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Help......Lower gear set, car ran slower.


Monteman1971

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As some may have seen, we went racing on the 10th at Atco Raceway in NJ. Rented the track for the day with a bunch of local guys....great times!!!

 

Unfortunately the Monte didn't run as expected. Last spring I had a lower gear set installed in the transmission so I was expecting to go faster than last year’s times. The trans guy was optimistic and claimed I would get 2 tenths. The only other changes I made were adjustable upper rear control arms, new dist cap, wires and I reduced the jet size by one (the spark plugs were black but now are a golden brown).

 

So last year it ran 11.70’s with 1.74 60 foots all day with a best of 11.66 at 116.87mph and 1.73 60 foot. This year it ran 11.90’s consistently with a best of 11.88 at 113.89 with a 60 foot of 1.724 and an average of 1.760 60 foots.

 

So I spoke with the guy who built the trans, before I mentioned the jet change he said that it sounded like I was losing power and questioned me on my fuel delivery. When I told him about the jet size he said to go back to the bigger jets that although the plugs were black it maybe what the motor wants.

 

So..that’s my story..any thoughts?

 

Oh, and one of the regular race guys said I should leave my front sway bar in to prevent the car from twisting off the line even though I have an air bag. Here’s a video of the launch.

 

 

 

Steve

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As some may have seen, we went racing on the 10th at Atco Raceway in NJ. Rented the track for the day with a bunch of local guys....great times!!!

 

Unfortunately the Monte didn't run as expected. Last spring I had a lower gear set installed in the transmission so I was expecting to go faster than last year’s times. The trans guy was optimistic and claimed I would get 2 tenths. The only other changes I made were adjustable upper rear control arms, new dist cap, wires and I reduced the jet size by one (the spark plugs were black but now are a golden brown).

 

So last year it ran 11.70’s with 1.74 60 foots all day with a best of 11.66 at 116.87mph and 1.73 60 foot. This year it ran 11.90’s consistently with a best of 11.88 at 113.89 with a 60 foot of 1.724 and an average of 1.760 60 foots.

 

So I spoke with the guy who built the trans, before I mentioned the jet change he said that it sounded like I was losing power and questioned me on my fuel delivery. When I told him about the jet size he said to go back to the bigger jets that although the plugs were black it maybe what the motor wants.

 

So..that’s my story..any thoughts?

 

Oh, and one of the regular race guys said I should leave my front sway bar in to prevent the car from twisting off the line even though I have an air bag. Here’s a video of the launch.

 

 

 

Steve

 

 

 

well to start the conversation Steve, I would love to hear an in car of that run, you really can't hear with the other car next to you....I'm not sure where the trans guy came up with 2 tenths either, that's pretty big. I've seen a tenth from a light weight TH350 trans with aluminum internals unless he thought the low first gear was going to do that, which it won't (IMHO)....plugs should never be "black" but you're better rich than lean. If nothing else is wrong then I agree it wants some more fuel, either what's available isn't being delivered or what's being delivered isn't enough. Putting the front sway bar back on is dead wrong, it will bind up the front suspension and kill what transfer you are getting, if it's twisting too much you need more air in the right rear bag. The only way to really cure the twist is an ARB.....I know the primary purpose of the car is cruising so you may have to live with the 1.70 60's...to make that better would hurt your ride. One thing you could do (I was talking to Scott about this) is put on some double adjustable rear shocks. Then you can have some race setting and some street settings, you could probably improve your 60 with a set of those.... also whenever jetting always move in steps of 2 and move both front and back, anything less really won't show up, less than that is ultra fine tuning stuff....this is just my experience...I'm sure there are different ideas/opinions....there's more we can talk about but we'll start with this... confused

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Thanks Davey,

 

From the video you can see that the car leaves without too much twist already but doesn't really have much weight transfer either (car looks relatively flat now). I'm running 20lbs in the right rear bag which eliminated the twist I had in years gone by.

 

The lower first and second gear are suppose to make my rear a 3:64 and then 3:46 although I don't feel much of a difference. Which should make the car 60 foot better. I never expect 2 tenths but I was hoping for 1...high 11.50's

 

Now I did only reduce all four jets by one but it made a big difference in the plugs. They were black (not horrible) but now they are a golden brown....which I thought was perfect but could the car still be running out of gas so for racing it needs to be richer is what I'm thinking.

 

Here's the in car video

 

 

We're thinking of another day trip in October....hopefully I'll have this figured out.

 

Thanks again

Steve

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that's a great in car Steve, thanks for posting that.....first impression is a good converter could really help you, it's really getting pulled down on launch. Again I know what the car is mainly used for but a good 10" 3500 would allow the converter to flash a little better and give the motor a chance to stay up where it belongs. Anything that low first gear might give you is being killed by the converter. I think Coan builds the best street/strip converters as they tend to be a little tighter than most. What shift points are you using? They sound a little short but I'll have to listen to it some more.

 

As far as how the plugs look one jet size would not turn them from black to golden brown, something else was at play there. I don't remember if you have done anything to your fuel system but it would be nice to know what kind of fuel pressure it's carrying for the entire run...again if everything else is ok that mph says more fuel to me....

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I agree with all of Dave's points. I also would have changed plugs! One step in jet would not have made that much difference. and there is really no way of knowing where you are at with jaet changes with a set of fouled plugs. Where were you at with timing? I would have thought that the 2.75 first gear would have blown off the tires.

Did you change anything from you last years set up other than the trans gears?

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Guess I'll jump in so he may get a response back before he gets to work.

 

All he did since last year was:

 

Dbl adjustible upper arms

Adjusted pinion angle

downsized to one size smaller jets

New high performance wires (was running a cheap $33 set prior)

New Distributor Cap bc found hairline crack in old

Swapped plugs with ones he only uses on track days (so same as last year)

....and the 2:75 lower gear set.

 

based on my memory thats all that was done since last year when he ran with your aluminum heads for the first time. It just doesn't add up?

 

Dan

 

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Guess I'll jump in so he may get a response back before he gets to work.

 

All he did since last year was:

 

Dbl adjustible upper arms

Adjusted pinion angle

downsized to one size smaller jets

New high performance wires (was running a cheap $33 set prior)

Swapped plugs with ones he only uses on track days (so same as last year)

....and the 2:75 lower gear set.

 

based on my memory thats all that was done since last year when he ran with your aluminum heads for the first time. It just doesn't add up?

 

Dan

 

There was a stiff head wind...............

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Dan has most of it but the plugs where only used for 2 passes at Super Chevy in July. I took them out when I got home. And the distributor cap wasn't cracked but was green and full of moisture inside.

 

The prior plugs were blackened, not horrible so I reduced one jet in all 4 corners, after the plugs got golden brown.

 

The new plugs after 4 passes were golden brown as well.

 

Something I did notice was that the new rear upper control arms have a lot stiffer ride and did raise the back of the car? I know that the car isn't hooking as well because I never spun the tires with the old set up but at Super Chevy I spun both times and at Atco I spun once and the second time (best pass) I felt the tire do like a skip.....but even at that, it was never a big spin just the tires squeeled a little, not enough to take 3-4 tenths off and the other 2 passes it did seem to hook fine...the video doesn't show any spin and the in car there is no spin either...but when the car spins doesn't that usually mean faster mph?

 

Thanks for all your input,

Steve

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Thanks Davey,

 

From the video you can see that the car leaves without too much twist already but doesn't really have much weight transfer either (car looks relatively flat now). I'm running 20lbs in the right rear bag which eliminated the twist I had in years gone by.

 

The lower first and second gear are suppose to make my rear a 3:64 and then 3:46 although I don't feel much of a difference. Which should make the car 60 foot better. I never expect 2 tenths but I was hoping for 1...high 11.50's

 

Now I did only reduce all four jets by one but it made a big difference in the plugs. They were black (not horrible) but now they are a golden brown....which I thought was perfect but could the car still be running out of gas so for racing it needs to be richer is what I'm thinking.

 

Here's the in car video

 

 

We're thinking of another day trip in October....hopefully I'll have this figured out.

 

Thanks again

Steve

 

Steve

let me know when you go in Oct. take the front sway bar off. bring your jets box, couple new set of plugs of different heat range. see what we can do to sort this out.

 

thanh

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Dan has most of it but the plugs where only used for 2 passes at Super Chevy in July. I took them out when I got home. And the distributor cap wasn't cracked but was green and full of moisture inside.

 

The prior plugs were blackened, not horrible so I reduced one jet in all 4 corners, after the plugs got golden brown.

 

The new plugs after 4 passes were golden brown as well.

 

Something I did notice was that the new rear upper control arms have a lot stiffer ride and did raise the back of the car? I know that the car isn't hooking as well because I never spun the tires with the old set up but at Super Chevy I spun both times and at Atco I spun once and the second time (best pass) I felt the tire do like a skip.....but even at that, it was never a big spin just the tires squeeled a little, not enough to take 3-4 tenths off and the other 2 passes it did seem to hook fine...the video doesn't show any spin and the in car there is no spin either...but when the car spins doesn't that usually mean faster mph?

 

Thanks for all your input,

Steve

 

I would have to say....huh??? Control arms should not affect the ride or change the ride height...are the springs seated correctly? I've had that happen.....how did you set the pinion angle?

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I agree with Dave, there is no way the control arms can afect ride height but you might check the spring seating and make sure it is ok.

 

Regarding the trans gears here is my theory: Street BBC put out tons of torque but are not notoriously fast revvers. The more torque our cars make, the more "highway" gears people install. The torque of the engine will push through the tough gearing. I have heard of lots of guys changing to lower rear gears (I know it is not 100% the same as trans gears but similar deal) and lose ET. I would wonder if your car likes the original higher gears in the tranny than the new ones.

 

Regarding the sway bar, I would probably leave it on. If you are spinning the tires and can't get her to hook, then yeah, take it off. If you are hooking, there is no need to remove it though--just more work for you. The car took off pretty square, just a little twist.

 

What heads do you have on the engine? For some reason I am thinking Edelbrock? I was surprised to see that my AFR heads did NOT like 38 degrees like I used to use on my factory rectangle port iron heads, they ran best with 34 degrees on my 454. I would play around with timing some more.

 

It didn't look or sound like it had any major bogs, nor did the engine rev up real high on the launch but it was hard discerning your car from the other one. From that, I would think that like Dave said, a good converter could help you out a lot--I think your current one looks like it might be just big enough to keep you from bogging but more could help.

 

The plugs can be deceiving--it is hard to tell what rpm or loading of the engine they are running lean/rich in. Maybe the actual run was good, but then the idling back to the pits was rich and blackened them, or maybe it is backwards from that. I always found that tough. There are some websites that go more in-depth into plug reading like looking at different areas of the porcelain etc. They might be able to help you figure out the plugs too.

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Thanks guys...sorry to take so long to get back to this but I was away last week.

 

So with all this talk of ride height I checked my springs...and duh....The left side was out of it's perch...must have happened when I had the rear low to swap the upper control arms....but the rear was still high so Jim and I swapped rear springs. Seemed his car sat a bit low and mine a bit high. We both had new rear springs but for whatever reason the cars sat differently. Jim hasn't put mine in his car yet but his lowered my rear 5/8 (after I corrected my perch issue and remeasured) which may not sound like a lot but has a noticeable difference.

 

I have to recheck my pinion angle after swapping the springs but it was set at 2 degrees lower than parallel to the transmission angle.

 

Thanh, thanks, once we can figure out a date I'll get back to you but it may end up not being until spring.

 

Scott, I had the front sway bar out during all of this and 20lbs of air in the right rear air bag. I have the Edelbrock RPM heads that were prepared by Mike 57....gained 4 tenths that year!!! Changing the timing from 38 to 36 had no impoact at all so I left the timing at 37 where it's been set since the engine was built...10,000 miles ago...love to drive my Monte...

 

At this point I'm going to have to agree and think it is fuel....I had everything to swap the jet's at the track but for whatever reason didn't do it because I didn't think one jet size would have such a big impact but it maybe that now with the gear set I need even more fuel.

 

Thanks for everyones input...you guys rule!!!

 

Steve

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ok..update....Test drove the car last night with the different springs and more important with both springs properly positioned in their perches....The car once again rides like it use to. I thought the hard ride was due to the new polyurethane bushings in the upper control arms but apparently it was all due to the spring not being positioned correctly.

 

So now I'm hoping with the suspension issue fixed (still need to recheck the pinion angle)and I'll richen the carb a bit that I'll hopefully go faster than last year.....Now to just find time to get to the track.

 

Steve

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