My version of the pump gas thread and quest for lost ET.

[BlueCuda340]

I have been chasing some lost ET and MPH and I am starting to wonder if its fuel type related.

November 2011 I go to MoKan dragway(because tulsa was thought to be closed at this time) for a small mopar race. This 360 was fresh with less than 50 miles on it and Zero passes. I run a best ET that weekend of [email protected] and several more passes in the 11.40s. The air was 1100ish feet and the track was great.

I sign up for drag week and proceed to do no testing until July 2012. To keep it short I have run this car at 4 different tracks with DAs from 300ft to 4000ft and can't get this thing to respond to jet on the AF meter or on MPH. My best ET since last year was this last friday in Tulsa where the DA was 300ft and the car set a new best 60ft but only an [email protected].

I have tried several things Including putting EVERYTHING back just like it was in MoKan with the exception of one thing. I have been running E10 ever since I signed up for drag week and thats the ONLY thing I haven't tried, could the ethanol fuel really be the source of my nightmares? Fuel system is good, it has rock solid fuel pressure down track, I even borrowed a bigger pump just to make sure.

Also, I did a leak down and compression test pre drag week. 3% leakdown average and 178psi cranking compression average with very little variance so the longblock is healthy.

My short list of things to try
Larger Needle and seat
Non ethanol fuel(at least according to Hapu's sign)
Finish my 418 stroker

Thanks for any input

[todd1955]

It doesn't seem totally unreasonable that your combo could slow two tenths from November to July, I probably have made as many passes as any one on drag week, I ran the bracket race the Saturday before at Tulsa (two classes). My truck will pick up two tenths if the temps any humidity are both low, humidity being very important. I keep log books and just this year had the same thoughts that something was going wrong but looking back at the same time last year realized it was just wishful thinking on my part that it should be quicker. Hope this helps.

[lun40119]

What tire is on the back of that thing? Looks like some et in your tire.

[BlueCuda340]

What tire is on the back of that thing? Looks like some et in your tire.

MT ET Street Radial. That was my first weekend on a radial and the pressure was probably a little low. I am about up 3lbs of air since I started running them and I would imagine they look better than that.

That weekend it would either dead hook or smoke the tires, it hadn't done that since I went up on air pressure.

[Lilracr]

Not sure how radical the cam may be, but have you check valvetrain? Spring pressures? Lash if solid?

What do you plugs show? Is it running lean by the plugs? Any signs of detonation?

[BlueCuda340]

Not sure how radical the cam may be, but have you check valvetrain? Spring pressures? Lash if solid?

What do you plugs show? Is it running lean by the plugs? Any signs of detonation?

I honestly haven't done much with the plugs as they have a ton of street driving on them. I was leaning on my LM2 and the MPH to show me results from jetting, although I know reading plugs would be better lol.

Its got a solid roller [email protected] and .640(iirc) lift. The springs have about 2500 miles on them and I will be changing them soon as a precaution and to gather some data on spring life.

[Lilracr]

Depending on how aggresive the lobes are or the quality of the spring, you could very well be running into valve float or bounce at higher rpm.

Make sure you are pulling W/O at the carb or even make sure the brakes are not dragging some.

I know it's frustrating knowing you have more there and trying to figure out where it went.

[milner351]

I'm not sure the availability of race fuel in your area - but it seems you could eliminate the fuel questioning by running a few passes on race fuel just to eliminate that variable, don't change anything else for those runs (if you optimized timing for the higher octane for example it wouldn't be a true test of the fuel as the only issue)

[JeffMcKC]

@ 178 psi on the starter I am doubtful it needs a race fuel with high oct. but they have a lower. I would be looking at plugs, they tell the story of whats safe. Jet to MPH and forget all the trick stuff then see what AFR your engine likes, you dont pick a AFR and then tune to that. If it spins the tire on the line it will have more MPH showing.

Can you post a complete time slip?

[JeffMcKC]

It doesn't seem totally unreasonable that your combo could slow two tenths from November to July, I probably have made as many passes as any one on drag week, I ran the bracket race the Saturday before at Tulsa (two classes). My truck will pick up two tenths if the temps any humidity are both low, humidity being very important. I keep log books and just this year had the same thoughts that something was going wrong but looking back at the same time last year realized it was just wishful thinking on my part that it should be quicker. Hope this helps.

Wise man here. Everyone always slows a bit for the week it seems from their home tune ups also.

[milner351]

You guys are teaching me the importance of a log book / spread sheet to track all this stuff.

[BlueCuda340]

It doesn't seem totally unreasonable that your combo could slow two tenths from November to July, I probably have made as many passes as any one on drag week, I ran the bracket race the Saturday before at Tulsa (two classes). My truck will pick up two tenths if the temps any humidity are both low, humidity being very important. I keep log books and just this year had the same thoughts that something was going wrong but looking back at the same time last year realized it was just wishful thinking on my part that it should be quicker. Hope this helps.

Logs are for sure something I need to get better at keeping. I should learn from my dad, as that is the first thing he does after he gets out of his car. I usually end up with time slips all over the car and under the seats etc haha.

@ 178 psi on the starter I am doubtful it needs a race fuel with high oct. but they have a lower. I would be looking at plugs, they tell the story of whats safe. Jet to MPH and forget all the trick stuff then see what AFR your engine likes, you dont pick a AFR and then tune to that. If it spins the tire on the line it will have more MPH showing.

Can you post a complete time slip?

I was basing the AFR off of my best ETs I had in Mokan. The little plug reading I have done show everything to be safe, no speckles or anything and it never gives a hint of detonation(audible at least). Its 11:1 with aluminum heads and .039 quench.

Here is a slip from this last friday the DA was about 330.

60ft 1.669
330 4.765
660 [email protected]
1000 9.681
1320 [email protected](best ET since last year)

I'm not sure the availability of race fuel in your area - but it seems you could eliminate the fuel questioning by running a few passes on race fuel just to eliminate that variable, don't change anything else for those runs (if you optimized timing for the higher octane for example it wouldn't be a true test of the fuel as the only issue)

I am not concerned so much with octane as I am with quality. I will go back to the place I can get alleged 100% gas and try again if I can squeeze some more TnT in this year. It didn't dawn on me really until recently that I had changed the fuel up. Once I knew I was going to run drag week I just started using whatever gas was around because I knew thats what it would be on all week.

Thanks for the responses

[Lilracr]

Do you a slip for the faster times to compare?

The ET you listed does not look out of whack, but it could be based on the prior ET's.

I agree with Jeff, don't tune your motor to a specific AFR or what someone suggests from another combination, test what your combo likes and document it with weather conditions to have in the future.

With my bracket car I can dial pretty close to dead on without a time run if the track is good based off the weather conditions by using my past run log.

[632STANG]

We found for racing some cars like alot more jet than you think. Usually we put a new set of plugs in for each race so it is one less variable between trips.

[JeffMcKC]

We found for racing some cars like alot more jet than you think. Usually we put a new set of plugs in for each race so it is one less variable between trips.

This can be,,, can be,,, because of a bad carb signal from the intake or carb setup chosen also to use huge jets.