738 replies to this topic

[claysummers]

All the other lifters are coming out easily. I wonder if the base is mushroomed. So I will pull the cam and try and catch it before it falls in the sump. Had to be the back one. That is the one I couldn't get turning when I put this engine together. May have to retitle this thread the Forsyth Saga....

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[Bruiser]

Oh poo that is lousy
How long has your motor been together? 2 odd years?
When I pulled my lifters after nearly 20 years they came out like they were put in yesterday
Never had anything more special than regular oil changes and not a trace of gunk
or buildup on any of them
How about draining the oil and giving the stuck one a dose of something like pure alcohol,
metho, thinners or brake/carby cleaner to try and soften the crud?
(If it is crud)
Not sure which (or any) of those would safely evaporate and not leave any bad residue behind.
You could well be right though, if it had troubles turning from the start it could be damaged
Hopefully you are wrong this time

[claysummers]

Not much over 2 years Bruce. Be lucky to have done 20,000 km. I’ve been able to apply reasonable force to it and all the others are no issue. I’m almost certain it is mushroomed. I will hoik the cam.


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[claysummers]

Rear lobe is a mess.
The same one that wouldn't spin the lifter on assembly not 3 years ago. Was a Dynotec cm205d if I recall. They seem to b NLA not that I'd seek one out. Was just a NOS item cheap from gumtree.

Good excuse to finesse the tune 8) 8)

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[claysummers]

I've been recommended Jonny Marshall at Campbelfield Vic. but interested in any feedback or Adelaide recommendations.

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[claysummers]

I don’t suppose this sort of thing could be caused by a crook lifter bore?


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[Bruiser]

Good thing to find so you now know what’s going on
Bad thing that you now have to spend more
Good thing that you can choose a nice new cam

I couldn’t find anyone in Adelaide who grinds cams
You’ve got tighe, Clive, crow, waggott, Marshall, surecam
and kelfords from nz that I know of.

Are you going to go a bit bigger?
Give those roller rockers something to think about

[claysummers]

Not just for the sake of it Bruce. I’ve got a Nullarbor trip lined up, and I love a road trip. So peak torque in the cruising range is the main goal. I’ll be on the phone to Marshall tomorrow after doing a few sums. I hope there isn’t too much of a wait.


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[Bruiser]

Good thinking.
You’re bound go have more power anyway,
With 12 good lobes

[claysummers]

At 2600 rpm I am doing 60kmh in second and 100kmh in top so that is where I want peak torque. Will see if I can talk to Jimmy tomorrow. He is apparently setting up to do a run of Holden six cams this week so timing might be good. I have a couple of EH HK factory cams if he can’t get blanks.

Only other thought was to swap cam and lifters from either this injected black motor, or the towing cam out of my old blue 202, but I should probably leave those motors complete.


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[claysummers]

Managed to slide this out up the cam tunnelthere is 0.300" or so missing off the base of the lifter. I wonder where all that metal has gone? Sump may have to come off If all that is floating around in there. Bugger.....

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[RallyRed]

Have you cut open the oil filter Clay?...they do an amazing job of collecting that stuff.

[yel327]

If you have a HT 186 cam Clay that is the one to use, as long as it's not from one of the final HT with a Trimatic. Or a manual HG 186 cam. These are all S camshafts, same cam as 186S, 2600S etc.

[dan097]

If you have a HT 186 cam Clay that is the one to use, as long as it's not from one of the final HT with a Trimatic. Or a manual HG 186 cam. These are all S camshafts, same cam as 186S, 2600S etc.

are these the camshaft with the ring cast into them towards the front?

[Bruiser]

That’s a fair bit of grinding down on that lifter there
A lot of very small metal particles into the oil ((over a fair bit of time)?)
Would any of those particles be flung off the spinning cam face anywhere they really aren’t wanted?
Or would they make their way straight down into the sump?
All oil from the sump goes through the filter
So
The filter should take care of these particular particles
If you were to pull off your sump to clean it out,
there might still be shit everywhere else inside the crankcase
making that a waste of time.
Is it right through the motor, and still there or not is my question.
My guess is it went down in the sump and the filter caught it.
I hope someone else can shed light on this for me (and you, mainly)
You can have the cam mentioned below if it helps

are these the camshaft with the ring cast into them towards the front?

I have one I have marked as 186s, has the raised cast ring between #1 exh and #1 inlet.
Stamped part number 7428531

[claysummers]

Col,
I foolishly sent the filter off to landfill, not in any way envisaging the degree of carnage wreaked. 15 grams of lifter are missing. Most of it will be in the sump and filter hopefully. Will be sump off and probably have the crank out for a look.

It is also an opportunity to revise the clutch fork and slave setup on the all synchro three speed, and repaint the engine bay. Which means I may as well change the booster over. I still haven't finished reinstalling the reproduction firewall insulation and modified parcel tray after the mods for triples. Then somewhere at the end of the list is tweaking the pinion angle. On it goes......

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[Bruiser]

Good on you for being positive about it mate
Looking at crank and bearings is a good idea too
My previous thinking out loud idea was the dopeyest
one I’ve had for quite a while
Hope it comes up looking clean for you

[claysummers]

I have ordered a cam and lifters from Jonny Marshall at Mulwala. 205 duration at .05", 109 separation, 0.435" valve lift. That was his recommendation for my setup, but he recommends increasing compression. Scope creep strikes again.

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[yel327]

What chamber head are you currently running?

[claysummers]

Open chamber and not much off the face as far as I can recall Byron. Here is the spec sheet:

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[claysummers]

I have a closed chamber head off a running motor if that looks to be the way to go, but I didn't ask for anything aggressive. Runs beautifully on 91, or did.....

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[yel327]

Run the cam and head cc plus piston dish/dome and deck clearance through through a dynamic compression calculator - there was on this forum, I think it was SHTSTR on his AWB Torana thread maybe.

 

Being able to use 91 or even better E10 does make a huge difference if you are doing decent km. This is one of the big reasons I like my 5.7L Hemi in my Ram, it only requires 89 MON fuel which equates to 94 RON, which is what E10 is. All these little baby engines that the trucks are moving to like the 3.0L turbo inline 6 in the Rams and the 3.5L turbo V6 in the F150 etc all require 98. 20-40c per litre makes a HUGE difference on a 121L tank. Yes they can produce similar power and torque to a 6.0L NA V8 but you have no choice but to run 98. You don't have to be a rocket scientist to work out that at 20c per litre, on a 120L tank that is $24 saving. If I'm towing I put 98 into it to avoid any chance of pinging, but for general run around E10 is enough and it makes no noticeable difference to economy.

 

So do some more thinking about what your static and dynamic compression will look like and if you have to run 98. If you can get away with 95/94 then that is not bad either if you have access to E10.

[yel327]

Here are the HQ combustion chamber design specs. As far as I know 173 and 202 heads are the same chambers as the earlier closed and open chambers.

 

173HC - 45.37 +/- 1cc

202HC - 53.50 +/- 1cc.

 

I'm pretty sure original GM and GMH head gaskets are less than 20 thou, whereas aftermarket are 40 thou hence why you take 10 thou or more off the head or the block or both or get a gasket to suit your deck clearance. I'd check this for your calcs.

 

What I'm disappointed about is in Chevrolet Engineering Technical Specs, they actually quote the entire combustion chamber volume with the engine assembled and piston at TDC. So that takes into account deck height, gasket etc. Whereas GMH give you the combustion chamber alone with valves and spark plug in place.

Edited by yel327, 11 October 2023 - 01:00 PM.

[claysummers]

Rough figures based on the factory chamber volumes,
I get:
Open
Static 8.0 Dynamic 7.7

Closed
Static 8.9 Dynamic 8.5

I would think 8.5:1 dynamic would be OK on 91 or certainly 94. I suppose the fuel pump diaphragm and plastic floats in the SUs would handle E10 ok?
If so I might see about getting the small chamber head smikked up a bit.

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[Bruiser]

How did he describe the way that cam would operate powerwise , Clay?
It’s a bit smaller than the one you had in there
What is your compression as it sits now?
What number did he recommend?
Did you speak to any of the other guys for a second or third opinion?
Sorry, that’s 4 questions