Doggy Engine on take off

Posted By: weazel

Doggy Engine on take off - 10/23/13 02:50 AM

Hi guys and gals, I recently had my engine built and everything together. I have probably 100 miles on the engine and I cant get it to run right. If Im at a dead stop and punch it the engine just bogs down. If I try to do a brake stand the engine almost acts like it wants to die and will if I let off the gas. Here are the specs of my car.

LA 360 (bored .030)
Magnum heads
Air Gap Intake
XE268H cam
Street Avenger 670 Carb (out of the box, no changes have been made yet)
TTI Headers
Stock Electronic Ignition (dizzy, ECU)
Timed to 24* initial and I have 14* Mechanical, for a total of 38*
Compression is 9:1 (but not entirely sure. Im not sure how to figure this)(i know the engine was not zero decked, just standard resurfacing)
727 Trans
2000 stall converter
3:73 gears

I've had the dizzy curved, I've tried different degrees of timing, but not entirely sure where it should be set. It seems to run the same anywhere from 11* to 24* initial setting.

One thing I did notice is that if Im timed in the teens and I put it in gear I will only drop a couple hundred rpm. Timed at 24* initial I drop 450-500 rpm in gear. I've checked for vacuum leaks and cant find any.

I've had suggestions of the carb running to lean or a bad torque converter. Im about ready to shoot my car because I cant even enjoy driving it this way. Please help me!

Posted By: RapidRobert

Re: Doggy Engine on take off - 10/23/13 03:00 AM

Total is too high but that ain't causing your symptoms. Are the floats correct & is the accel pump tip in immediate & sufficient duration. Cam might need degreeing (some timing sets are way off). Might do a quick compression test just to get a baseline. I'm assuming the reluctor gap/rotor phasing is OK. ported or manifold vacuum? What springs in the dist? 5 & 7 plug wires correct? We will solve this

Posted By: weazel

Re: Doggy Engine on take off - 10/23/13 03:14 AM

Quote:

Total is too high but that ain't causing your symptoms. Are the floats correct & is the accel pump tip in immediate & sufficient duration. Cam might need degreeing (some timing sets are way off). Might do a quick compression test just to get a baseline. I'm assuming the reluctor gap/rotor phasing is OK. ported or manifold vacuum? What springs in the dist? 5 & 7 plug wires correct? We will solve this

Ok first thing, Where do you think my total should be at? I only have about 12* of mechanical in my dizzy. I've checked my float level with the engine off and the gas barely trickles out of the plug on the side of the bowl. I have not checked the accel pump but the squirters do shoot gas in immediately when I give it some throttle. The carb is a reman from Holley so I was going to check to see if the power valve was sized correctly. I also tried a Eddy 600 on the car and it ran exactly the same way.

I was told that my cam was degreed when built but no way to verify this. My compression was 148-155. The reluctor gap was corrected when it was curved. As was the springs. My mechanical starts at 1600 and full in by 2400. Im on Timed port, side of metering block. I can double check the 5&7 wires, but 99% sure they are correct.

Posted By: 340SHORTY

Re: Doggy Engine on take off - 10/23/13 04:21 AM

You need a higher stall converter..

Posted By: dragduster71

Re: Doggy Engine on take off - 10/23/13 09:25 AM

MY 2 CENTS XE 268 YOU CAN USE STOCK STALL 2000 IS ENOUGH I WOULD THINK

Posted By: weazel

Re: Doggy Engine on take off - 10/23/13 11:43 AM

Quote:

MY 2 CENTS XE 268 YOU CAN USE STOCK STALL 2000 IS ENOUGH I WOULD THINK

Comps website even says 2000 stall is ideal for this cam.

Unless there is something wacky with my converter and its not functioning properly. I wish I had a spare one to throw in the car just to try it.

Posted By: RapidRobert

Re: Doggy Engine on take off - 10/23/13 03:11 PM

For it to bog that bad I'm thinking carb but with 2 carbs acting the same I'm thinking vac leak. Total normally should be 35 on a SB (checked with vac adv capped) but with mags then 31-32 is a good ballpark & that get set AFTER the initial is set (vac gauge method works good for initial) but all that needs to wait till the problem at hand is solved. On a side note what is the idle speed in drive & the advance starting at 1600 is a bit late but that's not what's causing it to bog that severely. the compression test tells me the long block is healthy & that only leaves ign or vac leak (intake/PCV). I ain't a cam guy so no opinion on the TC but that is a SEVERE bog

Posted By: weazel

Re: Doggy Engine on take off - 10/23/13 05:27 PM

Quote:

For it to bog that bad I'm thinking carb but with 2 carbs acting the same I'm thinking vac leak. Total normally should be 35 on a SB (checked with vac adv capped) but with mags then 31-32 is a good ballpark & that get set AFTER the initial is set (vac gauge method works good for initial) but all that needs to wait till the problem at hand is solved. On a side note what is the idle speed in drive & the advance starting at 1600 is a bit late but that's not what's causing it to bog that severely. the compression test tells me the long block is healthy & that only leaves ign or vac leak (intake/PCV). I ain't a cam guy so no opinion on the TC but that is a SEVERE bog

Well I have checked the entire top side of the engine for vacuum leaks. I've sprayed all around the intake, carb etc.. no idle change at all. Is there anywhere else it could be sucking from that would cause a leak? Also if there was a vacuum leak wouldnt it run crappy threw the entire range of the engine? Not just on the low end?

Idle speed in drive is around 450-500. I checked the timing while in drive and it is solid at 24* initial. Cant remember if I stated this or not, but when my timing was turned back into the teens I only dropped about 200rpm so idle speed in drive was about 650-700.

Im sooooo frustrated!!!!

Posted By: buildanother

Re: Doggy Engine on take off - 10/23/13 05:46 PM

If idling pretty decent, I'd not think vacuum leak. I would forget about timing light for a minute, and advance distrib and see if it wakes up a little. That converter sounds like a bit on the low side stall wise, if that is a somewhat lopey cam.

Posted By: weazel

Re: Doggy Engine on take off - 10/23/13 05:56 PM

Quote:

If idling pretty decent, I'd not think vacuum leak. I would forget about timing light for a minute, and advance distrib and see if it wakes up a little. That converter sounds like a bit on the low side stall wise, if that is a somewhat lopey cam.

Should I add timing until the engine doesnt start when its warm and then back it off slightly?? I've heard of that.

Posted By: superwrench

Re: Doggy Engine on take off - 10/23/13 05:58 PM

I would definitely check TDC on the dampner. I had a 440 that I couldn't get to run good or pull hard from an idle, and I found that the damper was off 9*. I never realized there was different timing chain covers/dampers before until that!!! Remarked TDC and set the timing and it screamed!!!

Posted By: Golden-Arm

Re: Doggy Engine on take off - 10/23/13 10:13 PM

i'd run at least a 2500, 2800 would be my choice. 2000 sounds very low, no matter what the cam card says.

Posted By: stumpy

Re: Doggy Engine on take off - 10/23/13 10:51 PM

Even with a stock convertor that thing should boil the tires.

Posted By: weazel

Re: Doggy Engine on take off - 10/23/13 10:59 PM

Quote:

I would definitely check TDC on the dampner. I had a 440 that I couldn't get to run good or pull hard from an idle, and I found that the damper was off 9*. I never realized there was different timing chain covers/dampers before until that!!! Remarked TDC and set the timing and it screamed!!!

Yep I did that, My balancer was actually very close with in 1* of being right on. Im using a 71 318 timing cover on a 74 360 engine. Im assuming it is correct for my engine.

Posted By: weazel

Re: Doggy Engine on take off - 10/23/13 11:04 PM

Im not disagreeing that I may need a larger converter. I just wish I had a spare one to try to see if it makes a difference. Mine could be messed up but with out another to throw in there no way to know and I dont want to throw down a lot of cash for something it may or may not be.

I had a SBC I stuffed in my jeep wrangler and that had 33" tires. I had a stock converter on that and sure thing I could smoke the heck out of those tires.. So this makes no sense to me since I know this engine is a whole lot stronger than that one along with way smaller tires.

Posted By: weazel

Re: Doggy Engine on take off - 10/23/13 11:32 PM

One thing that someone locally mentioned and was not sure about.. Since Im using the magnum heads with a 1.6 ratio I was told to use the comp cam push rods P/N 7642-16 which are 7.650 in length. Are those the correct push rods to use with the LA magnum head swap?

Posted By: RapidRobert

Re: Doggy Engine on take off - 10/24/13 03:02 PM

since the compression is normal I'm assuming the long block is healthy which includes preload. I am in the middle of a LA 360/mag swap on a circle burner & I have the MP P5007477 pushrods which are 7.625" for the swap which I think are now NS1 but I am using MP adjustable ones which are slightly longer than the MP ones. I will check the lengths later on today if I get over to my buddys shop

Posted By: YO7_A66

Re: Doggy Engine on take off - 10/24/13 03:27 PM

""Street Avenger 670 Carb (out of the box, no changes have been made yet)""
""Idle speed in drive is around 450-500. I checked the timing while in drive and it is solid at 24* initial.""

A solid 24 degrees in drive is a good start. 500rpm in D seems a little low, but if you can get a steady vacuum reading at that rpm, then good. If the vacuum reading is jumping around at that rpm, then I would suggest bumping up the idle rpms until you get a solid vacuum reading.

Have you tuned the carb to show the best vacuum reading in D with the brake applied? If not, try that first once the engine is up to running temp. Then see if the bog is still there. If it is, then try backing out the metering screws 1/4 of a turn and test for the bog again.

Posted By: weazel

Re: Doggy Engine on take off - 10/24/13 05:13 PM

Quote:

""Street Avenger 670 Carb (out of the box, no changes have been made yet)""
""Idle speed in drive is around 450-500. I checked the timing while in drive and it is solid at 24* initial.""

A solid 24 degrees in drive is a good start. 500rpm in D seems a little low, but if you can get a steady vacuum reading at that rpm, then good. If the vacuum reading is jumping around at that rpm, then I would suggest bumping up the idle rpms until you get a solid vacuum reading.

Have you tuned the carb to show the best vacuum reading in D with the brake applied? If not, try that first once the engine is up to running temp. Then see if the bog is still there. If it is, then try backing out the metering screws 1/4 of a turn and test for the bog again.

I have tuned the carb while in park, but I have not done so while in drive. I also took the carb apart last night and my primaries are 65s, secondaries are 68s and power valve is 6. Can you carb guys tell me if that is a good spot or should I change something?

Posted By: YO7_A66

Re: Doggy Engine on take off - 10/24/13 05:28 PM

""I have tuned the carb while in park, but I have not done so while in drive.""

Since you have an auto, you need to complete this first before swapping parts. Drive the car and get it up to running temp, then either apply the parking brake, or ask a partner to put it in D, then start with one of the metering screws. Turn one of the MS's inward about 1/8 of a turn and wait about 30 seconds or so. Then reset your idle speed if needed and check your vacuum reading. If you gained in vacuum, then make the same adjustment to the next MS. If the vacuum reading got lower, then turn the MS back to where you started and then 1/8 of a turn outward and wait another 30 seconds or so. Once you go back and fourth between the MS's 2-3 times, you may need to reset your idle rpms again. But you should start to see a difference in your vacuum numbers (after turning the MS's in or out) unless it was tuned correctly to begin with.

Note: Make sure that your MS's are set the same distance out before your start. Try to keep them the same turns outward. I like to take a permanent marker and I make a mark at 12:00 on each MS after I lightly snug them inward. This way I have a "visual" of how far out each MS is while I am tuning.

Posted By: weazel

Re: Doggy Engine on take off - 10/24/13 06:01 PM

Quote:

""I have tuned the carb while in park, but I have not done so while in drive.""

Since you have an auto, you need to complete this first before swapping parts. Drive the car and get it up to running temp, then either apply the parking brake, or ask a partner to put it in D, then start with one of the metering screws. Turn one of the MS's inward about 1/8 of a turn and wait about 30 seconds or so. Then reset your idle speed if needed and check your vacuum reading. If you gained in vacuum, then make the same adjustment to the next MS. If the vacuum reading got lower, then turn the MS back to where you started and then 1/8 of a turn outward and wait another 30 seconds or so. Once you go back and fourth between the MS's 2-3 times, you may need to reset your idle rpms again. But you should start to see a difference in your vacuum numbers (after turning the MS's in or out) unless it was tuned correctly to begin with.

Note: Make sure that your MS's are set the same distance out before your start. Try to keep them the same turns outward. I like to take a permanent marker and I make a mark at 12:00 on each MS after I lightly snug them inward. This way I have a "visual" of how far out each MS is while I am tuning.

Very good info! Thank you I didnt know to do that while in drive. I only thought you did that while in park. Damn I learned something!! I'll let you know how it goes.

Posted By: RobX4406

Re: Doggy Engine on take off - 10/24/13 06:15 PM

I don't think any amount of metering screw tuning is going to solve a 400-500 rpm drop from park to in gear. Something is VERY wrong.

Isolate the carb from everything else. If you have anything vacuum related hooked up to the carb, pcv/PB, remove it and block at the carb.

This is the same basic build and it idles at 850rpm in park and 750-800 in gear. It would kill the tires with a 2500 converter and 2.94 gears.

Posted By: YO7_A66

Re: Doggy Engine on take off - 10/24/13 07:04 PM

""I don't think any amount of metering screw tuning is going to solve a 400-500 rpm drop from park to in gear. Something is VERY wrong.""

WOW, I did not catch that note. I thought that he had 24 degrees of initial timing at 500rpm idle in D.

Posted By: RobX4406

Re: Doggy Engine on take off - 10/24/13 07:57 PM

Quote:

""I don't think any amount of metering screw tuning is going to solve a 400-500 rpm drop from park to in gear. Something is VERY wrong.""

WOW, I did not catch that note. I thought that he had 24 degrees of initial timing at 500rpm idle in D.

Correct. I read 24 initial and that huge RPM drop indicates there is something going crazy. A huge vacuum leak, etc. It should idle easily like the car in that video, 16 initial/34 total all in at 2500. 24 is a lot with that set up.

A stock converter works fine with an xe268H, no need for a stall converter with that camshaft.

I think there may be an assembly issue. This has been an ongoing series of threads on another board. I doubt the camshaft was degreed so there is no idea where it's installed. If assembled correctly, cylinder pressure should be in the 160+ range is my guess. Hopefully it's something easy hooked to the exterior of the engine.

Posted By: Ply72rr

Re: Doggy Engine on take off - 10/24/13 10:10 PM

You already tried another carb and that made no difference,if you have access to spares I would try swapping another distributor, ECU, and coil(one at a time).

Posted By: MoparJ

Re: Doggy Engine on take off - 10/24/13 11:04 PM

For what it�s worth, I have had a very similar issue with a 318 + .040 overvbore, XE268, SA 670 carb, 3.23s, and 2500 stall TC, all in an A body. Initial timing was/is at 18 degrees, total at about 37 degrees, all in by 2400. Car had big idle speed drop when put into drive and zero guts on the low end or from a stop. Turns out the converter�s insides had come apart. One new TC later, it easily will roast the tires from a light brake stand and break loose from a hard launch at a dead stop. Pulls hard for a small motor.

Currently, I run 69 jets in the primaries and 73s in the secondaries, with a fairly light secondary spring. The stock settings were a little lean on cruise.

Posted By: weazel

Re: Doggy Engine on take off - 10/24/13 11:47 PM

As pointed out by Rob, yes this has been a ongoing series of threads on another board. I've thought maybe some new opinions would help trigger something.

As for the car being timed at 24* initial. Its because I only have 12* of mechanical in my dizzy. I did the mopar muscle dizzy upgrade.
http://www.moparmusclemagazine.com/techa...em/viewall.html to try to fix my issue. For some reason it really limited my mechanical. My dizzy was exactly the same as the one in the arcticle along with the plate. I have thought about buying a new one, but the guy that curved my dizzy said there is nothing wrong with it.

I brought my carb to a performance shop today just to have them look at it. He upped my primaries to 69 and left the secondaries alone for the time being. He also changed my power valve to a 4.5, and the squirter to a 31.

I reassembled the carb and took for a drive. No change on the dead stop start/low end but man the response driving it is so much better.

While talking to him he is pretty sure the converter has a issue. Especially since I told him that it bogs and dies if I take my foot off the gas while doing a brake stand. He thinks the converter is way to tight or something wrong with it. You certainly wouldnt think a new converter would have issues but obviously one other member has had something very similar happen.

I sure wish I had my old converter to try, but that was scrapped.

Posted By: RapidRobert

Re: Doggy Engine on take off - 10/25/13 01:20 AM

Since I took the time to measure em here's the specs FYI. The P5007477 ones for the LA/mag swap are 7&5/8". The adjustable MP LA ones have a range from 7&3/8 to ~7&11/16". With my LA 360/felpro thick head gaskets/mag heads I need ~7&21/32" to get ~.030" preload & the 7477 ones gave me almost zero preload. Keep us informed how this turns out.