Printable Version of Topic

Posted by: deloreandude86 Aug 16 2011, 08:13 PM

Hey all, I'm having some issues with my engine. its a 1.7L Dual Carbed. Everything electrical is brand new, Plugs, wires, distributor, (including points), coil. I believe its getting proper gas flow but it's weird though because it idles fine. If reved and the instantly released it sounds great kicks right up no problem, however if brought up to about 3500-4000 or greater and held, it makes a poping noise and looses rpms. also on take off, give it a couple revs, sounds great, put it in first and take off, it'll throw you back in the seat then it hits about 3000 rpm and starts bogging down, shift to second and its about the same deal. In 3rd it starts to bog down and tops out about 45mph. 4th is really starting to bog and on the road can hit about 50. 5th gear is a notch above chugging it out completely. pedal clear to the floor and its loosing speed, any ideas guys?

Posted by: wingnut86 Aug 16 2011, 08:25 PM

1 Bad gas
2 Carbs
3 Fuel pump

...I had a similar issue with my Pontiac tri-power many years back, the carbs were picky about gas and gave me hell after each rebuild...


Hah! And I thought dividing an 8 cylinder in half would be easier

Posted by: deloreandude86 Aug 16 2011, 08:33 PM

QUOTE(wingnut86 @ Aug 16 2011, 09:25 PM)

1 Bad gas
2 Carbs
3 Fuel pump

...I had a similar issue with my Pontiac tri-power many years back, the carbs were picky about gas and gave me hell after each rebuild...


Hah! And I thought dividing an 8 cylinder in half would be easier

Posted by: ppetion Aug 16 2011, 08:41 PM

I am thinking carb sync/ cross link bar adjustment. I would check the cross link bar to make sure the carbs are getting the same amount of gas at the same time.

Posted by: deloreandude86 Aug 16 2011, 08:49 PM

QUOTE(ppetion @ Aug 16 2011, 09:41 PM)

Posted by: 914Mels Aug 17 2011, 11:20 AM

What kind of air cleaners are you running? What kind of carbs?

Posted by: rnellums Aug 17 2011, 01:53 PM

I had problems like this with water in the jets in my webers. I removed and cleaned the jets and the problem went away. It is an easy check.

Posted by: underthetire Aug 17 2011, 01:58 PM

Valves/valve adjustment. Too tight will cause this.

Posted by: deloreandude86 Aug 17 2011, 10:43 PM

all great suggestions guys, but i think we resolved that the problem runs deeper. Getting low compression (30) in #3 and about (60) in #4, didn't even bother checking the other 2, engines gonna have to come back down, new seal kit, Took a shortcut and payed for it in the end.

Posted by: kg6dxn Aug 17 2011, 10:58 PM

I had a similar problem. I ended up being the fuel filter. As fuel velosity increased a large burr from machining would clog the output barb. The engine would die when it reached 3500rpm.

If your compression is that low, you have other issues...

Posted by: McMark Aug 18 2011, 05:23 AM

Check your valve adjustment first.

Posted by: wingnut86 Aug 18 2011, 05:33 AM

Agreed w/valve adjustment 1st - easy speasy compared to a reseal 1st.

Posted by: Haudiosolutions Aug 18 2011, 05:50 AM

I had a very similar problem. Resetting my points gap and timing resolved it completely