This is a copy of a local forum post on the planned rebuild, but eventual replacement of the 327 in my 1968 vette. I am coping it here due to the impending shutdown of the forum. I will be adding to this post as the work continues.
Fri May 19, 2017
So the 327 in my ’68 has been in need of work for, well for as long as I’ve owned it. Only work done 4 years ago was to replace the valve springs and seals as the dampers in them had shattered and chewed up the valve stem seals. I did wonder where the metal went but am just hoping based on the engine still running that somehow it got flushed out in one of the many oil changes. Even with the new umbrella valve seals oil is still leaking down the probably worn valve guides from the heads and drowning the spark plugs meaning every 200km they are caked and dripping (but I still run them for another 1000 km or so). Had one of the rockers come loose and pop off a while back as well but didn’t seem to damage the pushrod but could be another problem waiting to happen. So have decided to splash out after a few years saving and replace the old heads with nice new alloy ones and see what happens.
First up, a list of what I have decoded over the years that I am working with currently in the car at the beginning of this process:
- 327 block from a ’68 K20 truck, single bolt main, original 327 small journal forged steel crank. Can still read pad so possible it was never decked.
- Dual plane high rise aluminium intake from a 1969 Z-28 Camaro
- 1977 Heads off a 305. If still stock they are 63cc with 1.72/1.5 valves, but notes from prev owner indicate they might have been modified.
- Stamped steel roller tip rockers
- Trick Flow 7.200 hardened pushrods
- Doug Herbert retro fit roller cam. Grind details from his site shows info like advertised duration 280/305, duration at .050 225/235, lift .500/.500 with 1.5 rockers, lobe center 112 degrees
- Hydraulic roller lifters.
- Double roller timing chain
- SummitRacing HEI dizzy. Initial set at 12 degrees. Mechanical adds 10deg by 1500RPM, Vac advance provides 10degrees.
- Holley 650 DP (list 4777-7) running rich (or theres a vac leak). I jetted it down to 66/71 last time i fiddled with it – as was super rich at 69/73!!!, 28 nozzles.
So all that put down a current eye watering 207 rwhp at about 4100rpm on the dyno (the eye watering is from all the unburnt fuel out the exhaust). Engine still pulls hard especially as at 100kph it’s at 3100rpm and planting the foot gives a nice burst despite gassing anyone in a car following.
So the plan is to just get new heads, pushrods and rocker arms, take the top of the engine off and hope the deck/pistons/cylinders still all look ok (as budget will be taken up by the heads), and then bolt on the new shiny bits and maybe borrow a known good spare Holley 600 vac secondary carb off a bloke in the local club to test with.
And the first step is the new heads. Spoke with a lot of people and looked at a lot of google. Then hunted for what discount vouchers I could find for online. In the end have ended up with these that arrived yesterday from Summitracing. Possibly would have been cheaper in the end to order online locally from VPW, but they didn’t have them in stock and quoted end of June to get them in. I’m too impatrient for that.
Edelbrock Aluminium Performer RPM heads. 64cc chambers, 185cc intake runner, standard 2.02/160 valves, and springs that support up to .600 lift.
Next purchase decision will be working out what the best value rocker options are to top it off as I feel it deserves new ones and not just reuse of my old ones.
Then on to pulling things to check the internals, ordering gaskets, probably stripping the orange paint off the intake, and planning on putting it all back together again in the hope it runs.
Buying from the US just came back to bite me in the a$$. Opened up the other box out in the shed to check out the nice shiny head in it, turned it over and F*ck me it’s got a scratch in the mating surface running fully between the middle two chambers, enough to catch a fingernail on. Will check it further once it’s light tomorrow but will be cheaper to get it resurfaced I’m guessing than return postage to the US.
A bunch of other small nicks here and there on them. Also need blowing out with air to get rid of some machining swarf I’ve fouund stillin there. May also do a bit of bit of sanding/grinding with the dremel where they left some rough spots in some of the ports. I think I know now why head shops charge the way they do. Lots to be done on even a new out of the box Edelbrock head.
In better news a box just turned up with the head bolts, pushrods and some spark plugs. Just gaskets and rockers left to buy. Oh and thread sealer as just found mine has gone off after 3 years in my hot shed.
And some advice at the time from my mate Doc
The Scratch looks super minor. Trying to sand it down will only lower the head at that point.
A touch of 1104 3bond sealer, Just a touch, will be all that will be needed, if that.
A few less than perfect marks in your ports really wont mean shit in a street engine.
It’s the shape of the port that matters as with the size. Polished ports my look great. But it has been proven they don’t flow any better.
And who the F**k is going to see them when it’s all bolted up.
And some more advice from Bazza77
Just be careful with those Edelbrock heads!! A mate here bought some for his mustang ( with the same quality control?) and he had a valve bind up within minutes of getting it running . He LOST HIS BRAND NEW MOTOR, totally destroyed it. No warranty as it was a “performance application ”
If you got any paperwork with them , check and see if it says anything about opening up the tolerances on the valves for performance usage. If none then go on their site and look for disclaimers
After his effort I wouldn’t put them anywhere near your engine until they are checked out .
Finally advice from Ollie
If I can offer my two bobs worth, I do a lot of night shift and you tube is my friend, anyway do a leak down test of the inlet and then the exhaust valves.
IE: place the head on its side and fill the inlet with liquid, ( brake cleaner or wd40 ) and leave it over night. in the morning check and see if there is any runs into to the bowl or chamber. Flip it over and do the exhaust, its a easy inexpensive test to ensure the valves have been seated correctly.
So I’m guessing that 2 exhaust and all 4 intake valves failing the leak test on a head is a bad thing right? Jury rigged a lever to push some valves open a bit and put some low pressure air through the intake then re ran test. Didn’t leak as much, so gonna borrow a spring compressor and drop the valves to check no crap is in the seat like I have found in the rest of the head. Edelbrock definitely gets a F for quality from me now.
Took the spring off and dropped one of the leaking exhaust valves. Looks like it is some bronze dust/filings from the guides stuck in some light assembly oil that was on the valve seat. Will clean it off and check the others as I suspect they are all the same. Messy assembly job from the factory though in my opinion.
More advice from Doc
Well, Were starting to look at time passing by. So I thought I’d put in my 2 bobs worth.
I agree that it sounds like Edlebrock has done a fairly sloppy job cleaning up and assembling these heads.
But, 2 minutes of running and these heads would most likely seat themselves in.
I’m wondering if all this time cleaning them up and reseating Valves that would likely bed in quickly is truly worth the trouble.
This is a street car after all, Your not going for top times at the strip.
You need to run the new cam in for about 30 minutes at 2,000 to 2,500 RPM to break in the lifters.
Should be enough to set the valves into the seats as well one would think.
How about you get this baby going?
Since the last post I’ve gone over the new heads and pulled all the springs so I could clean up around the valves. Most seems good after that a couple were still seeping a bit. A little lapping with a very fine lapping fluid seems to have gotten them sealing perfect or good enough for me anyway.
Now that that was done I started taking apart the engine on Sunday to get ready for the head swap. Pulled off the altenator, took off the clutch fan (for access to turn the crank later) drained the radiator and and took off the top radiator and heater hoses. Fluid was good looked a lot cleaner that I was expecting. Even found the slight mystery leak on the left hand side was actually coming from the drain tap.
Next started on the Dizzy. Tried undoing the tach cable and found it was really stiff to turn. Didn’t remember it being this tough 7 years ago when I put it on. Turns out it didn’t want to separate and actually unscrewed the entire tach drive gear unit from the dizzy!
Unplugged the wires at the spark plugs, and left them on the dizzy as I removed it. Labelled the wire separators so I knew which wire was which for later. It all looked in ok condition as it came out. After it was out I did notice the oil pressure tube fitting looked to be leaking a bit so there’s one more thing to add to the list of things to replace. Also as I was pulling wires i knocked the vacuum line off the wiper door actuator. As some oil seeped out I’m going to have to figure out how that got there (although I am guessing the loose vacuum connection I found may have been sucking oil mist from under the hood for a long time). Actuator still worked well under vacuum so at least it’s not too much to worry about.
Next up pulled the carby off, and unbolted the intake manifold. It was held on with about a metric ton of solid grey RTV at both ends but using a putty knife I managed to get through it and separate the ends and eventually pull it off. Using a broomstick handle down the oil fill tube to get leverage also helped in the process. Seems to have super thick intake gaskets on it as well.
Most of the intake gasket seals looked like they were ok and not actually leaking into the ports, although the amount of oil residue in the intake runners was about what I expected given what I expect to be poorly sealing valves, and from when the PCV was actually blowing oil mist through back into the carb.
Started pulling bits off the intake and the water neck came off easy as it had a sweet reusable gasket under it sealing everything up. Unfortunately Bubba had had his way with the thermostat and there are 8 large holes drilled in it. One I have heard off for letting air bubbles bleed through, but 8? Must have been for flow given he installed it backwards!!!
Leaving that I headed back to the heads. Removed the left rocker cover and started pulling the rocker arms and pushrods. Most were ok, although on one I’m picking there must have been a bit play than there should be as it looked like the nut had started cutting into the pivot and there was a little loose material in between them.
And at this point is where things start going downhill in my quick and easy head swap plans. Pulled the roller lifters and on Cylinder 3 there was a bit of marking on one of the rollers (exhaust side).
Then I pulled the lifters for Cylinder 5, they looked sweet. Next Cylinder 1’s lifters, not so much. Roller is toast which was the best part of the problem. First pic is what I found in my sump 3 years ago and always wondered what it was. Second pic is it’s source
All I can say is that in the last 3 years I am glad all those little needle bearings didn’t manage to escape and grenade the whole engine, especially on some of the full throttle runs around Lakeside raceway earlier this year! So at this point I’m thinking I’m now up for a a new set of lifters and probably a new cam as peering down the #1 lifter bore I can see matching etching on the cam lobes. So next I go to remove the last set of lifters and…. nope. The back exhaust port lifter on cylinder 7 will only pull out some of the way before it catches. Tried a little bit more force but no way it is coming all the way out. All I can think is that maybe something like the roller pin has backed out a bit and it stopping it coming up through the lifter bore.
Well a little percussive maintenance and the final lifter is out. Looks like it had a tiny bit of grit in the groove on it that was catching in the bore as it was coming out. Seems like it might actually be a tiny fragment of the old plastic valve stem seals.
So now I think my quick head swap has turned into pulling the whole engine and trying to get the cam and stubborn lifter out, getting it rebuilt by someone else, or looking for a 2nd hand replacement. However with a wedding coming up in just over a month it’s probably gonna be next year some time before I can save up the $$$ again for any more parts let alone a new heart for the vette.
Back from a break and not sure if I have any money left once the wedding/honeymoon bills finish flowing though this week, but time to start thinking about this again. Have decided to pull the engine from the car so that it can all be gone over rather than just bolting bits back on top and hoping nothing was missed deeper in the engine. One of the guys from the club have said they’d help with the extraction and lend of an engine stand etc. Having a chat next week with the local engine builder who my neighbour has used before to see his opinions on it
Took another small step in removing bits from the engine. Unbolted a/c bracket, and took out all bolts for the cast exhaust manifolds. Some were stubborn and some were finger tight only. However even with all bolts out the manifolds are stuck to the heads like glue even with mild use of a hammer and prybar. Guess I need a bigger hammer and bar.
Also still can’t seem to shift a plug in the intake manifold where i want to move a water hose to. Tried using an easy out and some heat but am guessing the steel from the plug and the aluminium from the intake have corroded seperately to for a nice stuck mess.
On a positive note while under the car I found out why my lhs headlight didn’t want to go up easily. Turns out it’s dropped one of the springs somehow so pressure is wrong to pop it up when the vacuum is applied.
And some advice from Riverracer
Will you be putting the original cast exhaust manifolds back on the new alli heads?
If so, you’ll probably have to do a bit of grinding along the outside edge.
They don’t fit well and won’t bolt up square.
Ask me how I know… only found the problem after I put engine back in vette.
Was thinking of putting them back on purely for budgetary purposes, if I can ever get them off in the first place. Preferably would be nice to match a set of headers to the heads and pipes as the cast manifold will be the restriction point.
Engine builder is back from holidays so going in tomorrow to discuss what’s to be done and how much it’s likely to cost. My plan is to reuse block, crank, pistons/rods if possible if cylinders just need a hone and not a bore, intake if I can get a water passage plug out of it. Then use the new heads and roller rockers I have. Will need new cam, lifters and pushrods, and bearings.
Any advice on pulling engine? Have seen online some suggest engine and gearbox, and others engine only. Given it’s a manual with a non removable crossmember under the box I’m not sure which way to go.
Not sure on the pulling, mine is an auto.
But I unbolted the block from the bellhousing, and removed that way.
Had a sling under the bellhousing to support the weight.
4yrs ago I removed the radiator and shroud to give extra room.
This time we bolted the waterpump and fan on in the car.
1 month later and not a lot of progress yet. All accessories are off the engine, radiator is out and found the pinhole source of an occasional leak in the process. Radiator support and a/c cooler are still in though.
Last weekend picked up an engine hoist from a mate. Plan for Saturday is to take off hood, rad support etc and pull engine. Don’t have a leveller so planning on pulling engine and not trans to make it easier. Figured i can use trolley jack under the trans to get it out later while the motor is at the shop. Also gives me time to find a leveller before trying to put it all back in as one.
Well weekend didn’t go to plan and had less time for the car than planned. Spoke to a few people last week and got talked into pulling the motor and trans as one. Removed the gearbox shifter linkages and reverse sensor switch. Somehow managed to imitate a dwarf contortionist and get my hand in to remove the speedo cable from the trans. Didn’t help that everything under there was coated in a nice slick of old oil. Unbolted the trans support bolts, and the bolts holding the diff uni from the yoke. Started unbolting the radiator support and all was going well until I hit the two bolts on the side at the bottom. Both seem to be rounded off (or covered with 20 years of baked on crud) with stuff all room to get to them. Abandoned them and started on the engine mount bolts. Damn the nuts on the bolts were tight. Needed a good spanner, a 3′ bar and a big hammer to get them to start turning. LHS bolt is a loose fit and can be pulled out but the RHS may need some persuasion with a hammer.
So at that point I had run out of time. Will see if I can get home from work today to take a crack, or else it will likely be Wednesday before I try anything more. On a different note, as I was under the car I noticed a nice small patch of fluid under the diff. Guess I should really have done that the other year when I had the trailing arms off. Live and learn I guess.
And engine is out. Ended up removing radiator support bolts and tilting it forwards to get move room. Bottom the bolt was a bastarrd as someone had partially glassed around it doing a repair rears ago. Once the glass was ground back it came out easy. Well easier than the the engine mount bolt which would not budge. Big hammer and a bit of rod from one end got it moving in the end. Glad I didn’t need to pull the support and only had to tilt it forwards a bit as the wiring running through it would have been a bugger to get out – unique to the 68.
Saw some advice online to tie off the yoke in the trans to one of the gear selector bolts. Glad I did as it saved a bunch of oil out the back. Ended up lifting the block slowly then jacking the trans up a bit to slide the lot forwards. Then just slowly jacked up the engine until the sump would clear over the very front of the fender. Then just manhandled the end of the trans up and over the front of the car. The lifting plate had 4 holes to choose from and looks like selecting the second from the front gave a perfect weight balance to do the job.
Sometime this week will need to start stripping the engine and remove the trans and bellhousing. And sometime clean 7 years of oil mist/sludge residue from the engine bay.
Pics of progress
Radiator support bolt that was partially glassed in that I had to grind the glass away on to get it out.
Bit of percussive persuasion was needed to get an engine mount bolt out.
Jacked up the rear of the trans so it would slide along with the engine and not catch the yoke on the crossmember
Bringing it up and angling it in the engine bay allowed the sump to clear the fender. Could then slide the lift out while lifting the end of the trans to clear things.
Fortunately the only fluids lost were some coolant still in the block as the engine was tilted forwards into the stand, and about 12 litres of sweat from doing it all in my hot shed.
So now she’s just left there sitting on a makeshift stand waiting for time to pull the trans, bellhousing, clutch etc and start stripping it back to send to the builder.
Pulling it as one now seemed simpler given I needed to do the seals on the gearbox and didn’t feel like benchpressing it out later with the car only on jack stands. Good thing I did look under there as the nuts on the shifter linkages had backed off a bit which was why the stick was getting a little slopping selecting some gears. When it all goes back together will probably also move the linkages to the short shift positions on the selector arms as well. Lots of room to get at that now the box is out too. Just need to find the time
Spent a bit of time today stripping back the engine and found a few interesting things. Gearbox came out nicely and the casting number combined with the input shaft id ring confirms it as an M21 (assuming no one has messed with the internals). Other than the crank in the block it is likely the only original Corvette part as block is 1968 C20/K20 truck, heads are ’77 305 Chevy II/Nova, bellhousing is from a truck as well, and the intake was camaro.
As far as the heads go, turns out they have had work as despite the casting being for 305 heads with tiny valves, I found 2.02/1.6 valves in there. Will have to check capacity to see if they were still only 58cc as suspect they look a bit bigger to me. Lots of carbon coating everywhere on pistons and valves. No scoring that I could see in the bores but measured and they are already bored 040 just to clean the cylinders could be in order. Will check with the builder next week.
Pulled the cam and found a scored lobe that matched the dodgy roll so a hone would be good news or maybe try to 060. Also found a few nicks out of the edge of a lobe or two where I think the missing piece of lifter must have traveled through things. Ran some of the numbers though a compression calculator and it came out at over 11:1, so may double check a few measurements tomorrow to see if i can get it more accurate.
Separation was easy. Was surprised how light the box was
Truck bellhousing to suit larger clutch should I so desire. Clutch fork was rattling round so need to work out how to fix or replace. Also soooo much oil residue coating the clutch.
Engine mounts are in need of replacement
Brains of the outfit with a slight brain injury
Surprise big valve heads have seen better days
And the awesome looking pistons with just a little bit of carbon buildup
Been compiling the list of new bits I (and/or the builder) will likely need as part of the engine build that I don’t already have:
– 50000L of degreaser to clean up the existing bits, engine bay, and everything south of it that got covered in an oil mist film
– head gaskets
– rear main seal
– engine mounts
– muncie gearbox seal kit
– fuel pump gaskets
– Radiator (have a line on a spare unneeded one here in Brisbane but if no good can look at getting existing one fixed)
And the maybe need list
– pistons (as not sure if existing are good enough to clean up once out)
– intake manifold (if I can’t get a busted fitting/plug out of the existing one so I can reuse it)
– timing gear (sprockets looked good but there seemed around 1″ or more of play in the existing chain and am sure it should be tighter)
– clutch kit (throwout fork always seemed really loose and rattling on the throwout bearing so may need to look into that too)
– exhaust manifolds (would just be nice to replace the stock rams horns with some headers to match the new heads)
And the parts I already have:
– exhaust gaskets
– intake gaskets
– rocker cover gaskets
– heads (complete)
– ARP head bolt kit
– full roller rockers
Bound to have forgotten something but will add it into this post so I can keep track of it later.
Engine is now with the builder. He
was a bit concerned about the buildup on the upper cylinder ridge but is going to pull the bottom end and look at it all then whether it can be cleaned up, or if it needs a sonic test to see if it is a candidate for going from 040 to 060 or may need to be replaced. There was a sweet HQ in his shop that they were dropping an LS1 into and he did suggest that would possibly be a cheaper option. I thought not once the extras (like gearbox, headers, clutch etc) are factored in.
So….time for a new engine. Spoke with builder today and crank had already be ground .020 in the past, rods were out of round, and sonic testing of block showed 7 good cylinders and 1 that could not go to .060.
So picking the now boat anchor up from him later this week and reassessing what is to go back into the vette. May go 350 short motor and bolt on the stuff I already have, or just go full crate and sell off the heads etc to offset costs. There may also be a line on another used 327 or 350 that I need to follow up on to see if it is an option.
Either way, farewell old truck motor.
So have done a lot of thinking about the car and the engine and what I was wanting it for. Decided it’s not really a daily drive as the wifes car is way more fuel efficient while being stuck in traffic commuting. So it’s more of a fun car for planting the foot and smiling while going on cruises and the occasional track day. With that in mind and with the fact that I had some cash come available this month and came across a good deal, a Chevy Performance Fast Burn 385 is heading my way later this week. Is basically a ZZ4 plus the aluminum fast burn heads and a few extra bits.
Sure the thing may only drink 98 due to the compression, and a 383 would have given more torque, but no rational decisions have ever been made about my vette so why start now. Am also hoping to get about $2-2500 back on selling off some of the old bits and pieces I will no longer need.
So I guess this weekend I’d better get busy cleaning up the engine bay and sorting out the order for the additional parts I still need (engine mounts, clutch, muncie seal kit etc). Still undecided if I leave it black or paint the block with torch red or similar.
26 April 2018 – Picked up the engine today so guess it’s time to hurry up with the cleanup of the engine bay and the purchase of a few extra parts to get it in.
Now just need to buy:
-clutch (as old one is impregnated with oil and half worn)
-pilot bushing (as old crank had pilot bearing which apparently is not ideal for inprecise old muncies)
-water pump (as found crack in old one)
-some suitable break in oil
-radiator (have a line on one from a Qld club member)
-engine mounts (another Qld member has a set I’m buying)
-temp sensor (that will suit the ohms required for a 68 gauge)
-new battery (as moving the 8 year old Optima Red Top I found even though it still held 12V after 8 months not being used, one of the terminals was leaking acid when the battery tipped)
Also have to decide whether to use the dizzy that came with it and convert the tach to electric, or see if the drive gear from the new dizzy will fit on my old one). Also will need to check sump measurements to see if it will clear things like steering etc or if I’m going to have to see about a new one of them too. Finally I’ll need to decide if I paint the black block red