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Search found 596 matches

by ClassAct
Tue Jul 27, 2021 10:12 am
Forum: Engine Tech
Topic: New spark plug design
Replies: 21
Views: 1173

Re: New spark plug design

I wouldn't say ' spark plugs are by & large the same'. Don't see 18mm plugs, magnetos & 0.015" plug gaps any more. Just like some of the people on this thread are deriding these new plugs as a ' gimmick', much the same response happened with the introduction of projected nose core plugs, copper cen...
by ClassAct
Sat Jul 24, 2021 10:05 am
Forum: Engine Tech
Topic: Pontiac 400 heads
Replies: 59
Views: 2011

Re: Pontiac 400 heads

It is about the application. You might run 16:1 CR on a race engine, but not on a street engine..... Very true. But that low port Pontiac head is no different than any other low port wedge head. It will respond to a 45 degree seat. As I posted long ago, I can’t think of an application where a 30 de...
by ClassAct
Sat Jul 24, 2021 10:01 am
Forum: Engine Tech
Topic: 423 SBC combo help
Replies: 106
Views: 4580

Re: 423 SBC combo help

in your opinion with the bigger header- poor exhaust flow due to early casting design compared to later castings header complemented lift and duration used at the time rpm used on that combo not really questions but interesting theories on why the bigger header helped. i think the exhaust side is v...
by ClassAct
Fri Jul 23, 2021 7:38 am
Forum: Engine Tech
Topic: Pontiac 400 heads
Replies: 59
Views: 2011

Re: Pontiac 400 heads

It is about the application. You might run 16:1 CR on a race engine, but not on a street engine..... Very true. But that low port Pontiac head is no different than any other low port wedge head. It will respond to a 45 degree seat. As I posted long ago, I can’t think of an application where a 30 de...
by ClassAct
Wed Jul 21, 2021 10:20 pm
Forum: Engine Tech
Topic: 850 Brawler carb tuning
Replies: 6
Views: 409

Re: 850 Brawler carb tuning

The bigger MAB is delaying the mains activating. You went the wrong way. Also set your power valve opening by cruise vacuum, not idle vacuum.
by ClassAct
Sat Jul 17, 2021 1:19 pm
Forum: Engine Tech
Topic: Pontiac 400 heads
Replies: 59
Views: 2011

Re: Pontiac 400 heads

Here’s my flow test results. The head in this test started life with a 1.960” intake valve with a 30 seat. In the first test listed here I the head for a 2.11” valve with a 30 seat. This seat OD was 2.04”, so still way way under the 2.10” that could have been used and it’s available curtain area! T...
by ClassAct
Sat Jul 17, 2021 1:18 pm
Forum: Engine Tech
Topic: Pontiac 400 heads
Replies: 59
Views: 2011

Re: Pontiac 400 heads

Exactly my point Geoff! No one seems to have kept in mind the detail in the OPs post as to his usage and the level of work he was stating he was comfortable in doing to his heads. Most everyone replying back here has launched straight into race motor world which the OP clearly stated is not what he...
by ClassAct
Sat Jul 17, 2021 2:44 am
Forum: Engine Tech
Topic: Pontiac 400 heads
Replies: 59
Views: 2011

Re: Pontiac 400 heads

pastry_chef wrote: Sat Jul 17, 2021 12:28 am Valve seats
http://www.eng-tips.com/viewthread.cfm?qid=84437
Interesting. That’s worth reading.
by ClassAct
Fri Jul 16, 2021 5:32 pm
Forum: Engine Tech
Topic: Pontiac 400 heads
Replies: 59
Views: 2011

Re: Pontiac 400 heads

8)
mag2555 wrote: Fri Jul 16, 2021 10:31 am It would seem then that you do not have a flow bench to support your claims.
Sure do. But I have nothing to prove to you. You aren’t important. Keep doing the wrong thing and trying to bully people who don’t follow your bad advice.
by ClassAct
Fri Jul 16, 2021 9:06 am
Forum: Engine Tech
Topic: Pontiac 400 heads
Replies: 59
Views: 2011

Re: Pontiac 400 heads

Valve lift has everything to do with seat angle. Pontiac used low lift cams, just over 0.400" with most engines, where the 30* gave superior flow up to about 0.450" lift. I know of an Edel head for a Pontiac that had the intake converted to a 30* seat from the as delivered 45* seat. It had substant...
by ClassAct
Fri Jul 16, 2021 8:58 am
Forum: Engine Tech
Topic: Pontiac 400 heads
Replies: 59
Views: 2011

Re: Pontiac 400 heads

mag2555 wrote: Fri Jul 16, 2021 8:17 am ClassAct, when you have the time put your flow sheets where your Mouth is please.

I will respond in the same.
LOL. Another dick measuring contest I see.
by ClassAct
Fri Jul 16, 2021 1:34 am
Forum: Engine Tech
Topic: Pontiac 400 heads
Replies: 59
Views: 2011

Re: Pontiac 400 heads

Do not follow others misguided advice to convert the intakes over to a 45 degree seat unless your planing on running over .550” lift and a big duration roller Cam to hold the valves open longer , and especially not if you are only interested in doing some minor clean up work in the ports and your u...
by ClassAct
Thu Jul 15, 2021 8:42 am
Forum: Engine Tech
Topic: Pontiac 400 heads
Replies: 59
Views: 2011

Re: Pontiac 400 heads

I would make it a 45 degree seat on the intake. I don’t waste time with any 30 degree seat.
by ClassAct
Thu Jul 15, 2021 12:46 am
Forum: Engine Tech
Topic: PVCR jetting Vs no PVCR jetting ??????
Replies: 6
Views: 2583

Re: PVCR jetting Vs no PVCR jetting ??????

The math to answer this question is found in Dave Emmanuel's book "Holley Carburetors". -the old school Holley power valve design is actually a cheaper? way to make a 'mid jet' metering circuit -using vacuum signal instead of a dedicated air bleed -has no precise orifice/air bleed to admit air; jus...
by ClassAct
Sat Jul 10, 2021 10:14 am
Forum: Engine Tech
Topic: Bolt Stretch on SCAT Connecting Rods
Replies: 28
Views: 951

Re: Bolt Stretch on SCAT Connecting Rods

I’ve heard Tom Leib’s explanation as to why he doesn’t suggest stretching rod bolts. In a nut shell, you can have one bolt at X amount of torque to make it stretch whatever the stretch number is, and the other bolt on the same rod may need Y amount of torque to get the same stretch. Leib said he wou...