[DCVING]

Well my first outing in my first Pontiac build was somewhat a success. The car performed very well, went nice and straight and hooked up good. So I know my suspension is working. The engine ran strong but I felt it was down in power. Once it got off the line it felt a little lazy, especially up top. The E.T and MPH were down considering how strong it was leaving on footbrake.

So the best pass of the day was a 10.27@126.6 , 1.37 60ft time. I was thrilled how it ran but feel it was off. So the 60ft tells me my 3400lb GTO should have been running 9.80’s according to Wallace Racing Calculator.

One of the not so immediate things I noticed was my AFR in 2nd and 3rd gear was showing a very lean 13.8-14.1 afr. This was concerning to me so I called it a day after my third pass. First two passes I was too busy watching tach and oil pressure. Wasn’t till the 3rd pass I noticed this lean reading. Yes I know you can’t just go off AFR and I need to read the plugs. Unfortunately I didn’t have an extra set with me. I also didn’t have jets or air bleeds with me to try and richer it up.

Engine: 1968 YC 400 Block now 461ci, Drilled for Kauffman Billet 4 bolt mains w/studs, 3/4 filled, Kauffman bore brace, Ohio Forged 4.250 stroke Crank, Eagle Forged 6.800 rods, Icon Forged flat top pistons 4.155, Old Style Edelbrock Round Ports 64cc 330CFM heads w/studs & cometic gaskets, Lunati Solid Roller 282/282 .404/.404 lobe lift 104IC Crower 1.65's w/stud girdle, Port matched Victor 4150 intake, ProSystems 1000cfm carb, MSD Crank Trigger, 13.1: compression, MSD 6AL

Fuel - VP X16
Timing 38*
Plugs - NGK R5671A-8 .035
Carb - 4150 w/ 84/92 jets

So what’s a good octane fuel for my build?
Should I run a hotter plug? #7’s
Timing on old E-Heads?
Jetting?

[johnta1]

What's the jetting on the carb?


I'd richen it up a lot I think?

[Scott Stoneburg]

I would richen up the carb, and see if you can record the TPM at the finish, use that to determine the amount of converter slip. What torque converter is in it. The 60' times are sweet!

[Formulas]

If 60's are sweet driver claims lazy top end, could be fuel delivery as well, no mention of the components there

[steve25]

Please tell us what if any difference there is between this new and old combo?

[chuckies76ta]

Be interesting to see what a 1050 dominator and Victor intake would do. Were running 34* and #7 NGK plugs. Like mentioned jet it up. Excellent times

[DCVING]

Originally Posted by Formulas

If 60's are sweet driver claims lazy top end, could be fuel delivery as well, no mention of the components there

Fuel system consists of a single Holly HP Billet pump with -10 lines Y fitting double feeding carb -8 return line. Shouldn’t be fuel delivery issue but like I did state in my post there are some things I do need to monitor better. Fuel pressure being one of those things. Need to get my gauge in a location I can get on camera.

[grandville455]

What's up with that plug? were those plugs new for the track or still from the dyno? That thing looks sketchy to me

[Tim Corcoran]

Congrats on the great 60' time and a very nice working suspension. What is the GPM rating for the Holley pump? What fuel are you using? The plugs indicate a lot of detonation, this can hurt your engine. For 13:1 you need a minimum of 110 octane race gas, my preference is Sonoco purple 110 but 110 VP will work too. The factors that you need to look at are, 1. fuel delivery 2. Ignition timing, 3. fuel octane, 4. carb jetting. Once you get these factors sorted get a new set of plugs and buy one extra. Do a 1/4 run and shut the engine off clean at the finish line. Let the car coast to the return road and pull over. With the spark plug socket and ratchet you brought along change one of your plugs with the extra one you bought. Now you can accurately read the plug.

[bluegoat65]

Pretty heavy fuel for that compression if your not going to use nitrous. VP 113 is a good fuel at that compression if your running strictly NA. Slightly oxygenated, nice pop to it. By the looks of that garbled fuel ring, it looks rich. Plus the specks on the porcelain, are they aluminum? Just asking here, is your rotor phased with your crank trigger? Also I like to run projected tip plugs in NA motors, like a set of NGK R5672A-8 in your app.. Without a pic of the ground strap, can t tell where timing is at. The great 60 ft and the lay down could be the convertor slip. New combos, stalls usually need correction at the get go. Keep workin it, you ll get it.

[Elarson]

Originally Posted by Tim Corcoran

Congrats on the great 60' time and a very nice working suspension. What is the GPM rating for the Holley pump? What fuel are you using? The plugs indicate a lot of detonation, this can hurt your engine. For 13:1 you need a minimum of 110 octane race gas, my preference is Sonoco purple 110 but 110 VP will work too. The factors that you need to look at are, 1. fuel delivery 2. Ignition timing, 3. fuel octane, 4. carb jetting. Once you get these factors sorted get a new set of plugs and buy one extra. Do a 1/4 run and shut the engine off clean at the finish line. Let the car coast to the return road and pull over. With the spark plug socket and ratchet you brought along change one of your plugs with the extra one you bought. Now you can accurately read the plug.

x2

38 degrees sounds pretty sporty for a typical Pontiac build...especially if it's running lean. Detonation kills power as well as parts. Just guessing that more fuel and less timing will make your engine a whole lot happier.

Eric

[Dave Polichena]

I would definitely change fuel, C12 or equivalent will work. Remove and block off the Power Valve and square up to 92 jets.

That Spark plug looks scary! Turn down the timing a little before you melt something. Changing the fuel may help too as the X may require more jet than what you have.

Tims suggestion of having another plug to swap will be extremely helpful in checking your tune up.

[Dave Polichena]

I would definitely change fuel, C12 or equivalent will work. Remove and block off the Power Valve and square up to 92 jets.

That Spark plug looks scary! Turn down the timing a little before you melt something. Try the -8 plugs. Changing the fuel may help too as the X may require more jet than what you have.

Tims suggestion of having another plug to swap will be extremely helpful in checking your tune up.

[grandville455]

X3 on everything said! The plug concerns me the way it looks! , i would definitely change fuel, and square jet it, i would also run it to the 1000 ft and kill it, 1/8 might even be fine, and change the plug, typically the back two are the leanest, but ,maybe do like 1-7? Did you use your ignition box on dyno or theirs, and make sure u check rotor phase like was said above

[DCVING]

So let me ask this? The car has a TH400 RMVB, how do I just shut the car off at the finish line and not blow up my transmission. Not only is there no fluid being supplied but I’ve heard horror stories about the direct drum failing.

[Tim Corcoran]

I have a TH-400 also and have done it many times and didn't have a problem. I don't know it it's hard on the trans or not but I never had a problem. I assume you mean a reverse pattern manual valve body. My trans is the same.

[72projectbird]

Nice GTO! I hope to see it in person sometime at NED!

[BILL BOWMAN1]

Originally Posted by DCVING

So let me ask this? The car has a TH400 RMVB, how do I just shut the car off at the finish line and not blow up my transmission. Not only is there no fluid being supplied but I’ve heard horror stories about the direct drum failing.

I always ease off the throttle, and leave in high gear, apply brakes, 140mph. Thirty years and thousands of passes that way, never an issue.

[slowbird]

That thing has had detention at some point. X16 fuel is good fuel. I ran it in a very high compression engine without issue. I'd double check your time and make sure you have good fuel supply.