Author Topic: vortec headed 383 has no power  (Read 20478 times)

Offline 305chevy c-10

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Re: vortec headed 383 has no power
« Reply #30 on: June 12, 2014, 11:51:21 PM »
Full duals with xpipe,is this a simple fix ,get some new gaskets and im. Done
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Offline 305chevy c-10

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Re: vortec headed 383 has no power
« Reply #31 on: June 13, 2014, 10:28:24 PM »
puzzled do know whats wrong? checked modulator on trans and no fluid come out .there is no water in oil .but still smokes like a train if u mash gas .
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Offline rich weyand

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Re: vortec headed 383 has no power
« Reply #32 on: June 13, 2014, 10:49:32 PM »
You can have a leak from the water jacket into a combustion chamber without getting a lot of water into the oil.

Let me ask you this.  If you sit and idle, like at a light, for a couple minutes, then you give it gas, do you get a lot of white smoke right away, then it sort of dies down as you are driving?

And, does it miss first starting out from that sit and idle, then even out as the smoke dies down?

Does the exhaust smell "sweet"?
Rich

"Working Girl": 1978 K-10 RCSB 350/TH350/NP203 +2/+3 Tuff Country lift

Offline 305chevy c-10

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Re: vortec headed 383 has no power
« Reply #33 on: June 13, 2014, 11:31:43 PM »
yes if u give it gas its a lot of white smoke.if i let it idle theres a little but hardly noticable . only have water in on antifreeze .the more gas the more white smoke .i used stock rebuild head gaskets not high performance gaskets .may drain oil tom to see whats in there
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Offline rich weyand

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Re: vortec headed 383 has no power
« Reply #34 on: June 14, 2014, 01:17:21 AM »
Sure sounds like you dynamited a gasket.  What about the smell of the exhaust?  You can usually smell it if it's antifreeze.

Ask me how I know....

Another thing you can do is pull the plugs and inspect them.  Let it idle for about five minutes, then shut it off.  When it cools down, pull the plugs and check them.  Why at idle for five minutes? Highest vacuum is at idle, so it'll pull the most water, and won't blow it all out.  Check the plugs for wet.  Should be obvious.  You can also stick a long (12") pipe cleaner down each plug hole to the bottom edge of the piston and see if it pulls up wet and smells of antifreeze.  (Of course, if you have a bore scope laying around, that's the way to go.)  Might want to pull the center four plugs first (3, 4, 5, 6), they run at the highest temperature, then the end four (1, 2, 7, 8).

Another question: This didn't begin right after you filled up with gas, did it?
Rich

"Working Girl": 1978 K-10 RCSB 350/TH350/NP203 +2/+3 Tuff Country lift

Offline 305chevy c-10

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Re: vortec headed 383 has no power
« Reply #35 on: June 14, 2014, 09:18:10 AM »
No ,it begin shortly after driving it hard ,trying to do burnouts .
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Offline 305chevy c-10

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Re: vortec headed 383 has no power
« Reply #36 on: June 15, 2014, 07:19:00 AM »
Checked all fluid ,oil has no water in it ,radiator has no oil in it .changed vac modulator it had a little trans fluid in it .still smokes like a train .when u cut it off one tailpipe still smokes for a while  .i'm thinking rings did not seat or went bad .this motor may have 50 miles on it .when i first drove it ,it never smoked even when it had no power because of wrong plugs .i was told u can drive it in 2nd gear 30-45mph @25-3000 rpm and take foot off gas and let it coast about 5-6 times and this will sometimes seat the rings .my thing is with all that smoke i dont want to blow it .other option is take apart and re ring  it .
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Offline LeftysRodandCustom

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Re: vortec headed 383 has no power
« Reply #37 on: June 15, 2014, 08:27:15 AM »
Did you happen to use chrome moly rings? Takes quite a bit more heat to seat them..

Offline 305chevy c-10

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Re: vortec headed 383 has no power
« Reply #38 on: June 15, 2014, 08:47:47 AM »
Hastling rings .i may have spelled it wrong
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Offline HAULIN IT

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Re: vortec headed 383 has no power
« Reply #39 on: June 15, 2014, 08:58:33 AM »
Do a compression test. If the water is getting into the combustion chamber (to blow out the tailpipe) it will have to show up as a LOW reading. A leakdown or simply air plumbed into the sparkplug hole will likely tell the story also. Bubbles in rad cap, head gasket, crack, ect. Lorne

Offline 305chevy c-10

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Re: vortec headed 383 has no power
« Reply #40 on: August 31, 2014, 01:18:56 AM »
UPDATE***compression test 105 it was 180 but after my big foot gaskets let go.*  blown head gaskets (both sides )i used stock head gaskets instead of some good performance one .* busted a rocker arm (stamper steel roller tip ).*destroyed roller lifter (hydraulic plunger part on top of lifter).* bent a valve .*and block was not decked piston .025 from top (gonna be decked to zero this time).   guy told me i must have over rev it because one cylinder had glazed walls .he said i can get more hp by going with flat tops because it will raise compression (10.5.1 from about 9.1). machinist told me unless i put forged pistons in stay with dish because higher compression increases detonation chances and it may not be pump gas friendly .he said mixing gas everytime u want to take a cruise gets old fast .
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Offline 305chevy c-10

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Re: vortec headed 383 has no power
« Reply #41 on: December 11, 2014, 09:48:41 PM »
Update ....motor being put back togather(machine shop was way behind with dirt track motors )  .totally redone , decked to .005 , new rings , reused my speedpro dished pistons, new stainless valve , replaced roller lifter , correct cam timming (index wrong is why it made no power ).polished crank , reseated valves , beehive springs (z28 springs did not have enough seat pressure and was binding at full lift ),trashed my steel procomp roller tips rockers  for a set of full 1.5  aluminum roller rockers .Vortec heads milled flat for a good seal with copper gaskets .hopefully this is the last time building this motor .
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Offline Stewart G Griffin

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Re: vortec headed 383 has no power
« Reply #42 on: February 05, 2015, 08:25:18 PM »
would a stock stall cause me to not have no power until rpm reaches above recomended stall piont

No, the cam spec says you will have no power until rpm reaches the recommended stall converter rpm.  That's what "recommended stall converter rpm" means.  That "2500+" stall speed torque converter recommendation says it all.

I had the same problem with the GM 350/290 hp engine.  It was a two-lane terror.  The 50-90 times were incredible.  Getting off the line?  Not so much.  All the hot rod guys will tell you, horsepower gets the headlines, but torque is what you drive.  And those cam specs you have are close to the cam specs in the GM 350/290 engine.  Yes, vortec heads help a lot, but still.
......  They both completed the quarter-mile in the low 13s, in darned near a dead tie.  In contrast, the 1970 Buick GS 455 Stage 1 was only 360 hp, but it had 510 lbft of torque at a low 2500 rpm.  It was a quarter-second slower than the Chevelle and the Hemi Cuda in the quarter-mile, but it would positively smoke both of them in the 1/8th mile.  Gonna race in circles?  Hard to beat that hemi.  Drive on the street?  I'll take the Buick.

What I did was swap out the cam in my 350/290 (yeah, the cam I paid $500 extra for over the 350/260 hp base crate engine) and put in a torquer cam.  I gave up a little horsepower, and there's no "choppy idle", but I am getting over 420 lbft of torque at 2500 rpm.  So my cam is in the middle of its torque curve at the same rpm that your cam specs say is where your torque curve starts.  When you think about it, it makes sense.  Unless you are a circle-track racer, you are almost always in the 1500-3500 rpm range in normal driving; that is, in the lower half of the working rpm range.  And "choppy idle" means the engine doesn't like to run at low rpms.

I just ran a dyno simulation on your setup and ran through some choices on a cam ............

i realize this thread is a few months old----but i just saw it now.  Could you give us the cam brand/model/specs that you used?

Offline rich weyand

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Re: vortec headed 383 has no power
« Reply #43 on: February 05, 2015, 08:46:56 PM »
Assuming you're talking to me, I used the Comp 12-300-4.  This is a torquer cam, with 420+ lbft at 2500 rpm, and 275 hp at 4500 or thereabouts.  Then it runs out of steam.  The Comp 12-235-2 has also got a lot of torque, 410+ lbft, but winds up more, for 290 hp at 500, I think.

Google my last name and those cam numbers and you will get a lot of discussion, dyno curves, etc. from various forums.
Rich

"Working Girl": 1978 K-10 RCSB 350/TH350/NP203 +2/+3 Tuff Country lift