Hot or Cold spark plugs with turbo and propane

[zayne2427]

I'm running a 1989 4.3 v6 on propane and a small t3/t4 turbo.
Original builder was running a Delphi plug from one of his racing buddies that they do not sell to the public. It was the **coldest plug they make ( heat range 1) said he could get me some for around $11 a piece.
**(correction) I spoke with David that built the buggy and I misunderstood him. It need a heat range 0 or 1 which is a super cold plug.

A few weeks ago I blew my head gasket and decided to have engine rebuilt from bottom up.
Bored .040 over
Hyperuetectic pistons
Comp can
Polished crank
Blocked deck
Full head work
Marine grade head gasket
ARP Head studs
Bumped compression up to around 9.5:1
And upgraded rest of the internals

Long story short the original plug stuck into the engine about 3/8-1/2 inch and were a very hot plug and engine builder said he could not figure out why this was done this way.
However, the engine builder recommended running a very cold plug with the turbo. As well as when I called the parts store I told him how the engine was built and he recommended a colder plug as well

Any help or recommendations would be appreciated.
Thanks

 

[muddinmetal]

NEVER, EVER EVER RUN A HOT PLUG WITH BOOST!!!! Depending on the boost level and compression you want the coldest, or at the very least one step colder, plug you can find. This is why you blew a HG. Also you will want to close your plug gap also to prevent a high rpm, high boost miss from blowing out the spark

 

[altfuel1991]

Generally with a propane engine in a light duty engine running the original heat range works. On an engine running under a heavy load or boost it is recommended to go two ranges colder. And do not use platinum tip plugs. Platinum retains heat and at high cylinder temperatures can turn into glow plugs in a propane engine.

 

[muddinmetal]

I run an autolite AR23 (8.0to1 buick 231 on 30lbs) If you prefer AC Delco it'd be a CR42TS, NGK makes a great plug, but I don't not know the interchange right off the top of my head. As far as making power goes, low compression high boost it the way to go, but for crawling having a little more CR and bottom end torque would definitely be helpful. I also wouldn't run anymore than a .022-.025 gap

 

[zayne2427]

That's the way he explained it but the engine has been in this buggy for about 6 years. Granted I just fixed some recent leaks in the intake system. It was running great after they were fixed but then blew the head gasket on first hill I hit.
It always has felt like it had a miss at higher rpms.
My boost gauge reads vacuum instead of boost so I don't know exactly what it boost. Guy who built it said around 10 psi. I'll try and get that fixed

 

[muddinmetal]

I run an autolite AR23 (8.0to1 buick 231 on 30lbs) If you prefer AC Delco it'd be a CR42TS, NGK makes a great plug, but I don't not know the interchange right off the top of my head. As far as making power goes, low compression high boost it the way to go, but for crawling having a little more CR and bottom end torque would definitely be helpful. I also wouldn't run anymore than a .022-.025 gap

I think you'll be a happy feller if you'll try this ^^^^ A brand new motor may foul the plugs anyways, but one you get the rings seated it should be a whole new animal. How much boost are you gonna run?

 

[zayne2427]

My boost gauge reads vacuum instead of boost so I don't know exactly what it boost. Guy who built it said around 10 psi but who knows. I'll try and get that fixed. First turbo buggy I have had. Only thing I have done until now is just change the oil and drive it. I've been researching like crazy to learn all I can on it.

 

[zayne2427]

I got back in touch with David that built the buggy. I misunderstood when I talked with him. He said the range 1 plug was a cold plug and it needs coldest plug I can find

 

[muddinmetal]

Are they Vortec heads? If not, if you know, What year are they and where did they come from?

 

[zayne2427]

Engine is from a 1989 blazer. Stock heads just ported and polished now

 

[muddinmetal]

Engine is from a 1989 blazer. Stock heads just ported and polished now

Damn dude, you would have picked up 40-50 horsepower by swapping in a set of stock vortec heads and a matching aluminum intake for $300, over your heads stock. Put an autolite 23 or ar23 with a .23 gap and

 

[zayne2427]

Live and learn right. Oh well. It should be a lot better than what I had either way.

 

[zayne2427]

Here are the plugs that were in it.

 

[kmcminn]

Looks like they needed changed. Lol

 

[zayne2427]

lol yeah it does. I'm sure the bad head gasket and sitting for 3 weeks with water/antifreeze on them for 3 weeks before i dropped it off at the builder didn't help any.

 

[zayne2427]

Went with the acdelco cr42ts and gapped them right at ..026-.027. We will see what happens with these

 

[zayne2427]

Another quick question. What will the timing need to be set at?
also i ve been running the Valvoline VR1 20w50 before but that was with a pretty tired old motor. After the rebuild everything should be much tighter clearances. will the VR1 be too thick of an oil.

 

[muddinmetal]

Another quick question. What will the timing need to be set at?
also i ve been running the Valvoline VR1 20w50 before but that was with a pretty tired old motor. After the rebuild everything should be much tighter clearances. will the VR1 be too thick of an oil.

I would shoot for mid to high 20s and vr1 is also made in a 10w30, I see no reason not to run that

 

[zayne2427]

yeah i just can't find the VR1 in a 10w30 in stock and advanced auto says they cannot order it

 

[muddinmetal]

yeah i just can't find the VR1 in a 10w30 in stock and advanced auto says they cannot order it

We used to order it all the time at oreilly's. Most people at the part stores are near useless, you'll prolly have to give them the part # to get anything done