Engine dies when braking
Discussion
I've got real problems with a stalling engine whilst braking heavily. Any ideas?
Another issue is hot starting (a real pain with the above) When warm the starter motor does not throw over the engine very quickly (if at all). The battery is fine, could it be the earth straps need improving?
Thanks
Another issue is hot starting (a real pain with the above) When warm the starter motor does not throw over the engine very quickly (if at all). The battery is fine, could it be the earth straps need improving?
Thanks
It's a problem with the carb float levels I think, if you do a search there's lots of stuff about it here I seem to remember...here's just one:
www.pistonheads.co.uk/gassing/topic.asp?t=27466&f=20&h=0&hw=Stalling
HTH
Alan.
www.pistonheads.co.uk/gassing/topic.asp?t=27466&f=20&h=0&hw=Stalling
HTH
Alan.
Alan is right. A common problem. I found winding the tick over up a little helped, although not ideal. Also a good heel & toe gear change whilst braking also helped.
As for the hot starting problem. I've not heard of one where the starter is slow. You can have a problem where the fuel vapourises in the carb and the car struggles to start. Usually in very hot ambient temps. This can lead to stalling too!
Do a search, there is plenty of discussion on these subjects. You may have to go back a while though.
Paul.B
As for the hot starting problem. I've not heard of one where the starter is slow. You can have a problem where the fuel vapourises in the carb and the car struggles to start. Usually in very hot ambient temps. This can lead to stalling too!
Do a search, there is plenty of discussion on these subjects. You may have to go back a while though.
Paul.B
As many others I had the same problem, engine was flooding under heavy breaking. Tried to play with float levels, installed jet extensions, played with idle screws,... Nothing helped.
Then the Ultima factory told me that they had good experiences with a different carb, a Holley "HP" type. It is basically the same as the usual double pumper, but has some additional features, eg. removable air bleeds. Can´t explain how, but what I know for sure is that it really solved the problem. Now rpm drop to around 500 under heavy breaking (whilst clutch is pressed), but it does not stall, not once. Lambda sensor only shows very rich condition for some seconds.
One disadvantage is that this is a race carb and has no choke. No problem in summer months but on cold days it is a pain to start. We are just installing an engine pre-heating system which will raise the water (and block) temperature to 80 deg. C before starting, this should fix the problem.
Then the Ultima factory told me that they had good experiences with a different carb, a Holley "HP" type. It is basically the same as the usual double pumper, but has some additional features, eg. removable air bleeds. Can´t explain how, but what I know for sure is that it really solved the problem. Now rpm drop to around 500 under heavy breaking (whilst clutch is pressed), but it does not stall, not once. Lambda sensor only shows very rich condition for some seconds.
One disadvantage is that this is a race carb and has no choke. No problem in summer months but on cold days it is a pain to start. We are just installing an engine pre-heating system which will raise the water (and block) temperature to 80 deg. C before starting, this should fix the problem.
I had some hot starting problems with the older model starter motor.Would turn smartly when cold and start, the hotter the engine got the slower it would turn over and longer it woould take to start.
Swapped for latest one from Ultima and problem gone away... no changes to earth strap or battery.
Swapped for latest one from Ultima and problem gone away... no changes to earth strap or battery.
You do not mention which carb you are using. Often times, builders remove a small "tongue" from from the Holley carbs (not knowing what it is for) that is used to prevent fuel from draining from the bowl during hard braking. I will provide more information to you when I get home this evening. I do not have the information with me at work.
Allen
Allen
Andy,
What carb do you currently have and what HP are you running? If you are going to fuel inject, I may have some information for you that would be helpful regarding brands and required fuel injector sizes and pressures.
I had to upgrade my injectors from stock 27 lb on the Edelbrock system to 40 lb to hold the horsepower on my engine. Not a big deal, but certainly something to be aware of. It was fuel starved and the injectors were running at 100% duty cycle, and we have found a significant amount of horepower in the engine on top of it all. Thats a good thing of course, but required some chassis dyno time and parts to make it all play nice together.
Allen
What carb do you currently have and what HP are you running? If you are going to fuel inject, I may have some information for you that would be helpful regarding brands and required fuel injector sizes and pressures.
I had to upgrade my injectors from stock 27 lb on the Edelbrock system to 40 lb to hold the horsepower on my engine. Not a big deal, but certainly something to be aware of. It was fuel starved and the injectors were running at 100% duty cycle, and we have found a significant amount of horepower in the engine on top of it all. Thats a good thing of course, but required some chassis dyno time and parts to make it all play nice together.
Allen
On a Holly carb, there is a "whistle" or "tongue" that prevents fuel from sloshing forward in the secondary bowl and shooting out the vent tube during hard braking (flooding the engine). These are often discarded during a rebuild.
The whistle can be checked by removing the secondary bowl from the carb. It will be a piece of flat, white plastic that sits in the slot. (you know it when you see it. If it is missing, the replacement part number is PN26-40 and runs about $7 USD.
Drag racers often place a length of tubing between the vent tubes to prevent this as well.
Hope that helps some of you!
Allen
The whistle can be checked by removing the secondary bowl from the carb. It will be a piece of flat, white plastic that sits in the slot. (you know it when you see it. If it is missing, the replacement part number is PN26-40 and runs about $7 USD.
Drag racers often place a length of tubing between the vent tubes to prevent this as well.
Hope that helps some of you!
Allen
Allen-GTR said:
Drag racers often place a length of tubing between the vent tubes to prevent this as well.
This fix was what I used last year after being given the tip by a McLaren Canam racer at the Goodwood revival meeting. He was just fitting the same carb as mine and we had a long discussion about it.
Cut a small slit in the loop at the top to let air in-out.
It worked for me.
Steve
I have to admit that the fuel level was set up very carefully as part of a detailed tune-up prior to fitting the pipe. It did stumble/stall without it but not with it. I have used a rather large bore pipe that can hold a large overflow before spilling out of the slit.
It's funny that we all seem to have tried various solutions (jet extensions, pipes, whistles etc) and come up with a range of results.
I would be very unhappy if I had bought the recommended SBC engine and then find that the only solution is to replace the carb with a new HP carb. A question springs to mind: Why is the Ultima engine package sold with that carb?
Phil
>> Edited by canam-phil on Wednesday 19th January 19:38
I have to admit that the fuel level was set up very carefully as part of a detailed tune-up prior to fitting the pipe. It did stumble/stall without it but not with it. I have used a rather large bore pipe that can hold a large overflow before spilling out of the slit.
It's funny that we all seem to have tried various solutions (jet extensions, pipes, whistles etc) and come up with a range of results.
I would be very unhappy if I had bought the recommended SBC engine and then find that the only solution is to replace the carb with a new HP carb. A question springs to mind: Why is the Ultima engine package sold with that carb?
Phil
>> Edited by canam-phil on Wednesday 19th January 19:38
Another thing to keep in mind is that Holley is not the only manufacturer of good carbs...
Demon, Predator, Edelbrock, Dambest... all very good carbs too...
Demon and Dambest are both race carbs. I know the owner (and engineer) of Dambest - John Satterfield. Knows his stuff, and one SMART guy. Anyway, the point is that not everyone is crazy about the Holley line of carbs, and the market has a number of extremely good alternatives.
Allen
Demon, Predator, Edelbrock, Dambest... all very good carbs too...
Demon and Dambest are both race carbs. I know the owner (and engineer) of Dambest - John Satterfield. Knows his stuff, and one SMART guy. Anyway, the point is that not everyone is crazy about the Holley line of carbs, and the market has a number of extremely good alternatives.
Allen
Thanks for all the tips.
I picked the HP up today and she's already bolted on. Just need to sort out the twin fuel feeds and we'll have "fire in the holes" again
Thank's for the tip on the ignition Mack. It's funny you mention that. When Pete Knight set up the car after I'd purchased it the timing was 10^ retarded.... Mmmm maybe I now know why..... Are you running some kind of engine management to retard for start-up? (silly question with a F/I engine
) Is there any way of sorting this with std Jacob's ignition?
I picked the HP up today and she's already bolted on. Just need to sort out the twin fuel feeds and we'll have "fire in the holes" again
Thank's for the tip on the ignition Mack. It's funny you mention that. When Pete Knight set up the car after I'd purchased it the timing was 10^ retarded.... Mmmm maybe I now know why..... Are you running some kind of engine management to retard for start-up? (silly question with a F/I engine
) Is there any way of sorting this with std Jacob's ignition?
Hi Mrloudly,
Yes. I am running an EFI system and I retard the timing at startup with it. In your case, though, you may look for a device that would allow you to retard or advance the timing. I know such a thing exists, it will just take some hunting around for.
Good luck with everything.
Cheers!
-Mack
Yes. I am running an EFI system and I retard the timing at startup with it. In your case, though, you may look for a device that would allow you to retard or advance the timing. I know such a thing exists, it will just take some hunting around for.
Good luck with everything.
Cheers!
-Mack
Here's what I was talking about. I'm sure other manufacturers offer the same thing.
Cheers!
-Mack
www.msdignition.com/tc_7.htm
Cheers!
-Mack
www.msdignition.com/tc_7.htm
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