Author Topic: 86 C10 262 to 305 swap  (Read 1337 times)

Online Stewart G Griffin

  • Site Supporters
  • Senior Member
  • ******
  • Posts: 3024
Re: 86 C10 262 to 305 swap
« Reply #15 on: March 22, 2019, 08:05:47 AM »
3) Also, i would like to amend my thoughts concerning 4.3 vs. 305 and 305's in general:

i was looking at the torque curves of both engines (that's what i do......) in the gm heritage section.   While the 305 "only" makes about 5hp and 5lbs torque more than the 4.3 AT PEAK,  it does it a a lower rpm AND it's torque curve is much flatter than the 4.3's.

So the 305 not only makes more power, it does it at a lower rpm, and more consistently in the lower and higher rpm ranges;   The 4.3's power curve looks more like a mountaintop, while the 305's is more like a plateau.   

i think the 305 would likely make a better towing engine.  On the other hand, with the right gears, the 4.3 could do ok for towing, but still wouldn't be as fast as the 305.

i think the takeaway here might be-----don't just look at peak numbers, look at the entire power curve.

4)  The 305's radiator hoses "should" plug right into the 4.3's radiator.    This radiator could probably be adequate for a while if you're not towing/hauling.   Personally, i would not run this way for too long and would get a v-8 radiator, but  that's just me.

5) The 305 might run even better because of the 4.3's torque converter.   Which trans do you have?

i will try to get a picture of the mounts this weekend, but might take a while since they are somewhere in the garage........

Online Stewart G Griffin

  • Site Supporters
  • Senior Member
  • ******
  • Posts: 3024
Re: 86 C10 262 to 305 swap
« Reply #16 on: March 25, 2019, 07:04:40 PM »
Actually let's forget #4 +#5 for now----we are jumping ahead and should only do one step at a time.




It appears to be the top set of holes.

For these mounts, i have used nothing but SBC  (305 and 350).

i am not sure why there are two sets of holes?    Could it be transmission dependent?    i have only had a TH-350.