Derek's 308 engine rebuild

I reamed the new rod bushes today and it was quite easy to turn the reamer by hand and do it in several stages until I got to 18.515mm. I will be taking a break from tomorrow-- it's supposed to be -33C with wind chill so we are heading to Florida to feed the rat and visit the Keys. Back in a couple of weeks.
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Thanks Rob,

I had originally planned for about 10.5:1 based on past experience and the numbers suggest this is a better solution. Now that I've reamed the rod bushes, I'll do a test assemble when I'm back in two weeks with one piston, head, cams to check valve/piston clearance and will lose a few cc's in de-shouding the valves etc. If I need to I can always get shorter rods but I prefer longer rods and I think I can reach 10.5:1 with the current rods.

 

Back from Florida to more snow :-( I put a rod and piston into No. 1 and valves into the head so I could check for clearance at TDC. Lift of the Cat cams at TDC is 3.65mm IN and 3.10mm EX.

Before torquing down with the old head gasket, I checked valve movement and could feel the inlet rubbing on the valve pocket in the piston (see marks in the pic) so I took out the piston and polished off a mm to get clearance before reassembling and torquing down the head. I measured the lift with both a dial guage mounted to an inlet stud and then a vernier caliper and both gave results within .05mm. I had .65mm clearance IN and .70mm clearance out with the old gasket compressed to 1.6mm when squashed.

I wanted to open the pockets up a bit anyway to un-shroud the valves and will take off some of the thin wall outside the inlet as per the original pistons (it's a localized hot spot and blocks flow.) Next step is to put the weaker valve springs and cams/belt into that head so I can check the clearances before and after TDC. This is taking far longer than I expected but it is my first 308 engine and I am using a motley mix of parts.

I am thinking about wheels to drive on (not show) and am thinking of getting some 17" wheels made to the original 16" design or as coffin spokes (as on the Stratos and GR4 Michelotto cars.)
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I too have noticed that hemi "orange peel" combustion chambers need more ignition advance. It's not just the flow but the lack of squish which reduces turbulence plus the flame front has to follow the orange peel chamber down the sides of the dome. I'm hoping the multi sparks and programmable timing of the MSD 6530 will help.

My test assembly hit two snags. First the one exhaust cam had a thicker axial thrust flange so it was hitting the bucket. I've asked Cat cams whether I should machine it or send it back. Next issue is that my new valves need different valve shims than the worn old ones so I have ordered a couple from Volvo to do the valve/piston tests and will order one of the CRP 100 shim sets for $200.

On a more cheerful note, after rebuilding my single distributor with the two re-insulated VR sensors, my MSD 6530 works fine with the sensors connected in series. Just spinning the distributor by hand gives a phenomenal blast of lightning that is an almost constant thick arc of fire. Very impressive! I'll dig out an old XP PC I have with an RS232 serial connector and try to program it a bit.
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I got my old PC out of the basement and hooked up the MSD 6530 to try programming it. I downloaded Prodata+ and Graphview from the MSD website and looked at their very sparse programming instructions (almost as bad as IKEA instructions.) For anyone trying this, the ignition box has to be hooked up to 12V and the red (ignition "on") wire has to have +12v. Then the Graphview will recognise it and you can add dots to the run and boost retard curves by right clicking the point on the graph and clicking "add dot."

I set the rpm curve to zero and will start with the mechanical advance in the distributor which should work fine to start with. I set the rev limit to 3000 just as a precaution during first startup. I'll order a GM 1 bar MAP sensor for the vacuum advance. You have to think a bit backwards as the programmed curves are all retard curves so lower pressure (more vaccuum) gives less retard.

I was amazed at the 6530 and SS coil shooting a barrage of sparks across more than an inch last night. I stopped at about 3cm as I didn't want to risk frying anything. Getting the cam flange machined thinner today so hope to do more tests later.

 

Scott, the MSD ignition is capacitive discharge so dwell is not an issue. As long as the pulses from the VR sensors are sufficient to trigger the unit, it works. I was surprised that my two sensors worked well in series as the resistance is just above the MSD magnetic sensor range of 400-1300 Ohms. It might not work at higher rpms in practice so I may have to put the sensors in parallel with a resistor in series and maybe a couple of diodes to separate the two VR coils.

I got the rear exhaust cam flange ground and polished down so it clears the bucket and picked up a couple of 1 Bar GM MAP sensors for the vacuum advance curve. The MSD system uses absolute pressure (psia) so sea level is 14.7psia and vacuum is below that. I'll try starting with the rpm curves suggested by a few people and see how the car drives and the exhaust reads (2 lambda sensors.) I will see if anyone here in Ottawa has a dyno. I'll add vacuum advance once the rpm curve is good.

Off to London for a week tonight to look at schools, flat (apartment) and ask around about car storage for the 308 and my 911E.
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Got back to find most of the snow gone so I might soon start work in the garage again (changing all the old rubber hoses etc.)

I used this link Full Scale Printable Degree Wheel Templates - Check Camshaft Valve Timing - Metric and put the CatCams timing numbers into it and then printed out a few timing degree wheels. I did a 27cm OD wheel for the crank (use anticlockwise if you put it on the back like I did) and glued it to a frozen pizza card. I also did a couple of wheels to glue onto old CDs for the cams. The cams turn at half the speed so 2 degrees will be one crank degree.

I put them on the engine and today I'll use them, the CatCams lift/timing specs, and a dial guage onto the bucket shim to get the timing set and mark the cams for TDC (not notch on the front thrust flange.)

My cams are near the limit of their end play-- any easy way to reduce it a little? Does it even matter?
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Micky, I'm going to use the cam wheels later to fine tune the markings on my adjustable pulleys. I won't use them to get the initial timing. The reason I put the degree wheel on the back of the crank was because it is just cardboard and held on by paper glue and magnets. I don't want it to be bumped as I work on the pulleys and belts at the front. I'm going to set the initial timing using the lift at TDC as suggested by the Cat Cams website: Cam Timing Guide

 

So here is how I did the timing. First off, when I put the timing cover on I put the crank to TDC and aligned the notches on the inside face of each drive pulley with the "V" in the boss on the cover above the shaft. This way the gear teeth will match their original positions (they will have worn each other in a particular way.)

With the crank at TDC and locked (I used a rubber wedge under a counterweight), and the drive pulleys at their TDC marks, I then put a piece of paper under one of the inlet cam bearing caps and tightened it just a little so the cam could still turn. With a dial gauge onto the inlet bucket, I rotated the inlet cam forwards until the bucket had moved 3.45mm (3.65mm if you have a .2mm clearance.) I then tightened the cam bearing cap with paper to lock the inlet cam at its TDC position.

I then did the same with the exhaust cam but turned it forwards past max lift until it was about to close and the lift was 2.90mm (3.1mm if you have the .2mm valve clearance.) Again, lock the cam with paper under one rear bearing cap.)

I then put the belt onto the drive pulley, marked the belt to match the TDC mark on the drive pulley and held the belt on with a clip. With the belt tensioner loose (loosen the bearing nut, push it down and to the right to compress the spring as far as possible and then tighten the nut.) Also loosen the three tensioner bracket nuts as much as possible as it helps a lot to have more play in the belt. Then put the belt over the outer "fence" of the right hand cam and get it as tight as possible and seated on the cam teeth. You will need to try different holes for the cam dowel until you find one that lines up with the belt tight and seated. Use a torch (flashlight) from the other side to see which holes work for the dowel.) Once you have the dowel in and the belt tight, mark one tooth on the belt and pulley so you can line it up again later (and transfer those marks to a new belt in 5 years

Then do the same for the left pulley with the inside "fence." Because the tensioner is locked in the loose position and the three nuts on the tensioner bracket are loose, it's easy to get the belt onto this third pulley. Again find the dowel holes that allow the belt to be very tight on the left side of the belt that goes straight down to the drive pulley. Then tighten the three tensioner bracket nuts and loosen the tensioner bearing nut to allow the spring to tighten the loose side of the belt.

Remove the paper from the two cam bearing caps and free the crank to move. Rotate it a few times and make sure the marks are lining up correctly and the lifts at TDC are as per the specs. You can also check if the inlet cam is hitting max lift at 105 degrees after TDC and the exhaust cam at 105 before TDC.

The first time I did this I set both cams at opening lift instead of exhaust closing and inlet opening-- took me a while to figure it out (looked down a port and saw both valves opening together Be very gentle turning the crank as it's easy to bend a valve.
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Just a correction. It should be (3.65mm if you DON'T have a .2mm clearance) and for the exhaust cam (3.10mm if you DON'T have a .2mm clearance.) I had no valve clearance so used the bigger numbers. Once I checked the degrees of max lift for each cam I was only about 2 degrees away from 105 degrees before or after TDC. Close enough for a test of the valve to piston clearance.

 

It took me longer to find some play-doh than to assemble and test the dynamic valve-piston clearance. My kids play-doh had dried out so I hit the dollar store. While there I found a nice brass BBQ brush that I re-fashioned to clean the galleries.

The play-doh test showed ample clearance so I don't need to do the more accurate test checking the clearance at a few positions around TDC with a dial gauge onto the bucket and pressing it down until it touches the piston. Next job is opening all the valve pockets and bit to de-shoud the valves and remove some of the inlet pocket "wall" as per the originals to reduce that obstruction.
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I donned some goggles and a mask and used the sandpaper roll on the Dremel to open up the valve pockets a couple of mm and blended away the corners to de-shroud the valves. It should improve the flow and lose me a cc or two. I will check the volume of the pistons again and see how much more I should remove to get 10.5:1 static CR.

Does anyone know the compressed height of the El-ring head gasket (or can you measure it for me?) Thanks.
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I measured the new effective dome volume with a syringe, some water, dye and a little dish soap (to break the surface tension.) It's now about 6.74cc and using Summit's online CR calculator I'm sitting at about 10.3:1 which is great.

I haven't decided what to do about the end to end imbalance in the original rods. I'm leaning towards getting new H-beam rods with both the Ferrari and Suzuki G16 rod bearing tab slots so the next owner can fit the .015" bearings I have bought for the next rebuild in 20-30 years (if petrol is still available.) The rods are about $600/set and I can probably get a lot of that back selling my original rods (with new Al-bronze wrist pin bushes.)
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More sets would make it less than $600 as part price drops a little and shipping/clearing is shared by more sets.

 

Decided against new rods as I realised I can fix the small end weight mismatch with the piston weights (match small ends plus pistons.) I'll match the lightest piston with heaviest small end, then polish weight off the corners of the big square bosses on the pistons to get a match where needed. Saves me $600 and a few weeks waiting . I'll do it later today and post some photos.

The sun is out so I'll start to do final pressure cleaning of the block, galleries, jackets, heads etc. before the final assembly. The end is in sight though I still need to look at the transmission which has been in the garage on a table waiting for the warmer weather...

 

I used two digital scales to get the big and small end weights of the rods. It took a while to get a system that was repeatable/accurate. I stuck toothpicks onto the middle of the scales and 137mm apart and then drew the big and small end circles on the scale surfaces with pencil to aid placing the end centers on the toothpicks. I got to within .2 grams repeatability end to end and used the known total weights to check my two readings. You could do the same with one scale and turn the rod around.

Once I had the small end weights, I matched the heaviest small ends to the lightest pistons and got all the totals to within 0.3 gram, except for two where the small end + piston were heavier by 1.3-1.5 grams. I polished this much off the piston boss corners underneath. Next I will match the big ends by polishing a bit off the material around the bolt.
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Scott I used a level to set up the heights of the scales (note the books and CD case) and my scales are more accurate (.1g and .01g) than my method which was only repeatable to within .2g. This is still 20x more accurate than the factory spec and will certainly be balanced to less than a gram. This is already pretty pedantic, some may even say anal...

 

Pete, to simplify the mechanics of the conrod and piston, think of it as two masses, the big end rotating with the crank pin and the small end, piston and pin reciprocating. The mass at the small ends should be the same and it doesn't make much difference which part is lightened to match the other reciprocating group (as long as you don't weaken it

I didn't want to touch the rods' small ends as I might need to peen them afterwards depending on how much I would remove -- plus there was extra material on the piston that was easier to remove (soft aluminium.)