CCCUK logo

 Ian Allan Motors

Website Control

Recent threads

New Forum Posts

» Touch up kits for my 1979 coupe by Vetteheadtony on Fri 20 Apr 18 01:30

» Harmonic balancer by Vetteheadtony on Fri 20 Apr 18 01:25

» '64 "Survivor" C2 Corvette 327ci 365hp Roadster Just Arrived by youkaygreen on Thu 19 Apr 18 22:28

» Corvette Nationals 2018 - pre booking. by JJVETTE on Thu 19 Apr 18 21:59

» Sunday Scramble - Bicester Heritage Centre by Bowler on Thu 19 Apr 18 18:07

» Concours of Elegance by curious bystander on Thu 19 Apr 18 17:19

» 2019 Zr1 by stevel98 on Thu 19 Apr 18 17:08

» How do you get a l48 to 300 ish hp or engine swap by stevel98 on Thu 19 Apr 18 12:58

» 1981 corvette 64,000 mile on it way over by Vetteheadtony on Thu 19 Apr 18 10:40

» Importing C4, but need to temporarily register in the UK by EIRE V8 on Wed 18 Apr 18 21:57

» C4R-FEST tickets by curious bystander on Wed 18 Apr 18 15:35

» Corvette C6 oil filter and correct Oil / Owners manual by Eddie101 on Wed 18 Apr 18 13:08

» What did you do with your Vette today? by stevel98 on Wed 18 Apr 18 10:09

» Parking brake adjustment by Nigelcurry on Wed 18 Apr 18 08:59

» C2 - Headlamp Not rotating by Bowler on Wed 18 Apr 18 07:01

» AACI Open Nationals by Bowler on Wed 18 Apr 18 06:51

» Youngest Member of the CCCUK? by Howard on Tue 17 Apr 18 22:25

» Corvette Club badge by kentvette on Tue 17 Apr 18 19:19

» Weather predicting by stevel98 on Tue 17 Apr 18 16:53

» Website clock by VetteWeekend on Tue 17 Apr 18 13:22

» Car Detailing by FIVE RED on Tue 17 Apr 18 08:00

» PO2 wheel trim please just one!! by Vetteheadtony on Tue 17 Apr 18 00:52

» Now we're digital - Membership Renewals by Wacjac on Mon 16 Apr 18 22:04

» C3 l48 side pipes and adjusting by stevel98 on Mon 16 Apr 18 13:41

» cold start injector union on fuel rail? by rayquayle on Mon 16 Apr 18 05:17

» Corvette C3 parts by k11ngc@hotmail.com on Sun 15 Apr 18 18:41

» Manchester Car Show - 15/16 September 2018 by curious bystander on Sun 15 Apr 18 16:09

» Auto gearbox by Barrelmaker on Sun 15 Apr 18 13:50

» 1993 Cutting Out by voguev8 on Sun 15 Apr 18 09:57

» New member, new c3 on order! by MIT on Sun 15 Apr 18 00:26

SBC engine


Go to page: 1, 2, 3 / Next


Reply to topic
View previous topicEmail to a FriendPrinter FriendlyView next topic

Author

Message

Dellb

Club Member

Sat 02 Dec 17 18:39

SBC engine


Hi All
At last I got round to firing up the beast after rebuild of engine. Alas all is not well.
The engine fires up fine and oil pressure is fine, but it is very difficult to keep going, and is heaving out clouds of black smoke.
The carb is a Holley 4160, and I have overhauled it with new Holley parts etc. Float levels are fine, and I canít find anything amiss with the carb. There is no backfiring through the carb and I think the timing is ok.
Anybody out there had similar probs?
Delb


--------------------
Derek L G

Reply with quote

sssammm

Club Member

Sat 02 Dec 17 19:27


Have you got the right needles?


--------------------
2013 Z06 White, 1953 Chevy 3100, 2002 Ford Boss

Reply with quote

stevel98

Club Member

Sat 02 Dec 17 20:10

Re: SBC engine


Black smoke usually means its very rich, either too much fuel or not enough air. If so, I wouldn't expect it to spit back as it doesn't sound like its leaning out.

Plugs ok? Correct heat range?


--------------------
RIP Gunny.. Hoo Ra, Semper Fi..

Reply with quote

Dellb

Club Member

Sat 02 Dec 17 21:14

Re: SBC engine


Plugs and timing are new and fine. Air filter is off for testing. I have onerhauled the carb, and fitted new joints and needle valves etc. The carb is modified to replace the secondary metering plate with a metering block. Primary jets are 72, and secondary jets are 79. The engine is a 400 with a very serious cam. The engine ran fine when I bought the car albeit with a bent crank. There was no smoke, and the idle was lumpy due to the cam.


--------------------
Derek L G

Reply with quote

roscobbc

Committee Member

Sun 03 Dec 17 00:52

Re: SBC engine


What hg are power valves (4.5hg?) Big cam means low vacumn - low vacumn means stock power valves will flood engine with too rich mixture at low rpm. Use 1.5hg. (Might be other way around - it's getting late!)


--------------------
CCCUK Chairman & Editor, Vette News
'68 coupe - 4 speed - 3.08 - 489 cu in - 570 bhp @ 5850 rpm - 606 ft/lbs torque (821 Newton Metres) @ 3850 rpm
Image

Reply with quote

aaroncorvette

Club Member

Tue 05 Dec 17 08:48


Could be the choke? Manual or auto choke?


--------------------
'71 vette convertible + the odd mod.
I thought we won the war?

Reply with quote

roppa440

Club Member

Tue 05 Dec 17 10:50

Re: SBC engine


Same old story.

You need a lot of initial advance with a big cam.

Once you have that and the idle speed right you can measure the manifold vacuum and fit a power valve rated 2-inches of vacuum below that.

With the correct timing the engine will be only running on the idle mixture circuits. Currently the throttle blades will be open too far for the idle circuit to work. You are trying to idle on the main jets and probably a stock 6.5" power valve fluttering away.

To get the high initial advance (probably around 20-25 degrees) without increasing the total (mechanical only) advance (36 degrees) you either need to connect the distributor vacuum can to manifold vacuum instead of ported OR, if you don't have vacuum advance on the dizzy or enough vacuum, modify the distributor to limit the amount of mechanical advance it gives to about 10 degrees.

You will thank me for it.

Reply with quote

stevel98

Club Member

Tue 05 Dec 17 12:11

Re: SBC engine


Excellent solution as usual, Dave.. Thumbs up

We've all been waiting for this, ..what kept you? Very Happy


--------------------
RIP Gunny.. Hoo Ra, Semper Fi..

Reply with quote

roppa440

Club Member

Tue 05 Dec 17 12:20

Re: SBC engine


stevel98 wrote (View Post):Excellent solution as usual, Dave.. Thumbs up

We've all been waiting for this, ..what kept you? Very Happy


Mainly a few worrying hospital appointments. Rolling Eyes
But it looks like I am not going anywhere in a hurry.

Reply with quote

stevel98

Club Member

Tue 05 Dec 17 13:28

Re: SBC engine


Not good.. Sad

Hope your going to be ok and not have to swap your C5 for an SUV. Rolling Eyes


--------------------
RIP Gunny.. Hoo Ra, Semper Fi..

Reply with quote

Reply to topic
View previous topicEmail to a FriendPrinter FriendlyPrivate MessengerView next topic

Go to page: 1, 2, 3 / Next


Permissions

You cannot post new threads in this forum
You cannot reply to threads in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot add events in this forum
You cannot attach files in this forum
You cannot download files in this forum