Changed cam, having major issues...
03-30-2015, 02:16 AM
#22
Instructor
Check ignition timing again. If retarded it will be sluggish and backfire. I would start with 12 to 14 Degrees initial. You need a timing light with an advance built in it
Run the valve lash again. A valve might be too tight past zero lash.
Check for vacuum leaks, intake and carb base gaskets. A lean condition will do this also.
Run the valve lash again. A valve might be too tight past zero lash.
Check for vacuum leaks, intake and carb base gaskets. A lean condition will do this also.
03-30-2015, 04:55 AM
#23
Safety Car
Sounds like a few things, one you may have valve's over tightened. Or ignition issue.
1 8 4 3 6 5 7 2 check firing order .
Pull a valve cover , use aluminum foil or a rag to block rockers from spitting oil everywhere.
Start motor , back off each arm until u hare a clacking.. Now tighten slowly until the clacking goes away , From that point with 1/4 turns tighten nut until you get 3/4 additional turn. Done. Do all 16 of them this way.
1 8 4 3 6 5 7 2 check firing order .
Pull a valve cover , use aluminum foil or a rag to block rockers from spitting oil everywhere.
Start motor , back off each arm until u hare a clacking.. Now tighten slowly until the clacking goes away , From that point with 1/4 turns tighten nut until you get 3/4 additional turn. Done. Do all 16 of them this way.
03-30-2015, 04:22 PM
#24
Safety Car
Sounds like a few things, one you may have valve's over tightened. Or ignition issue.
1 8 4 3 6 5 7 2 check firing order .
Pull a valve cover , use aluminum foil or a rag to block rockers from spitting oil everywhere.
Start motor , back off each arm until u hare a clacking.. Now tighten slowly until the clacking goes away , From that point with 1/4 turns tighten nut until you get 3/4 additional turn. Done. Do all 16 of them this way.
1 8 4 3 6 5 7 2 check firing order .
Pull a valve cover , use aluminum foil or a rag to block rockers from spitting oil everywhere.
Start motor , back off each arm until u hare a clacking.. Now tighten slowly until the clacking goes away , From that point with 1/4 turns tighten nut until you get 3/4 additional turn. Done. Do all 16 of them this way.
03-31-2015, 05:28 AM
#25
Heel & Toe
The problem your describing sounds exactly like what my 79 L48 was doing when my cam decided to go out, it started backfiring and blowing exhaust out of the carb when the engine was under a load.(2 lobes completely rounded and 2 others with less than 1/8 inch lift) I replaced my cam 2 weeks ago and no problems since. just a couple things I would check, first did you adjust your carb after the cam swap? my carb was last tuned with 2 wiped lobes so I had to completely start over and it was way off. did you ensure all vacuum lines were reconnected and when you timed it the vacuum advance was removed and vacuum hose was plugged.
I am not an expert at all and a lot of people on here have way more experience, just my 2 cents.
I am not an expert at all and a lot of people on here have way more experience, just my 2 cents.
04-01-2015, 01:24 PM
#26
Safety Car
The problem your describing sounds exactly like what my 79 L48 was doing when my cam decided to go out, it started backfiring and blowing exhaust out of the carb when the engine was under a load.(2 lobes completely rounded and 2 others with less than 1/8 inch lift) I replaced my cam 2 weeks ago and no problems since. just a couple things I would check, first did you adjust your carb after the cam swap? my carb was last tuned with 2 wiped lobes so I had to completely start over and it was way off. did you ensure all vacuum lines were reconnected and when you timed it the vacuum advance was removed and vacuum hose was plugged.
I am not an expert at all and a lot of people on here have way more experience, just my 2 cents.
I am not an expert at all and a lot of people on here have way more experience, just my 2 cents.
04-01-2015, 03:07 PM
#27
04-02-2015, 03:28 PM
#28
Drifting
Did anyone answer the question about a catalytic converter? Are you still running one? If so, disconnecting the air pump could cause it to load up.
04-02-2015, 09:45 PM
#30
Race Director
I think it would be beneficial to go back to some basic info......what is the vacuum when the car is idling? did you change the vacuum advance canister to compensate for the lower vacuum the engine is now producing? I think your friend is correct that the timing is way off. can you give us a timing curve using a dial back light and let us know at each 500rpm interval what the timing is. from idle to 4000 rpm. Lars has a really good paper on how to adjust the valves
Last edited by bobs77vet; 04-02-2015 at 09:47 PM.
04-03-2015, 08:57 AM
#31
Race Director
I think it would be beneficial to go back to some basic info......what is the vacuum when the car is idling? did you change the vacuum advance canister to compensate for the lower vacuum the engine is now producing? I think your friend is correct that the timing is way off. can you give us a timing curve using a dial back light and let us know at each 500rpm interval what the timing is. from idle to 4000 rpm. Lars has a really good paper on how to adjust the valves
04-03-2015, 03:53 PM
#32
Instructor
Member Since: Jan 2013
Location: Missouri
Posts: 218
Likes: 0
Received 0 Likes
on
0 Posts
Two things come to mind on this issue. First, mechanical time. Was this cam properly installed with a degree wheel? Second, some newer camshafts have a firing order swapping two cylinders. I would check these two things as well. The other information in this thread is also very good information to help find the problem of your engine.
04-03-2015, 04:04 PM
#33
Le Mans Master
If all the ignition issues have been checked, I would say wiped lobe like ducti don and freddy4099 think…I had a wiped lope on a 73 Nova SS and the symptoms sound familiar...
04-04-2015, 12:45 PM
#34
Melting Slicks
Yep I took my 67 camaro with a fresh 327 rebuild on a road trip way back in HS...wiped the lobe 50 miles into it. Drove another 300 miles on it before I got home.
Ran just like you describe.
Ran just like you describe.
04-04-2015, 01:10 PM
#35
Le Mans Master
Sounds like you have a good excuse for a crate motor now
04-05-2015, 09:01 AM
#36
Instructor
Hi, I'd like to help you diagnose your issues and with any luck it will be something simple and overlooked. To help maybe you could add some more information and answer some trouble shooting questions.
1) what is the vacuum at idle, is the needle steady or eratict?
2) what intake and heads?
3) what carburetor?
4) what was the compression before you did the cam change?
5) what rear gears?
6) transmission auto or manual, if auto what rpm is the stall converter?
7) when you say break in, can you run down the procedure in which you broke in the cam and include what measures were taken with the lifters and lube you coated the cam in?
8) what is the initial, mechanical and vacuum timing set at?
9) what method did you use to install the cam, dot to dot, degree wheel?
10) how did you set preload and adjust the rockers?
11) stock headers? Stock manifolds will choke most cams but the 262 would work alright with rams horns, but a decent set of headers would compliment the cam, but this wouldn't be the issue.
12) what did you use for intake gaskets and how did you install them.
13 did you use new valve springs or stock valve springs.
So..if your cams not wiped, the stock intake, heads, compression ratio, gears, stall converter and headers are not a very good match for the xe262h,
1) what is the vacuum at idle, is the needle steady or eratict?
2) what intake and heads?
3) what carburetor?
4) what was the compression before you did the cam change?
5) what rear gears?
6) transmission auto or manual, if auto what rpm is the stall converter?
7) when you say break in, can you run down the procedure in which you broke in the cam and include what measures were taken with the lifters and lube you coated the cam in?
8) what is the initial, mechanical and vacuum timing set at?
9) what method did you use to install the cam, dot to dot, degree wheel?
10) how did you set preload and adjust the rockers?
11) stock headers? Stock manifolds will choke most cams but the 262 would work alright with rams horns, but a decent set of headers would compliment the cam, but this wouldn't be the issue.
12) what did you use for intake gaskets and how did you install them.
13 did you use new valve springs or stock valve springs.
So..if your cams not wiped, the stock intake, heads, compression ratio, gears, stall converter and headers are not a very good match for the xe262h,
Great info and troubleshooting guide lines from you. Considering it was only a cam swap I agree with you. He has either ignition timing issues, valve adjustment issues or wiped cam lobes. Or hopefully one Hell of a vacuum leak!
04-05-2015, 04:48 PM
#37
Safety Car
This OP has not replied in any significant way . I doubt any post is even noticed
04-05-2015, 07:44 PM
#38
Race Director
Member Since: Nov 2006
Location: Athens GA
Posts: 19,446
Received 351 Likes
on
304 Posts
St. Jude Donor '12-'13, '15- '16-'17-'18-'19, '21
Without priming the lifters I think he has wiped a lobe. Mainly because he has driven it enough to have wiped the cam as others have mentioned.
I always let hydraulic lifters sit in oil overnight to fill them up. Install them loosely. Then use a priming tool through the distributor to make sure oil is getting to top of heads.
Then set the valve lash - either the manually crank around to each cylinder or the old method of doing it while running.
That way the valves/lifters are not over-tightened.
Hope I am wrong. Will be an expensive lesson.
Feel bad for his "friend".
Good luck
Bman
I always let hydraulic lifters sit in oil overnight to fill them up. Install them loosely. Then use a priming tool through the distributor to make sure oil is getting to top of heads.
Then set the valve lash - either the manually crank around to each cylinder or the old method of doing it while running.
That way the valves/lifters are not over-tightened.
Hope I am wrong. Will be an expensive lesson.
Feel bad for his "friend".
Good luck
Bman
04-05-2015, 10:51 PM
#39
Melting Slicks
04-06-2015, 07:59 AM
#40
Safety Car
I think he may have wiped a lobe too.... I never soaked my new lifters before breakin with my lunati 262 cam but I did disconnect my coil and fuel and turned my engine over in increments a few times till oil came out of the rocker lubrication holes before starting... the op never said anything about running the engine for breaking or procedures used to break in the cam? did he use a high zinc or substitute oil? my guess is the mechanic may be unfamiliar with flat tappet setup and requirements.
BTW the voodoo 262 has plenty of lope... not as sure about the comp cam version.
BTW the voodoo 262 has plenty of lope... not as sure about the comp cam version.