I ordered a Cloyes sbc timing chain set and a comp cam/ lifter set from speedway motors for my tt pickup. Its a standard bore 283, 270H hydraulic cam, small valve 350 heads, new eldebrock 600 carb, stock alum GM intake and petronix in the distributor (switched back to points with no difrence). When i put the timing set on , i lined up the dots in the 12 and 6 oclock position. Then I noticed the intake valve was starting to open after compression stroke on #1. At 12 and 12 the exhuast was opening after compression. Put it together at 12 and 12 and it starts fine but I had to advance it alot (off the timming tag) to get it to run half way decent. Under normal driving conditions it runs fine but when you get on it it has nothing, no power at all. It wont even think about spinning the tires from a dead stop. Will just pop ans die. At a constant speed on the freeway it runs great (drove it 3hrs to Round up and never got above 160 degrees, ran great) but give it a little gas and it bangs and pops and agian no power. I am at a loss, does this cam need to be need to be advanced or retarded with the timming gear? thanks for your help. David
The timing tab is a crude way if setting the timing. In other words not accurate. You must find true TDC then mark that as 0 on tab and balancer from that if the balancer has no degrees on it buy a timing tape at a speed shop to put on it. Then you will see actual degrees of timing both initial and advanced with the light. I wouldn't advance or retard the cam just run it at 0. Your lack of performance could be a few things. Lack of fuel in bowl of carb. Wrong timing. Ignition etc. Sorry if it kinda rambles on.
when you line the dots up on the timing set,the cam gear dot will be at 6 oclock and he crank gear will be at 12 oclock...... .the engine will NOT be on number 1 firing order, so the valves on number 1 cylinder will be in motion, the engine when the timing marks are aligned correctly is actually on number 6
^^^ when the dots are lined up at 6 and 12 the intake valve opens after the compression stroke on # 1. Shouldn't the exhaust valve open?
Today was the third time I pulled the front apart , just to check again. I already did find tdc and marked the ballencer at 0 with the timing tab. I have to advance it completely off the timing tab to get any kinda throttle response out of it.
It was a running joke in our family for years that when I would put a new engine together and try to start it the engine was always 180 out of phase. I couldn't understand why if you line up those two dots on the sprockets it shouldn't be on number one. Now what I do is take number one spark plug out and hold my thumb over it while someone turns the crank with a rachet. You can feel the compression start to blow your thumb off start watching the timing mark on the damper and the timing tab. When the compression stops blowing fine tune the position of the timing marks so you are about at zero, then drop your distributor in so that number one is where you want it pointing. Put that wire to number one and the rest on where they belong in sequence and you will be close enough to get it fired up. Then you can turn the distributor until it runs better and finally set the timing with a light. Since I started doing that I no longer have a problem with backfiring and shooting flames out of the carb. Don
which way are you rotating the engine? really dont worry about what number 1 cylinder is doing. alot of guys get confused because they think when the dots are lined up correctly the engine should end up on TDC of number 1.......when in fact when the dots are lined up correctly the engine will be on TDC of number 6
yep, but you are gonna have to have the timing chain and gear componets lined up correctly before you can get it on tdc and stab the distributor in....he is trying to get the timing componets lined up properly....THEN he can get it to TDC number1 and stab the distributor.
Yeah, I kinda missed that he originally had it right with them at 6 and 12 (close together) but then he played around with it and moved it to 12 and 12. Gotta go back to the original alignment. Don
have you checked the mechanical advance in the dizzy? sounds like it may not be working. there could be lots of other causes but if advancing the timing to the extreme cures it or at least helps that would be the first place I checked.
With 350 heads on a 283 you have about 7 to 1 compression, and the 270 cam will knock the engine down to know low end torque. You need to run a 50-59 cc head with your combination or you'll never get rid of the soggy low end. A higher stall torque convertor wouldn't hurt either, but the low compression is killing you right now.
When I first built the truck I had a 305 in it, I was going to use the 305 heads buy when I pulled them to lap the valves and clean them up they where cracked. I already had these heads so I am using them for now till I can afford a good set of double hump heads. So maybe I am wasting my time with the performance end with these heads on it? It's just the whole intake valve opening on compression that has me all confused.
i agree 350 heads on a stock bore 283. you don't have much for compression which means no get up and go. used heads on a used motor . not wanting to spend money on a good valve job? just going to lap them? there are only 2 ways to work on motors the right way or half assed. you have tried the second now try the first.
The heads that are on it have about 1000 miles on them. They where fresh from the machine shop when I got them, never used them till now. The 283 was check and was low milage with almost no wear on the cylinders so it got cleaned and new rings and bearings. And was checked for tolerances by a machinist friend of mine.
A stock bore 283 cannot accept the larger 350 heads, the smaller bore gets shrouded. If you use a stock 283 head and put valves from a 305, that is about the max you can go with the stock bore. It takes a little more attention to detail with a 283 because of the smaller bore. They will scream when done right.
I think I will just wait till I can get a good set of double humps to worry about the performance side. Like I said it runs great under normal driving conditions. Thanks guys
With your dots lined up @ 12 and 6 (6 on the cam gear) you should have been @ TDC on #1. You should make sure that you are not looking at the #1 exahust valve a common mistake. Another common mistake is that people turn the engine over backwards and thing that the intake is opening after TDC when infact it is just getting ready to close if you turn the engine in the correct direction. Not to say that you made either of the previously mentioned mistakes but 12 and 12 is wrong.
Its just easier to use 12 and 6 and not be a tooth off. One turn of the crank and your at 12 and 12, same thing. The question I have is, do you have only one key groove on the crank gear or 3?
I always use the timing tape myself. I think you have the cam and crank properly aligned, something else minor must be going on like the distributor being a tooth off. Been there, done that! Bob
It still amazes me to watch people trying to start a motor where the distributor has been out or a new motor, they crank away twisting the distributor trying to get it started, Try this proceedure to start a new engine, it will work every time. Bring the engine up to TDC on number one. Look at the timing tab and move the damper to your desired setting, lets say 6 degrees BTC. Now, drop in your distributor so you have room to rotate it for adjustments and locate where the Rotor is pointed, this will be #1 plug wire. - You can adjust the rotor to point wherever you want. Put all the wires on. NOW, this seems to be the one step that people either don't know or forgot or WHATEVER!!!! Take #1 plug, in the #1 wire and ground the electrode on a good ground source. - turn on the ignition and rotate the distributor until you get a spark from the plug - now you have the #1 plug sparking at 6degrees BTC. Tighten the distributor and install #1 plug. If you have gas - IT WILL START EVERY TIME. BigSkyBob
When I put it together at 12 and 12 it fired right up, just had no power. The timing set does had the 3 position but I have pulled the front apart 3 times to check and make sure it was in the factory setting and was not any teeth off. It runs great under normal driving, starts as soon as you hit the key, and doesn't get above 160 degrees. It's just when you get on it , it has no power. Not really bogging down, just pops and sputters when you take off hard of passing on the freeway. Runs 80 mph all day long and doesn't really have a problem getting there as long as you dont just floor it to get there. I guess because of the timing at 12 and 12 I thought maybe the power problem had some to do with it, but maybe it is the heads.
lets try this dots should be aligned like this.. you will notice that number 1 and number 6 cylinders are at the top of their stroke if you rotate it slightly you can see that the number 1 cylinder lifters are in motion and the number 6 are not...because when the dots are aligned correctly the number 6 is on compression tdc and the number 1 cylinder is not.... .once you get the mechanical timing correct you can then rotate it to number 1 tdc compression and install your dizzy and time the engine this assumes all the marks on gears are correct , you could verify that by degreeing the cam in, but i am guessing the marks are fine
But which valve opens after the compression stroke on #1? Ok I found a chart online ( don't know how accurate it is ) but it says a standard bore 283 with the 350 heads I have on it has 6:1 compression.
just to add to the confusion; Lunati cam I bought instructions said to put the marks (on the gears) at 12 & 12. I called bull shit and set them the way I have always set them, engine was sick. followed the instructions and BINGO. First time I had ever seen this in my years.
This stumps a lot of guys. Cam @ 6 o'clock crank @ 12 o clock is the correct way to install. With that being said you now have 2 cylinders @ tdc. #1 is on tdc exhaust and # 6 is on tdc compression.If you don't rotate from this position you must put the dist in with rotor pointing at # 6 in the cap. If you insist to install dist with rotor pointing to #1 on cap you are required to rotate engine one full turn and install dist pointing to # 1 on cap.This is ok also but the timing marks on the gears are now both @ 12 o'clock.Are you confused yet? LOL Hope this helps Tig.