Recommended spark plugs for stock 1967 435hp

[Chris C.]

I purchased my 1967 435 this past April. I have put 2500 miles on it so far after a complete frame off restoration. I pulled the plugs just to have a look. The plugs in the car are AC Delco R45XLS. I have read many posts on this forum and I don't think the 1967 should have these plugs. I believe the R stands for resistor which didn't apply on 67s. I do drive the car spiritedly and will not hesitate to take it to 6000 rpm. What are your pick spark plugs and why? I don't have to use Delco plugs, so please recommend your favorites. Thanks in advance for any advice. Merry CHRISTmas to all as we celebrate the birth of SAVIOR, JESUS in this world to save us from our sin!!!

Chris Covinsky

[Larry M.]

Re: Recommended spark plugs for stock 1967 435hp

Chris:

I think the R45XLS plugs are a good choice today. The 45 heat range is what most of us want/need with these cars today. 44 and 43 heat range are too cold for most of us with these cars. Check your plugs to see their condition.

You are correct that "R" plugs were not used back in 1967. If you can find the above plug without the R that would be even better.

I guess you could go for a platinum tipped plug. Others may have suggestions.

I would be more concerned about taking the engine to/past 6000 RPM under load UNLESS you have replaced the original valve springs and know the rods/rod bolts are high quality replacements. These were weak links in the BB of the day.

Are you also running a higher octane gasoline than 93 unleaded?? This may be needed if you have altered the distributor curve or even if you have retained the original curve and timing and you are high-reving the engine. If you have not done so already, verify your distributor curve, and also changeover the distributor vacuum advance from ported vacuum to full time manifold vacuum. It will help street performance and idle and engine idle temperature.


Larry

[Duke W.]

Re: Recommended spark plugs for stock 1967 435hp

The R45XLS should work fine. Heat range "5" is best for normal road operation even though "3" was OE (the "4" stands for 14 mm thread) Resistor plugs became standard in 1969 with no other changes to the ignition system that I am aware of.

Non-resistor equivalents - to the 45XLS that I don't think are any longer produced include the NGK BP5ES and Denso W14EP-U.

The major plug manufacturers all have online cross reference charts, which can be found with a simple Google search if anyone is interested in other brands.

I also recommend converting to full time vacuum advance, but you will need to replace the original 201 15 VAC with a B26. This subject has been discussed numerous times, so you should do a search for all the whys and wherefores.

Duke

[Robert M.]

Re: Recommended spark plugs for stock 1967 435hp

Not one to disagree with Duke's expertise, this time I have a different opinion. OEM was R44 and that is what is in my car now and it runs perfectly with no issues.

[Michael W.]

Re: Recommended spark plugs for stock 1967 435hp

Not one to disagree with Duke's expertise, this time I have a different opinion. OEM was R44 and that is what is in my car now and it runs perfectly with no issues.

Good luck finding any. Long discontinued.

[Robert M.]

Re: Recommended spark plugs for stock 1967 435hp

Good luck finding any. Long discontinued.

http://www.ebay.com/itm/Acniter-AC-R...#ht_291wt_1234

Michael
The above is just one listing on Ebay for NOS R44 plugs. I have two sets of 8 sitting on the shelf.

Rob

[Michael W.]

Re: Recommended spark plugs for stock 1967 435hp

If paying $100. for $20. worth of plugs is a good idea, sure.

[Nick L.]

Re: Recommended spark plugs for stock 1967 435hp

I have been using R44XLS in mine. It is regularly driven (1,000 miles a year) on a 50/50 mix of 100 & 93 pump fuel. Distributor set up to OE specs, with the exception of full time vacuum advance.

[Robert M.]

Re: Recommended spark plugs for stock 1967 435hp

If paying $100. for $20. worth of plugs is a good idea, sure.

They won't sell for $100. I bought my two sets for $40 per set and I felt that was fair to have the original plugs.

[Duke W.]

Re: Recommended spark plugs for stock 1967 435hp

I have been using R44XLS in mine. It is regularly driven (1,000 miles a year) on a 50/50 mix of 100 & 93 pump fuel. Distributor set up to OE specs, with the exception of full time vacuum advance.

The TI system (and HEI) generates about twice the per spark energy as the single or dual point systems, so you can get away with a colder plug. The additional energy will create a spark on a fouled plug that can cause a misfire with the single or dual point systems.

Duke

[Robert M.]

Re: Recommended spark plugs for stock 1967 435hp

The TI system (and HEI) generates about twice the per spark energy as the single or dual point systems, so you can get away with a colder plug. The additional energy will create a spark on a fouled plug that can cause a misfire with the single or dual point systems.

Duke

Duke
I have followed your advice for years. I am just happy that my car runs great with the original plugs. If you want original it is worth paying a bit more for NOS. That is like saying that original KH bolt on wheels should still be $263.00! HA

[Larry M.]

Re: Recommended spark plugs for stock 1967 435hp

They won't sell for $100. I bought my two sets for $40 per set and I felt that was fair to have the original plugs.

Original, factory installed plugs in the 427 engine in 1967 were AC 43N.

Larry

[Robert M.]

Re: Recommended spark plugs for stock 1967 435hp

Original, factory installed plugs in the 427 engine in 1967 were AC 43N.

Larry

Larry
You are correct I was having a senior moment. I went to look at the two boxes I have and phew! They are 43N