383 overhaul

[Colin Shaw]

Hi 383 HP engine overhaul. Going to replace original shim head gasket with thicker one from felpro set. No head skim. Does this affect push rod length much will it require shim adjustment on rocker shaft.
Engine been standing a few years so will change original valve springs the exhaust spring has another flat coil inside not seen this type before ! is there a need to replace same ?

[Philip Lochner]

Thicker head gasket moves the heads away from the cam. That distance must either be taken up with longer push rods, or by the hydraulic lifters (if fitted) or by adjusting the rockers (if possible). You do NOT want excessive valve play. Engine will be very noisy and somewhat less efficient.

That extra coil is a "damping spring". Supposed to help prevent valve bounce at very high RPMs. Friend had this on his Corvette. After the 3rd Edelbrock cam failed within minutes of starting he realised something seriously was wrong. Turned out that flat tappet cams (like our engines have) were not meant to be run with those dampers as they create cam pressures outside of design specs - way outside.

Make VERY sure if those damper springs are meant to be fitted to your engine otherwise you may also have premature cam (and lifter) failure.

[Basil McKinley]

The spring dampers were installed by Chrysler in the 383 high performance engine

[Grant]

Hi 383 HP engine overhaul.
Engine been standing a few years so will change original valve springs the exhaust spring has another flat coil inside not seen this type before ! is there a need to replace same ?

From memory ... I thought they had double valve springs on both the exhaust and the inlet valves?

[Grant]

Thicker head gasket moves the heads away from the cam. Friend had this on his Corvette. After the 3rd Edelbrock cam failed within minutes of starting he realised something seriously was wrong. Turned out that flat tappet cams (like our engines have) were not meant to be run with those dampers as they create cam pressures outside of design specs - way outside.

Make VERY sure if those damper springs are meant to be fitted to your engine otherwise you may also have premature cam (and lifter) failure.

Philip .. we rebuilt a 440 last year (not mine but a friends) using "440 source Alloy heads" with single springs on the valves , he has done 2k miles now and it has damaged 2 of the lobes on the cam and the followers are damaged quite bady I may add, not sure why this has happened yet, need to look deeper into the problem.. all I keep hearing of late is damaged cams .. they dont seem to be particully good quality any longer, ... when we called about getting another new cam they specifically asked "Did the car have double valve springs as the cam being supplied would only be suitable for single springs
On another note ... Our Convertible Interceptor had a fuel problem for a good while, its a low milage car 34K, when we stripped the engine in the end to De-Emission the bugger ... the fuel pump cam lobe (original cam) was so worn and damaged I was shocked how this could have happpened ... bloody cam shafts

[Philip Lochner]

There are 2 main problems with cams nowadays:

1) Cams are not (or not enough) hardened (Nitrided) - more so if they were made in China...
2) From what I've read on the internet (yeah right) modern oils being used in the engine does not have sufficient quantities of ZDDP. ZDDP is a sacrificial molecule that acts to prevent cold welding to happen between the cam and the lifter. Keep in mind that unlike main, big-end bearings and rings that hydroplanes on the film of oil, no such hydroplaning occurs between cam lobe and lifter. Modern oils are made for cars with catalytic convertors and lambda sensors and ZDDP kills those. This is a very well known problem with Land Rover V8 engines (which I am also very familiar with). Using an oil with very low levels of ZDDP is guaranteed to lead to premature cam failure. Here in South Africa, 20W50 oil with an SG spec is still readily available and I use only this. "SG" is an older spec and SHOULD contain higher quantities of ZDDP. Otherwise, I know that Mobil 1's 15W50 also had very high levels of ZDDP (their tech info stated as much). I also change oil not later than 10 000km. One can also buy little bottles of ZDDP on Ebay - if that is for real. I believe (I dont know this for sure) that engine assembly lube is also high concentration ZDDP or equivalent and again intended to lubricate metal to metal interaction immediately after first starts.

Please note that installation of a new cam MUST also have BRAND NEW lifters. They "take" to each other. Installation of the cam must be done with copious amounts of "cam lube". This cam lube is similar to ZDDP (if not the real thing) in that it acts as lubricant until oil pressure comes on line.

The first 20 minutes after starting a newly built engine is also important. First prize is to prime the oil system before starting the engine and once it starts, it should be kept at 1500rpm minimum for about 20 minutes to maintain good oil pressure and oil feed to the engine while the "cam is broken in".

Valve springs that are too hard is also guaranteed to destroy a cam and lifters. This I learnt from my friend's Corvette.

[Grant]

Thank you for your time with all of the above Philip, we are/were aware of this ZDDP and followed the recommendations with as much Camlube as we could and high zddp oil.
The "China" thing ... it's so hard to know whats coming from China Now ... Everything!! even when its says Made in USA or whatever .. it then being shipped from China gives the game away .... Priming an engine up to pressure before firing is alway a Must in My Head ... but strangly Philip the instructions on the Cam and followers is NOT to Prime the Hydraulic lifters as not priming them is part of the "Break In Period" .. we used to leave them all in a bowl of Oil overnight and reverse them in the morning to make sure there was no air in them, but as said the instructions tell you not to prime them
I must say though with the problem Cam we have ... we did have a problem within the 1st 20mins last year, the power steering sprung a leak that then lead to a P.Steering pump issue, so we had to shut the engine down, then the poxy alarm immobaliser went "Up the Pictures" and so consequently we couldn't get the bugger started again untill the following day.. maybe this had a big influence on these 2 lobes and lifters that have failed.
One last thing please philip... why is there Not an Oil Layer between the lifter and cam Lobe
Sorry for the Thread Hijack here Colin... but hopefully it will be good info for you during your rebuild

[Philip Lochner]

Priming an engine up to pressure before firing is alway a Must in My Head ... but strangly Philip the instructions on the Cam and followers is NOT to Prime the Hydraulic lifters as not priming them is part of the "Break In Period" .. we used to leave them all in a bowl of Oil overnight and reverse them in the morning to make sure there was no air in them, but as said the instructions tell you not to prime them

One last thing please philip... why is there Not an Oil Layer between the lifter and cam Lobe

Priming the engine and priming the hydraulic lifters is not quite the same thing. Indeed, before installing the lifters, they should be opened and the oil inside should be REMOVED (thus the lifters should indeed NOT be primed) before installing them into the engine!! Otherwise, they may have too much oil inside them and this could cause the lifter to be "pumped up" too much which may result in the valves never closing and thus having no compression when you try to start the engine - and hence, possibly no start.

Once the engine is assembled and you THEN prime the oil system, oil is only fed into the lifters on the down stroke of the cam lobe when the 1-way valve in the lifter opens. So when you start the engine in this condition, the lifters make quite a bad noise (due to excessive play on the valve train) but that typical lifter noise should die away quickly once the engine has started, and oil pressure is good and that excessive play is taken up by the lifters now being pumped up. The lifter noise should die away within 1 minute if the engine's oil system was primed before starting. Although, I have had some rather "lazy" lifters that took a lot longer than the others to quiet down.

There IS an oil layer between the cam and lifters but because the actual contact area between cam an lifter is so small and the relative speed between the moving parts is so low, there is no hydroplaning effect that happens there. This is why those sacrificial ZDDP molecules are so important. Also consider that the cam lobe is not flat but tapered to one side. This makes the contact are with the lifter even smaller than the width of the cam lobe and this is done so that the lifter will rotate in its socket thus presenting a fresh, oil covered area of the lifter with each rotation of the cam.

[jglarkin]

Compcam and melling cams are made from the same forging! maybe they all are. You can see a difference in the grinding technique and finish so at least there are differences to justify the wildly different costs.

Priming the engine with a proper break-in oil is highly recommended. Special cam lube should be placed between cam and lifter before initial start-up.

[Grant]

Hi Mr Larkin
I know John Sleath supplies Comp cams doesn't he as I spoke with him yesterday ... What cam specs are these please Mr Larkin? ... The cams I think perform the best in Interceptors are fitted in the "E" series 383's but I dont know what the spec of them are... do you please? did you fit one of these cams in the above pics in your CV8? not sure what spec they used in a CV8.. but I should imagine it was the same as the E series ... 4 Barrel High performance, the same cam as in the early 440 known as the Magnum Engine I believe, giving brilliant low down torque & overall the range good HP and yet still keeping a good Vacum for the brakes... do you have any knowledge of the spec used pleased Mr Larkin?
With my kind regards
Grant

[jglarkin]

This is not going to be helpful to you because I am running a 'LPG only' engine. I have just removed the compcam 21-215-4 after only a 20 min running-in because I did not like the less than perfect idle and also, the (quite nice) exhaust note caused a slight resonating sound in the car, which would have become unbearable if stuck in traffic
I have now fitted a cam called an RV cam (melling MTD2) which should give a very good idle (500-600 rpm) and is biased towards torque rather than top end power. This is more suited to my 4 speed transmission and is recommended for LPG use.

I hope this is interesting information even if it is useless.

Jon.

[jglarkin]

Ran the melling cam in yesterday, fans failed to cut in so had to stop in the middle of the process (still no clue why that happened).
I then became rather concerned about the fact that my HP engine, with the additional damper springs (you are supposed to remove the damper during break-in and refit them later, if required) may have ruined the cam lobes.

I couldn't stop worrying about it so I pulled the intake manifold back off and examined the lifters and cam.

Everything looks perfect........so far.

I need to run the rest of the engine in. The oil in the engine is special break-in (all of it) with a bottle of additive thrown in too. When I change the oil I will put in "classic oil" plus a bottle of the additive for good measure.

[jglarkin]

Ran the melling cam in yesterday, fans failed to cut in so had to stop in the middle of the process (still no clue why that happened).

Lazy thermostat! Need to get a new one

[Grant]

Ran the melling cam in yesterday, fans failed to cut in so had to stop in the middle of the process (still no clue why that happened).

Lazy thermostat! Need to get a new one

I'm bloody glad for you that there was no damage evident Jon

[Grant]

Ran the melling cam in yesterday, fans failed to cut in so had to stop in the middle of the process (still no clue why that happened).
I then became rather concerned about the fact that my HP engine, with the additional damper springs (you are supposed to remove the damper during break-in and refit them later, if required) may have ruined the cam lobes.

I couldn't stop worrying about it so I pulled the intake manifold back off and examined the lifters and cam.

Everything looks perfect........so far.

I need to run the rest of the engine in. The oil in the engine is special break-in (all of it) with a bottle of additive thrown in too. When I change the oil I will put in "classic oil" plus a bottle of the additive for good measure.

This is what happened to the one we were doing last year Jon.. well sort of the same, the power steering pump siezed and so we had to shut down, we thought (this year) this is why we now have issues with the cam.. but..; it has turned out that the 440 source heads did have double valve springs (as mentioned earlier by Philip) , this was never a problem years ago with new cams and double valve springs.. you would just put them in and go, but now days it all seems different ... everything changes I guess
Good luck Jon