My new engine has no power either-need help
Thread Starter
Le Mans Master
Joined: Mar 2001
Posts: 6,640
Likes: 287
From: Ann Arbor Michigan
I hooked the A/F ratio back up and went for a ride. Floored it (engine hot) in 2nd gear from 1000 to 5200 RPM. A/F ratio as follows:
1900 RPM=13.86
3500 RPM=12.87
4500 RPM=12.51
5300 RPM=13.60
It looks like A/F ratio has a change in slope (flatter) at about 1900 RPM and stabilizes at about 3500 RPM then starts to lean out at about 4800 RPM.
Am I to lean?
1900 RPM=13.86
3500 RPM=12.87
4500 RPM=12.51
5300 RPM=13.60
It looks like A/F ratio has a change in slope (flatter) at about 1900 RPM and stabilizes at about 3500 RPM then starts to lean out at about 4800 RPM.
Am I to lean?
Thread Starter
Le Mans Master
Joined: Mar 2001
Posts: 6,640
Likes: 287
From: Ann Arbor Michigan
Well, now I'm getting somewhere. Dug out Lars distributor tuning paper and pulled the cap to remove the springs as he suggests. Discovered that the advance plate was stuck. No corrosion evident, but squirted it with WD-40 and it seemed to work better. This is a 2 year old Summit HEI unit, rather disapointing. Is there a better HEI distributor out there, as I notice that this one seemed to have lots of end play too. It seems to run much better with no hesitation. I'm going to try richer as suggest by Matt Gruber. Thanks for all the help.
Race Director
Joined: Apr 1999
Posts: 11,520
Likes: 13
From: CORVETTE 77 385 C.I. TEXAS
It should really take off & go from about 3000 up (compared to stock) properly tuned w/ Dynomax headers.
A good 2101 & a good stock fuel pump are not the problem. The first Performers were not as good as the latter ones about 1989 & the newer ones may not be either.
Besides tuning, how was the valve lash set.
Like what- perf. for looks- not rec.!
A good 2101 & a good stock fuel pump are not the problem. The first Performers were not as good as the latter ones about 1989 & the newer ones may not be either.
Besides tuning, how was the valve lash set.
Headers are far too big.
Originally Posted by SteveG75
FYI, Hooker sidepipes for the SBC only come with 1-7/8" primaries. Sometimes we need to sacrifice to get what we want.
Last edited by Ganey; May 29, 2005 at 10:43 AM.
Thread Starter
Le Mans Master
Joined: Mar 2001
Posts: 6,640
Likes: 287
From: Ann Arbor Michigan
[QUOTE=Ganey]It should really take off & go from about 3000 up (compared to stock) properly tuned w/ Dynomax headers.
A good 2101 & a good stock fuel pump are not the problem. The first Performers were not as good as the latter ones about 1989 & the newer ones may not be either.
Besides tuning, how was the valve lash set.
Valve lash was set at 1 turn after all pushrod slack was taken up.
A good 2101 & a good stock fuel pump are not the problem. The first Performers were not as good as the latter ones about 1989 & the newer ones may not be either.
Besides tuning, how was the valve lash set.
Valve lash was set at 1 turn after all pushrod slack was taken up.
Thread Starter
Le Mans Master
Joined: Mar 2001
Posts: 6,640
Likes: 287
From: Ann Arbor Michigan
Just to close out this thread, I replaced the distributor with a MSD HEI unit (top quality piece!) and it made a huge difference. No hesitation anywhere and power is much improved. Apparently, the mechanical advance on the old unit just wouldn't work correctly. There certainly is a BIG difference in the quality of operation between the $350 MSD and the $150 Summit. Guess you get what you pay for. Thanks to everone for your help.
Le Mans Master
Joined: Feb 1999
Posts: 8,351
Likes: 75
From: Tampa Bay FL
Stumble sounds like timing issues. Have you taken it to a tuner to dial the combination in? Well worth the time and $$$. I had mine set at 8BTDC, and tuner coaxed 40 more hp just by laying in the proper timing curve.
Sorry, seems you solved the issue. I should have read last posts...
Sorry, seems you solved the issue. I should have read last posts...
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Burning Brakes
Joined: Feb 2005
Posts: 894
Likes: 91
360HP x 390FT.Lbs w/Stock GM Cam!
That cam, if I read it right, XE262H, is good if you're chasing fuel economy only. Can't see Comp recommending something that small? This is a lesser cam than the "bone-stock" L82 option from G.M. How can a cam this size be hooked up to headers (1.875) that want to see about 500HP. Change it to an XM270H and see some serious power gains. The motor really needs 1.625 pipes. What do them "tech-guys" know? Thanks, Gary in N.Y.
PS I've posted this on other sites, but I'll give it here again. SB 355 C.I., Ross pistons (9.7:1 C.R.), #186 G.M. heads(2.020x1.600), 224/224 x .450/.460 x 114LS cam (we love this L82 grind), stock alum. intake, 650 CFM Holley carb, and "stock cast iron" exhaust manifolds, off the dyno at 360+HP @ 5900 RPM and 390+Ft.Lbs. torque @ 4000 RPM. And a "super-flat" torque curve. This motor made equivalent power to the original LT1 (higher C.R. and larger cam), but runs fine on 93.
PS I've posted this on other sites, but I'll give it here again. SB 355 C.I., Ross pistons (9.7:1 C.R.), #186 G.M. heads(2.020x1.600), 224/224 x .450/.460 x 114LS cam (we love this L82 grind), stock alum. intake, 650 CFM Holley carb, and "stock cast iron" exhaust manifolds, off the dyno at 360+HP @ 5900 RPM and 390+Ft.Lbs. torque @ 4000 RPM. And a "super-flat" torque curve. This motor made equivalent power to the original LT1 (higher C.R. and larger cam), but runs fine on 93.
Race Director
Joined: Oct 2000
Posts: 15,055
Likes: 79
From: central FL, near the beach.
gofast
kudos to u for 360hp5900 w/obsolete cam and heads.
my xe262 is a better cam because of its fast ramps, it makes it's peak at only 5000-flat to 5700 i had the 151 cam, this is better imo(for me w/3.08) and w/9.7 it loves 87- no ping ever
kudos to u for 360hp5900 w/obsolete cam and heads.
my xe262 is a better cam because of its fast ramps, it makes it's peak at only 5000-flat to 5700 i had the 151 cam, this is better imo(for me w/3.08) and w/9.7 it loves 87- no ping ever
Last edited by Matt Gruber; Jun 3, 2005 at 07:34 AM.
Race Director
Joined: May 2003
Posts: 11,814
Likes: 9
From: Science Bitch! Mississauga, Ontario
Canadian Events Coordinator
Originally Posted by bobs77vet
did you follow there build precisely or did you swap/change parts along the way? if you followed it precisely you should have similar results....it may be more of a tuning issue then you think.
and good luck
Melting Slicks
Joined: Oct 2001
Posts: 3,025
Likes: 12
From: Pleasant Grove AL
Originally Posted by Duke94
Besides tuning, how was the valve lash set.
Valve lash was set at 1 turn after all pushrod slack was taken up.
Valve lash was set at 1 turn after all pushrod slack was taken up.
Very easy to get the valves too tight if zero lash is slightly miscalculated. I would back all of the valves off a half turn I never tighten the lifters more than a quarter to half turn past zero
