[performerrpm]

i seen on the sm sight they are offering 78cc heads now, i wondered if its a typo for 87cc but i also see there 230cfm runners vs 215. think if the bare castings go on sale black friday i might snag a pair just for the helluvit

[ponjohn]

Originally Posted by performerrpm

i seen on the sm sight they are offering 78cc heads now, i wondered if its a typo for 87cc but i also see there 230cfm runners vs 215. think if the bare castings go on sale black friday i might snag a pair just for the helluvit

They're offering CNC ported runners that have been flowed, around 300 cfm IIRC.

[chiefbigb]

I will probably get another set this year.

[ponjohn]

I emailed Speedmaster. They confirmed after CNC the comb chamber they are 78 cc.

[Skip Fix]

I still have not measured my CNC ones. I did dig the burrette out to though.

[mysticmissle]

the cnc ported head had a different chamber than the cnced standard offering 72cc? someone must have confirmed this in 12 months they have been available?
is 78 any better than 72? still cant use it on a 455 wo race gas or e85 i wouldn't think

[Skip Fix]

I'll try and do mine tomorrow.

[Skip Fix]

75.5-76cc. Be sure to chase spark plug holes CNC was after and a little thin layer laid over

[blueghoast]

I run the sm and the e-heads with comp-ratio's @ 11.75-12.00.1 comp.
91 octane pump gas on all of mine with no issues, Race gas when spraying.

GT

[ponjohn]

Originally Posted by blueghoast

I run the sm and the e-heads with comp-ratio's @ 11.75-12.00.1 comp.
91 octane pump gas on all of mine with no issues, Race gas when spraying.

GT

What cam/ cubic inch?

[blueghoast]

Originally Posted by ponjohn

What cam/ cubic inch?

One is a 464 and the other is a 462
The 464 is 11.7 something and the 462 is 11.98.1 cams are simuliar
Cam specs 630s-660s dur@50 273 int 278 ex 108 lsa and 274-278 106 lsa

GT

[Tim Corcoran]

Originally Posted by blueghoast

I run the sm and the e-heads with comp-ratio's @ 11.75-12.00.1 comp.
91 octane pump gas on all of mine with no issues, Race gas when spraying.

GT

12:1 on 91 octane pump gas, this goes against the limits generally accepted. I'm curious about this maybe the accepted standard is incorrect or it's the cam duration and LSA that is critical. I am building a new engine right now that has E-heads with the earlier style combustion chamber and my compression is coming in around 11.75 with a zero deck and .04 thick gasket. I would like to have a pump gas engine even though it a track only car. I have been told 11.75 is too high for pump gas so I was planning on milling the heads for more compression since I would need race gas anyhow. If I can use 91 or 93 pump gas at 11.75:1 That would be my preference. Comments? Thoughts on this?

The cam I will be running is an Ultradyne solid roller, Master Lobes R44/R41, 264/268 @ .050, 176/187 @ .200, .3944/.3944 Lobe Lift .592@1.5/.651@1.65, LSA 108

[slowbird]

Originally Posted by Tim Corcoran

12:1 on 91 octane pump gas, this goes against the limits generally accepted. I'm curious about this maybe the accepted standard is incorrect or it's the cam duration and LSA that is critical. I am building a new engine right now that has E-heads with the earlier style combustion chamber and my compression is coming in around 11.75 with a zero deck and .04 thick gasket. I would like to have a pump gas engine even though it a track only car. I have been told 11.75 is too high for pump gas so I was planning on milling the heads for more compression since I would need race gas anyhow. If I can use 91 or 93 pump gas at 11.75:1 That would be my preference. Comments? Thoughts on this?

The cam I will be running is an Ultradyne solid roller, Master Lobes R44/R41, 264/268 @ .050, 176/187 @ .200, .3944/.3944 Lobe Lift .592@1.5/.651@1.65, LSA 108

That odds of you being able to run straight pump gas all the time and not knock the rod bearing out are slim. You'll need to spike it with race gas to be safe.

[AG]

My motor is 11.2:1 static CR with a cam similar to Tim's and I have run straight 93 pump and a 70/30 mixture of 93/110 octane without any signs of detonation. I've had the motor apart and the rod bearings were all good. It's not 12:1, but is a data point for reference.

[Tim Corcoran]

I am curious how/why blueghost gets away with 12:1 on 91 octane. I'm not going to risk hurting my new engine by trying to push the limit. I think I'll stick to my original plan and mill the heads to get about 12.75:1 and continue to use 110 race gas. The engine I'm building is to replace the previous engine which I was using Sonoco 110 and that engine had 12.3:1. I will use the same cam as was in the previous engine but will put 1.65 rockers on the new build and the previous engine had 1.5's. The previous engine had valve to piston restrictions, but the new build will not.

[grandville455]

Originally Posted by Tim Corcoran

I am curious how/why blueghost gets away with 12:1 on 91 octane. I'm not going to risk hurting my new engine by trying to push the limit. I think I'll stick to my original plan and mill the heads to get about 12.75:1 and continue to use 110 race gas. The engine I'm building is to replace the previous engine which I was using Sonoco 110 and that engine had 12.3:1. I will use the same cam as was in the previous engine but will put 1.65 rockers on the new build and the previous engine had 1.5's. The previous engine had valve to piston restrictions, but the new build will not.

I'm also curious about that! Why not just bump the comp to 13 and run E85?

[Dragncar]

People sure like that E85 once they make the switch. The nice thing about it is converting your system/ carb over to it is not near the undertaking converting to straight alcohol is.
I wish it was available here without the 4 hour drive.

[mysticmissle]

Did your track close ? Sacramento?

[Tim Corcoran]

I know that alcohol is corrosive I am not sure about if 85% alcohol will corrode my fuel system or if I have to purge the system after every event like alcohol racers do. And I don't think we even have E-85 in my area. I would need to re-jet, larger squirters change timing, might even have to go with a colder plug. Seems like a lot of extra work to get an ideal tune. If they had E-85 in my area it might be worth the fuel savings. It's a thought but most likely I will stick with race gas I get it by the 55 gallon drum so that is convenient.

[Dragncar]

Originally Posted by mysticmissle

Did your track close ? Sacramento?

Mine ?
Sacramento is done. Samoa Drag Strip (Eureka CA) is going strong.
Trying to keep it 1/4 mile as Redding CA has went to the 1/8th.
I think too many people watch Street Outlaws and want to go 1/8 mile!