged pistons and rods. The guy that did the balancing was very surprised at the little work it took to balance the rotating assembly and charged me $60 less then what he told me over the phone. The crank, which I deburred also, only took three little holes that go maybe 3/8" deep and one piston had to be ground a little on the big end. The pistons are Probe and I'll have to look at the brand of rods, they are bushed at the small end and full floating. The two rod pics give you an idea of how much they took off the big end. Compare how the one stands flat on the surface and the other one has a dome.








 

samIam

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The heads have been ran through as y'all have probably seen in the 493 intake port thread. But maybe 10 hours into them. New stainless valves, 2.11 intake and 1.77 exhaust. New swirl guides and decked the heads. I still have to measure the actual cc's with the cc testing tool I got from ebay. I did some work in the combustion chamber as well so I'm sure it will be well over 120cc.
My numbers....
.200 132in 98ex
.300 190in 136ex
.400 212in 166ex
.500 238in 188ex
.600 257in 204ex
put me right at 80%

After looking for stock flow numbers on this forum, this is what I came up with for stock numbers
.200 96in 58ex
.300 147in 110ex
.400 195in 126ex
.500 225in 137ex
.600 240in 143ex







As for the intake, I've got an old molested Bulldog(ports opened on the cal head side), a stock edelbrock and a homemade high-rise intake. After talking to Marty and other on the forum, I decided on the Bulldog and the heads were worked based on running it. I do plan on bringing the homemade one to the dyno session to see what it does also but thats more just to see, not sure if I'd use it this time around.
 

samIam

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Still haven't got a carb picked out though I have a vacuum sec 870 holley SA and a modified 800 double pumper from a friends 14sec S10. Any concerns y'all see yet?

Here's my baby next to my friends S10 at the track last year. Went 14.69 on current motor.
 

The Mad Cadder

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Are those back grooved bearings ?? If they are dismiss the following

Hard to tell from pics but if they are not they are not lined up with the feed holes
 

8ad-f85

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Don't forget to deburr the edges around the combustion chambers and sharp corners on the piston tops!
 

The Mad Cadder

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After a better look Iam certain the cam bearings are NOT lined up
with the block feed holes !! It looks like I can see the edge of the
hole on some.. Since they were that wreck less knock out them
cup plugs and take out those pipe to make sure it is cleaned right

After all the machine shop bs I've been thru I would not trust them
on anything ..check it all
 

samIam

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Enlarge the pushrod holes....whats the routine for doing it at home? Or is that something better off for the machine shop?
The comp is expected 10/1 but I've done some combustion chamber work and I've seen some people measure these heads at 128cc.
I can't remember if the bearings are back grooved or not but I do have an extra set of grooved cam bearings, I'll talk to the shop tomorrow.
I've deburred the combustion chamber but haven't prepped the pistons yet. Probe's piston prep video is on youtube and it included some file work.

Thanks for the help so far.
 

8ad-f85

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Your work looks great so far!
I presume you mean that you deburred the chambers after the pics?
Referring to where the fresh surfacing cuts outline the chamber, this is more important than a couple of "points" of ratio (9.x, 10.x, etc).
Don't forget the raised area in between the intake and exhaust valves, or anywhere somewhat sharp that you could picture glowing just a bit if you held a torch on it.
.015"-.020" radius minimum, use flap rod after sharp tool (burr or file or ?).
 

Member 3508

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Regadring pushrods, you can just do the holes with a burr. Thats what i did. You want to enlarge them towards the center of the head. If you do a search here, you can find that some people just enlarge them with a bigger drill bit. I just dont know what that size is.

I did mine with a burr, and i went as far as i was comfortable. In the pic, the one in focus is enlarged. The one in the background is not.

 

samIam

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f85, I was just out looking at the sharp edges you are talking about and I can see what you mean, they are SHARP. I'll handle that.
Thanks Regal, after spending countless hours with the die grinder, I can do that no problem.

Thanks again
 

dave brode

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dave brode

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The Mad Cadder said:
Are those back grooved bearings ?? If they are dismiss the following

Hard to tell from pics but if they are not they are not lined up with the feed holes

Ditto. Either they are not, or, they are, and are not installed in ideal position. Iirc, the back grooved brgs have two holes, 180* from one another.

viewtopic.php?f=3&t=8176&p=184362&hilit=back+grooved+bearings#p184362
viewtopic.php?f=3&t=8176&p=184383&hilit=back+grooved+bearings#p184383





Dave
p.s. - do you know the dome volume?
 

shiftless

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Excellent work, and wicked looking car. :thumbup:

The port job is very nice and those flow numbers look great. Huge improvement at low lift.

Don't forget to grind/mill down the tops of the valve guides. Otherwise with an aftermarket cam your retainers may run into them at higher lifts. :twocents:
 

Darius

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The excellent picture quality helps to tell the story. Thanks for taking care to provide them. Very nice work overall!

Best,

d
 

samIam

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I will post some pics of the cam bearing layout soon. I have some Durabond back grooved cam bearings with one feed hole in

my parts collection.I would like to measure to make sure the new valve guides are short enough to clear a big cam, how can I

measure that at home? The pistons are +15cc

I still have no carburetor, convertor or cam for this motor yet.

Here is the homemade intake, I'd use it if it gave me enough power to justify cutting the hood.
 

8ad-f85

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Put a valve in, along with a retainer and locks, no spring.
Pull up and measure with a caliper (top of guide to bottom of retainer).
I use a 12" caliper because the ID part is long enough to reach the valvestem.
 
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