back cut large valves or not? on a 402 CID.. - Page 3 - ZR-1 Net Registry Forums

A26B · 12-13-2020

Quote:

Originally Posted by Jagdpanzer

Imagine they are running Jerry's stronger IWIS secondary chains
https://www.jerrysgaskets.com/chain-...e1607869129850

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Affirmative

wfot · 12-13-2020

Marc, thank you for the input. I understand that the stock computer has its highest rpm a fuel adjustment can be changed is 7,000. to get the engine "fueled" after 7,500, you need to trick it a little and after 8,000, there is no real way to alter the fuel curve. I was wondering if the engine was allowed to bounce or stumble above 7,500, if that would create the same jerking situation as a bad injector?? and if the chain was allowed to slap around long enough it would fail...

I was considering Jerry's chains, thought it might be a little overkill, but then again that is what I am trying to build, right?

Jerry are those chains in a 350? and/or a big inch motors? Any feedback on how many miles they have gone or service life yet? And what about the crankshaft chain? any aftermarket progress on them?

again thank you guys for all the info/input
John

Marc Haibeck · 12-14-2020

An LPE Titanium valve spring retainer weighs 10 grams. The OE steel retainer weighs 19 grams.

The spark and fuel tables end at 7000 rpm. The last datum in the table applies from 7000 to 7500 rpm. I would expect that the system would use the 7000 to 7500 rpm value beyond 7500 rpm.

wfot · 12-14-2020

Marc,
Yes I agree, that is what I have found. the main tables allow for changes for 7,000 and they should hold until 7,500. after that you can't really put in exactly what you want.

and thank you for the titanium weight information. so I am thinking with 9 gram on the retainer and then 24 grams for the lifters, I would be lightening the valve rotating weight by about 33 grams per valve. I think with the stage 3 cams and 7,500 limit, it might would make a tangible difference. I will be happy to report my findings if I ever get it together AND it runs.....

I already have Jerry's cam followers ready to go in.. still on the fence about if the chains are worth the squeeze. I do not think there is ANY aftermarket crank to cam chain gears chains available.. Correct??

John

Marc Haibeck · 12-15-2020

The OE type primary chain is all that you need. I have never heard of any problem using it. Install it with new facing on the tensioner.

wfot · 12-15-2020

Quote:

Originally Posted by Marc Haibeck

The OE type primary chain is all that you need. I have never heard of any problem using it. Install it with new facing on the tensioner.

OK good enough for me on the primary chain and I have jerry's facing for it. So done on that.

thank you sir

12-13-2020	#22
wfot Join Date: Jan 2009 Location: New jersey Posts: 156	Re: back cut large valves or not? on a 402 CID.. Marc, thank you for the input. I understand that the stock computer has its highest rpm a fuel adjustment can be changed is 7,000. to get the engine "fueled" after 7,500, you need to trick it a little and after 8,000, there is no real way to alter the fuel curve. I was wondering if the engine was allowed to bounce or stumble above 7,500, if that would create the same jerking situation as a bad injector?? and if the chain was allowed to slap around long enough it would fail... I was considering Jerry's chains, thought it might be a little overkill, but then again that is what I am trying to build, right? Jerry are those chains in a 350? and/or a big inch motors? Any feedback on how many miles they have gone or service life yet? And what about the crankshaft chain? any aftermarket progress on them? again thank you guys for all the info/input John

12-14-2020	#23
Marc Haibeck Join Date: May 2007 Location: Addison IL Posts: 250	Re: back cut large valves or not? on a 402 CID.. An LPE Titanium valve spring retainer weighs 10 grams. The OE steel retainer weighs 19 grams. The spark and fuel tables end at 7000 rpm. The last datum in the table applies from 7000 to 7500 rpm. I would expect that the system would use the 7000 to 7500 rpm value beyond 7500 rpm.

12-14-2020	#24
wfot Join Date: Jan 2009 Location: New jersey Posts: 156	Re: back cut large valves or not? on a 402 CID.. Marc, Yes I agree, that is what I have found. the main tables allow for changes for 7,000 and they should hold until 7,500. after that you can't really put in exactly what you want. and thank you for the titanium weight information. so I am thinking with 9 gram on the retainer and then 24 grams for the lifters, I would be lightening the valve rotating weight by about 33 grams per valve. I think with the stage 3 cams and 7,500 limit, it might would make a tangible difference. I will be happy to report my findings if I ever get it together AND it runs..... I already have Jerry's cam followers ready to go in.. still on the fence about if the chains are worth the squeeze. I do not think there is ANY aftermarket crank to cam chain gears chains available.. Correct?? John

12-15-2020	#25
Marc Haibeck Join Date: May 2007 Location: Addison IL Posts: 250	Re: back cut large valves or not? on a 402 CID.. The OE type primary chain is all that you need. I have never heard of any problem using it. Install it with new facing on the tensioner.