[czar97]

Always ran AC Delco R45TS plugs and always look amazing.

Now putting on a CLIFF's carb kit 4bbl QJet.

Any reason I should switch to something else?

[steve25]

Say with the AC plugs , but start off one heat range colder with the 4bbl set up.

[HWYSTR455]

TS is long reach, right? I was under the impression it should be R45S? What year/casting heads?

.

[abefromen]

TS= tapered seat moderate long reach

[JSchmitz]

They'll be just fine unless you have high compression ratio (10:1+) or run the crap out of it for extended periods. T= tapered seat, S= extended tip

["QUICK-SILVER"]

Originally Posted by JSchmitz

They'll be just fine unless you have high compression ratio (10:1+) or run the crap out of it for extended periods. T= tapered seat, S= extended tip

The HP increase going from 2bbl to 4bbl "MIGHT" call for a cooler plug heat range if you run it WOT for extended periods of time.

Normal driving conditions the plug heat range wouldn't change.

And yes, T=tapered seat and S=extended tip. R45S (washer seat) and R45TS (tapered seat) both have the same thread reach. If you look at washer seat heads, there's a taper between the flat and where the threads start. Dealers where the first I saw that went ahead used taper seat plugs in washer seat heads. I don't myself, don't know why, because they seem to seal fine and work all the same. That's factory cast iron heads not aluminum.

Clay

[JSchmitz]

We put four barrels on a few two barrel engines "back in the day". I recall it not being very impressive.

I ran R45TS plugs in my 455 for decades at 9.25:1 compression ratio. Engine probably pushing around 450hp. No problems.

[unruhjonny]

your plugs are more about the style and heat range based both on the cylinder head design.

An R45TS is a pretty standard plug for post-1971 Pontiac heads;
I would sick with those unless you've done some pretty extensive shortblock moifications - which might necessitate a heat range change.

[Formulajones]

Originally Posted by HWYSTR455

TS is long reach, right? I was under the impression it should be R45S? What year/casting heads?

.

The T = taper seat which is also the small 5/8 hex plugs.

The S = Extended tip so they reach into the cylinder a pinch further.

[77 TRASHCAN]

Pontiac's started using tapered seat plugs in 1972. I am no expert, but my general rule of thumb is based on compression ratio and possible engine power level. Lower comp ratios and power levels are generally ok with warmer plugs. Higher compression and power need cooler plugs. I'm not sure if there are any AC plugs other than the 43's and 45's available any more. I think all the 44 heat range plugs
(with either washers or tapered seats) have been discontinued.

Just going from a 2 bbl to a 4 bbl, I would leave the plugs alone...

My engine builder liked to use the non extended tip plugs in most engines. Many disagree with that...my 77 TA engine used R45TSX plugs which were the extended tip .060 gap plugs. I would not use them in anything, if possible. It's just an emission thing..and puts more resistance towards jumping that plug gap.

[Formulajones]

The non extended tip plugs we always called "oil burnin plugs" because if you had an engine that liked to burn oil, that was the plug to use

Since they are short they aren't out there in the main stream of the mixture motion and tend to not foul so easily. That was the story behind that anyway.

Technically speaking, every engine builder or tuner I've ever been affiliated with that was good at what they did prefers the extended tip plugs. They are out in the chamber further and promote better flame travel. All of your race style plugs, and most all of your NGK's and Autolites are all extended tip style plugs even though they don't even have any nomenclature in the part number of the plug denoting as such.

[JSchmitz]

I think it's better to get the spark farther into the chamber. Technically the extended tip raises your compression ratio a tiny bit too.

[czar97]

Lol. Very true! 8.0019:1
I better think about using high octane now


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