F54/P79 Swap Project

[240260280]

I can send you FW bolts and a new bushing to add to the cause. Just let me know.  I have your address ?

 

 

[siteunseen]

I can send you the 2 bottom bolts and  nuts that secure the dust cover to the bottom of the tranny pan.

Let me know, I can get your address from Phillip.

[Jeff G 78]

On 9/12/2019 at 3:57 PM, siteunseen said:

@Jeff G 78

Hey guys, sorry I missed the tag until now.  I've been super busy lately and haven't been on here.  Give me some time to read the six pages to figure out what the discussion is about and I'll chime in.  ?

I do see that it's about the F54/P79 and yes, that's what I run.  I run the stock valves and did not shim the towers after shaving 0.050" off the head.  I modified the slack side chain guide a bit and use the stock cam gear modified per the "How to Modify..." book to use a Chevy V8 eccentric washer kit to dial in the timing.  It runs great and makes good power with a mild cam, header and SU's.

Now let me go back and read for a bit to get caught up...

[Jeff G 78]

Okay, I'll admit that I didn't read every word, but it sounds like you have a very good grasp of the tension, timing, and chain position as it glides over the guides and tensioner block.  

I slotted the slack side guide holes much more than stock so that I could move them closer to the chain and get the slack right.  I loctited the chain guide bolts in, but others who have done the mod drilled them bigger to use a larger bolt.  I chose not to do that as I could get more movement with the smaller bolt.  I'm not sure I could get the guide in the right location had I shaved more than 0.050" off the head.  If I were to do it today, I would get the Kameari tensioner kit and a real adjustable gear to make everything easier.

Here are a few pics of my build from about six years ago.  I had the engine apart recently and dialed the timing back in using a different eccentric washer after the chain had about 20 race hours on it.  As you can see from one of my pics, I had to straddle the actual timing compared to the spec sheet that comes with the cam.

Edited September 22, 2019 by Jeff G 78
Added pics and info

[240260280]

Oooohhh

[Captain Obvious]

On ‎9‎/‎20‎/‎2019 at 2:26 PM, 240260280 said:

I can send you FW bolts and a new bushing to add to the cause. Just let me know.  I have your address ?

Thanks bud! That would be fantastic. I've been making up a list of parts that I'll need for this endeavor and anything I can cross off will help.   

Let me know what the shipping is and I can at least cover that!

[Captain Obvious]

12 hours ago, Jeff G 78 said:

it sounds like you have a very good grasp of the tension, timing, and chain position as it glides over the guides and tensioner block.  

I slotted the slack side guide holes much more than stock so that I could move them closer to the chain and get the slack right. 

Thanks Jeff, my confidence in the plan grows. What you did to your head is pretty much what I was planning to do with mine. I was thinking I would go .040 off rather than .050, and that should make my timing chain tensioning mods just that little bit easier than yours.

And I don't know if you read this part of the previous pages, but I've already verified that I can chuck the cam gear up in my lathe and I have enough swing to index it to the side and bore out the original dowel pin holes for the eccentric bushings. So I'm confident that I've got the valve timing issue under control.

In case you missed that part... Cam gear on the lathe. Indicated to a fraction of a thousandth on the original hole. I didn't cut anything yet, but I'm confident I can when I need to:

[Jeff G 78]

7 minutes ago, Captain Obvious said:

...and I have enough swing to index it to the side and bore out the original dowel pin holes for the eccentric bushings. So I'm confident that I've got the valve timing issue under control.

In case you missed that part... Cam gear on the lathe. Indicated to a fraction of a thousandth on the original hole. I didn't cut anything yet, but I'm confident I can when I need to:
 

When I modified my gear for the eccentric bushings, I leterally just used my drill press and punched the #2 hole the right size.  There is almost no meat left on the inboard side of the hole, but it does fit.  One thing I forgot to mention was that I had to cut a piece of 3/8" stock and use it as a plug once the eccentric was in place.  The cam gear is about 1/2" thick and the eccentric bushings as well as the cam dowel are only about 1/4", so the bushing could walk off the end of the dowel with the bolt and washer in place.  The plug keeps the eccentric bushing in place once you set your timing.

From what I recall, I ended up with about 9.5:1 CR.  I don't have my calc sheet handly.  You will see a bit less with 0.040" cut off, but it should still make good power.  The guides were super easy to modify with a small burr and a file.  I wouldn't be afraid of taking 0.050".  I spent almost nothing building that engine.  The hot tanking of all engine parts, measuring everything, crank polishing, head milling and valve job was $500.  I bought a quality made in USA timing set, new oil pump, new bearings, rings, and gaskets and then had my stock flywheel lightened by about 10 lbs.  The whole build was about $1,200.  I use a distributor from an '82 ZX which has a lot of advance, but it has no issues with 93 pump gas.  I already had the cam (Web Racing #91) and the header was given to me by a friend.  It was beat up and needed some work.  I added an O2 bung so I can keep an eye on the AFR.

With a bigger budget, I'd opt for the Kameari tensioner and cam gear, but those two components cost the same as the rest of my build. I did add a BHJ damper and Kameari bolt kit this time around after failing my stock damper and chewing up a bunch of parts in the process.

What are you doing for fuel delivery?  My SU's with SM needles do a good job.  I had to ditch the stock fuel rail though for racing.  It created terrible vapor lock on the track.  

[240260280]

Glad to help!

I'll send it out tomorrow. Anything else you need?

I'll try to get over the next time I'm in NJ so we can fight over a lunch bill for re-payment.  I certainly miss Doyle's Town.

[Captain Obvious]

Thanks much.  There's lots of other stuff I need, but it's not the kind of things I can lean on vou for. Bigger stuff like gasket set, rings, head bolts...

You have a pair of piston ring pliers or a ring gap grinder? I don't have that stuff and I'll probably only ever use them this once.

And I'd love to fight over another lunch bill.  My house is your house!

[Captain Obvious]

11 hours ago, Jeff G 78 said:

The cam gear is about 1/2" thick and the eccentric bushings as well as the cam dowel are only about 1/4", so the bushing could walk off the end of the dowel with the bolt and washer in place. 

From what I recall, I ended up with about 9.5:1 CR.  I don't have my calc sheet handly.  You will see a bit less with 0.040" cut off, but it should still make good power.  The guides were super easy to modify with a small burr and a file.  I wouldn't be afraid of taking 0.050". 

Yeah, I could just use the drill press, but the lathe would be more accurate. On the lathe I can index the part to be spot on and it also doesn't mind the interrupted cut so much if you cut through the wall into the center hole. I can also size the hole so the bushing is a slight press fit into the hole. I'm not quantized to drill bit sizes.

And that's a great piece of warning about the bushings being thinner than the gear. What I can do on the lathe is mount the gear back side out and bore from that side. I can control the depth of the bore so it doesn't go all the way through the gear. That way I can leave a shoulder in there to keep the bushing from possibly walking out. Easy peasy, but I didn't know that until you brought it up!

For fuel delivery, at this current point the plan is to redress it back up with the stock fuel injection. I suspect I'll have to tune the system a little, but I'm hoping that will work. I've heard that the stock system doesn't adapt well to modifications, and I guess I'll be able to confirm or deny that accusation. That's the current plan.

If that fails, I'll throw on a pair of flat top carbs or maybe an aftermarket EFI system.

Your 9.5 compression ratio sounds pretty much in line with my calculations. I came up with about 9.3 at .040 off.

Thanks so much for the info, I appreciate the details!

[Jeff G 78]

8 hours ago, Captain Obvious said:

I can also size the hole so the bushing is a slight press fit into the hole. I'm not quantized to drill bit sizes.

And that's a great piece of warning about the bushings being thinner than the gear. What I can do on the lathe is mount the gear back side out and bore from that side. I can control the depth of the bore so it doesn't go all the way through the gear. That way I can leave a shoulder in there to keep the bushing from possibly walking out.

I would suggest NOT doing that.  The bushing actually needs to be easy to slide in and out from the front so you can swap different sizes in and out as well as rotate them a bit as needed to get the hole in the right orientation for assembly onto the dowel.  The eccentric bushings work great, but they are easiest to install after the gear is on.  You pick a bushing that you think will be right and then slide it into the large gear hole and over the dowel at the same time while you rotate the cam into the right position to line everything up. The offset is very small in some cases and it is almost improssible to line up exactly if you try to make it a tight fit in the gear.  It also has to be installed from the front as you will need to swap them in and out to get the cam degreed in.  As I found, the cam will be a degree or so off on either the intake or the exhaust.  Unlike a dual cam, you have to work with what you have.  I'm not sure why mine was like that, but I'm guessing it's normal.  I never tried to degree a stock cam to see if it is a tad off too.  Are you running the stock cam?  If not, you will get frustrated very quickly if you attempt to use the stock FI system.  I tried numerous times to use this same cam with FI in a different L28 and it sucked.  The stock EFI hates low vacuum which is what you will get with any mild duration cam.  It made no power and idled like crap.  No amount of tuning will change the L-Jet's need for vacuum.  That's when I gave up and put the cam on a shelf for 10 years until I built this motor with SU's.  My 10:1 street Z still runs the stock cam and EFI for this reason.  This motor at 9.5:1 is way better.

Good luck and feel free to throw ideas at me.  I'm happy to share my good and bad experiences.