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My sons 350 build

3K views 14 replies 6 participants last post by  chas350 
#1 · (Edited)
Hey guys

This is the engine me and my son built for his 71K10, 373 gears 33" tires.
Tell me what you think.
We have started it and broke in the cam but not driven yet.

'83 4 bolt 350 from 2500 truck
bored .040 over, decked.
line honed, Eagle cast crank
Scat forged rods 5.7"
KB -18cc D cup, .040 quench, moley rings.
New Stock oil pump.
SFI flywheel and stock 6.5 balancer
Whole rotating assbly balanced

GM Perf parts #8060 vortec heads decked .010-.020 ?, port matched to intake, combustion bowl left stock, intake and exhaust passages ported, , area around valve guide smoothed/ported, including short and long radius.
Restricted area under valve anlge enlarged. Mistake here? should I have left that alone?
Pocket cut for LT4 springs/retainers, viton seals, screw in studs, guides plates.
CAT alum 1.5 roller rockers, new std lenght push rods.
Comp Extreme 4x4 Flat Tappet cam X4262H .218/.226 @ .050 LCA 111 .462/.480 107 ICL Degreed out straight up.
Comp flat tappet lifters
ZZ4 water pump, take off from crate.
Edlebrock RPM air gap Vortec Manifold
Barry Grant Speed Demon 575 Mechanical with annular boosters and electric choke kit.
Cheap ebay red top ProComp? Billet HEI dist, for now.
Hedman Elite coated Headers, Cherry Bomb Vortex , 2.5 ss all the way.
Fel-Pro gaskets, all.
I think compression came in around 9:1-9.25:1 after cutting the block/heads.
I think I got everything :rolleyes:


PS I forgot to check the rocker geo for push rod length. Probably need shorter? because of block and head surfacing?

I know I know, heres the question :D How about Opinions on TQ/HP and general build suitability.

Thanks fellas
Happy Thanksgiving

Chas
 
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#2 ·
It looks like a good truck package other than the intake. I would have gone with a performer intake. It'll give up 15 hp up top, but it'll give you that in torque down low plus better running in cold conditions and better milage. Not bad though. You're probably looking at 320hp and 360tq- my seat of the pants guess.
 
#6 ·
chas350 said:
320/360 thats all :(

chas

Well, that's not a bad thing. You basically just have a stock Vortec engine with an intake and a flat tappet cam.

A real Vortec engine would be running a roller cam, but the intake will help you some. I would install that cam advanced a few degrees too. Never can have too much low end with those tires.
 
#7 · (Edited)
GMC Boggie "That is a nice build."

thanks Boogie,

we will hope the cam is not to big :D

A few pics, the last of my son smiling while we brake in the cam, running 2000 rpms

chas
 

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#9 ·
The cam is a little bit big, and the lack of a full divider in the intake plenum may hurt some, but you will make up for this due to the carbs small cfm rate, it was a big plus to pick a carb with annular boosters, had you used a bigger carb with downleg boosters it would have been sluggish in the low rpm ranges. When you drop it into low range it`ll become a throttle responsive monster and I`m sure you and your son will love it.
 
#10 ·
Yes, the air gap intake really sucks in cold weather. You should use a performer or a regular rpm intake and use the exhaust cross over under the intake. makes a huge difference.

I ran an air gap for a few months and pulled it off and sold it because of the very slow carb warmups.

That cam is about 10 degrees to big for the compression, load, and gear (plus tires). However, it does have very quick ramps and therefore a low advertised number (262), which is more like it. So it might be OK. Make sure to use a ZDDP additive in the oil to prevent the cam from going flat. Todays oils are very hard on flat tappets.

365hp/380ftlbs is my guess.
 
#11 · (Edited)
454C10 said:
Yes, the air gap intake really sucks in cold weather. You should use a performer or a regular rpm intake and use the exhaust cross over under the intake. makes a huge difference.

I ran an air gap for a few months and pulled it off and sold it because of the very slow carb warmups.

That cam is about 10 degrees to big for the compression, load, and gear (plus tires). However, it does have very quick ramps and therefore a low advertised number (262), which is more like it. So it might be OK. Make sure to use a ZDDP additive in the oil to prevent the cam from going flat. Todays oils are very hard on flat tappets.

365hp/380ftlbs is my guess.

Thanks 454C10, I never found any mention of the cold weather problem with the air gap in my research, but that was done 1 1/2 years ago. Maybe we will end up with the EPS manifold if its made in a vortec version? After it is drivable we can determine if the low end is lacking.
What do you think my compression is? I thought it came in at 9-9 1/2:1 with the head and block milling.
We did use GM EOS and shell Rotella, hoping the lobes are ok, it didnt fire as quick as I wanted resulting in a little more cranking than normal. Its been a year last summer since we first started it. My son got a little lazy this year and has not got much done on it. :spank:


DoubleVision
"The cam is a little bit big, and the lack of a full divider in the intake plenum may hurt some, but you will make up for this due to the carbs small cfm rate, it was a big plus to pick a carb with annular boosters, had you used a bigger carb with downleg boosters it would have been sluggish in the low rpm ranges."

Life is full of Compromise! That carb was highly recommended to us because of the annular boosters. We may end up with the EPS for the winter use, we will see,

Thanks for the comments guys! Keep them coming!

Techinspector1 , if you have a chance, we would love to see a DD curve :D

chas & logan
 
#12 ·
assuming a zero deck height and 63cc heads (-1cc for 64cc vortec). I came out with 9.1:1 cr. Not sure how much they milled off the block or the deck height. You may have 8.9 or 9:1 cr if the piston is below the deck 0.010.

I would use the regular performer RPM intake (non-airgap) for a square bore carb. I had tried both the rpm and performer intakes on the same engine and it seems to me the RPM intake makes the same low end power as the performer intake but more mid and upper rpm power. In theory, low end power difference should be especially not noticeable with a little more stall converter (2000 rpm) since the rpm intake has a power band from 1500 to 6500.

I would use a ZDDP additive in every oil change. Cost about 10.00 more per oil change but worth it. Then you can use any gas engine oil. They are now reducing zinc in diesel oils. meanie emission guys. :spank:
 
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