truck bogs in third

hot_roder09 · Post by **hot_roder09** » March 12, 2011, 8:47 pm

hey guys just put a 302 in my 65 it had a 390 with a three speed still have the three sped any way my question is that the truck runs good in firs (will burn the tires of the truck) not bad in second but when you go to third the truck bogs down until you are running about 50+mph so what might cause this iam running a 302 with .30 over bore parker funnel web intake with a comp cam kit big mutha thumper cam .512/.498 lift rpm range 2400-6400 with a holey 1850 600 carb do yall think i need more transmission or a smaller carb or is it something else the whole truck is stock except the motor and have 373 gears outback

MadMaxetc · Post by **MadMaxetc** » March 12, 2011, 8:55 pm

Sounds like you are running way to rich.

Pull the plugs, they should be clean and dry with a nice tan color.

hot_roder09 · Post by **hot_roder09** » March 12, 2011, 9:00 pm

did that the are good like i said it oly bogs in third but i can wind the truck up in second to over 40mph and then go to third and it will be better but not great. i have been told that i am running to much carb and need to down size that my 302 will not handle a 600 cfm carb

MadMaxetc · Post by **MadMaxetc** » March 12, 2011, 9:12 pm

What RPM are you shifting into 3rd. Should be about 4500 with that cam.

What intake? a single plane will not like low RPM at all.

3 things could be wrong.
1) Compression. But you know thats not it.
2) Fuel. Runs fine and the plugs look good.
3) Spark. Hmmm.

What is you ignition setup?

Here is some good reading on timing:
http://www.fordmuscle.com/archives/2000/03/timing/

R Pope · Post by **R Pope** » March 13, 2011, 7:50 am

A bog like that is more likely caused by a lean condition, not rich. Try pedaling the gas when it bogs, the accelerator pump will make it "catch" again if it's lean.
A 600 CFM carb might be larger than ideal. but it should at least run. Try advancing the timing a bit, but not too much if it's really lean, it will ping like mad. Lean and advanced is a bad combo!
I think bigger secondary jets will fix the problem. Does it cruise OK at part throttle with only the primaries working?

MadMaxetc · Post by **MadMaxetc** » March 13, 2011, 12:51 pm

Good point Pope. I always for get that you can have it the other way.

frdnut · Post by **frdnut** » March 13, 2011, 5:15 pm

A parker funnelweb is a pretty high rpm single plane intake..My guess is that you are falling too far out of the powerband between gears and going into 3rd...I think a peformer rpm or wieand stealth would be a an intake much better suited to a heavy truck with a relatively small engine like a 302...Either that or go to a 4.30-4.56 gear and or a trans with gears closer together.....A 600 cfm carb is fine on a 302..Might even be a tad small on your combo but probably works better on the truck...

Post by **Greg D** » March 13, 2011, 6:26 pm

You have a higher RPM range cam and an intake to match - if you shift into too much "load" without enough RPMs the engine is going to bog.
Ford used 600 Holleys on 302s so the size is right there on that.
A T-5 or 4 speed would likely help too - ratios are a little closer.

hot_roder09 · Post by **hot_roder09** » March 13, 2011, 6:59 pm

will check some of these things out thanks guys