Torque Converter & new 350 / 290 hp engine

Clarkwb100

Clarkwb100

Not-quite-so-new-guy
Feb 7, 2019
20
3
Sugar Land, Texas
My "87 El Camino came with a four speed auto trans from the factory. I have replaced the 305 engine with a new 350 / 290 HP from Jegs. Last weekend I added a tach. Engine runs great, shifts about 2200 rpm, cruises at 65mph about 1800rpm. I dont think I am taxing this powerful engine enough.

But....The car won't lay rubber. Could it be that the engine (paperwork says it has an "aggressive cam") doesn't get up to rpm to produce enough power? How would I fix this? Change out the torque converter to a higher stall speed?

Does anyone have experience with this engine transmission combo? IS the torque converter locking up way below the power curve of the engine?

I would appreciate some thoughts on this. Thanks
 
Turbolq4

Turbolq4

Royal Smart Person
Sep 25, 2017
1,263
113
Nampa Idaho
Converter shouldn't be locking in first or second. What rear gears are in it?
 
olds307 and 403

olds307 and 403

Comic Book Super Hero
Oct 14, 2008
4,539
113
Melville,Saskatchewan
I find the low stall 2004R converter flash around 1900 rpm. What is the power band of that cam? I would bet a convertor in the 2200 to 2500 rpm stall range would do want you want.
 
spidereyes455

spidereyes455

Master Mechanic
Mar 6, 2013
345
63
Northeastern PA
The stock converter in that el Camino should be either a D6 or a D7 one stalls at about 1300 the other about 1600. The D5 converter only came in the hi po code transmissions and should stall in neighborhood of 2000- 2200 rpm. Last time I checked the D5 could still be had as an off the shelf reman from rock auto or just about any where else for less than $150.
 
olds307 and 403

olds307 and 403

Comic Book Super Hero
Oct 14, 2008
4,539
113
Melville,Saskatchewan
I know my 350 converters both stall at 1600 rpm, one lock up, one not. All my 2004R that I checked had D9 converters, I take it they are a mid stall converter?
 
spidereyes455

spidereyes455

Master Mechanic
Mar 6, 2013
345
63
Northeastern PA
The D5, D6 and D7 are the only ones im aware of. Are you sure your D9 isnt a 6 ?
 
M

Max Headroom

Greasemonkey
Sep 8, 2011
127
28
If your engine has less than 9.5 to 1 static compression, a mid to hi rpm power band and highway gears, you may not get rubber. As the comments above suggest, your converter probably grabs to low in the rpm range and you are not yet making enough torque to overcome all of the resistance. You could try dialing in a little more timing advance and see if that helps any. Do it in small steps. Another thing is your carburation. Hi intake air velocity is a must for crisp throttle response. A mondo 4 bbl carb pulling big air may be great for mid and top end but may not create enough air intake velocity for bottom end torque. One last thing. Are you on single exhaust or true dual? If its factory single exhaust, you aren't getting anywhere close to 290 hp out of you 290 hp engine. Exhaust back-pressure will also choke the performance and keep you from spinning the tires.
 
383_GrandPrix

383_GrandPrix

Master Mechanic
Sep 9, 2016
405
63
Quebec, Canada
Ima put my money on rear gears; 3.42 is a nice ratio for these cars, especially if your 4th gear is 1:1.
Rev that sumbich to 3000 and pop the clutch; you might get some rubber before the spider gears launch through the rear cover. :twisted:
That's the kind of thing I used to do to my ford pickup, the thing didn't last long... The tires even less 😂
 
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olds307 and 403

olds307 and 403

Comic Book Super Hero
Oct 14, 2008
4,539
113
Melville,Saskatchewan
The D5, D6 and D7 are the only ones im aware of. Are you sure your D9 isnt a 6 ?
Yes, pretty sure D9, had two or three, all from big cars, one a 85 Lesabre that would have had an Olds 307. They stall better than the 350 stock converters, I will have to test what it stalls behind the 260. Unless his lock up isn't working he already sounds like he has 3.08 gears with a stock tire height. What does your trans shift at full throttle? Probably, 3000 to 4000 rpm, which sucks.
 
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