Motor just wont RPM. Any suggestions welcome

Hello everybody,

I am currently helping out a outlaw promod car that has a small problem. The motor just won't rev beyound 8600 at the shift points. The combination is built to go 9000 and 9100 at the shifts. The valve springs have good pressure on the seat and the graph shows the fuel pump is good. After leaning it out several runs in a row the same rpm limit still appears. Fuel system is very basic with no high speed. It has 33* timing with no retards. Any thoughts or ideas? Let me know if you need more specifics if that will help.

 

IT MAY BE TO LEAN.

 

What does it have for ignition? Sounds like it is hitting a chip without any more info that what is posted.

Rapid

 

Is the blower fresh and making good boost? How fast are you spinning it, maybe a combination of too much OD and a loose blower is causing it to go fat at high rpms, especially with no high speed.

 

First thanks for the replies.
The fuel combination was run with a 80 pill first run then a 100 second and finally a 120 on the last run. The plugs all look safe. The egts averaged 1100. Same results each run. Just won't rpm over 8600.

The blower is an older mert littlefield high helix. It was restripped and was fresh this year. The runs in question were made at 50 over and the thing made only 38 pounds boust at 8600 rpm. The boost is slow to come up though. On the leave its 22 pounds and the boost curve comes on slowly till the shift point when its 38lbs.

The ingnition is a msd 20 with no chips at all. 33 degrees timing. If you have more that can help please post it here or email me at oldmannick60@yahoo.com

Thanks for the help.

 

will hit it right on... replace the box and coil. my experience with msd stuff is that 'checking it' is a moot point. never fails when msd has it in their rig and they spin it up that bitch'll just spark her ass off to 11,000. put it back on your hot rod and go make a round... and it's a pup and won't get out of its own way! change them (or use some one's you know works) and eliminate the ignition as the source of your problem. if thats not it you have a spare.

if you do send it to some one leahy is the dude... shop phone:740.362.0251 website: www.electrimotion.com

 

Could the blower rotors possibly be swapped side-for-side? Have seen that happen a couple times around here in the past, the car will run- but definitely not very good.

 

Thanks Nathan,

Since the blower was restripped over the winter before i got here i will check it out and let everybody know.

Nick

 

i think the boost number is fair for an older blower at that rpm depending on motor size and compression that is a respectable number. what size is your pump and how do the plugs look after the end of the run. you have good egt's i agree with the guys on the ignition the rest of your combo sounds close.

 

Thanks for the help so far.

I checked the blower and the rotors are on the correct side in the case. The pump is a 990 and the plugs had the cad burned down only 1/2 of the first thread. The cad is also burned about 3/4 of the way down on the inside near the ceramic. The look like they are safe as far as fuel goes. The racepak was just sent back to make sure the egts are reading correct. The 1100 average and the plug readings don't seem to match. Just want to be sure. Any more ideas are sure welcome here.

Nick

 

If you have spark plug inserts in your heads, the plugs will look leaner than they really are.

 

Electrimotion - Dave Lehey ph 740-362-0251 Just had him go through my stuff in record time last week. Tell him I said "Hi" and "Thanks"! Tim Stevens

 

is the clutch locking up? if it doesn't lock up and load the motor, it won't rev up. it should scream for the moon when the clutch comes in. just a thought that i have seen in the past.

 

I see 3 potential problems.
1. Clint is on to someting. Make sure you have at least 1/2 inch air gap between the clutch fingers and throwout bearing with the clutch released.
2. Have the MSD checked out. Then get rid of the 20's and put in a single 44. You'll save about 20lbs. and a lot of guessing when it doesn't work. The more wiring you have, the more gremlins you have.
3. How can you go from an 80 to a 100 to a 120 main and the plugs read good? EGT's are deceiving. This tells me you don't have enough fuel pressure. Without enough fuel pressure, the fuel just flows out of the nozzle (instead of a fine spray) and you can't burn fuel like that. It's highly unlikely this is preventing your engine from revving, this is just my observation.

 

Goodmorning,

To clint, The clutch locks up in high gear on the graph.

To alkydrag, I have a single msd 20. I will check the throwout bearing for 1/2 clearence as you suggested. As far as fuel pressure its a 990 enderle pump. Any thoughts as to how much pressure is good at the 8600 rpm we are stuck at. I will check the graphs to see what it was at the only race i was with this car with so far and post that info later.

Thanks again
Nick

 

You haven't said what motor you are running. But I would normally not like to see anything under 150 PSI @ 8000 RPM. Unless your running a hemi with big chambered heads, 33 degrees of timing is too much.

 

To everybody who has taken the time to give ideas here THANKS. We are going to test at a local 1/8 mile this Friday if it does not rain. We will update everybody as to the results soon as possible here.

Nick Todaro

 

Hello Everybody

Well we were booked in for a match race this last Friday at our local track (1/8Th mile at Lancaster , NY). So i took all of the answers and information that you provided and made a change. First we got the Racepak back and as I thought Ron fixed wrong reading EGT.s. The air was 1000 foot worse than the run at cayauga so we decided to lean it out to a 136 pill. The thing left on the bar good this time and even though the driver had to lift and get back into it because of sidways drift it got to 9160! The plugs do look hot now but not excessively so. Our next 3 races are on the 1/8Th mile tracks so i will leave the main jet alone. The starting line EGT average was 689 so i will put 2 or 3 flats in the barrel valve to calm that down a bit. Also the clutch seems to need 3 more grams as it just started to shake near the top of first gear.

Anyway thanks for all the help with this. It great to be able to turn to people willing to talk it over with me. I will keep in contact during the race season.

Nick Todaro