360 LA installing Promaxx Aluminum heads
- Thread starter 74Scooter
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Okey~dokey. A few tanks of gas later and pulled a plug. That small spot on the porcelain is just a spec of gyrotis from uninstalling. I don't think I'd be able to do any better than this with EFI. Timing mark.. heat range and ring all reporting good. I'll eventually get around to cutting a plug down to see what's up at WOT.. but she pulls really nice with the fun petal down and I doubt I'll find anything surprising. Think I can call it a wrap on this aspect of the project unless something pops up. Thanks all for the input and for following along!
Next item.. T/A hood installation.
Next item.. T/A hood installation.
Sweet - send it!
Rat Bastid
Dunamis Metron
I tried piecing together just the parts I needed but everything was out of stock. Last week amazon showed one kit in stock, then when I checked again they were sold out. Today they showed one in stock again, so I ordered it.
Summit usually has the calibration kits and gaskets too... I was able to pick up at counter all the parts I needed.
Demon Carburetion Street Demon Calibration Kits 1921
I was trying to avoid cross border shipping. I bought it on Amazon.ca so it has free shipping in Canada.
My kit arrived today. Looking at the card it appears that the stock primary jets must be 78's as that is the one missing from the kit. The 60/52 rod is also the one missing from the kit. I am going to Moparfest this weekend, which is about a 1 1/2 hour drive each way so it will be a good test. I don't want to pull the carb completely apart in case I mess something up and miss the show, so I will install the 64/56 rods and see how that works.
IIRC the stock primary and secondary jets are both 80. I'd start by swapping in the biggest metering rod as you don't need to take it apart and risk tearing a gasket to do so. Just be wary of that dang E clip on the choke side. I got pretty good at removing and reinstalling it.
Yes, I am going with the biggest rod for now. I already lost one of those clips on the accelerator pump linkage. I will be careful but the kit came with 3 spares.
I pulled out the stock rods and they were 60/52 as I guessed. I popped in the 64/56 rods. It took less than 5 minutes. Beginner's luck maybe, but I had no trouble with the e clip. We'll see how it runs on the weekend.
Finally I have a brief update on my carb tuning. I changed the rods to the 64/56 rods. I noticed a slight part throttle hesitation, so I changed from the green springs to the silver ones which step up the rods at 8 inches of vacuum. I had a chance to drive it about 30 miles today, and the hesitation is gone. I pulled a different plug and it looks a lot better. The plugs have not been changed, so they still have some soot on them.
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Rat Bastid
Dunamis Metron
You are getting there. You can take some fuel out at idle and cruise. Can’t see WOT in those pictures.
It looks like it will take 1-2 degrees more total timing. The witness mark on the ground strap needs to be at the shell for pump gas.
Also, that 14 seems pretty hot for anything other than a dead stock engine deal.
It looks like it will take 1-2 degrees more total timing. The witness mark on the ground strap needs to be at the shell for pump gas.
Also, that 14 seems pretty hot for anything other than a dead stock engine deal.
Plug looks pretty good! Give it another 1~2 degrees of timing. Heat range might be just a tad high as it looks like all your threads are brownish.
The engine is a 361 with an actual calculated 8.5:1 compression ratio. I upgraded to a small cam which is essentially the same as the stock 383 four barrel cam. I figured due to the low compression I would stick with a hotter plug, hence the 14's. I am not up on the whole ground strap and thread reading. I could drop down to a 12 if that seems better.
You'd likely be fine with a cooler plug.
Rat Bastid
Dunamis Metron
Yeah, you have a problem with heat range availability with that style of plug. That J series short reach plug SUCKS for heat range. Everyone pretty much has made obsolete that style of plug.
You might want to screw a set of 12’s in there and see what they look like. Then you may want to see what Autolite and NGK have in that heat range because even though the cross reference charts show the equivalent heat range, they can and often are different.
The only way to know for sure is to start testing with other brands of plugs to see if you can get the heat range where the plug wants it.
So what do I look for to see that I have the right heat range? Also what do you look for on wide open throttle?
Rat Bastid
Dunamis Metron
You look at how many threads are showing heat for heat range. For Champion’s I use 2 threads max. If more threads are showing heat I drop a range.
With NGK’s, 3-4 threads is where the heat should be. Autolite’s are 2-3 threads showing heat.
All these plug manufactured use different coatings on the plugs so they all “read” differently. You learn this by testing. And yes, it’s a royal PITA but that’s the only way I know of to learn this stuff.
To check for WOT you need to be able to see the very bottom of the plug where the porcelain meets the shell. You want to see about a .100 wide carbon ring down there. If you are really good at keeping up on your tune up, you can go down to .080 wide but if the weather makes a big move and you don’t correct for it you can start hurting parts. W you can cut the shell off the plug to make it easier to see the carbon ring.
On a street engine the fuel ring can be .120 or so wide and not hurt you power wise.
I managed to find a set of RJ12YC's so I'll put them in and put some more miles on it and see what they look like. If it needs to be leaned out further I probably won't pull the carb apart until the off season, just so I don't have any down time during what's left of the good weather.
I don't think the timing will give an accurate reading as this is still the stock points distributor, and I doubt that I am seeing full advance at highway speeds. I also still run full vacuum advance. Again, I have a modified electronic distributor with a faster curve and limited centrifugal advance that will probably go in until the off season.
I don't think the timing will give an accurate reading as this is still the stock points distributor, and I doubt that I am seeing full advance at highway speeds. I also still run full vacuum advance. Again, I have a modified electronic distributor with a faster curve and limited centrifugal advance that will probably go in until the off season.
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