Gear surge

[GBowman]

The surge I am getting seems excessive to me but I'm new to the car. Anyone have actual knocking in the trans mount area when between gears-when pulling hard or downshifting its perfect but when in between gears and trying to cruise the surge knock is excessive. Maybe im shifting at too low an RPM?

[jhv48]

What rpm are you turning when you notice the surging?

[RICK LAKE]

GBowman Gary Gary you have a motor with a cam that is NOT able to cruise at low rpms. Do you have the specs on it? Also what trans and ratio is in, and what are the rearend gear ratios. It's not a surge, it's lugging. If the motor has a nice nasty idle, runs like a bear at 2,700 rpms and up you have a combo issue with the car. I am sure the car looks and runs great but is not a cruiser at low speeds. If you can come up with the specs on the car, we can do some looking to possible change the drivability and make it more injoyable to drive. Sound like another bigger is not better issue. Sorry. Rick L.

[emm427]

Drive like you stole it!!!!!!!!

[DJPlaster58]

Are you sure it is the transmission? If you have LSD differential it will chatter a bit starting out and if you shift at low rpms. After putting some miles on it went away.

[GBowman]

Thx all here is what I have:
Tremec 600 5-speed/3:46 gears
Ford Racing Alum Block 427
11.0:1 compression ratio (nominal)
Ford Racing aluminum 4-bolt main block M-6010-Z351
Forged Mahle pistons
Forged steel H-beam connecting rods
Solid Roller Cam
Intake duration 258? @ .050" intake
Exhaust duration 260? @ .050" exhaust
Valve lift intake .644"
Valve lift exhaust .653"
Roller Rocker Arms (1.65:1 ratio)
Rocker arm stud girdle
Double Roller Timing Chain M-6268-B302
Forged steel crankshaft
High performance rear sump oil pan
CNC ported Ford Racing aluminum "Z" cylinder heads M-6049-Z304P with 2.08"intake valves and 1.60" exhaust valves

The car runs like a dream but lower RPM's (under 1800 approx) cruising the car "bucks a bit unless I give it some pedal, say in my neighborhood trying to do 25-30 mph in 3rd it bucks but 2nd its fine-I probably need to get used to driving in lower gears. Its been a while since I drove a hot rod so prob need to get used to it. My Corvette did the same thing at times but that was an automatic 700R4 that I put in a '71 Stingray with a 400HP small block-the overdrive was alway bucking if I didnt manually control it.

This 427 is pretty lumpy at 900 RPM's at 1000 it seems perfect. Again I've only had it 2 days and need to learn the nuances, thx.

[jhv48]

You answered your own question.

That engine does not like low rpm's. Keep it above 2000 rpm and it should be happy, though not thrilled!

[GBowman]

I agree thx for the input.

[Dwight]

we call it trailer hitch jerk


keep the rpms up


Dwight

[MT nester]

is it cold blooded?
IMHO the idle is too lean

[RICK LAKE]

GBowman The problem is the camshaft Way to big for cruising at low rpms. I have a 482 with a 587-607 and 3.31 gears and have to be careful not to lug the motor on cool off laps.
3 choices, use more rpms and go with a lower gear in the trans.
Replace the camshaft with something in the .550"to .580" with a 112 LSA. I am sure that your motor makes 500/500+ in torque and HP but not in the low rpm range. Unless you are going to abuse this car hard, a hydro roller will do the same as a solid for street driving and extend the life of the motor. If you goto a camshaft catalog they give you all the specs for the camshaft and tell you where they make the most power and range to run in. Being your block is a 351 and your cubes are 427, you can run a little larger camshaft than one for a 351 cubic motor.
Replace the rockers with a 1.50 ratio. This will kill some of the total lift and let the motor run a little lower in the power bands. It will kill about 15-25 HP and about 10-30 ft of torque easy.
Keith Craft sell alot of custom solid and hydro roller camshafts. Give him a call with all your specs and tell him what you are looking to do. He should be able to match up a nice in the middle of the road camshaft for you.
You didn't say anything about how nasty the car sounds at idle, Some guys live by this others like to sneak up on others. Only side not is, if you are going to run a solid roller camshaft in the motor, no long term idling even with oil pressure rollers, pins or bearings. The first sign of valve tap after everything has been setup right, start looking for damage to roller lifter or camshaft lobe going flat. Hydro rollers go 200 K miles. Solids depending on rpm and size of camshaft,rpms, valve springs, will go 3-10K mile before needing checks with good oil and additives. If you limit your rpms to 6,000 a good hydro roller will last for years. Have 8 years on my setup, Broken rocker shafts but no problem with camshaft or lifters. Crane setup. Have learned Bigger is not always better either, just cost more in the long run. Rick L.

[GBowman]

Rick, yes it sounds super nasty at idle. I've been driving a bit-until it snowed here anyway. If I keep the RPM's >= 2000 It is smooth as can be. The only prob is 3rd gear because that is where in the side streets im cruising 30 mph or so I am just leaving it in 2nd and its fine-just get more looks from the people walking their dogs along with more barks from the dogs themselves.

Actually I am considering the hydr set up-this car has way more power than I need but man to lower the HP/Torque is a little against my grain since all Ive ever done was try to get more! But those were heavier cars. I am told even with the right hyd set up I'll still be over 500 ft #/550 HP so that is plenty.

Your info is spot on with what the Ford Racing tech said regarding the valve train. I am running the Joe Gibbs non synthetic and trying not to idle much.

Thanks for the info I really appreciate the input. This is a great site with so many folks who don't seem to have any agendas other than helping each other out-unlike my fishing club!

[GBowman]

Rick just noticed you are from NJ-we have an office in Clifton and one also in E Hanover. We are demolition contractors/environmental contractors-bought a company called Mazzocchi Wrecking up your way a few years back you may have heard of them from the 911 site work they did in NYC. I get up there a lot. Let me know if there are any events or whatever that you know about-thx again!

[olddog]

The cam is pretty big and it may all be to the cam, however timing may be making it a bit worse. If it is pulling the timing in too fast it will make the engines manors worse. You may want to understand how quick the centrifugal advance is coming in, and how much the vacuum advance is pulling in at what vacuum level.

Too much timing will cause the engine to surge. Some of the power is trying to turn the engine backwards and it gets a bit unstable.

[madmaxx]

Keep rpms up cheaper and zero risk as compared to other options. Statistics show in nuclear industry that 59 percent of the time they repair a piece of equipment they creat another problem which must be repaired within 45 days, trust me there is a lot of checks and QA in industry, zero at most auto shops

[GBowman]

Funny since Im headed to a nuke tonight-have a job going in WA state-Hanford DOE site. Yeah, some of the guys I talked to said not to worry about the solid lifters etc... others said that driving on the street it will destroy the valve train. I drive pretty hard on the street and will always have the rpm's up once i get out of my neighborhood. I will keep an eye on everything and adjust valves as necessary. If I keep it at 2000 its a total bear-even below that its ok unless downhill in 3rd. If im uphill its fine.