Motor help needed!!!

Jeff Olson

Well Known Member
Supporting Member 2
Ok. Dirt car question. Friend of mine bought a concept motor for her circle burner and we can only get 4900 rpm out of it, acts like you are bumping the chip but we have bypassed the limiter and same thing. To save time I will tell you what we have done so far. My thought is its an electrical issue. Maybe.
Checked wiring, battery, ground.
Limiter set at 6200, bypassed it.
Checked timing and advance. Ok
Changed distributor anyway. Same thing.
Checked and adjusted floats. Even changed carbs.
Checked valves, springs, rockers and studs.
Maybe intake or carb spacer leak? Running out of things to check.
Help
 

Mearl

Well Known Member
Supporting Member 6
A friend of mine once bought a motor at a racers auction that acted that way. He found out it had a mix of pistons and rods that left top dead center a little short of the deck, it had about 5:1 compression.
 

Jeff Olson

Well Known Member
Supporting Member 2
On the track it almost sounds like valves floating but builder had engine on dyno and says it can't be the motor.
Maybe worth a compression test.
 

MRHP

 
Supporting Member 1
Plug gap too wide? Tach shorting out? Fuel delivery issue? Thinking out loud.
 

Jeff Olson

Well Known Member
Supporting Member 2
Here are the specs, I cannot tell you exactly what the manufacturer is for all parts. I do know just because running out of options we did change the fuel pump Sunday and no difference. She is going to take the car and put it on a wheel dyno Tuesday, hopefully we can get it figured out. Probably something simple and stupid we overlooked.

WISSOTA STREET STOCK & MIDWEST MOD
CONCEPT ENGINE

• Same bottom end as WISSOTA currently allows in the Streets and MWMs. 350
Chevy engines maximum over-bore .060.
• Spec Icon flat top piston P/N SO2733 or Mahle flat top piston P/N WIS50030F05,
WIS50040F05 or WIS50060F05. Must use wrist pin that comes with piston
package.
• Steel oil pan with inspection hole
• No lightening of any internal or external engine parts including block.
• Edelbrock intake P/N 2701
• 4 barrel carb or same carb as GM crate engine
• Spec carburetor spacer Speedway Motors P/N 135-1960
• Any hydraulic cam, maximum .450 valve lift. No hydraulic roller cams allowed.
• Stock diameter steel lifters. Lifters must collapse a minimum of .100”
• EQ-CH3501 heads untouched. Valve size 1.94 intake 1.50 exhaust valve stem
11/32.
• No hollow or titanium valves
• Minimum valve weight intake 103 grams exhaust 87 grams
• Stock steel valve spring retainers. Stock diameter valve springs only. No
beehive/conical valve springs allowed.
• Stock stamped steel rockers 1.5 ratio
• Maximum compression 9.5 to 1
• Current Street Stock and Midwest Modified ignition.
• MSD soft touch box P/N 8728 or MSD P/N 8727CT only
• Maximum RPM 6200 limit
• MWM headers no step or try y or merge collectors
• Street Stock—stock exhaust manifold
• Gas only up to 12% ethanol no other oxygenates. No other oxygenated fuel CHP
All options subject to review/changes as deemed necessary.
If rules do not specifically say you can have said part, it means you cannot have said part or
alterations to said part.
 
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Jeff Olson

Well Known Member
Supporting Member 2
Thanks so much to all for the help. We have basically done everything suggested here short of a compression test, hopefully we will know more tomorrow after the dyno.
 

Jim Sullivan

Well Known Member
Supporting Member 10
I'm not familiar with dirt track racing at all, but do you run some type of exhaust system / mufflers? Maybe a restriction somewhere?:dunno
 

Jeff Olson

Well Known Member
Supporting Member 2
Yes, both street stock and modified run mufflers, sort of, basically an open chamber. Only difference is on the mods the mufflers are built into the headers.
When we looked over the valves again Sunday the rocker arm on #1 intake was sitting a bit farther off the valve than the others, push rod was straight, rocker was OK and stud is fine. Should have pulled the head but no time.
 
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