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454 not running right, need help

7K views 44 replies 8 participants last post by  Boilermaker128 
#1 ·
Hi guys,

I finished up my polly bushing install and was able to get the car out since it was a nice day with snow on the roads. The car isn't running very well... it's coughing through the carb under load, and has a serious lack of power, but will start and idle fine. I bumped the timing up to 17deg from 8, swapped out carbs, (from a vac advance to mechanical) and both carbs are new. I ensured that the firing order was right and all wires are firing. I tried hooking up the vac advance, and it with it plugged off. The issue is the same, no matter what I do. What could the possible causes be for my problem? Do I have a stuck valve?

When I put the car away (4-5 months) ago, it had a lack of power then too, but didn't cough, it ran fine. I have been starting it in the shop over the time is was laid up working on the bushings....

Also have 7-9 psi fuel pressure according to the pressure gauge on route to the carb. It does bounce around a bit...

Any help would be great, I'm running out of ideas.

thanks,
 
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#3 ·
Try some fresh fuel.
 
#4 ·
Just did compression check, here's what I got;
#1- 145psi
#2- 145psi
#3- 145psi
#4- 145psi
#5- 150psi
#6- 92psi
#7- 142psi
#8- 125psi

Could #6 be the issue? I'll grab some fresh fuel also...
 
#5 ·
Just to be sure, check the plug and the wire at that cylinder. Hopefully it was/is a misfire.
Squirt some oil in that one and do it again.
 
#9 ·
I adjusted the rockers (with the engine running), backed off each one till they started to "clack" then tightened till the clack went away and then an additional 1/4 turn. Took the car out and it works better, but still get coughing and a serious lack of power especially with higher revs. I'm starting to lean on the cam being bad, so I have a few questions...

If I go ahead and replace the cam, is this all that is required? What about all the metal that I lost from this cam? Do I yank the engine and rebuild? How can I ensure my new cam won't flatten out also?
 
#8 ·
After you check the cam, do a leak down. Both 6 and 8 are lower than the rest of the cylinders. They are side/side and it may be a blown head gasket?????

Make sure the valves are not adjusted too tight on those cylinders.
 
#10 ·
To check for a flat cam, pull the valve covers and then start the engine. With it idling, look for any rockers that are not moving much, for that will be where the flat lobes are.

If you have a flat cam then that cam dust will have gone through the bearings and they and the crank will be rather second hand. Your oil pressure will probably be a bit down as well if that is the case.
 
#11 ·
but will start and idle fine

Sorry, I have to take this back. Yes the engine will start and idle, but I did notice that it has a bit of a shake to it when at idle (almost like a miss-fire).

When driving the car, it feels like I'm driving a 6cyl car, or I'm running on 2 barrels not 4, although the carbs are working as they should.

I checked all plugs and found most are running fairly rich, can't remember what ones...I cleaned them and put them back in. I'll do a vac check with the engine running, then take the plugs out and look at them again & number them.

I'll also hook up an oil pressure gauge and see where I am...
 
#12 ·
Your hiccups through the carb could be a burned intake valve, possibly number 6, because of a too tight rocker.
 
#13 ·
I drained the oil and ran a magnet through. Also cut open the oil filter and did the same with no unusual amount of metal found with either…

I “watched” the rocker move while turning the engine over, and I don’t see an abnormal amount of movement on #6.

Your suggestion is a new one and seems possible. I ordered a new cam and lifters. I’m going that deep, I may as well pull the heads and replace the gaskets. While the heads are off, I can inspect the valves etc…
 
#14 ·
Still waiting for my new "duel gauge leak down tester" to come in tho..... that will be the first thing I do...

forgot to mention that :D
 
#15 ·
Excellent move ^^^^^ ;). Have a real good look at the valve springs on 6 and 8. Maybe a broken intake spring/rocker arm or ball.
 
#16 ·
I have the valve covers off now and see no obvious broken parts. With the engine running, I think this would stand out more when looking at them....but who knows...

To tell you guys the truth, I have another engine. I am hoping for a quick fix, but worse case, I'll swap them out and enjoy the season, and start a rebuild on this one. I'll find and post the casting no's...

Current engine in the car is:
block-1401544 seems to be another number at the end that looks like a 6, but not sure...
heads-14081045

spare engine
block-361959
heads-781

I haven't dug into either engine yet, so I don't know what I have...all I know is that the spare works....I pulled it from a drag boat I bought, so it may have some goodies in it.... I didn't want to take it apart with no reason for doing so as it would probably not be put back together and I'd have parts all over the shop...(tell me I'm wrong).....been there done it.

Now I just have to put up with the GF complaining that I spend too much time in the shop and that I love the car more then her....

Yes, somethings never change....
 
#19 ·
Just saw this add and it's local. If I do have a head/valve issue I'm wondering if this would be a wise option... (for $800)

New never used BBC oval port heads with valves from Procomp.
Part number on them is PC3021-396

I've heard procomp heads arn't the best...but the price is right, even for a season or two...

whatca guys think?
 
#21 ·
LOL! Sorry man. I'm trying not to tear it down, I took a good hit buying this car, I'm now into it for over 30k..................save it, I hear it enough from the girl friend. Now I have to explain that the engine isn't quite working good enough...etc etc...

What I would like to do is simply change out the top end, and have a nice "normal" amount of power that I can live with for a weekend/nice day driver.

I have a Voodoo cam and lifters on order. The more I think about it, the more I want to change out the heads. I have a brand new 750 holly double pumper vac and another mech one I can use. Edelbrock alum intake. I'd love to run a set of aluminum heads also, for weight and flow... I think it's a good bang for the buck.

Looking and searching sounds like a set of AFR 305's would work good for this car.

summit price is $2300 and change. This motor should be good for 400+ with this combo, and would be ideal for street use.

tell me I'm wrong and that i can be happy for a lot less and spend a lot more time out of the shop....:D

ah, gotta love the projects...
 
#25 ·
FU&* me!:mad:

When it rains it pours I guess. I missed the shop today and didn't get my tester. With a "free" night in the shop with no one to bug me, I thought I could get something done. Well, I fired up the stove and grabbed a few beers and headed out anyway. I figured I'd pull the spare engine out and start preparing it for a swap if need be. I hauled the valve covers off, pulled the intake and started inspecting....I put a ratchet on the front of the crank and inspected the cam and lifters all working until................................yep, you guessed it. #1 intake lobe is down to a near lump compared to the rest. I simply cannot believe my luck.:noway:
 
#26 · (Edited)
After seeing the lobe gone in the spare engine I came across this add............. feel free to pick it apart/thoughts/comments...

500+hp/550+ft/lbs torque

$4500 Outright!

460 ci after overbore – 4.29” bore
Mid 70’s Mark IV BBC block, 2 bolt mains
TRW Forged Pistons – 9.2:1 compression
Ported early Closed Chamber, large oval port heads – 98cc chambers
Stainless Steel one piece 2.19/1.88 valves with performance 3 angle valve job
Isky Hydralic cam – 280Mega , 232@50 duation, .565 lift, 109 LCA and matching valvetrain with double springs, Chrome Moly retainers, machined locks, 3/8” moly pushrods, and Stainless Steel full roller rockers
Melling High Volume/ High Pressure Oil pump
High Capacity 7qrt Oil pan
Cloyes Double Roller Timing Chain
Clevitte performance bearings
Felpro performance gaskets
Victor Jr Oval port Intake manifold
Cast Aluminum Cal Custom style Valve Covers
Precision ground stock cast crankshaft – secured by high strength main bolts
Precision reconditioned heavy duty truck connecting rods with high strength rod bolts
Specially built for high RPM usage
Runs best with an aftermarket high performance intake, 1 7/8" long tube headers, 850cfm or larger carburetor - 6500 RPM redlinemy spare engine...I'd be hard pressed to rebuild for this price for a new one... check it out.
 
#28 ·
After seeing the lobe gone in the spare engine I came across this add............. feel free to pick it apart/thoughts/comments...

500+hp/550+ft/lbs torque

$4500 Outright!

460 ci after overbore – 4.29” bore
Mid 70’s Mark IV BBC block, 2 bolt mains
TRW Forged Pistons – 9.2:1 compression
Ported early Closed Chamber, large oval port heads – 98cc chambers
Stainless Steel one piece 2.19/1.88 valves with performance 3 angle valve job
Isky Hydralic cam – 280Mega , 232@50 duation, .565 lift, 109 LCA and matching valvetrain with double springs, Chrome Moly retainers, machined locks, 3/8” moly pushrods, and Stainless Steel full roller rockers
Melling High Volume/ High Pressure Oil pump
High Capacity 7qrt Oil pan
Cloyes Double Roller Timing Chain
Clevitte performance bearings
Felpro performance gaskets
Victor Jr Oval port Intake manifold
Cast Aluminum Cal Custom style Valve Covers
Precision ground stock cast crankshaft – secured by high strength main bolts
Precision reconditioned heavy duty truck connecting rods with high strength rod bolts
Specially built for high RPM usage
Runs best with an aftermarket high performance intake, 1 7/8" long tube headers, 850cfm or larger carburetor - 6500 RPM redlinemy spare engine...I'd be hard pressed to rebuild for this price for a new one... check it out.
It's your money (which you said you're trying to save). Assuming your existing heads have issues, they can most likely be fixed for less than $500...or stuff the new cam in the spare engine....or swap heads from the spare to your existing engine. Good luck with whichever choice you make.
 
#27 ·
#29 ·
Thanks for the links. And yes....you are 100% correct, as usual, I am creating a monster. Good thing she loves me, because I drive her nuts too :D
 
#31 ·
Got my new fancy duel gauge leak down tester. Hooked it up this morning to #6 and pounded 60 psi into the sucker. Shut the compressor off and listened for leakage. It was leaking so much, I didn't know where it was coming from, so I took the header of and that just about said it. I yanked the intake and head off. Looks like I have a burnt valve. I called the local shop and am taking it over to them in the morning.....we'll see what happens.

Don't know if I did this the hard way or not, but I removed the front bumper, rad, support, grill etc and did the work all from the front end. (I hate leaning over the fenders....). While I'm in there I can replace some nasty looking body mount bushings and the bolts for them & fix up some head light wiring.

On the bright side, it snowed again this weekend, so I'm in no hurry. I just hate when I haul it apart and it's nice out! :)
 
#32 ·
Fancy new tester....

Hit 60 psi on the left gauge, and it hit about 95% in the "cylinder leakage" side of things...
 

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#33 ·
pic of the cyl head. looks like a few valves are running hot. #6 was the worst, but I have a greasy finger smudge on it (sorry), I had to touch it.
 

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#34 ·
Front of car removed. Just found it better this way. Other side will come off tomorrow....

Yes, a bud light is in the corner of the pic.... You didn't think I would do this without beer....???
 

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#35 ·
The most important part...the boss applying a new sticker to the beer fridge..
 

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#37 ·
Did someone say...."my bet is valves"

Sorry, Had to do it :hurray:

Also, make sure your "old" valve springs are up to the job with the new cam.
 
#38 ·
wasn't it a 50/50 shot between the cam??:D
 
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