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DOHC minus one

13K views 30 replies 6 participants last post by  driller 
#1 ·
I haven't been here for quite a while but I thought this may inspire some discussion. :dunno2:

I went to move the '93 when it made an awful sound for a couple of seconds and stuttered and died.

Autopsy photos...





Big cam 1.

Sprocket and chain 0.

:stretcher
 
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#6 ·
Block, crank and rods are all good. New Diamond flat top pistons, rings and bearings will be on the way.

Heads will be sent to Fox Lake. I expect some new valves and possibly valve guides will be involved.

Ordered the AccuFab secondary kit with HD chains and tensioners and looking to buy Cloyes billet secondary sprockets.

Placed an order for a Hogan sheet metal intake and I am considering switching the fuel system to E85.

Font Auto part Metal Nickel Aluminium


I know I need to find a high performance inline fuel pump to replace the Weldon 600A pump.

Automotive tire Vehicle Motor vehicle Automotive wheel system Gas


Not sure, but I think the -10 and -8 steel braided fuel lines will be OK? I have -10 from the tank to the pump and -8 from the pump to the fuel rails and -8 for the return.

I'm sure the 42# injectors will need to be upsized. 60's seem to fit the calcs but it may need 80s?
 
#7 ·
Driller, If you haven't ordered the Diamonds yet you ought to take a look at the Gibtec alternative.

Click here for the pics and story => Gibtec Billet Pistons

These were purpose built for blown Modmotor engines from a clean sheet of paper and incorporate some attractive piston engineering specifically for blown motors.

Ed
 
#9 ·
Absolutely! They are custom everything. That said, this winter there is a blown modmotor that looks like it will get built with 12.5:1 compression and Gibtec will build the pistons for him. The 3.700 bore is easily accomodated by the Gibtec guys. Talk to Nick over there. Tell him we spoke and you are not blown but you do want 12:1 compression for the 3.700 bore block. He can easily take care of you.

Ed
 
#12 ·
The block was picked up, measured and the Gibtec billet pistons have been ordered built for high compression and future nitrous application. I was told about 3 weeks to build the pistons. Heads have been sent off to Fox Lake for refurbishing. I need to follow up with Hogan's and start picking up some fuel components.

Hopefully, this time next month, things will start coming together.
 
#16 ·
FedEx made a delivery today... :dancing:

View attachment 143113
Looks like a late Christmas visit from Santa, driller (BTW, if you want, I'll use a first name if you share it)

I think you will will be quite happy with your Gibtec choice. Hopefully you never hurt one but if you do they have the ability to make a single replacement piston in 0.001" increments that will come in within a gram of the one you hurt!!

Keep us posted as your build progresses.

Ed
 
#17 ·
Thanks Ed... most everyone on forums I frequent refer to me as "JP". :)

It was indeed a late Christmas gift from Santa based on the reaction I had when they were delivered! LOL

Nick at Gibtec was very cordial to deal with and quite professional without trying to up-sell as is so common these days. I was pleasantly surprised with the time from quote to delivery. I think too often we lower our expectations and don't give credit when people deliver what they advertise. Kudos to Gibtec!

I hope to drop off the pistons and some other parts I have accumulated to the shop this coming weekend. Hogans should ship out the new intake this week and it looks like the final pieces will be the heads coming back from Fox Lake. Meanwhile I best be shopping for some fuel related items to prepare for the switch to E85.

Hopefully, updates will be forthcoming sooner rather than later, but regardless, we'll follow through to the end product. ;)
 
#18 ·
Excellent battle plan JP.

Something to consider as you begin to size the bores for the Gibtec pistons; If you check the piston data card (the one in the top left of your pic above) Gibtec will call out a 0.0045" PTW spec. If your car is primarily street driven, you can maintain an engine operating temperature below 180˚F, your boost is between 18 and 20 psi and you run a conservative tune (none of the lean is mean stuff) you can go as close as 0.0035" PTW. The higher the boost is, the better your cooling system needs to be to keep you at 180˚F or cooler.

If your car is or becomes primarily a race car you want to be loving the 0.0045" side of the suggested PTW clearance window. If you want a good middle ground0.004" is a happy place to be.

On a separate but closely related subject;

If you run gasoline (as I suspect you do) you really need to have a J&S Safeguard sometimes called Vampire. This is a detonation detection and correction device that will detect detonation on a cylinder by cylinder basis and in real time pull timing from that one hole before the next ignition event - even at 7000rpm! All the other detonation detection devices on the market today will basically send you a get well card. All they do is detect the event and then, after the fact, alert you to the destructive event's occurrence. They take no steps to correct the detonation and if you have among the best hand eye reflexes you still need a minimum of 300 - 350 milliseconds to respond.

To get a sense of what that means consider that at 3500 rpm you have an ignition event in each cylinder every 34 milliseconds. That is one ignition event, per cylinder, every other revolution 1750 times per minute or every 1/1750 of a minute. With 60 seconds in a minute it works out to 60/1750 seconds or one ignition event every 0.0342 seconds (34.2 milliseconds). That means there is enough time for 10 or so ignition events to occur before you could even begin to lift off the gas assuming you had the best reflexes in the world and immediately saw the indicator - and that's at 3500 rpm. I guarantee you will operate you engine in excess of 3500 rpm and when you do you will be quite involved with a variety of 'things' none of which will be watching your detonation indicator.

The J&S Safeguard / Vampire is smart money spent in a smart way. It will detect and prevent detonation at the earliest signs of detonation on a cylinder by cylinder basis in real time when properly installed. Nothing else even comes close.

Ed
 
#19 ·
The block was torque plate honed prior to ordering the pistons. We passed that dimension to Nick @ Gibtec and left the PTW clearance in his capable hands and it was indeed listed as 0.0045" on the spec sheet. The build is basically a high compression naturally aspirated big bore stroker for what is now admittedly primarily a track toy, so I don't necessarily have the issues others may have with in regards to the PTW clearance.

The primary discussion point now is the preferred ring gap with the new setup. The immediate plan is to run E85 and future plans include nitrous. I have seen numbers ranging from 0.0065 to 0.0080 times the bore recommended for 150+HP nitrous applications compared to street/strip recommendations as low as 0.0045 times the bore. That is a big swing from 0.0166" to 0.0296" for the ring gap!

I actually already have a Vampire kit for the car on the shelf. :good:
 
#20 ·
Things are moving along, albeit somewhat slower than expected. Latest snag is waiting on a 3V oil pump and billet gears to arrive from Boundary Engineering. The Melling pump was showing some slight scars and no chances were going to be taken at this point.

Heads were reworked with new PAC Racing springs and SS valves at Fox Lake. Crank, rods and pistons are installed in the block. Next step is to check PTV clearance (fingers crossed).

Delivered some parts to the shop over the weekend...

Modified k-member to accommodate the aluminum Canton Racing oil pan.
Bumper Automotive exterior Rim Auto part Composite material

Bumper Automotive design Wood Automotive exterior Gas


I decided not to re-use the previously refurbished stock throttle body and went with a new Accufab oval throttle body...
Motor vehicle Automotive lighting Hood Automotive design Bumper


And the crown jewel from Hogan's Racing Manifolds has arrived... :)
Automotive tire Automotive exterior Automotive wheel system Gas Bumper

Automotive tire Hood Wheel Motor vehicle Automotive lighting


Fuel components still need to be sourced for the E85 swap and I'll likely need to have my prior cowl hood repaired or possibly source one like on my '96 to clear the intake manifold.
 
#21 ·
The pieces to the puzzle are coming together and the mystery of the broken secondary sprocket and chain has some new developments.

The PTV clearance was checked and during this the discovery was made that the exhaust camshaft journals were wore beyond allowable specs. Rather than the recommend 0.0010" to 0.0015" clearance, they were 0.0030" or more. So much that you could physically 'feel' the slop in the cam. There were also telltale signs of scarring of the camshaft journals. The passenger side was worse than the drivers side. The passenger side was the one with the broken secondary sprocket and chain.

The heads and the intake camshafts were just fine but I was not going to allow the exhaust camshafts to ride. Of course they do not supply just exhaust camshafts, they are done in sets of four. So now I get to wait another 3 weeks for another set of cams to be ground.
 
#23 ·
Apparently, after being unable to log on for months, my username is now different.

But I figured I'd at least update this old thread for anyone who may be interested how this all turned out.

Long story short, after many delays the (re)build did get finished...

Automotive tire Motor vehicle Engineering Automotive exterior Machine


Automotive tire Motor vehicle Automotive exterior Vehicle Auto part


Motor vehicle Gas Auto part Machine Engineering


Wheel Tire Car Vehicle Automotive tire


Motor vehicle Hood Automotive design Automotive tire Automotive fuel system


N/A 5.0 Boss Modular block
3.800 stroker crank
3.700 Bore
5.3L Displacement
Fox Lake ported 4 Valve B heads
PAC Racing springs, retainers, etc...
Custom Gibtec billet pistons
Manley H-Beam Rods
~12:1 compression
Hogan's Racing sheet metal intake
Accufab throttle body
Long tube headers

Dyno tuning on a Mustang dyno followed up with 307 RWTQ / 333 RWHP and a bad day at the track for test and tune only to get some datalogs that showed it needed some tweaking on the tune to try to get anything under a 2.2 sixty foot launch.

But we followed up with a better track event with some tuning and did manage to end the season running 12.7s just shy of 107 mph with 1.8x sixty foot launches.

Current plans are to change the 4.30s to 4.88s to take advantage of the upper rpm power band and start the spring off with a day on the dyno. Meanwhile we're looking to do some cooling mods and suspension tweaks along with drag brakes and new wheels to try to get the combo to consistently run mid 12s or better.
 
#24 ·
Nice job JP!

A while back some bad guys managed to hack vBulletin software and we along with other sites began a more rigorous approach to protection. When that happened you had to log in with your old credentials and reset your password. If the clock timed out on you then you needed to start over entirely as you have just had to do.

If you would like, I will look into getting your two accounts merged into a single account. Let me know which account name you would prefer to use.


Ed
 
#25 ·
Nice job JP!
Thanks Ed, it was a rough and bumpy ride but I think we're finally on the right course. I believe there is a fair amount of tuning left to accomplish but the abbreviated results with the initial dyno tune are beginning to show promise. :)

Car Land vehicle Wheel Tire Vehicle


Yes, if could merge the two username accounts into 'driller' it would be appreciated. Thanks in advance.
 
#28 ·
I'm not sure there are any specific part numbers but "16757" was the reference number I selected among several options for form factor presented to me. Each manifold is built according to a spec sheet you supply upon the order. I never actually measured the plenum volume but recall the runner length being about 5-1/2" to 6".

It's a nice piece though I'm sure it's overkill for my application but I was determined not to leave anything on the table.
 
#29 ·
Update: With the higher revs, the first casualty ended up being a shredded serpentine belt. I suspect the obsolete steel Cobra tensioner was jumping around, so I decided to update.

Automotive tire Crankset Bicycle part Rim Bumper


Fearful of the 'over the counter' stock belt, I decided to upgrade there as well with a Gates Blue Racing Micro-V serpentine belt.

Electric blue Bicycle part Font Tool Eyewear
 
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