Asking for ideas and/or opinions [Archive] - El Camino Central Forum : Chevrolet El Camino Forums

: Asking for ideas and/or opinions


jmask99
06-06-2008, 09:15 AM
I have a 1970 Elky that I converted from an inline 6 to a 383 2 years ago and have been tinkering with on and off and now I am using as a driver. Some of the other stats: 3.23 rear end, 3 spd Saginaw(I know!), dual flowmaster exhaust. The engine has a 7102 edelbrock performer rpm cam with stock 1.96/1.50 heads (thinking of installing 1.6 roller rockers- dont know what that does to my lift), edelbrock 1406 carb that has a tendency to stall on me when in idle and upon initial load sitting on a weiand 8004 intake. My buddy believes Im under carbed. My end goal is to have a vehicle that has great power and still be able to cruise the highway comfortably at 60 mph without giving me the feeling its gonna blow up. It seems like the tranny is revving really high (tach reads 2700 @ 50 mph) so I dont believe its the engine and i cant see the rear end being the issue either. I know the tranny needs to go, but what else am I missing?

TheEmrys
06-06-2008, 10:58 AM
Honestly, I'd look at the heads. You've got some good mods their, but your engine just might wake up with some new heads. There's lots of good options. I wouldn't mess around with port and polishing your current heads as new ones are about the same price.

464elky
06-06-2008, 01:51 PM
With a 3:23 rear that RPM at 60 is about right. My 3:42 at 60 is right at 3000 without the overdirve.

rbohm
06-06-2008, 08:17 PM
:cool: first set your idle speed at about 800-950 rpm. with the cam you have the idle rpm needs to be a bit higher than stock. the carb is a bit small for your engine IF you are racing. 600cfm however will do just fine for what you want from the engine. i would dump the 3spd and swap in a 700r4 overdrive trans, and keep the 3.23 gears. that will drop your engine rpm at 60 rather substantially, down to about 1900 or so. i also would invest in a better set of heads than the stock ones, but i would keep them a bit on the small side. the 1.94in/1.60ex valves are great for a street engine. use something like the edelbrock performer rpm heads, or the world products s/r torquer heads. they will give you better flow than the stock heads, and the world products heads wont bust the budget. if you have the stock exhaust manifolds, if they are the rams horn type you can keep them by having them extrude honed for better flow, but a set of headers would be better. shorty headers fit real nice, long tubes give you better torque. dual exhaust with 2 1/4" pipe is best, but with the added cubes you can also use a 2 1/2" pipe with no problem.

84 G camino
06-07-2008, 08:27 AM
revs seem off for the mph. my 3.55s at 60 are only 2700. in my old car with 4.10s at 60 was like 3100. speedo correct?
anyhow, 600 cfm should be ok unless you are looking for mega top end power. heads as stated are the answer i feel. some vortecs or sportsmans would be fine. i have the eddy rpms on my 406 and like them.
never noticed any power when i went 1.5 to 1.6 . i know there is some to be had but lets just say i couldnt justify the $200 more i spent that i couldnt "feel". maybe a 7101 eddy intake would be my first move then the heads. or better yet do them as a complete combo...

jmask99
06-08-2008, 09:33 PM
Thanks for the feedback guys, I just happened to get a holley for my birthday last week and I just finished installing it and I am experiencing the following: starts fine idles at 1600 rpm. after the car is warm, rpms go down to 1000 then just keep going down until the car dies unless I keep tapping the accelerator. I just starting noticing this before I switched carbs. I hooked up a vacuum gauge and it reads 15 but that was right after startup. checked and couldnt find any vacuum leaks. Timing is at 8 degrees. I guess the plugs are next...

jmask99
06-10-2008, 07:33 AM
plugs look ok, read a post from another owner who had the similar symptoms and it ended up having to do with the engine overheating. Does that sound right to anyone? Im kind of confused and frustrated because I took alot of time setting this engine up and I cant figure out whats not right on it. What are some alternatives at his point without teardown and inspection, or IS that my alternative?

464elky
06-10-2008, 07:42 AM
It doesn't sound like you have to run it that long to be dieing from over heating and you should see symptoms of that - like blowing coolant out or gurgling from the radiator and etc.
I wouldn't think it was anything internal in the engine if you are not hearing any noises and can keep it running by just giving it some throttle.

It still sounds like vacuum leak or carb problem. Since you can keep it running by tapping the accelerator it is too lean at idle.

When it starts to die try pushing the choke plate over and see if it keeps running.
How did you check for a vacuum leak?

jmask99
06-10-2008, 03:33 PM
I sprayed fluid along the manifold and saw no bubbles. I had 15 on my vacuum gauge but I have not checked when the engine is completely warmed up. I will push on the choke plate and check my vacuum at idle again when i get home.

CoyoteOn2
06-10-2008, 04:06 PM
Sorry to break this to you, but, you won't see bubbles if it is a Vaccume leak, no matter what you use.

464elky
06-10-2008, 04:18 PM
And here I was just sailing along trying to be as helpful as I could for Alex and you go and Bust his bubble. :)
Alex what he is saying is that the engine will just suck in what ever you spray. It is not blowing out so that you would see bubbles like you were hunting a natural gas leak. Try spraying something like WD40 (or if you are really adventurous use a propane torch that is not lit - I repeat NOT LIT. Just barely open the valve - you don't need much) at the base of the carb and along the intake and all the places where vacuum lines are connected. When you hit the spot that is leaking the engine should speed up.

CANTED
06-10-2008, 07:16 PM
One thing that has not been mentioned is that even though the Weiand 8004 is a good performing two plane intake, it is designed for a spreadbore carb like the Qjet. You are now on your second squarebore carb so I assume you are using some sort of adaptor plate. While these adaptors can work, the chance of a vacuum leak is increased.

jmask99
06-11-2008, 04:10 PM
right! No bubbles, but you can see the fluid being sucked down and there will be a change of condition. I didnt know about propane, I may try that but I will also use vacuum gauge after the car is completely warm. another note, when the choke plate is closed as rpms drop, engine will shut off and when I flip up the choke plate ( its 3/4 open) the engine will rev up to 1600-1700 rpm

jmask99
06-11-2008, 04:23 PM
also forgot to add that the only adjustment made was idle speed and I can get that down to only 1000 rpm. I will connect the gauge and perhaps adjust the air mixture tonite.
Canted, I did have the adapter plate on, the intake takes both square and spreadbore carbs, I was able to bolt them on with no leak. So i am running the holley without it. With that said, I will mount it again to rule that out.

turboapache3132
06-11-2008, 09:35 PM
In answer to your question about the 1.6 lifters. You gain .030 inch lift and and an effective increase of about 4 degrees duration. On the dyno you can see about 10 HP from the lifters in general but that all depends on the engine mods. You wont be able to feel any difference on a street engine as a rule. Something you might try is to increase the initial timeing to 12 degrees or so and them back down on your edle screw. If the problem started after a manifold change you might want to check the distributer installation. The engine can be made to run with the dist. off one tooth. Just something to think about if the engine seems lazy.

464elky
06-12-2008, 05:46 AM
when the choke plate is closed as rpms drop, engine will shut off and when I flip up the choke plate ( its 3/4 open) the engine will rev up to 1600-1700 rpm

By what you say here maybe we are going in the wrong direction. If you can open the choke and it revs up it is too rich.
Is the choke electric or exhaust heated? sounds like it is staying on too long.
Try backing the adjustment off a couple of notches.

jmask99
06-12-2008, 01:23 PM
electric. But i cannot adjust idle speed down to 700-800 rpm and i dont know why. If I adjust down past 1000 RPM while warm, the engine starts to die so I adjust it back up. I will be putting the adapter plate back on to reduce that from the equation. next post will have results

CoyoteOn2
06-12-2008, 03:14 PM
Alex, What Neil was saying was to adjust your choke, THE BIG BLACK CAP, on the choke, you do that by looseing the 3 screws and turning it towards the - side. It may be set to tight or rich, then re adjust the Idle screw and see if that works. WHEN the Engine is warm, or at operating temp, the choke plate should be all the way open, not just part way.

elcamino74guy
06-12-2008, 09:24 PM
I had a similar issue when I switched to the 680 Holley Street Avenger with an electric choke. In the end the choke had to be pulled apart and reinstalled because it wasn't allowing any adjustment. Also had to richen the primary jets by two sizes to keep it from cutting out. The cut-out was most noticeable at 75MPH too and the engine was running about 20 degrees higher than normal too.

:D

jmask99
06-18-2008, 01:00 PM
Hello all, first I had to take off the choke housing because the pin for the choke plate was not lined up on the tab for the housing bimetal spring so I wasnt getting any adjustment. We also adjusted the float levels, timing, and idle mixture. To this point we have good solid idle of 800 rpm, 12 inches of vacuum @ 8 degrees TDC. The engine ran well until yesterday when it started "sputtering" off idle into gear and wouldnt smooth out until I put some real rpm into it. Im thinking fuel filter or air, so I will open the hood tonight and check.