Engine issues - advice needed

Mr. Cricket

Committee Member
One of my rockers worked loose (No.3) and it sounded like the engine was eating itself. Pulled leads to find the offending one then left it disconnected until I got home. Might be worth a try..

Sorry you missed a great Nationals
 

Roscobbc

Moderator
As unlikely as it perhaps seems - perhaps the adjusting nut is backing itself-off?. The aftermarket roller tip rockers have a locking allen headed screw so this can't happen.
Are we happy that the respective hydraulic lifters haven't collapsed or push rod end haven't worn excessively?
Do the respective rockers appear to be getting the same amount of travel as 'known' good ones?
 

MilkyNoSugar

CCCUK Member
I think that is my next plan of action. Take the air intake off and have a proper look at the lifters and push rods. I will also get all the plugs out and get the camera in each cylinder to make sure there is no obvious interference/damage - just waiting for a new set of plugs to arrive so I can put some new ones back in.

Struggling to upload a video, and wonder if a link will work

 

Roscobbc

Moderator
Link works ok. That is loud. It appears to be from the top end of the engine although that can be deceptive. When you rev up and then hold at a constant rpm. And then slow it down........is the clattering all the same for all three 'modes'?
 

teamzr1

Supporting vendor
Video is too short a timeframe to tell
Record again but slowly up the RPMs to see if the clatter rate follows the RPMs and then slowly off the throttle
Also, if recording covers, moving camera around all sides of engine and lower to exhaust
How's the clutch of coolant fan, sounds OK and damper off crank

Which tranny ?
If manual sound change when clutch is in or out and if
auto tranny in park, neutral or drive
 

johng

CCCUK Member
Is it just me or does the cooling fan movement look jerky? I'm sure mine moves more smoothly than that.
 

ClassicLineInsurance

Supporting vendor
My journey to the Nationals on Sunday was cut rather short by an engine failure. I am not too sure how big/bad at this stage but it sounded terminal.

It is a 1972 454 big block on 54000 miles, and other than a recent air intake and carb upgrade is pretty much stock. Convertible 4 speed manual, power steering but no air con. It has been mine for just over a year.

First of all, thanks to the two Corvette drivers who stopped to make sure I was ok. Mark Brailsford, and the other chap whose name I cannot remember in a metallic orange c3.

M1 southbound just before J20 and doing 65 ish, what started out as a tapping noise from the drivers side, very quickly turned into a bag of spanners rattling. I dipped the clutch and pulled over as quickly and safely as I could. By the time I came to a standstill on the hard shoulder, the engine had cut out. I noticed the oil pressure had dropped significantly but cannot remember if that was before or after the car cut out - it was all a bit sudden.

I opened the bonnet expecting to see everything coated in oil, but nothing, not a drop anywhere in the engine bay or under the car.

I got recovered home by Unity, provided through the recovery service of my ClassicLine insurance policy. Excellent service was provided by both Unity and ClassicLine with welfare calls to me every 10 to 15 minutes to update me and make sure I was ok. Picked up just over an hour after calling and back home with the car in the garage by lunchtime.

I have checked the oil and coolant with the engine cold. Both are still full and both are still separate so no significant gasket failures or internal damage based on that very rudimentary check.

Assuming (perhaps incorrectly) I could not make it much worse, I did remove the coil lead and turned it over on the starter for a very brief moment, and it turned without any problems and did not sound too different than normal.

My suspicion is a timing gear failure, could be worse, could be much less but do not know.


Work and other commitments meant today is the first time I have been able to think about doing anything with the car.



My questions are;

What are the sensible next steps?
Do I just try and start it and see what happens - perhaps not sensible I know?
Is it worth getting the rocker covers off and see if there is anything noticeable?
Getting to the timing gears looks possible, albeit slightly challenged due to the large block with the engine in the car, but would be easier with the engine out.
Is it worth taking the heads off with the engine still in the car?
Is getting the engine out the next sensible option?

I know this is such an open-ended question, but are there any guide prices for a top end , bottom end and full rebuild?

Assuming the worst, and it needs a full or partial rebuild are there any good engine specialists around Leicester, or even national that I should be contacting or avoiding?

So far I have found or had the following recommendations.
  • Williams Brothers - Northampton
  • Andy Fanshaw - Chesterfield,
  • John Sleath Race Cars - Doncaster
  • Boost Performance - Nottingham
  • Lincolnshire Corvette - Grantham
  • JE Engineering - Lancashire


I have an excellent group of friends that can help get the engine out if needed, and between us we have enough skill to start stripping the engine down. I have access to a double cab truck and trailer so moving the engine and car is not too big a deal. However, rebuilding the engine correctly and any machining required is pushing our capability to its limits or beyond. Would an engine builder expect to see the engine as is before we take it apart?

I am open to sensible suggestions and advice.

Jeremy
Sorry to hear that you had an issue and needed to call for recovery, but thank you for the great feedback. Glad you got home safely and good luck with the fix.
 

MilkyNoSugar

CCCUK Member
I took the air intake off today to inspect the cam and followers.

The verdict is that the cam and some of the followers are worn and some of the followers are solid with no movement left in them. Cylinder 5, that had the most play in the rocker arms, also has the most wear on the cam lobes and the followers are damaged so much that they will not lift out of the block (there is a very small lip on the face of the lifter).

The heads are the original GM4T heads and look ok, other than what appears to be some odd holes. Although the shape of the holes is slightly different on each head, they are effectively in the same place so I expect this is how they are supposed to be albeit with some casting differences.

PXL_20240810_135654654.jpgPXL_20240810_135702678.jpg

My next job is to put together a list of parts required and decide what cam to go for. I will not be racing the car nor taking it to a drag strip, so need a good cam for fast road use. It is a manual gearbox, 454 big block on 54000 miles. Other than the recently fitted Holley double pumper carb and GM LS6 aluminium air intake the car is standard with the original cast headers. Advice is required, please....

I was planning on getting a cam kit to include timing gear, push rods, followers, rocker arms, springs etc, and I think it makes sense to change the water pump as part of this work. Is there anything else I should look to change as part of this project?

I had started looking at top-end kits but at the moment that feels excessive -I welcome thoughts on this from the experts.

Jeremy
 

Roscobbc

Moderator
'Irregular' shaped holes in cylinder head casting are standard. When choosing a cam there are quite a few things to condsider. Car useage being the most important.....but you've answered that.....fast road use. You have a LS6 inlet and DP carb.....750 cfm I presume?. Camshaft - three or more choices on what type here....1. hydraulic flat tappet cam. 2. Hydraulic roller cam. 3. Mechanical 'solid' roller cam. You plan on keeping the stock heads so perhaps 1. may be the simplest and least expensive option. Ideally new roller tip rockers and new springs would be a good option but you'd need to check compatibilty with the rocker studs (and are they push-in or threaded)
Are your heads rectangular port or oval port? - irrespective of whatever you choose headers can be a good choice to make the best of other improvements.....if retaining stock manifolds perhaps 'dial-back' the cam specs a little. There are many choices out there and everyone will have their own views. Me? - I'd avoid Edelbrock.....nothing wrong with them to a point......but very 1970's IMHO. Comp cams are well respected. As are Lunati, Isky, Howards and others.
It might be worth checking out the cylinders......with that much cam wear and the potential for metal particles circulating within the engine.........
 

teamzr1

Supporting vendor
4 COMP CAMs I selected for a 454 CI that are close t stock grind and shows the part numbers and below what kit to get for the valvetrain
Performance would change by changing what RPM power range of CAMs selected and
engine compression
size of valves
Exhaust system type
Carb size


4cams.jpg
 

MilkyNoSugar

CCCUK Member
Thanks for the advice. Can I check the generation of engine. On the comp cams cam selector screenshot it has the engine shown as a generation 6. I thought it would be a gen 4 engine.
 

Roscobbc

Moderator
Thanks for the advice. Can I check the generation of engine. On the comp cams cam selector screenshot it has the engine shown as a generation 6. I thought it would be a gen 4 engine.
BB generations can be confusing - Mark 4 was used in Corvette and others (unless swapped-out for a later generation) up to - Mark 4 is not quite the same as the late Generation 4 (Gen 4), or later Gen 5 and Gen 6 versions were introduced after 1990 I beleive. Not all parts are compatible - may not have provision for mech fuel pump.
Cams and associated parts......not sure re. compatibility with earlier Mark 4.
 

Roscobbc

Moderator
That seems a nice 'sensible' choice Jon. Certainly a good choice if the OP wants to limit expenditure and still maintain easy driveability.
 

MilkyNoSugar

CCCUK Member
The advice received so far has been really good. Many thanks. I am reading as much as I can and learning as I go. Some of the cams recommended seem to be out of stock everywhere or discontinued. In an effort to limit my choices initially, I am looking at Comp Cams as a brand as there seems to be quite a lot of info available for those.

I think, and I am happy to be corrected, my choices are from the Nostalgia Plus, High Energy or Xtreme Energy range. See the attached PDF for a summary.

There is only one Nostalgia kit, K11670-4 and it looks like it is in stock and available. It comes with 2110 double row timing kit

High Energy kits are out of stock. 11-203-3 or 11-205-3 is available as a cam but not as a full kit. I have not yet searched for all the individual components of the kit. 11-203-2 and 11-205-3 seem like the best options from this range.

Xtreme Energy is a broader range, and most seem to be available. The milder cams seem to come with a 3210 single row timing kit, whilst the others come with a double row kit. 11-234-3, 11-238-3 or 11-242-3 seem like the best options from this range.

I am looking at getting the rocker kit 1411-16 and stud kit 4514-16. Is that sensible or excessive?

Am I aiming in the right area with this and is one of these a stand-out obvious choice? There is about £140 between the cheapest and most expensive, and this seems to tie in with the timing kit differences, although I am sure there are other differences to account for the costs.

At the moment most of the suppliers are US based and I do not mind buying from the US - is there a UK supplier that I should be talking to?

I will aim to replace the water pump while it is off. I know I need the gaskets for the rocker covers, air intake, timing gears, water pump and some silicone for the ends of the intake joints. I have a new set of plugs, oil, filter and coolant ready to go. Is there anything else I am likely to need, or special tools I am not likely to have to get this lot fitted? I am on the fringes of my expertise here, but thankfully have a couple of friends who have more general experience have have fitted cams in other cars and are offering to help although neither has worked on a chevy v8.

Jeremy
 

Attachments

  • cam choices.pdf
    261.8 KB · Views: 4

teamzr1

Supporting vendor
Some info for the 454 CI
BIG block Chevrolet Factory Performance CAMs

Factory # adv dur .050 dur cam liFt valve liFt lobe centers lash description
3874872 286/286 196/196 .234/.234 .398/.398 113.5 HYD THRU 69 STOCK
3963544 269/278 193/203 .234/.253 .399/.429 110.5 HYD 70-ON STOCK
353040 285/295 210/212 .259/.259 .440/.440 113.5 HYD 1973-75 454
3904359 289/302 214/218 .272/.282 .461/.480 115 HYD 396 L34 350-360HP, 427 390HP, 454 LS5
3904362 307/298 242/242 .306/.306 .520/.520 114 .024/.028 396-402 L78, 427 L71, 454 LS6
3925535 332/333 264/270 .329/.341 .560/.580 112 .024/.026 427 L88
3959180 327/333 262/273 .342/.365 .580/.620 110 .024/.026 427 ZL1, 454 LS7

Stock 1972 454 CI

Rocker ratio is only 1.7:1. may want to change to 1.8

Engine compression for damn smog engine is 8.5:1 may want to raise that

GM Engineering specs ( attached as PDF)


valveetrain.jpg454compression.jpg
 

Attachments

  • 1972-Corvette.pdf
    5.1 MB · Views: 0

Roscobbc

Moderator
I think your initial 'selection' of the Extreme Energy cam seems a good choice (especially if you are running with a higher numerical ratio rear axle. However........early/mid 70's 454 Vettes seems to have a bad reputation for being no-go fuel gobbling monsters. Not true. Even some simple timing tweaks can transform its performance. Performance engines love compression.....like 10/10.5 to 1. Yours if stock will have 8.5 c/r. There used to be (may still be available) cam grinds that take the low compression into account (usually RV type grinds) and deal with this with opening/closing valve 'events' that will produce lower revving torque monsters.
I've checked and BBC heads (unlike SBC's) have screw-in rocker studs, so you are OK there.
You could 'step-up' on cam selection 'if' you had headers and free flowing exhaust system. There may be future limitations there - I have noticed that some of the aftermarket header suppliers are only offering 'small' tube headers now (fine for most applications) for BBC powered Vettes. BBC engines (much like most V8's have relatively poor exhaust flow.....the Extreme Energy cams (and others) you'll notice have longer opening exhaust valve 'events' to try and improve that 'balance'.
The engine on mine was built-up 10 years ago on a 454 4 bolt block. I chose a new forged stroker 'rotating' assembly (489 cu in). This cost was much the same as a stock stroke unit - stroker crankshafts are a good way to increase low-end torque.
I bought new aftermarket cylinder heads - stock heads are a limiting factor without signifciant work - an expensive investment ......I could have gone with big rectangular port heads and perhaps 650/700 hp potentially......but wanted street drivabilty (much like stock) so chose oval port heads.
For simplicity and economy I went with a flat tappet cam that falls about half way between the Comp Cam XE-274H and XE-284H. The extra 1000cc helps smooth that out nicely with a power band between 3000 and 6000 rpm and 'pulls' comfortably from 1200/1300 rpm although can in town use be a little 'baulky'. You'll see the engine output on my 'signature'. 1 hp per cubic inch and bundles of torque should be easily achievable.
 

teamzr1

Supporting vendor
Should be illegal for a V8 engine to have only 8.5:1 compression, worse for a 454 CI
Was chicken sheet of GM to handle 1970s smog rules to output a 454 with only like 300 HP :-(

See a nice performance gain with my 99 C5 LS1 346 CI when I stroked it to 372 CI and raised compression to 11.3:1
Even better when upped to roller rockers with 1.8 ratio and redlined rev limiter to 6,800 RPMs
 

MilkyNoSugar

CCCUK Member
Taking on board the comments about low compression and RV cams, should I also be considering the Xteme 4x4 range or have I misunderstood this.
 
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