flat head problem

[alleramilitaria]

ok here is the issue....
the motor seems to work fine but has little power.
durring turns it will backfire through the carb and die, it will hit 2nd gear and go well till a turn and then i have to shift to 1st and back off to build up speed again, or backfire and die. at idle it sounds fine.

the ingition is 6vlt and i have a electric fuel pump. i have NOT had the eng compression tested.

im thinking that the carb may need rebuilt,
whats your thoughts?
thanks
dave

[Richard Farrant]

Originally posted by alleramilitaria
i have a electric fuel pump. i have NOT had the eng compression tested.

im thinking that the carb may need rebuilt,

Dave,

Sounds like it is not getting enough fuel when it really needs it. Go back to basics, is the tank free of crud, pick up pipe clear, no obstructions in the pipe, pump delivering, then check the carb for crap in it. Just a thought, maybe the accelerator pump in the carby is not working well, you should see it if you take the intake pipe of and look down the carb throat and work the throttle,...... without the engine running, in case it backfires in your face

Richard

[alleramilitaria]

thanks, im running the petral from a 20 ltr fuel can by way of adaptor.

[Lynn Eades]

Is your dizzy set up properly?

[alleramilitaria]

dizzy????
im here in texas i may need a translation for that word.

[Keith Webb]

Dizzy: n, Southern hemisphere slang word for distributor. A small crab-shaped thing found on the front of certain sidevalve V8 motors.

Similar to Carby: n, Carburettor

[alleramilitaria]

i think it is, whats a way to check, i did have it timmed but it may not still be that way.
thanks

[Alex Blair (RIP)]

Originally posted by alleramilitaria
dizzy????
im here in texas i may need a translation for that word.

I think he means distributor..
I think you have a combination of things..I think the vacuum advance is sticking or not advancing properly,the fuel,as Richard said may not be getting to the carb,under load ,but good enough for an idle and you may have a valve sticking ,due to sitting around,which those flatheads were notorious for..
I think you are loosing power through your advance ..
Make sure your distributor is clean and adjusted and your wires are new points set right and timed properly..
A cracked dist.cap will play havoc with it and even old gas will do what you are discribing..I aways used slick 50 of duralube in the engines of any vehicles that sat for extended periods..
So some of those things are pretty easy to fix..I'd start with fresh gas,if you run it off a 5 gallon gas can it should be a snap..
Good luck and keep posting and we'll get it fixed.
Just like we did for others..

[Bryan]

Dave,

I had the same problem with my flatty. It turned out to be the timming. The distributor fitted to my engine does give me some adjustment to advance or retard the timming but it was not enougth to clear the problem I ended up cheacking the timing marks of the cam gear and making adjustments.

Now I have lots of power and no fluffing around when running underlead.

Hope this helps

Bryan

[Neil Ashley]

I had a similar problem on my carrier where it would start perfectly but any attempt to rev the engine resulted in the engine dying.

A new carb had no effect so I then changed the distributor which remedied the problem. I was wondering at the time if the advance and retard in the distributor was stuck, but others had said since then that this would not have caused these symptoms.

[alleramilitaria]

ok changed the carb, now i have more power and bigger backfires

could someone tell me the best way to time this thing?
early type dizzy, not pancake or 59AB. im looking for a hot rod shop right now but would like some help to see if i could do it myself. i have been told that i might have the timing advanced too far.


NZ deaming

[Phil Waterman]

Was this engine taken apart since it was last known to run well? Reason I ask is it sounds like the cam could be one tooth off on timing. Have you check the compression to see if an intake valve is hanging?

[alleramilitaria]

changed the carb and timmed it, more power yes, minimal backfires. but im not there yet. im thinking i may have a stuck / burned valve. any advice?

im thinking about pulling the intake / heads and hone the valve seats and see if i have a broken or bent valve.

thanks everyone

[Richard Farrant]

Originally posted by alleramilitaria
changed the carb and timmed it, more power yes, minimal backfires. but im not there yet. im thinking i may have a stuck / burned valve. any advice?

Dave,

Standard practise would be to do a few basic diagnostic checks. You should carry out a compression check to note any patterns in low cylinder pressures. It could be valve trouble and again, could be a blown head gasket, between cylinders. The latter can give all sorts of misleading things, like backfiring through the carb, etc. It is not necessarily going to leak water, depends where it may be blown.

Don't forget when you do the comp. check, remove all plugs and hold throttle open while turning the engine over.

Richard

[Alex Blair (RIP)]

Originally posted by alleramilitaria
changed the carb and timmed it, more power yes, minimal backfires. but im not there yet. im thinking i may have a stuck / burned valve. any advice?

im thinking about pulling the intake / heads and hone the valve seats and see if i have a broken or bent valve.

thanks everyone

Dave
Do a compression test first...
Do a "dry" test first and write down the compression on each cylinder(With all the plugs out..)
Then ,one at a time ,squirt a little motor oil down the spark plug holes...
Record all the "wet" readings..
That will tell you if it is rings or valves..
I'm working from 40 years ago of memories here but I think any thing over 85 pounds compression should be good..
If there is no change between wet and dry readings and the compression is low it is valves..
If the compression goes up on the wet readings it is rings...
I would do that first before I pulled the heads to give me an indication of the condition of each cylinder anyway..
Others here will correct me on the theory and numbers ,but do a compression test first.It is in your workshop manual..
To adjust the valves on the flattie the stems AND seats have to be ground..Do not over heat..the valve stems are sodium filled..
(I think)

[Alex Blair (RIP)]

Originally posted by Richard Farrant
Dave,

Standard practise would be to do a few basic diagnostic checks. You should carry out a compression check to note any patterns in low cylinder pressures. It could be valve trouble and again, could be a blown head gasket, between cylinders. The latter can give all sorts of misleading things, like backfiring through the carb, etc. It is not necessarily going to leak water, depends where it may be blown.

Don't forget when you do the comp. check, remove all plugs and hold throttle open while turning the engine over.

Richard

Jeez,Richard..
I'm in here typing all this stuff out about compression tests and post it and then I read the forum and find out you are doing the same thing at the same time..
I gotta get up earlier(It's 06:30 AM Here) or you have to go to bed earlier(For your after noon nap)..

[Richard Farrant]

Originally posted by Alex Blair
Jeez,Richard..
I'm in here typing all this stuff out about compression tests and post it and then I read the forum and find out you are doing the same thing at the same time..
I gotta get up earlier(It's 06:30 AM Here) or you have to go to bed earlier(For your after noon nap)..

Morning Alex,

Its mid morning here, just having a coffee and reading latest messages, thought I would offer a little advice to our friend.

You know what they say here, "its the early bird that catches the worm"

Between us, we should should come up with the answer to Dave's problem.

Richard

[Alex Blair (RIP)]

Richard...
Hope you are having a crumpet or a strumpet with your tea..

I read these little problem threads and just itch to be there to check things out...Can't smell the grease in the virtual world ,but am going to change the front wheel bearing in the MIssus Toyota in a couple of hours so will get my hands full soon enough..

[Lynn Eades]

Sodium filled? I dont think so. Anyone know for sure?