355 build
Thread Starter
Intermediate
Joined: Apr 2014
Posts: 25
Likes: 5
355 build
Engine going together now specs are:
Forged flat tops, .017 in the hole with cometic .027 head gaskets, 64cc aluminum heads 190cc runners, howards 227/235 roller cam with 1.6 sharp rockers giving 550/560 lift, RPM air gap intake, 770 holley, msd pro billet distributor locked out at 36* ...So running the compression calculator I get 10.17:1...compression, just wanting some feedback on the setup, this is going in a 4 speed 3.55 rear gear car...
Forged flat tops, .017 in the hole with cometic .027 head gaskets, 64cc aluminum heads 190cc runners, howards 227/235 roller cam with 1.6 sharp rockers giving 550/560 lift, RPM air gap intake, 770 holley, msd pro billet distributor locked out at 36* ...So running the compression calculator I get 10.17:1...compression, just wanting some feedback on the setup, this is going in a 4 speed 3.55 rear gear car...
Race Director
Joined: Nov 2006
Posts: 13,149
Likes: 7,764
From: Sunshine Coast, Queensland, Australia
2025 C3 of the Year Finalist - Modified
2024 C3 of the Year Finalist- Modified
2022 C3 of the Year Finalist - Modified
Cruise-In VIII Veteran
Sounds real good. 4 cut pistons or 2 cut pistons? I'm thinking with 4 cut pistons a bit closer to 10-1. perhaps a tad under. quench sounds good. Not clear on cam timing. But Sounds very similar to my engine. Around 400 HP one would think.
Although I used hyperunetic pistons. A little more forgiving.
Although I used hyperunetic pistons. A little more forgiving.
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,809
From: Cool Northern Michigan
You locked-out the dizzy advance timing? Or do you mean you clamped the dizzy at 36*?
Also, that's quite a bit of lift on the cam. I would double check valve retainer to valve guide clearance. Off hand, I do not remember the minimum on that.
What does the head maker say about max lift with their springs, do you know?
Are the heads already on? If not, I would introduce the piston to a gob of clay, set the head on, no gasket, set the lash #1 cyl and rotate the crank.
I believe Exhaust valve to piston clearance is 0.080.
To get the projected lift of the cam, you need to track down the cam number and find the base circle diameter. Usually around 320. Them multiply that by your rocker ratio. (1.6)
Also, that's quite a bit of lift on the cam. I would double check valve retainer to valve guide clearance. Off hand, I do not remember the minimum on that.
What does the head maker say about max lift with their springs, do you know?
Are the heads already on? If not, I would introduce the piston to a gob of clay, set the head on, no gasket, set the lash #1 cyl and rotate the crank.
I believe Exhaust valve to piston clearance is 0.080.
To get the projected lift of the cam, you need to track down the cam number and find the base circle diameter. Usually around 320. Them multiply that by your rocker ratio. (1.6)
Last edited by HeadsU.P.; Jul 31, 2022 at 09:18 AM.
Thread Starter
Intermediate
Joined: Apr 2014
Posts: 25
Likes: 5
You locked-out the dizzy advance timing? Or do you mean you clamped the dizzy at 36*?
Also, that's quite a bit of lift on the cam. I would double check valve retainer to valve guide clearance. Off hand, I do not remember the minimum on that.
What does the head maker say about max lift with their springs, do you know?
Are the heads already on? If not, I would introduce the piston to a gob of clay, set the head on, no gasket, set the lash #1 cyl and rotate the crank.
I believe Exhaust valve to piston clearance is 0.080.
To get the projected lift of the cam, you need to track down the cam number and find the base circle diameter. Usually around 320. Them multiply that by your rocker ratio. (1.6)
Also, that's quite a bit of lift on the cam. I would double check valve retainer to valve guide clearance. Off hand, I do not remember the minimum on that.
What does the head maker say about max lift with their springs, do you know?
Are the heads already on? If not, I would introduce the piston to a gob of clay, set the head on, no gasket, set the lash #1 cyl and rotate the crank.
I believe Exhaust valve to piston clearance is 0.080.
To get the projected lift of the cam, you need to track down the cam number and find the base circle diameter. Usually around 320. Them multiply that by your rocker ratio. (1.6)
Le Mans Master
Joined: May 2007
Posts: 5,009
Likes: 1,115
From: North tonawanda NY
very similar to what im running only my cam is a bit smaller 270hr cam an smaller 680 carb. I have .041 quench with same size heads 1.6 RRs and same static compression as you I have a 3.55 rear end also just not yet installed with my 2004r
for what its worth, with my ebay head flow numbers and specs desktop dyno gave my build an optimistic 423hp...
for what its worth, with my ebay head flow numbers and specs desktop dyno gave my build an optimistic 423hp...
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,809
From: Cool Northern Michigan
Locking out the timing is seldom street-able. Its an all-out racing trick. So I assume this is a race motor only.
You do realize that with the locked timing at 36* at full throttle, it's also 36* when cranking right?
On the valve head / piston clearance:
You have piston 0.017 down, 0.027 gasket, over half inch of valve opening and an unknown fly-cut depth in the piston top.
PLUS! You need a minimum 0.080 clearance between exhaust valve head and piston relief.
Don't take someone's word for it. Get the clay in there and check it yourself. No need for a head gasket. Just lay head on the block with a couple head-bolts, set lash for one cylinder only.
I'm thinking you won't have 0.080 with that gasket. Hope so.
You do realize that with the locked timing at 36* at full throttle, it's also 36* when cranking right?
On the valve head / piston clearance:
You have piston 0.017 down, 0.027 gasket, over half inch of valve opening and an unknown fly-cut depth in the piston top.
PLUS! You need a minimum 0.080 clearance between exhaust valve head and piston relief.
Don't take someone's word for it. Get the clay in there and check it yourself. No need for a head gasket. Just lay head on the block with a couple head-bolts, set lash for one cylinder only.
I'm thinking you won't have 0.080 with that gasket. Hope so.
Last edited by HeadsU.P.; Jul 31, 2022 at 04:16 PM.
Thread Starter
Intermediate
Joined: Apr 2014
Posts: 25
Likes: 5
very similar to what im running only my cam is a bit smaller 270hr cam an smaller 680 carb. I have .041 quench with same size heads 1.6 RRs and same static compression as you I have a 3.55 rear end also just not yet installed with my 2004r
for what its worth, with my ebay head flow numbers and specs desktop dyno gave my build an optimistic 423hp...
for what its worth, with my ebay head flow numbers and specs desktop dyno gave my build an optimistic 423hp...
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Thread Starter
Intermediate
Joined: Apr 2014
Posts: 25
Likes: 5
Locking out the timing is seldom street-able. Its an all-out racing trick. So I assume this is a race motor only.
You do realize that with the locked timing at 36* at full throttle, it's also 36* when cranking right?
On the valve head / piston clearance:
You have piston 0.017 down, 0.027 gasket, over half inch of valve opening and an unknown fly-cut depth in the piston top.
PLUS! You need a minimum 0.080 clearance between exhaust valve head and piston relief.
Don't take someone's word for it. Get the clay in there and check it yourself. No need for a head gasket. Just lay head on the block with a couple head-bolts, set lash for one cylinder only.
I'm thinking you won't have 0.080 with that gasket. Hope so.
You do realize that with the locked timing at 36* at full throttle, it's also 36* when cranking right?
On the valve head / piston clearance:
You have piston 0.017 down, 0.027 gasket, over half inch of valve opening and an unknown fly-cut depth in the piston top.
PLUS! You need a minimum 0.080 clearance between exhaust valve head and piston relief.
Don't take someone's word for it. Get the clay in there and check it yourself. No need for a head gasket. Just lay head on the block with a couple head-bolts, set lash for one cylinder only.
I'm thinking you won't have 0.080 with that gasket. Hope so.
Last edited by badd73; Jul 31, 2022 at 04:26 PM.
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,809
From: Cool Northern Michigan
And how many starters did you go through because of kick-back? Holes in pistons? Cracked piston ring lands? Broken rings?
Not me man. I prefer fluctuating advanced timing.
However,
If one insists on this insane timing procedure for street use, then the trick is to have a starter button separate of the IGN switch.
Spin the engine over first, then "introduce the juice.
Not me man. I prefer fluctuating advanced timing.
However,
If one insists on this insane timing procedure for street use, then the trick is to have a starter button separate of the IGN switch.
Spin the engine over first, then "introduce the juice.
Thread Starter
Intermediate
Joined: Apr 2014
Posts: 25
Likes: 5
And how many starters did you go through because of kick-back? Holes in pistons? Cracked piston ring lands? Broken rings?
Not me man. I prefer fluctuating advanced timing.
However,
If one insists on this insane timing procedure for street use, then the trick is to have a starter button separate of the IGN switch.
Spin the engine over first, then "introduce the juice.
Not me man. I prefer fluctuating advanced timing.
However,
If one insists on this insane timing procedure for street use, then the trick is to have a starter button separate of the IGN switch.
Spin the engine over first, then "introduce the juice.
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,170
From: Hermosa
Hp is gonna be more dependent on head flow assuming no significant restrictions on the intake or exhaust flow. What heads are these? What kind of flow?
what's the LSA on that cam?
If it's and automatic what is the torque converter stall?
This one?
https://www.competitionproducts.com/.../#.Yub_97TMJBM
what's the LSA on that cam?
If it's and automatic what is the torque converter stall?
the cam is the a howards rattler,
https://www.competitionproducts.com/.../#.Yub_97TMJBM
Last edited by REELAV8R; Jul 31, 2022 at 06:20 PM.
Thread Starter
Intermediate
Joined: Apr 2014
Posts: 25
Likes: 5
Hp is gonna be more dependent on head flow assuming no significant restrictions on the intake or exhaust flow. What heads are these? What kind of flow?
what's the LSA on that cam?
If it's and automatic what is the torque converter stall?
This one?
https://www.competitionproducts.com/.../#.Yub_97TMJBM
what's the LSA on that cam?
If it's and automatic what is the torque converter stall?
This one?
https://www.competitionproducts.com/.../#.Yub_97TMJBM
Le Mans Master
Joined: May 2007
Posts: 5,009
Likes: 1,115
From: North tonawanda NY
Hp is gonna be more dependent on head flow assuming no significant restrictions on the intake or exhaust flow. What heads are these? What kind of flow?
what's the LSA on that cam?
If it's and automatic what is the torque converter stall?
This one?
https://www.competitionproducts.com/.../#.Yub_97TMJBM
what's the LSA on that cam?
If it's and automatic what is the torque converter stall?
This one?
https://www.competitionproducts.com/.../#.Yub_97TMJBM
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,444
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
The lift is mild even with a h-roller. I have not seen 4 valve relief forged flat tops in many years. Seems to me that I used some 30 years ago on a 355 and they were the heavy TRW brand.
Modern performance forged pistons with 2 valve reliefs are cut for bigger diameter valves. The bigger the diameter of the intake valves the less valve to piston clearance. Little 2.02 is generally not a problem with your small cam specs choice.
Locked out ignition is a very poor idea from 50 years ago when using magnetos. We were smarter and used MSD 20 degree timing retard boxes with the flip of a switch and later the adjustable retard boxes when they became available.
modern performance heads are made for sub 34 degrees of mechanical advance. My AFR are 32 degrees. They have heart shaped fast burn chambers.
I don't use aluminum rockers.
You do know that you can run solid rollers on h-roller cams. My little 355 did 7200 rpm in every gear. It was just my self proclaimed rev limiter red line
Modern performance forged pistons with 2 valve reliefs are cut for bigger diameter valves. The bigger the diameter of the intake valves the less valve to piston clearance. Little 2.02 is generally not a problem with your small cam specs choice.
Locked out ignition is a very poor idea from 50 years ago when using magnetos. We were smarter and used MSD 20 degree timing retard boxes with the flip of a switch and later the adjustable retard boxes when they became available.
modern performance heads are made for sub 34 degrees of mechanical advance. My AFR are 32 degrees. They have heart shaped fast burn chambers.
I don't use aluminum rockers.
You do know that you can run solid rollers on h-roller cams. My little 355 did 7200 rpm in every gear. It was just my self proclaimed rev limiter red line
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,170
From: Hermosa
That cam is 66* overlap. Pretty big for street, still fine, just getting largish. It sounds as if you’ve done this before? With that overlap and 10.17:1 you DCR will be about 8.1 if you’re running at sea level DA’s. Given the overlap I’d want closer to 8.5 or maybe more.
I'm running 8.8 DCR with 54* overlap @ 4000+ feet which computes out to 8.0 DCR at that altitude. I could have gone higher. Also have 3.55 rear. However running auto with 3000 stall.
Have you considered shaving the head for more CR? Have you computed in your altitude into the DCR?
https://www.jeepstrokers.com/forum/calculator/
I'm running 8.8 DCR with 54* overlap @ 4000+ feet which computes out to 8.0 DCR at that altitude. I could have gone higher. Also have 3.55 rear. However running auto with 3000 stall.
Have you considered shaving the head for more CR? Have you computed in your altitude into the DCR?
https://www.jeepstrokers.com/forum/calculator/
Last edited by REELAV8R; Aug 1, 2022 at 10:12 AM.