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Afr heads with PAC 8002 spring upgrade.

Old 01-20-2017, 08:02 PM
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Default Afr heads with PAC 8002 spring upgrade.

Just a public service announcement, learned with my new head guy the PAC 8002 spring "upgrade" you get with MK purchased heads is a standard hot rod spring, after talking to PAC they said in no way should them springs be used on a marine engine, may be ok in some applications but they do not recommend them, the 8002 is a PAC 1940 spring, or 1900 series, they say for marine you must run 1200 series or better

Not starting a war, just posting so when guys search in future the info is there, thread can be locked for all I care, as long as it's searchable.

https://m.summitracing.com/parts/rsc-pac-1940-16
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Old 01-20-2017, 11:04 PM
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the 8002 spring is for a max lift of .650.it is not a good spring and i would not use it in a marine endurance engine.this is not a mk upgrade,it is an afr package,in other words,this spring is offered from any afr retailer.

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Old 01-21-2017, 04:58 AM
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Originally Posted by mike tkach View Post
the 8002 spring is for a max lift of .650.it is not a good spring and i would not use it in a marine endurance engine.this is not a mk upgrade,it is an afr package,in other words,this spring is offered from any afr retailer.
That can be the case, but when I bought my heads from MK, he did the 8002 spring upgrade according to my paperwork, he told me it was upgrade, so if thats also .650 lift max then WHY is he using them springs when he knew my heads were going in a boat, and also 680 lift? the post is not to start a pizzing match about Bob or anyone, just info I found out.after this winter and round of upgrafdes I will have 8000+ into a set of bolt on ready to go MARINE AFR heads...

I want people to be aware when being sold products, I can care less who is selling them, just a informational post.

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Old 01-21-2017, 08:13 AM
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I wonder how many guys were told

"if you buy heads from me, you will have to change out the valve springs when they arrive, before you install them".

Prob not many. I dont know of many who actually knew that these were just dropped ship car heads with ductile iron seats and an inconel valve stuck in them. I used to think they were custom assembled marine ready packages.

At any rate, yea, that spring is entry level. If you have any fair amount of time on them, it be a good time to swap them out, and mic the spring heights while youre at it.
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Old 01-21-2017, 08:23 AM
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This really goes back for he fundamental point that buying "ready to bolt on and run" heads is not advisable. AFR, Dart, Brodix, Edelbrock, GM........whoever made them and whoever sold them really doesn't matter. You have to check every single thing you buy!

Didn't one pair of heads come from AFR with some really stout springs Tim? Something for a real big cam.
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Old 01-21-2017, 08:28 AM
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Also, application does not dictate the level of thoroughness before use! IE.....it doesn't matter if they are for a race car, a boat, a musclecar, whatever the end use is, everything has to be verified!

Call summit (get ATEC on the line instead of a counter jockey) and ask them if their AFR (or any other heads) are really ready to run, the answer will be "hell yes"! It's up to the customer to decide if they want to roll the dice or not.
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Old 01-21-2017, 08:31 AM
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One more thing.
The CC of the chambers should be verified too.
Using a "catalog" value for doing a REAL compression ratio calculation is gambling as well.
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Old 01-21-2017, 09:09 AM
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Esp chamber to chamber. Some castings can vary a little from chamber to chamber CC wise. Same thing with ports. They dont always measure what the box says. I havent measured an afr , but according to tony mamo, the 325 afr, actually pours around 317cc
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Old 01-21-2017, 09:09 AM
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Originally Posted by vintage chromoly View Post
This really goes back for he fundamental point that buying "ready to bolt on and run" heads is not advisable. AFR, Dart, Brodix, Edelbrock, GM........whoever made them and whoever sold them really doesn't matter. You have to check every single thing you buy!

Didn't one pair of heads come from AFR with some really stout springs Tim? Something for a real big cam.
One set camenwith solid roller springs and were ran because I thought I was buying ready to go heads at the time, I have learned since there is no such thing, if my seller knew they needed gone through I should have been advised to do, at that point what is the reason for buying complete heads? I now know that I never will again, hence why I am making this thread, if I saw a thread like this before I shopped I would have done different.
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Old 01-21-2017, 09:11 AM
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Originally Posted by vintage chromoly View Post
This really goes back for he fundamental point that buying "ready to bolt on and run" heads is not advisable. AFR, Dart, Brodix, Edelbrock, GM........whoever made them and whoever sold them really doesn't matter. You have to check every single thing you buy!.
I know this , you know this, some others know this, but many , have taken someones word, that they do not need to be checked, and are in fact ready to run, or "race ready" , and bolt them on and go. Sometimes it works, sometimes , it doenst.

Yes, one set of tims heads, cam with solid roller springs. Something like 700lb open pressure if i recall
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