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SBC lacking power

2490 Views 37 Replies 18 Participants Last post by  Moosecountry

I am hoping someone can help shed some light on my current set-up. I know this has been raised a lot on here before but I couldn’t find anything that really gave me an answer.

I have only just got my 66 C10 with a 350 on the road and it feels like a bit of a slug/like it is still a stock motor (before all the upgrades happended). I have measured the 0-100 and its around 10 seconds (shifting manually on the TH350) which is slower than my 1.2 litre Volkswagen Polo and from a rough calculation would equal around 150 hp at best. The engine is as follows:
  • Stock bottom end – standard bore and compression test is all within 4% of each other
  • New alloy heads with 195cc runners, 64cc chambers 2.02 intake and 1.60 exhaust which are a little big but looking to go a 383 in the future. Flow numbers are:
  • Lift Intake Exhaust
    200 145 106
    300 192 135
    400 232 160
    450 242 168
    500 242 178
  • XE262h cam – Was a comp cams kit with timing chain, lifters and springs
  • Edelbrockperformer RPM intake
  • Brawler 650 carb (brand new) vac secondaries
  • Flowtechheaders – 1 ½ primary, 3 in collector but runs a duel 2 ¼ in exhaust to Flowmasterstraight through mufflers
  • MSD StreetfireHEI distributer – new MSD leads and spark plugs
  • Initial timing is set at 14 degrees and total 34 degrees (all in by 2800 rpm)
  • Stock TH350
  • Stock Converter
  • Rear gear ratio 3.73
  • Rear tire height is 28 inches

The car starts, idles and cruises perfectly and sounds strong but just doesn’t seem to have much go at all. The plugs are not fouling or over rich or lean. My question is whether I am just expecting tomuch out of the engine (although looking at the dyno sheets from comp cams for the cam I am not) or whether it sounds like something is a misssomewhere? While I feel like it would benefit from a looser converter I don’t feel like this would change the accelationthat much.

I have ordered a cam degree kit to check whether it has been installed retarded and is the correct cam. No loose lifter and pushrods spin when cranking so don’t think I have wiped a lobe.

Hopefully I have provided enough info for someone who knows more then me.


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1 - 5 of 38 Posts
what you can do is advance timing until you get ping at higher rpm under power. Then back off timing slightly until it no longer pings at higher rpm. This is not accurate but close enough to see if you find power. If you find a bunch of power then go to the trouble to verify timing marks. If no substantial increase in power we have other issues to chase. If A/f is way off then dial that in next. 12.5-13:1 at wfo is a good place to start. I run my engine at 12.2:1 at WFO for the type of power I want with my parts. Also check carb linkage that gas peddle to the floor is actual w/o at the carb. Then we tune secondary opening rate (make sure it is opening)
after all this is confirmed do a roll on hard acceleration in second gear from 2500 rpm to redline. Note at what rpm the power rolls off? Should pull clean past 5500 rpm but sometimes if fuel delivery is weak then power drops off at higher rpms. Same can happen with a stock GM HEI coil. A separate coil is needed after 4500 rpm.
mike many members here are good contributors.
Bogie is good at long winded explanations for less experienced people. He is good.
1 - 5 of 38 Posts